Hafnium acid compound-containing substance and method for producing same

Abstract

This hafnium acid compound-containing substance contains hafnium, an organic nitrogen compound, and a solvent. The ratio (Ib / Ia) of the maximum XRD intensity (Ib) at a diffraction angle 2 [theta] of 5-6 DEG inclusive to the maximum XRD intensity (Ia) at a diffraction angle 2 [theta] of 31-33 DEG inclusive of a dry powder obtained by drying the hafnium acid compound-containing substance in a vacuum environment at 150 DEG C for 15 hours is 1.2 or more. The hafnium acid compound-containing substance according to the present invention contains hafnium, an organic nitrogen compound, and a solvent, and has a maximum transmittance of 70% T or more in a wavelength region of 550-700 nm.

Description

Technical Field

[0001] The present invention relates to a hafnium oxide compound-containing material and a method for producing the same. Background Art

[0002] Hafnium oxide, such as hafnium oxide (IV) and its composites, has a high relative dielectric constant characteristic and is therefore gradually used as a gate insulating film for transistors and the like. In addition, it is expected that hafnium oxide (IV) will be used as a ferroelectric material to achieve extremely thin film and low voltage ferroelectric memory. Furthermore, it is used as an insulating heat-resistant material such as thermocouples that utilize the extremely high melting point of hafnium oxide (IV). For example, Patent Document 1 discloses a crystalline hafnium dioxide sol comprising powdered hafnium oxide (IV), i.e., hafnium dioxide powder. Since the crystalline hafnium dioxide sol is a microparticle and is monodispersed, it can be used as a raw material for refractory materials, insulators, derivatives, etc.

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-223881 Summary of the Invention

[0005] Problems to be solved by the invention

[0006] However, the crystalline hafnium dioxide sol disclosed in Patent Document 1 is an acidic sol containing nitric acid, and therefore difficult to form a complex with a basic solution containing other metal elements, or is not suitable for complex formation or film formation with solutions containing oxygen-containing acids or halogen ions.

[0007] The present invention has been made in view of the above-mentioned problems and provides a hafnium oxide compound-containing material which is basic and highly dispersible, and a method for producing the same.

[0008] Means for solving problems

[0009] The hafnium oxide compound-containing material of the present invention, which has been achieved to solve the above-mentioned problems, is characterized in that the hafnium oxide compound-containing material contains hafnium, an organic nitrogen compound, and a solvent, and a dry powder obtained by drying the hafnium oxide compound-containing material at 150°C for 15 hours under a vacuum environment has a ratio (Ib / Ia) of the XRD maximum intensity (Ib) at a diffraction angle of 2θ = 5° to 6° to the XRD maximum intensity (Ia) at a diffraction angle of 2θ = 31° to 33°, of 1.1 or more.

[0010] From the viewpoint of excellent dispersibility, the hafnium oxide compound-containing material of the present invention is preferably a hafnium oxide compound-containing material containing hafnium, an organic nitrogen compound, and a solvent, wherein the hafnium oxide compound-containing material is dried at 150°C for 15 hours under a vacuum environment to obtain a dry powder having a ratio (Ib / Ia) of the XRD maximum intensity (Ib) at a diffraction angle of 2θ = 5° or more and 6° or less to the XRD maximum intensity (Ia) at a diffraction angle of 2θ = 31° or more and 33° or less of 1.1 or more.

[0011] It is presumed that the hafnium in the hafnic acid compound-containing material of the present invention exists in the material as ions formed by multi-step condensation of hafnium atoms and oxygen atoms in the material.

[0012] The hafnium oxide compound-containing material of the present invention also contains an organic nitrogen compound in addition to hafnium. Furthermore, the "organic nitrogen compound" of the present invention includes an organic nitrogen compound that is ionized in the hafnium oxide compound-containing material of the present invention. The method for producing the hafnium oxide compound-containing material of the present invention, described later in detail, is described. In this production process, a hafnium-containing precipitate slurry, namely, an aqueous ammonium hafnium oxide filter cake, is generated by a reverse neutralization method in which an acidic hafnium solution is added to aqueous ammonia. The organic nitrogen compound is then added and mixed to produce the hafnium oxide compound-containing material of the present invention. Consequently, the substituted organic nitrogen compound is present as a cation in the material.

[0013] Examples of solvents for the hafnic acid compound-containing material of the present invention include water and organic solvents. Examples of organic solvents include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents. These organic solvents may also be mixed with water. Examples of alcohol solvents include alcohols with 5 or fewer carbon atoms (methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol, and glycerol), and acetone.

[0014] Regarding the hafnium oxide compound-containing material of the present invention, from the viewpoint of excellent solubility of the hafnium oxide compound in a solvent, it is preferred that the ratio Ib / Ia of the XRD maximum intensity (Ib) at a diffraction angle 2θ = 5° or more and 6° or less of the dry powder obtained by drying the hafnium oxide compound-containing material at 150°C under a vacuum environment for 15 hours and the XRD maximum intensity (Ia) at a diffraction angle 2θ = 31° or more and 33° or less is 1.1 or more, more preferably 1.2 or more.

[0015] Here, the characteristic of the hafnium oxide generally available in circulation is that it has a monoclinic crystal structure at room temperature and pressure. Referring to card no.: 00-034-0104 Quality: S, its XRD spectrum has two peaks with maximum intensity around diffraction angles 2θ = 28° to 32°. On the other hand, the XRD spectrum of the dry powder obtained by drying the hafnium oxide compound-containing material of the present invention as described above is as follows:Figure 3 As shown, a specific pattern with a maximum intensity near a diffraction angle of 2θ = 5° to 6° is present, and this pattern is stronger than the maximum intensity near a diffraction angle of 2θ = 31° to 33°. Therefore, it is speculated that this is a crystal structure different from that of commonly available hafnium oxide, for example, a multi-crystal structure including an amorphous structure. Furthermore, it is speculated that if the ratio (Ib / Ia) of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) of the dry powder of the hafnium oxide compound of the present invention is 1.1 or greater, more preferably 1.2 or greater, the solubility of the dry powder in a solvent is improved compared to that of commonly available hafnium oxide.

[0016] The XRD maximum intensity (Ia) and XRD maximum intensity (Ib) of the hafnium oxide compound-containing material of the present invention can be measured by aliquoting 100 g of the hafnium oxide compound-containing material into a 100 mL TEFLON (registered trademark) beaker, drying the resulting dry powder at 150°C under vacuum for 15 hours, and subjecting the dry powder to powder X-ray diffraction measurement under the following conditions. The ratio (Ib / Ia) of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) of the dry powder is then calculated.

[0017] =Powder X-ray Diffraction Measurement Conditions=

[0018] Diffraction device: MiniFlex2 (manufactured by Rigaku Corporation)

[0019] X-ray tube: Cu

[0020] Tube voltage / current: 30kV, 15mA

[0021] Slit: DS-SS: 1.25 degrees, RS: 0.3mm

[0022] Graphite monochromator

[0023] Measurement interval: 0.01 degrees

[0024] Counting method: timed counting method

[0025] X-ray analysis software: PDXL2 Version 2.9.1.0

[0026] Furthermore, when the hafnium oxide compound-containing material of the present invention is dried under a vacuum environment to obtain a dry powder, the crystalline phase of the resulting dry powder changes depending on the heating temperature. For example, if the heating temperature is 150°C, the crystal structure of the dry powder is a multi-crystalline structure including an amorphous structure. However, if the dry powder is fired at a heating temperature of, for example, 800°C in an atmospheric environment and then cooled to room temperature (25°C), the crystal structure of the dry powder converges to a monoclinic structure.

[0027] Changes in the crystalline phase of the hafnium oxide compound of the present invention can also be observed by the half-value width of the XRD maximum intensity (Ia). Hafnium oxide, which has a monoclinic crystal structure, tends to have a narrow half-value width at the XRD maximum intensity (Ia) due to its simple crystal structure. On the other hand, the dry powder tends to have a wider half-value width due to changes in the crystal structure.

[0028] In addition, the "content" in the present invention refers to the liquid described below, including the liquid of gel. Furthermore, the so-called liquid is not limited to the solute dispersed or mixed in the solvent in a single molecule state, but also includes aggregates formed by multiple molecules attracted by intermolecular interactions, such as (1) polymer molecules, (2) solvated molecules, (3) molecular clusters, (4) colloidal particles, etc. dispersed in a solvent.

[0029] The hafnium oxide compound-containing material of the present invention is characterized in that the material contains hafnium, an organic nitrogen compound, and a solvent, and has a maximum transmittance of 70%T or more in a wavelength range of 550 nm to 700 nm.

[0030] From the viewpoint of excellent dispersibility, the hafnium oxide compound-containing material of the present invention preferably contains hafnium, an organic nitrogen compound, and a solvent, and has a maximum transmittance of 70%T or more in the wavelength range of 550 nm to 700 nm.

[0031] As described above, the hafnic acid compound-containing material of the present invention contains hafnium, an organic nitrogen compound, and a solvent.

[0032] Furthermore, from the perspective of excellent solubility of the hafnium oxide compound in a solvent, the maximum transmittance of the hafnium oxide compound-containing material of the present invention in the wavelength range of 550 nm to 700 nm is preferably 70%T or greater. Furthermore, the maximum transmittance in the wavelength range of 550 nm to 700 nm is more preferably 75%T or greater, further preferably 80%T or greater, particularly preferably 85%T or greater, still more preferably 90%T or greater, still more preferably 95%T or greater, yet more preferably 98%T or greater, still more preferably 99%T or greater, and most preferably 100%T or greater. A measured value exceeding 100%T due to measurement errors of the spectrophotometer used for transmittance measurement, etc., is deemed to be 100%T.

[0033] Furthermore, the hafnium oxide compound-containing material of the present invention preferably has a transmittance of at least one of 70% T or higher at wavelengths of 550 nm, 600 nm, 650 nm, and 700 nm, more preferably 75% T or higher, even more preferably 80% T or higher, particularly preferably 85% T or higher, still more preferably 90% T or higher, still more preferably 95% T or higher, yet more preferably 98% T or higher, even more preferably 99% T or higher, and most preferably 100% T or higher. A measured value exceeding 100% T due to measurement errors of the spectrophotometer used for transmittance measurement, etc., is deemed to be 100% T.

[0034] Furthermore, the minimum transmittance of the hafnic acid compound-containing material of the present invention in the wavelength range of 550 nm to 700 nm is preferably 70% T or higher, more preferably 75% T or higher, even more preferably 80% T or higher, particularly preferably 85% T or higher, still more preferably 90% T or higher, still more preferably 95% T or higher, yet more preferably 98% T or higher, still more preferably 99% T or higher, and most preferably 100% T or higher. A measured value exceeding 100% T due to measurement errors of the spectrophotometer used for transmittance measurement, etc., is deemed to be 100% T.

[0035] Thus, a liquid in which the hafnium oxide compound-containing material of the present invention has a maximum transmittance of 70%T or higher in the wavelength range of 400 nm to 700 nm is referred to as the "hafnium oxide compound-containing material" of the present invention. In this specification, unless otherwise specified, "transmittance" includes both "initial transmittance" and "transmittance over time." The "initial transmittance" refers to the transmittance of the hafnium oxide compound-containing material of the present invention immediately after its production, when the liquid temperature is adjusted to 25°C. The "transmittance over time" refers to the transmittance of the hafnium oxide compound-containing material of the present invention after it has been allowed to stand in a thermostat set at room temperature of 25°C for one month from the date of its production.

[0036] The transmittance of the hafnium oxide compound-containing material of the present invention in the wavelength range of 550 nm to 700 nm is measured by placing the material adjusted to room temperature (25° C.) in a quartz cell with an optical path length of 5.0 mm using a spectrophotometer under the following transmittance measurement conditions in accordance with JIS K 0115, 2004 "General Rules for Absorptiometry."

[0037] =Transmittance measurement conditions=

[0038] Measuring device: UV / visible / near-infrared spectrophotometer UH4150 (manufactured by Hitachi High-Tech Science Corporation)

[0039] Measurement mode: wavelength scanning

[0040] Data mode: %T (transmission)

[0041] Measurement wavelength range: 200~2600nm

[0042] Scanning speed: 600nm / min

[0043] Sampling interval: 2nm

[0044] Furthermore, the hafnium oxide compound-containing material of the present invention is characterized in that the hafnium content in the hafnium oxide compound-containing material is greater than 0 mass % and not less than 10 mass % in terms of HfO 2 .

[0045] In order to improve the stability of the hafnium oxide compound-containing material of the present invention, the hafnium content in the hafnium oxide compound-containing material is preferably greater than 0% by mass and not less than 10% by mass, as calculated as HfO2. The hafnium content in the hafnium oxide compound-containing material is more preferably 0.1 to 10% by mass, as calculated as HfO2.

[0046] The hafnium content in the hafnium oxide compound of the present invention is determined by measuring the hafnium oxide (HfO2) weight fraction by diluting the compound with dilute hydrochloric acid as needed using high-frequency inductively coupled plasma emission spectrometry (ICP emission spectrometry (manufactured by Agilent Technologies: AG-5110)) in accordance with JIS K0116:2014. The hafnium content in the hafnium oxide compound of the present invention is not necessarily present in the form of HfO2. The expression of the hafnium content in terms of HfO2 follows the convention for expressing hafnium oxide content.

[0047] Furthermore, the hafnic acid compound-containing material of the present invention may contain hydrogen peroxide in addition to the hafnium, organic nitrogen compound, and solvent described above.

[0048] The "hydrogen peroxide" of the present invention includes ionized hydrogen peroxide in the hafnium acid compound-containing material of the present invention. The method for producing the hafnium acid compound-containing material of the present invention will be described in detail later. It is believed that during the production process, the addition of hydrogen peroxide to the acidic hafnium solution complexes the anionic species containing hafnium, forming a peroxo complex with excellent dissolution stability.

[0049] Quantitative analysis of hydrogen peroxide present in the content is performed by, for example, measuring the absorbance of the content at a wavelength of 410 nm using a spectrophotometer (U-2900, manufactured by Hitachi, Ltd.) to quantify the hydrogen peroxide present in the content.

[0050] Furthermore, the hafnic acid compound-containing material of the present invention may contain water in addition to the hafnium and organic nitrogen compound described above.

[0051] The hafnic acid compound in the hafnic acid compound-containing material of the present invention has high dispersibility in water and good solubility in water, and therefore pure water can be used as a solvent.

[0052] Furthermore, the hafnic acid compound-containing material of the present invention is characterized in that the organic nitrogen compound is a quaternary ammonium compound.

[0053] The organic nitrogen compound is preferably a quaternary ammonium compound because it has high solubility and can suppress high crystallization and high solubility.

[0054] Examples of the quaternary ammonium include alkyl imidazolium, pyridinium, pyrrolidinium, and tetraalkylammonium. Specific examples of the alkyl imidazolium include 1-methyl-3-methyl imidazolium, 1-ethyl-3-methyl imidazolium, 1-propyl-3-methyl imidazolium, 1-butyl-3-methyl imidazolium, 1-hexyl-3-methyl imidazolium, 1-methyl-2,3-dimethyl imidazolium, 1-ethyl-2,3-dimethyl imidazolium, 1-propyl-2,3-dimethyl imidazolium, and 1-butyl-2,3-dimethyl imidazolium. Specific examples of pyridinium and pyrrolidinium include N-butyl-pyridinium, N-ethyl-3-methyl-pyridinium, N-butyl-3-methyl-pyridinium, N-hexyl-4-(dimethylamino)-pyridinium, N-methyl-1-methylpyrrolidinium, and N-butyl-1-methylpyrrolidinium. Specific examples of tetraalkylammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium, ethyl-dimethyl-propylammonium, and choline. Specific examples of anions that form salts with the above-mentioned cations include OH. - 、Cl - Br - , I - 、BF4 - 、HSO4 - wait.

[0055] Methods for measuring the content of organic nitrogen compounds present in the content include: gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), etc. In addition, a method for quantifying the N2 component in the vaporized sample using a thermal conductivity meter can also be used.

[0056] Furthermore, the hafnic acid compound-containing material of the present invention is characterized in that the quaternary ammonium is at least one selected from tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), choline, and benzyltrimethylammonium hydroxide.

[0057] The quaternary ammonium is preferably at least one selected from the group consisting of TMAH, TEAH, choline, and benzyltrimethylammonium hydroxide.

[0058] Furthermore, the quaternary ammonium compound may not be one selected from TMAH, TEAH, choline, and benzyltrimethylammonium hydroxide, but may be a mixture of two or more. Specifically, examples include mixtures of two quaternary ammonium compounds, such as TMAH and TEAH, TMAH and choline, or TMAH and benzyltrimethylammonium hydroxide; mixtures of three quaternary ammonium compounds, such as TMAH, TEAH, and choline; and mixtures of four quaternary ammonium compounds, such as TMAH, TEAH, choline, and benzyltrimethylammonium hydroxide.

[0059] Furthermore, the hafnium oxide compound-containing material of the present invention preferably has a pH of greater than 7.

[0060] This is because the stability of the hafnium oxide compound-containing material of the present invention is further improved when the pH is greater than 7. Furthermore, the pH is more preferably 10 or higher, even more preferably 11 or higher, particularly preferably 12 or higher, even more particularly preferably 13 or higher, and may be 14 or higher. In this specification, unless otherwise specified, "pH" refers to both "initial pH" and "time-dependent pH." The "initial pH" refers to the pH of the hafnium oxide compound-containing material of the present invention immediately after production, adjusted to a liquid temperature of 25°C. The "time-dependent pH" refers to the pH of the hafnium oxide compound-containing material of the present invention after being allowed to stand in a thermostat set at a room temperature of 25°C for one month from the date of production.

[0061] Here, the pH of the hafnium oxide compound-containing material of the present invention is measured as follows: the electrode (HORIBA: Standard ToupH Electrode 9615S-10D) of a pH meter (HORIBA: Glass Electrode Hydrogen Ion Concentration Indicator D-51) is immersed in the hafnium oxide compound-containing material of the present invention, and the measurement is performed after confirming that the liquid temperature is stable at 25°C.

[0062] Furthermore, the hafnic acid compound-containing material of the present invention may further contain a resin.

[0063] The hafnic acid compound-containing material of the present invention preferably contains a resin. This is because the resin is uniformly compatible with the hafnic acid compound and acts to adhere to the substrate, thereby improving film-forming properties and adhesion to the substrate.

[0064] Examples of the resin contained in the hafnic acid compound-containing material include polyolefin-based compounds and polyvinyl-based compounds.

[0065] Furthermore, the resin contained in the hafnic acid compound-containing material of the present invention may be an anionic water-soluble resin and / or a nonionic water-soluble resin.

[0066] If the resin contained in the hafnic acid compound-containing material of the present invention is an anionic water-soluble resin and / or a nonionic water-soluble resin, the anionic water-soluble resin and / or the nonionic water-soluble resin are uniformly compatible with the hafnic acid compound and thus exhibit a function of adhering to the substrate, thereby improving the film-forming properties and adhesion to the plastic film substrate.

[0067] Here, the term "cationic water-soluble resin" refers to a resin having a functional group in its polymer that is positively charged in water at pH 7, such as an amine group, an imine group, a tertiary amine group, a quaternary ammonium group, or a hydrazine group. Furthermore, the term "anionic water-soluble resin" refers to a resin having a functional group in its polymer that is negatively charged in water at pH 7, such as a carboxyl group, a sulfonate group, a sulfate group, or a phosphate group. Furthermore, the term "nonionic water-soluble resin" does not fall within the above-mentioned cationic water-soluble resins or anionic water-soluble resins, but rather refers to a resin having a functional group in its polymer, such as a hydroxyl group, an ether group, or an amide group.

[0068] Furthermore, the resins described above may contain one or more water-soluble homopolymers selected from the group consisting of acrylic polymers, urethane polymers, styrene polymers, olefin polymers, amide polymers, siloxane polymers, epoxy polymers, vinyl chloride polymers, and vinyl acetate polymers, and / or water-soluble copolymers formed from two or more of these polymers. Particularly preferred are water-soluble homopolymers containing one or more acrylic polymers, styrene polymers, and olefin polymers, and / or water-soluble copolymers formed from two or more of these polymers.

[0069] The hafnic acid compound-containing material of the present invention may further contain a high-boiling-point solvent. The high-boiling-point solvent preferably has a boiling point of 180° C. or higher at 1 atm, and examples thereof include polyol solvents and glycol solvents.

[0070] Here, examples of the polyol-based solvent include glycerin (boiling point: 290° C.), 1,6-hexanediol (boiling point: 250° C.), and 1,7-heptanediol (boiling point: 259° C.). Examples of glycol solvents include ethylene glycol (boiling point: 197.3°C), propylene glycol (boiling point: 188.2°C), diethylene glycol (boiling point: 244.3°C), triethylene glycol (boiling point: 287.4°C), oligoethylene glycols (boiling point: 287°C to 460°C), polyethylene glycol (PEG) (boiling point: 460°C or higher), polyethylene glycol (PEG)-polypropylene glycol (PPG) copolymers (boiling point: 460°C or higher), diethylene glycol monohexyl ether (boiling point: 260°C), polyoxyalkylene monoalkyl ethers (boiling point: 260°C or higher), polyoxyethylene sorbitan monolaurate (boiling point: 321°C or higher), other anionic fluorine-based surfactants (boiling point: 180°C or higher), amphoteric fluorine-based surfactants (boiling point: 180°C or higher), nonionic fluorine-based surfactants (boiling point: 180°C or higher), and amine oxides (boiling point: 180°C or higher). Glycerol is particularly preferred. The above-mentioned boiling point is the boiling point at 1 atmosphere.

[0071] Furthermore, due to the high boiling point of high-boiling-point solvents, if the boiling point at 1 atmosphere is too high, the high-boiling-point solvent may decompose before boiling, making it impossible to accurately measure the boiling point. In this case, it is also possible to measure the boiling point at reduced pressure and convert it to the boiling point at 1 atmosphere using a common boiling point conversion table.

[0072] Furthermore, the hafnic acid compound-containing material of the present invention may contain components other than components derived from hafnium or hafnic acid, components derived from organic nitrogen compounds, and hydrogen peroxide (referred to as "other components") as unavoidable impurities within a range that does not inhibit its effects.

[0073] Furthermore, the hafnic acid compound-containing material of the present invention may be appropriately added with a dispersant, a pH adjuster, a colorant, a thickener, a wetting agent, a binder resin, and the like depending on the intended use.

[0074] The method for producing the hafnium oxide compound-containing material of the present invention will be described below.

[0075] The method for producing a hafnium acid compound-containing material of the present invention is characterized in that it comprises the following steps: adding an acidic hafnium aqueous solution containing hafnium to an alkaline aqueous solution to generate a hafnium-containing precipitate; and adding an organic nitrogen compound to the hafnium-containing precipitate slurry obtained by slurrying the hafnium-containing precipitate to generate a hafnium acid compound-containing material.

[0076] First, hydrofluoric acid (HF) such as a hydrofluoric acid aqueous solution is added to hafnium, hafnium oxide, or hafnium hydroxide, and the mixture is maintained at 60°C to 100°C in a water bath for 1 to 72 hours to react and produce hafnium fluoride (HfF4), which is then dissolved in water to generate a hydrofluoric acid solution of the hafnium compound.

[0077] Here, the hydrofluoric acid solution of the hafnium compound is preferably adjusted to HfO2 by adding water (such as pure water) and containing 1 to 100g / L of hafnium in terms of conversion. At this time, if the hafnium content is calculated as 1g / L or more in terms of HfO2, it becomes a hafnium acid compound hydrate that is easily soluble in water, and thus it is preferred. In the case of considering productivity, it is more preferably 10g / L or more, and further preferably 20g / L or more. On the other hand, if the hafnium content is calculated as 100g / L or less in terms of conversion, it becomes a hafnium acid compound hydrate that is easily soluble in water, and thus it is preferred. In order to more surely synthesize a hafnium acid compound hydrate that is easily soluble in water, it is more preferably 90g / L or less, further preferably 80g / L or less, and particularly preferably 70g / L or less. In addition, from the viewpoint of completely dissolving hafnium or hafnium oxide, the pH of the hydrofluoric acid solution of the hafnium compound is preferably less than 2, and more preferably less than 1.

[0078] Next, hydrogen peroxide is added to the hydrofluoric acid solution of the hafnium compound and mixed to obtain an acidic or neutral aqueous hafnium complex solution. It is also estimated that at least a portion of the hafnium contained in the obtained aqueous hafnium complex solution forms a peroxo complex.

[0079] The hydrogen peroxide content of the hydrogen peroxide solution added to the hydrofluoric acid solution of the hafnium compound is preferably 0.5% to 35% by mass. Furthermore, the hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to hafnium (H2O2 / Hf) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, the molar ratio is more preferably 0.7 to 1.2.

[0080] In the step of adding the hafnium complex aqueous solution to the alkaline aqueous solution to generate the hafnium-containing precipitate, the hafnium complex aqueous solution is added to the alkaline aqueous solution, for example, to aqueous ammonia, i.e., by a reverse neutralization method, to obtain a hafnium-containing precipitate slurry. Subsequently, fluoride ions are removed from the obtained hafnium-containing precipitate slurry to obtain a hafnium-containing precipitate from which fluoride ions have been removed.

[0081] The ammonia content of the ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. If the ammonia content is 10% by mass, hafnium is less likely to dissolve completely, allowing hafnium or hafnic acid to dissolve completely in water. On the other hand, if the ammonia content is 30% by mass or less, it is closer to a saturated aqueous solution of ammonia, which is preferable.

[0082] From the above viewpoints, the ammonia content of the ammonia water is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, and particularly preferably 25% by mass or more. On the other hand, the ammonia content is preferably 30% by mass or less, more preferably 29% by mass or less, and further preferably 28% by mass or less.

[0083] In the reverse neutralization step, the amount of the hafnium complex aqueous solution added to the ammonia water is preferably such that the molar ratio of NH3 / HF is 95 or greater and 500 or less, more preferably 100 or greater and 450 or less, and even more preferably 110 or greater and 400 or less. Furthermore, from the perspective of generating a hafnium acid compound soluble in amine or dilute ammonia water, the molar ratio of NH3 / HF is preferably 3.0 or greater, more preferably 4.0 or greater, and even more preferably 5.0 or greater. On the other hand, from the perspective of cost reduction, the molar ratio of NH3 / HF is preferably 100 or less, more preferably 50 or less, and even more preferably 40 or less.

[0084] In the reverse neutralization step, the time taken to add the hafnium complex aqueous solution to the ammonia solution is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes. Specifically, rather than slowly adding the hafnium complex aqueous solution over time, it is preferably added to the ammonia solution as quickly as possible, for example, all at once, to allow the neutralization reaction to proceed. Furthermore, since the hafnium complex aqueous solution is added to the alkaline ammonia solution in the reverse neutralization step, the neutralization reaction can proceed while maintaining a high pH. Furthermore, the hafnium complex aqueous solution and ammonia solution can be used directly at room temperature.

[0085] Then, in the reverse neutralization step, fluoride ions are removed from the hafnium-containing precipitate slurry obtained by the reverse neutralization method, thereby obtaining a hafnium-containing precipitate from which fluoride ions have been removed. The hafnium-containing precipitate slurry obtained by the reverse neutralization method contains fluorine compounds such as ammonium fluoride as impurities, and therefore these are preferably removed.

[0086] Fluorine compounds can be removed by any method, including reverse osmosis filtration using ammonia or pure water, membrane filtration such as ultrafiltration or fine filtration, centrifugal separation, or other known methods. Furthermore, the removal of fluoride ions from a hafnium-containing precipitate slurry does not require temperature control and can be performed at room temperature.

[0087] Specifically, the hafnium-containing precipitate slurry obtained by the reverse neutralization method is decanted using a centrifuge and repeatedly washed multiple times until the amount of free fluoride ions is reduced to 100 mg / L or less, thereby obtaining a hafnium-containing precipitate from which the fluoride ions have been removed. Furthermore, by performing this decanting and repeated washing multiple times, for example, three times, the added fluoride ions are removed, and the hydrogen peroxide is also removed.

[0088] The cleaning solution for removing fluoride ions is preferably ammoniacal liquor. Specifically, it is preferably ammoniacal liquor having a content of 1% by mass or more and 35% by mass or less. If such ammoniacal liquor is used, ammonia is suitable relative to fluoride ions, thereby avoiding unnecessary cost increases.

[0089] The hafnium-containing precipitate from which fluoride ions have been removed, thus generated, is diluted with pure water or the like to obtain a hafnium-containing precipitate slurry from which fluoride ions have been removed. The hafnium content of the hafnium-containing precipitate slurry is calculated by collecting a portion of the hafnium-containing precipitate slurry, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate HfO₂. The weight of the HfO₂ generated in this manner is measured, and the hafnium content of the hafnium-containing precipitate slurry can be calculated from this weight.

[0090] Then, a mixture of the hafnium-containing precipitate slurry from which fluoride ions have been removed, an organic nitrogen compound, and pure water is maintained at 5° C. to 90° C. for 0.1 to 48 hours while being stirred, thereby obtaining the hafnium acid compound-containing material of the present invention.

[0091] As mentioned above, the organic nitrogen compound mixed with the hafnium-containing precipitation slurry is more preferably a quaternary ammonium compound.

[0092] In addition, from the viewpoint of solubility, quaternary ammonium preferably makes the quaternary ammonium content in the precipitation slurry that contains hafnium become the mode of following 40 quality % and mix, more preferably below 20 quality %.In addition, from same viewpoint, preferably makes the quaternary ammonium compound content in the precipitation slurry that contains hafnium become the mode of following 0.1 quality % and mix, more preferably makes the quaternary ammonium compound content in the precipitation slurry that contains hafnium become the mode of following 1 quality % and mix, in addition, can be more than 5 quality %, also can be more than 10 quality %.In addition, more preferably be selected from more than one in TMAH, TEAH, choline, benzyltrimethylammonium hydroxide.

[0093] Furthermore, the quaternary ammonium mixed with the hafnium-containing precipitation slurry may not be one selected from TMAH, TEAH, choline, and benzyltrimethylammonium hydroxide, but may be a mixture of two or more. Examples include a mixture of two quaternary ammoniums, such as TMAH and TEAH, TMAH and choline, or TMAH and benzyltrimethylammonium hydroxide; a mixture of three quaternary ammoniums, such as TMAH, TEAH, and choline; and a mixture of four quaternary ammoniums, such as TMAH, TEAH, choline, and benzyltrimethylammonium hydroxide.

[0094] Furthermore, the hafnic acid compound powder of the present invention is characterized by containing hafnic acid particles contained in the hafnic acid compound-containing material of the present invention.

[0095] The hafnium oxide compound powder of the present invention includes a dry powder obtained by drying, for example, vacuum drying, the hafnium oxide compound-containing material of the present invention; and a calcined powder obtained by further calcining the obtained dry powder. Furthermore, the hafnium oxide compound powder of the present invention also includes hafnium oxide compound powders having different physical properties, such as crystal structures, resulting from vacuum drying or calcining the hafnium oxide compound-containing material of the present invention. The hafnium oxide compound powders may have an amorphous structure, a single crystal structure, or a polycrystalline structure.

[0096] Next, the method for producing hafnium oxide compound powder of the present invention is characterized by comprising the step of drying and / or firing the hafnium oxide compound-containing material of the present invention to produce hafnium oxide powder.

[0097] Specifically, among the hafnium oxide compound powders, the hafnium oxide compound dry powder is produced by placing the hafnium oxide compound-containing material obtained by the above-mentioned method for producing the hafnium oxide compound-containing material of the present invention in a static furnace and drying it at a heating temperature of approximately 60° C. to 200° C. for 1 to 72 hours, for example, by vacuum drying. This allows the water content of the hafnium oxide compound-containing material of the present invention to evaporate, thereby obtaining a hafnium oxide compound dry powder containing hafnium oxide particles contained in the hafnium oxide compound-containing material of the present invention.

[0098] On the other hand, a method for producing a calcined hafnium oxide compound powder comprises placing the hafnium oxide compound-containing material of the present invention under vacuum drying as described above in a stationary furnace, and calcining the material under atmospheric conditions at a calcination temperature of 300° C. to 1200° C. and for a calcination time of 1 hour to 72 hours, thereby obtaining the calcined hafnium oxide compound powder.

[0099] Furthermore, the product obtained by pulverizing the hafnium oxide compound dry powder and fired powder can also be used as hafnium oxide compound powder. Furthermore, regardless of whether or not the hafnium oxide compound dry powder and fired powder are pulverized, the undersize fraction (fine particles) obtained by classifying the hafnium oxide compound dry powder and fired powder using a sieve or the like can be used as hafnium oxide compound powder. The oversize fraction (coarse particles) can also be pulverized again and classified before use. Furthermore, pulverization and classification can be performed simultaneously using a vibrating sieve in which iron balls coated with nylon or fluororesin are placed as a pulverization medium. By performing classification and pulverization simultaneously as described above, even if there is excessive hafnium oxide compound powder, it can be removed. Specifically, when using a sieve for classification, it is preferred to use a sieve with a pore size of 150 μm to 1000 μm. If the pore size is 150 μm to 1000 μm, the proportion of the oversize fraction will not be excessive, and repeated re-pulverization is unnecessary. Furthermore, the hafnium oxide compound powder that must be re-pulverized in the undersize fraction does not need to be classified.

[0100] The hafnium oxide compound powder obtained as described above is mixed with water and an organic solvent as a dispersion medium, and wet-pulverized using a medium such as beads to obtain a hafnium oxide compound powder-containing liquid. Examples of organic solvents used as dispersion media include alcohols, esters, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, ethers, and mixed solvents thereof. Furthermore, in order to improve the film-forming properties of the hafnium oxide compound film using the hafnium oxide compound powder-containing liquid, a binder such as a resin component may be added. Examples of resin components used as binders include acrylic resins, polyurethanes, epoxy resins, polystyrene, polycarbonates, glycol resins, cellulose resins, and mixed resins and copolymerized resins thereof.

[0101] Furthermore, the hafnic acid compound film of the present invention is characterized by containing hafnic acid particles contained in the hafnic acid compound-containing material of the present invention.

[0102] The hafnium oxide compound film of the present invention includes a dry film obtained by applying the hafnium oxide compound-containing material of the present invention to a substrate surface and then drying it, for example, by vacuum drying; and a fired film obtained by further firing the obtained dry film. Furthermore, the hafnium oxide compound film of the present invention also includes hafnium oxide compound films having different physical properties, such as crystal structures, produced by vacuum drying or firing the hafnium oxide compound-containing material of the present invention. These hafnium oxide compound films may have an amorphous structure, a single crystal structure, or a polycrystalline structure.

[0103] Next, the method for producing a hafnium oxide compound film of the present invention is characterized by coating the hafnium oxide compound-containing material of the present invention and then drying and / or firing the coating.

[0104] Specifically, among the hafnium oxide compound films of the present invention, the method for producing a dry hafnium oxide compound film of the present invention comprises: a coating step of coating the hafnium oxide compound-containing material of the present invention on a substrate surface; and a film drying step of drying the hafnium oxide compound-containing material coated on the substrate surface to obtain a dry film.

[0105] Specifically, the hafnium oxide compound-containing material obtained by the above-described method for producing a hafnium oxide compound-containing material of the present invention is filtered through a filter with a pore size of, for example, 2 μm, as needed, and then dropped onto the substrate surface using a syringe. The material is then applied by spin coating (1500 rpm, 30 seconds). Subsequently, the material is dried at a temperature of 110°C to less than 300°C for 30 minutes to 12 hours to form a dried hafnium oxide film on the substrate surface.

[0106] Furthermore, if the hafnium oxide compound-containing material obtained by the above-described method for producing a hafnium oxide compound-containing material of the present invention is a high-viscosity liquid or gelled, it can be applied to the substrate surface using a brush or the like. Subsequently, the material is dried at a temperature of 110°C or higher but less than 300°C for 30 minutes to 12 hours to form a dried hafnium oxide compound film on the substrate surface. Alternatively, the material can be dried at a temperature of 110°C or higher but less than 110°C for a long period of 1 hour to 3 days to form a dried hafnium oxide compound film on the substrate surface.

[0107] Among the hafnium oxide compound films of the present invention, the method for producing a fired hafnium oxide compound film of the present invention comprises: a coating step of coating a hafnium oxide compound-containing substance on a substrate surface; a film drying step of drying the hafnium oxide compound-containing substance coated on the substrate surface in the atmosphere or under vacuum to obtain a dry film; and a film firing step of firing the dry film in the atmosphere at a firing temperature of 300° C. to 1200° C. and a firing time of 1 hour to 12 hours to obtain a fired film.

[0108] Specifically, a substrate on which a dry hafnium oxide compound film is formed by coating the surface of the substrate with the hafnium oxide compound-containing material of the present invention and drying the dried film is placed in a static furnace and fired in the atmosphere at a firing temperature of 300° C. to 1200° C. for a firing time of 1 hour to 12 hours, thereby forming a fired hafnium oxide compound film of the present invention on the surface of the substrate.

[0109] In addition, the composite hafnium oxide compound-containing material of the present invention is characterized by comprising: the hafnium oxide compound-containing material of the present invention; and at least one element selected from the group consisting of Si, Al, Ti, Zn, Sn, Y, Ce, Ba, Sr, P, S, La, Gd, Nd, Eu, Dy, Yb, Nb, Li, Na, K, Mg, Ca, Zr, Mo, Ta, V, Ga, Ge, and W.

[0110] The composite hafnium oxide compound of the present invention is presumed to exist in the composition as ions ionically bonded between hafnium acid and at least one element selected from the group. The composite hafnium oxide compound of the present invention is not limited to the "containing liquid" of the present invention but also includes a composition in which a precipitate such as a gel is formed. Furthermore, the hafnium oxide content in the composite hafnium oxide compound of the present invention can be determined by appropriately diluting the composition with dilute hydrochloric acid as needed and measuring the Hf weight fraction in terms of HfO2 using an ICP emission spectrometer (AG-5110, manufactured by Agilent Technologies) in accordance with JIS K0116:2014.

[0111] At least one element selected from the above group can also be contained in the form of a compound. Here, the so-called compound, for example, can be listed: oxide, metal acid alkali metal salt, metal acid alkaline earth metal salt, chloride, metal acid alkoxide, polyoxometalate (polyoxometalate) etc. In addition, when the total mole (mol) of each element is set to X, the molar ratio X / Hf of the total mole (X) of each element in terms of metal conversion to hafnium (Hf) can be 0.001 to 75, or 0.002 to 50, or 0.01 to 40, or 0.2 to 30, or 0.5 to 25, or 0.8 to 1.5, or 0.8 to 1.3, or 0.9 to 1.2, or 0.9 to 1.1. In addition, each element is converted to P in the case of P and to S in the case of S.

[0112] In addition, the method for producing a composite hafnium oxide compound-containing material of the present invention comprises the following steps: mixing the hafnium oxide compound-containing material produced by the above-mentioned method for producing a hafnium oxide compound-containing material of the present invention with at least one element selected from the group consisting of Si, Al, Ti, Zn, Sn, Y, Ce, Ba, Sr, P, S, La, Gd, Nd, Eu, Dy, Yb, Nb, Li, Na, K, Mg, Ca, Zr, Mo, Ta, V, Ga, Ge and W to produce a composite hafnium oxide compound-containing material.

[0113] The composite hafnium oxide compound of the present invention is obtained by stirring a mixture of the hafnium oxide compound of the present invention and at least one element selected from the group while maintaining the liquid temperature at an appropriate temperature for a predetermined time. The at least one element selected from the group mixed with the hafnium oxide compound produced by the method for producing a hafnium oxide compound of the present invention may be in various forms, such as polyoxometalates, oxides formed from peroxo complexes, hydroxides, metal complexes, and salts.

[0114] For example, a method for producing a liquid containing a tantalate compound as one of the elements to be mixed with the hafnium oxide compound-containing material of the present invention will be described below.

[0115] First, tantalum, tantalum oxide, tantalum hydroxide, or tantalum alkoxide is reacted with hydrofluoric acid (HF), such as a hydrofluoric acid aqueous solution, to form tantalum fluoride (H2TaF7). This tantalum fluoride is then dissolved in water to produce an acidic metal aqueous solution, i.e., an aqueous tantalum fluoride solution. Alternatively, in the case of tantalum chloride, the dissolution step in hydrofluoric acid can be omitted, and the acidic tantalum aqueous solution can be produced by adding water to the tantalum chloride.

[0116] Here, the tantalum fluoride aqueous solution is preferably adjusted to contain 1 to 100 g / L of tantalum, calculated as Ta2O5, by adding water (e.g., pure water). In this case, a tantalum content of 1 g / L or greater, calculated as Ta2O5, is preferred because it forms a readily water-soluble tantalate compound hydrate. Considering productivity, a tantalum content of 10 g / L or greater is more preferred, and 20 g / L or greater is even more preferred. On the other hand, a tantalum content of 100 g / L or less, calculated as Ta2O5, is preferred because it forms a readily water-soluble tantalate compound hydrate. To more reliably synthesize a readily water-soluble tantalate compound hydrate, a tantalum content of 90 g / L or less is more preferred, 80 g / L or less is even more preferred, and 70 g / L or less is particularly preferred. Furthermore, from the perspective of completely dissolving tantalum or tantalum oxide, the pH of the tantalum fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0117] Next, the tantalum fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing tantalum hydrate filter cake. The alkaline aqueous solution used to neutralize the tantalum fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0118] The ammonia content of the ammonia solution used for neutralization is preferably 10% to 30% by mass. An ammonia content of 10% or greater prevents incomplete dissolution of tantalum, allowing tantalum or tantalate to be completely dissolved in water. On the other hand, an ammonia content of 30% or less is preferable, as it approaches a saturated aqueous solution of ammonia.

[0119] From the above viewpoints, the ammonia content of the ammonia water is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, and particularly preferably 25% by mass or more. On the other hand, the ammonia content is preferably 30% by mass or less, more preferably 29% by mass or less, and further preferably 28% by mass or less.

[0120] During the neutralization reaction, the NH3 / Ta addition amount is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a tantalate compound soluble in amines or dilute aqueous ammonia, the NH3 / HF molar ratio is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. From the perspective of cost reduction, the NH3 / HF molar ratio is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0121] The addition time for the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes. In other words, rather than adding slowly over time, it is preferable to allow the neutralization reaction to proceed as quickly as possible, such as by adding all at once. The tantalum fluoride aqueous solution and ammonia solution can be used directly at room temperature.

[0122] The fluorine-containing tantalum hydrate filter cake obtained by the neutralization reaction is decanted using a centrifuge with dilute ammonia water and repeatedly washed until the amount of free fluoride ions is reduced to 100 mg / L or less. This removes fluoride ions from the fluorine-containing tantalum hydrate filter cake, thereby obtaining a tantalum-containing precipitate. Since fluorine compounds such as ammonium fluoride are present as impurities in the fluorine-containing tantalum hydrate filter cake obtained by the neutralization reaction, these are preferably removed.

[0123] The tantalum content of the resulting tantalum-containing precipitate is calculated by collecting a portion of the tantalum-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate Ta2O5. The weight of the Ta2O5 generated in this manner is measured, and the tantalum content of the tantalum-containing precipitate is calculated from this weight.

[0124] The cleaning solution used to remove fluoride ions is preferably dilute ammonia. Specifically, dilute ammonia containing 1% to 35% by mass is preferred. This dilute ammonia solution provides an appropriate ratio of ammonia and ammonium ions to fluoride, thus avoiding unnecessary costs.

[0125] Fluorine compounds can be removed by any method, including reverse osmosis filtration using ammonia or pure water, membrane filtration such as ultrafiltration or fine filtration, centrifugal separation, or other known methods. Furthermore, the removal of fluoride ions from the fluorine-containing tantalum hydrate filter cake does not require temperature control and can be performed at room temperature.

[0126] A tertiary amine compound and pure water were then added to the obtained tantalum-containing precipitate, and the mixture was stirred for 10 minutes to obtain a tantalum-containing mixed solution. Subsequently, 35% by mass of hydrogen peroxide was added to the tantalum-containing mixed solution, and the mixture was stirred for 30 minutes to obtain a tantalate compound-containing solution.

[0127] From the perspective of solubility, the tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the tantalum-containing mixed solution is 30% by mass or less, more preferably 20% by mass or less. From the same perspective, the tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the tantalum-containing mixed solution is 0.1% by mass or more, more preferably 1% by mass or more, and may be 5% by mass or more, or 10% by mass or more. Furthermore, the tertiary amine compound is preferably one or more selected from trimethylamine, triethylamine, and tri-n-propylamine.

[0128] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to tantalum (H2O2 / Ta) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0129] Furthermore, the method for producing a tantalate compound-containing liquid preferably includes a step of removing hydrogen peroxide from the obtained tantalate compound-containing liquid. This is because if the tantalate compound-containing liquid contains hydrogen peroxide, the interior of a sealed container will be filled with gas produced by the decomposition of hydrogen peroxide, causing the container to expand or, in the worst case, rupture.

[0130] The method for removing hydrogen peroxide is any method, and examples thereof include stirring under open / reduced pressure conditions and drying under reduced pressure.

[0131] The following describes a method for producing a solution containing a niobate compound as one of the elements to be mixed with the hafnium oxide compound-containing material of the present invention. The description of any overlaps with the method for producing a solution containing a tantalate compound will be omitted.

[0132] First, niobium, niobium oxide, or niobium hydroxide is reacted with hydrofluoric acid (HF), such as a hydrofluoric acid aqueous solution, to form niobium fluoride (H2NbF7). This niobium fluoride is then dissolved in water to produce an acidic metal aqueous solution of niobium fluoride. Alternatively, in the case of niobium chloride, the dissolution step in hydrofluoric acid can be omitted, and the acidic niobium aqueous solution can be produced by adding water to the niobium chloride.

[0133] Here, the niobium fluoride aqueous solution is preferably adjusted to contain 1 to 100 g / L of niobium, calculated as Nb2O5, by adding water (e.g., pure water). In this case, a niobium content of 1 g / L or greater, calculated as Nb2O5, is preferred because it forms a readily water-soluble niobate compound hydrate. Considering productivity, a niobium content of 10 g / L or greater is more preferred, and 20 g / L or greater is even more preferred. On the other hand, a niobium content of 100 g / L or less, calculated as Nb2O5, is preferred because it forms a readily water-soluble niobate compound hydrate. To more reliably synthesize a readily water-soluble niobate compound hydrate, a niobium content of 90 g / L or less is more preferred, 80 g / L or less is even more preferred, and 70 g / L or less is particularly preferred. Furthermore, from the perspective of completely dissolving niobium or niobium oxide, the pH of the niobium fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0134] Next, the niobium fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing niobium hydrate filter cake. The alkaline aqueous solution used to neutralize the niobium fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0135] During the neutralization reaction, the NH3 / Nb addition amount is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a niobate compound soluble in amines or dilute aqueous ammonia, the NH3 / HF molar ratio is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. From the perspective of cost reduction, the NH3 / HF molar ratio is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0136] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0137] The fluorinated niobium hydrate filter cake obtained by the neutralization reaction is then decanted using a centrifuge with dilute ammonia water and repeatedly washed until the amount of free fluoride ions is reduced to 100 mg / L or less. This removes fluoride ions from the fluorinated niobium hydrate filter cake, thereby obtaining a niobium-containing precipitate. Since fluorinated compounds such as ammonium fluoride are present as impurities in the fluorinated niobium hydrate filter cake obtained by the neutralization reaction, these are preferably removed. Furthermore, the washing solution used to remove fluoride ions is preferably dilute ammonia water.

[0138] The niobium content of the resulting niobium-containing precipitate is calculated by collecting a portion of the niobium-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate Nb2O5. The weight of the thus generated Nb2O5 is measured, and the niobium content of the niobium-containing precipitate is calculated from this weight.

[0139] A tertiary amine compound and pure water were then added to the obtained niobium-containing precipitate, and the mixture was stirred for 10 minutes to obtain a niobium-containing mixed solution. Subsequently, 35% by mass of hydrogen peroxide was added to the niobium-containing mixed solution, and the mixture was stirred for 30 minutes to obtain a niobate compound-containing solution.

[0140] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the niobium-containing mixed solution is 0.1% by mass or more and 30% by mass or less.

[0141] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to niobium (H2O2 / Nb) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0142] In addition, it is preferable that the method further includes a step of removing hydrogen peroxide from the obtained niobate compound-containing liquid, similarly to the method for producing the tantalate compound-containing liquid.

[0143] The following describes a method for producing a solution containing a titanate compound of one element to be mixed with the hafnium oxide compound-containing material of the present invention. The description of the overlap with the method for producing a solution containing a tantalate compound will be omitted.

[0144] First, titanium, titanium oxide, or titanium hydroxide is reacted with hydrofluoric acid (HF) such as a hydrofluoric acid aqueous solution to form titanium fluoride (H2TiF6), which is then dissolved in water to obtain an acidic titanium fluoride aqueous solution. Alternatively, in the case of titanium chloride or titanyl sulfate, the step of dissolving in hydrofluoric acid can be omitted, and water can be added to the mixture to produce an acidic titanium aqueous solution.

[0145] Here, the titanium fluoride aqueous solution is preferably adjusted to contain 1 to 100 g / L of titanium in terms of TiO2 by adding water (e.g., pure water). At this time, if the titanium content is 1 g / L or more in terms of TiO2, it becomes a titanate compound hydrate that is easily soluble in water, and is therefore preferred. In consideration of productivity, it is more preferably 10 g / L or more, and further preferably 20 g / L or more. On the other hand, if the titanium content is 100 g / L or less in terms of TiO2, it becomes a titanate compound hydrate that is easily soluble in water, and is therefore preferred. In order to more reliably synthesize a titanate compound hydrate that is easily soluble in water, it is more preferably 90 g / L or less, further preferably 80 g / L or less, and particularly preferably 70 g / L or less. In addition, from the viewpoint of completely dissolving titanium or titanium oxide, the pH of the titanium fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0146] Next, the titanium fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing titanium hydrate cake. The alkaline aqueous solution used to neutralize the titanium fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0147] During the neutralization reaction, the NH3 / Ti molar ratio is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a titanate compound soluble in amine or dilute aqueous ammonia, the NH3 / HF molar ratio is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. From the perspective of cost reduction, the NH3 / HF molar ratio is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0148] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0149] The fluorinated titanium hydrate filter cake obtained by the neutralization reaction is decanted using dilute ammonia water in a centrifuge and repeatedly washed until the amount of free fluoride ions is less than 100 mg / L, thereby removing fluoride ions from the fluorinated titanium hydrate filter cake to obtain a titanium-containing precipitate. Since fluorinated compounds such as ammonium fluoride are present as impurities in the fluorinated titanium hydrate filter cake obtained by the neutralization reaction, these are preferably removed. In addition, the cleaning solution for removing fluoride ions is preferably dilute ammonia water.

[0150] The niobium content of the resulting titanium-containing precipitate is calculated by collecting a portion of the titanium-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate TiO2. The weight of the TiO2 generated in this manner is measured, and the titanium content of the titanium-containing precipitate is calculated from this weight.

[0151] Then, a tertiary amine compound and pure water were added to the obtained titanium-containing precipitate and stirred for 10 minutes to obtain a titanium-containing mixed liquid. Thereafter, 35% by mass of hydrogen peroxide was added to the titanium-containing mixed liquid and stirred for 30 minutes to obtain a titanate compound-containing liquid.

[0152] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the titanium-containing mixed liquid is 0.1% by mass or more and 30% by mass or less.

[0153] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to titanium (H2O2 / Ti) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0154] In addition, it is preferable that the method further includes a step of removing hydrogen peroxide from the obtained titanate oxide compound-containing liquid, similarly to the method for producing the tantalate oxide compound-containing liquid described above.

[0155] The following describes a method for producing a solution containing a zirconate compound of one element to be mixed with the hafnium oxide compound-containing material of the present invention. The description of any overlaps with the method for producing a solution containing a tantalate compound will be omitted.

[0156] First, zirconium, zirconium oxide, or zirconium hydroxide is reacted with hydrofluoric acid (HF), such as a hydrofluoric acid aqueous solution, to form zirconium fluoride (H2ZrF6), which is then dissolved in water to obtain an acidic zirconium fluoride aqueous solution. Alternatively, in the case of zirconium chloride or zirconium sulfate, the dissolution step in hydrofluoric acid can be omitted, and water can be added to these to produce an acidic zirconium aqueous solution.

[0157] Here, the zirconium fluoride aqueous solution is preferably adjusted to contain 1 to 100 g / L of zirconium in terms of ZrO2 by adding water (e.g., pure water). In this case, if the zirconium content is 1 g / L or more in terms of ZrO2, it becomes a zirconate compound hydrate that is easily soluble in water, which is preferred. In consideration of productivity, it is more preferably 10 g / L or more, and even more preferably 20 g / L or more. On the other hand, if the zirconium content is 100 g / L or less in terms of ZrO2, it becomes a zirconate compound hydrate that is easily soluble in water, which is preferred. In order to more reliably synthesize a zirconate compound hydrate that is easily soluble in water, it is more preferably 90 g / L or less, even more preferably 80 g / L or less, and particularly preferably 70 g / L or less. In addition, from the perspective of completely dissolving zirconium or zirconium oxide, the pH of the zirconium fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0158] Next, the zirconium fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing zirconium hydrate filter cake. The alkaline aqueous solution used to neutralize the zirconium fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0159] During the neutralization reaction, the NH3 / Zr molar ratio is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a zirconate compound soluble in amine or dilute aqueous ammonia, the NH3 / HF molar ratio is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. Furthermore, from the perspective of cost reduction, the NH3 / HF molar ratio is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0160] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0161] The fluorinated zirconium hydrate filter cake obtained by the neutralization reaction is decanted using dilute ammonia water in a centrifuge and repeatedly washed until the amount of free fluoride ions is less than 100 mg / L, thereby removing fluoride ions from the fluorinated zirconium hydrate filter cake to obtain a zirconium-containing precipitate. Since fluorinated compounds such as ammonium fluoride are present as impurities in the fluorinated zirconium hydrate filter cake obtained by the neutralization reaction, these are preferably removed. In addition, the cleaning solution used to remove fluoride ions is preferably dilute ammonia water.

[0162] The zirconium content of the resulting zirconium-containing precipitate is calculated by collecting a portion of the zirconium-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate ZrO2. The weight of the thus generated ZrO2 is measured, and the zirconium content of the zirconium-containing precipitate is calculated from this weight.

[0163] Then, a tertiary amine compound and pure water were added to the obtained zirconium-containing precipitate and stirred for 10 minutes to obtain a zirconium-containing mixed solution. Thereafter, 35% by mass of hydrogen peroxide was added to the zirconium-containing mixed solution and stirred for 30 minutes to obtain a zirconate compound-containing solution.

[0164] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the zirconium-containing mixed solution is 0.1% by mass or more and 30% by mass or less.

[0165] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to zirconium (H2O2 / Zr) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0166] In addition, it is preferable that the method further includes a step of removing hydrogen peroxide from the obtained zirconate compound-containing liquid, similarly to the method for producing the tantalate compound-containing liquid described above.

[0167] The following describes a method for producing a solution containing a silicate compound of one element to be mixed with the hafnium oxide compound-containing material of the present invention. The description of any overlaps with the method for producing a solution containing a tantalate oxide compound will be omitted.

[0168] The method for producing a liquid containing a silicate compound comprises: a mixing step of adding an acidic aqueous solution to a raw material containing silicon and stirring the mixture at a temperature of not less than 15°C and not more than 50°C to obtain a mixed liquid containing a precursor of a silicon compound; and a stirring step of adding a solution containing an organic nitrogen compound to the mixed liquid and stirring the mixture at a temperature of not less than 15°C and not more than 50°C to generate a liquid containing the silicon compound.

[0169] First, in the mixing step, an acidic aqueous solution is added to a raw material material containing silicon, and the mixture is stirred at 15° C. or higher and 50° C. or lower to obtain a mixed solution containing a precursor of a silicon compound.

[0170] Examples of the raw material containing silicon include tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and sodium silicate. The raw material containing silicon preferably contains at least one of tetraethoxysilane and sodium silicate.

[0171] Examples of the acidic aqueous solution include acetic acid, hydrochloric acid, sulfuric acid, and phosphoric acid. The acidic aqueous solution preferably contains at least one of acetic acid, hydrochloric acid, and phosphoric acid.

[0172] When the acidic aqueous solution is acetic acid, the acetic acid content is preferably between 0.001% and 3.0% by mass. When the silicon-containing raw material is TEOS, an acetic acid content of 0.001% or greater can efficiently hydrolyze the silanol ester groups Si-O-CH2-OH3 in the TEOS, thereby forming Si-OH structures. On the other hand, an acetic acid content of 3.0% or less is preferred because it reduces the acetic acid content in the final product, the silicic acid compound-containing liquid. From this perspective, the acetic acid content is preferably 0.001% or greater, more preferably 0.005% or greater, and even more preferably 0.01% or greater. On the other hand, the acetic acid content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, particularly preferably 0.05% by mass or less, even more preferably 0.04% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. Unless otherwise specified, the acetic acid content described in this specification is the content when added to the silicon-containing raw material in the mixing step.

[0173] The acetic acid content in the silicic acid compound-containing liquid is preferably 0.02% to 10% by mass. This acetic acid content is more preferably 0.05% by mass or greater, further preferably 0.1% by mass or greater, particularly preferably 0.15% by mass or greater, and even more preferably 0.2% by mass or greater. On the other hand, this acetic acid content is more preferably 5% by mass or less, further preferably 3% by mass or less, particularly preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0174] Furthermore, regarding the amount of acetic acid added to the silicon-containing raw material, the molar ratio of CH3COOH / Si is preferably 0.01 to 0.3, more preferably 0.02 to 0.25, and even more preferably 0.03 to 0.2. Furthermore, the time taken to add acetic acid to the silicon-containing raw material is preferably within 5 minutes, more preferably within 3 minutes, and even more preferably within 1 minute. Furthermore, regarding the acetic acid content in the silicic acid compound-containing liquid, the molar ratio of CH3COOH / Si is preferably 0.01 to 0.3, more preferably 0.02 to 0.25, and even more preferably 0.03 to 0.2.

[0175] When the acidic aqueous solution added to the silicon-containing raw material is hydrochloric acid, the hydrochloric acid content is preferably 0.001% to 3.0% by mass. If the hydrochloric acid content is 0.001% by mass or greater, sodium chloride can be efficiently produced from the sodium silicate when the silicon-containing raw material is sodium silicate. On the other hand, if the hydrochloric acid content is 3.0% by mass or less, residual chlorine is less likely to remain in the silicic acid compound-containing liquid as the final product, which is preferred. From this viewpoint, the hydrochloric acid content is preferably 0.001% by mass or greater, more preferably 0.005% by mass or greater, and even more preferably 0.01% by mass or greater. On the other hand, the hydrochloric acid content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, particularly preferably 0.05% by mass or less, even more preferably 0.04% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. Unless otherwise specified, the hydrochloric acid content described in this specification is the content when added to the raw material containing silicon in the mixing step and is a value calculated based on the weight of HCl in a 0.5N hydrochloric acid aqueous solution.

[0176] The hydrochloric acid content of the silicic acid compound-containing liquid is preferably 0.02% to 10% by mass. This hydrochloric acid content is more preferably 0.05% by mass or greater, further preferably 0.1% by mass or greater, particularly preferably 0.15% by mass or greater, and even more preferably 0.2% by mass or greater. Furthermore, the hydrochloric acid content is more preferably 5% by mass or less, further preferably 3% by mass or less, particularly preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0177] In addition, regarding the amount of hydrochloric acid added to the silicon-containing raw material, the molar ratio of HCl / Si is preferably 0.5 to 1.5, more preferably 0.55 to 1.3, and even more preferably 0.6 to 1.1. Furthermore, the time taken to add the hydrochloric acid to the silicon-containing raw material is preferably within 10 minutes, more preferably within 5 minutes, and even more preferably within 3 minutes. Furthermore, regarding the hydrochloric acid content in the silicic acid compound-containing liquid, the molar ratio of HCl / Si is preferably 0.5 to 1.5, more preferably 0.55 to 1.3, and even more preferably 0.6 to 1.1.

[0178] Furthermore, in the mixing step, after adding the acidic aqueous solution to the silicon-containing raw material, the liquid temperature of the mixed solution during stirring is preferably 15°C to 50°C, more preferably 20°C to 45°C, and even more preferably 25°C to 40°C. If the liquid temperature of the mixed solution exceeds 50°C, water in the mixed solution may evaporate excessively, causing dehydration condensation between Si-OH groups in the mixed solution to partially form SiO2 particles. This may result in the organic nitrogen compound not dissolving when added during the stirring step.

[0179] Furthermore, in the mixing step, the time spent on stirring after adding the acidic aqueous solution to the silicon-containing raw material varies depending on the type of the silicon-containing raw material, the amount of the acidic aqueous solution added, the reduced pressure conditions, and the like.

[0180] Specifically, when the raw material containing silicon is TEOS and the acidic aqueous solution is acetic acid, the stirring time is preferably 30 minutes to 24 hours, more preferably 1 hour to 15 hours, and even more preferably 2 hours to 12 hours.

[0181] When the raw material containing silicon is sodium silicate and the acidic aqueous solution is hydrochloric acid, the stirring time is preferably 10 minutes to 10 hours, more preferably 30 minutes to 7 hours, and even more preferably 1 hour to 5 hours.

[0182] By adding the acidic aqueous solution to the raw material material containing silicon in this manner and stirring the mixture at a temperature of 15° C. to 50° C., a mixed liquid containing a precursor of a silicon compound is obtained.

[0183] Regarding silicon compound precursors, it is speculated that the structure of the generated silicic acid becomes mostly linear when an acidic aqueous solution is added to a silicon-containing raw material. This is presumably because the absorption maximum intensity attributable to Si-OH stretching vibration increases in the infrared spectrum measured using a Fourier transform infrared spectrophotometer (FT-IR).

[0184] Furthermore, when the raw material material containing silicon is tetraethoxysilane and the acidic aqueous solution is acetic acid, the obtained mixed liquid containing the precursor of the silicon compound proceeds to the subsequent stirring step.

[0185] On the other hand, when the raw material containing silicon is sodium silicate and the acidic aqueous solution is hydrochloric acid, the following treatment is required for the obtained mixed solution containing the precursor of the silicon compound as a pretreatment before entering the subsequent stirring step. The precursor of the silicon compound contains NaCl generated by the reaction of a part of Na in the sodium silicate and a part of Cl in the hydrochloric acid during the above-mentioned stirring, so it is appropriate to remove NaCl from the precursor of the silicon compound. As a method for removing the NaCl, first, the mixed solution containing the precursor of the silicon compound is placed in a centrifugal sedimentation tube, and the precipitated transparent gel is recovered by centrifugal separation (4500 rpm, 10 minutes). Then, water is added to the recovered transparent gel, placed in a centrifugal sedimentation tube, the water is replaced, and multiple centrifugal separations (4500 rpm, 20 minutes) are performed to remove NaCl from the precursor of the silicon compound.

[0186] Next, in the stirring step, a solution containing an organic nitrogen compound is added to the mixed liquid containing a silicon compound precursor, and stirred at 15° C. to 50° C. to generate a silicic acid compound-containing liquid.

[0187] Examples of organic nitrogen compounds include primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. The organic nitrogen compound preferably contains at least one of a primary amine, a secondary amine, and a quaternary ammonium salt. Specific examples include methylamine, ethylamine, dimethylamine, diethylamine, and tetramethylammonium hydroxide. Furthermore, instead of adding an organic nitrogen compound, a solution containing an organic acid may be added to the mixed solution containing the silicon compound precursor.

[0188] Regarding the amount of the organic nitrogen compound added to the mixed solution containing the silicon compound precursor, the amine / Si molar ratio is preferably 0.5 to 15, more preferably 1 to 10, and even more preferably 1.5 to 5. Furthermore, regarding the amount of the organic nitrogen compound added to the mixed solution containing the silicon compound precursor, from the perspective of generating a silicon compound soluble in the organic nitrogen compound, the amine / Si molar ratio is preferably 1.7 to 1.7, more preferably 1.3 to 1.3, and even more preferably 1.3 to 1.3. On the other hand, from the perspective of cost reduction, the amine / Si molar ratio is preferably 1.5 to 1.5, more preferably 1.2 to 1.2, and even more preferably 1 to 1.

[0189] The time required to add the organic nitrogen compound to the mixed liquid containing the silicon compound precursor is preferably within 60 minutes, more preferably within 30 minutes, and even more preferably within 10 minutes.

[0190] Furthermore, in the stirring step, after the solution containing the organic nitrogen compound is added to the mixed liquid containing the silicon compound precursor, the liquid temperature during stirring is preferably 15° C. to 50° C., more preferably 20° C. to 45° C., and even more preferably 25° C. to 40° C. If the liquid temperature during stirring is higher than 50° C., the organic nitrogen compound and the like evaporate, making it difficult for the silicon compound precursor to dissolve, and the possibility of residual silicon compound precursor increases.

[0191] Furthermore, in the stirring step, after adding the solution containing the organic nitrogen compound to the mixed solution containing the silicon compound precursor, the time spent on stirring is preferably 10 minutes to 24 hours, more preferably 30 minutes to 20 hours, and even more preferably 1 hour to 15 hours.

[0192] By adding a solution containing an organic nitrogen compound to a mixed solution containing a silicon compound precursor in this manner and stirring at a temperature of 15°C to 50°C, a silicic acid compound-containing solution can be generated. As described above, the silicon compound precursor contains a large number of Si-OH structures and is therefore likely to be readily dissolved in water by Si acid.

[0193] The following describes a method for producing a liquid containing a molybdate compound of one of the elements to be mixed with the hafnium oxide compound-containing material of the present invention. The description of the overlap with the method for producing a liquid containing a tantalate compound will be omitted.

[0194] First, molybdenum or molybdenum oxide is reacted with hydrofluoric acid (HF) such as a hydrofluoric acid aqueous solution to form molybdenum fluoride (H2MoF6), which is then dissolved in water to obtain a molybdenum fluoride aqueous solution as an acidic metal aqueous solution.

[0195] Here, the platinum fluoride aqueous solution is preferably adjusted to MoO by adding water (such as pure water) and containing 1 to 100g / L of molybdenum by conversion. At this time, if platinum content is with MoO3, it is calculated as more than 1g / L, then it becomes a molybdenum acid compound hydrate that is easily soluble in water, thus it is preferred, in the case of considering productivity, it is more preferably more than 10g / L, more preferably more than 20g / L. On the other hand, if platinum content is with MoO3, it is calculated as less than 100g / L, then it becomes a molybdenum acid compound hydrate that is easily soluble in water, thus it is preferred, in order to more surely synthesize a molybdenum acid compound hydrate that is easily soluble in water, it is more preferably less than 90g / L, more preferably less than 80g / L, particularly preferably less than 70g / L. In addition, from the viewpoint of making molybdenum or molybdenum oxide completely dissolved, the pH of the platinum fluoride aqueous solution is preferably less than 2, more preferably less than 1.

[0196] Next, the molybdenum fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing molybdenum hydrate filter cake. The alkaline aqueous solution used to neutralize the molybdenum fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0197] During the neutralization reaction, the NH3 / Mo molar ratio is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a molybdate compound soluble in amines or dilute aqueous ammonia, the NH3 / HF molar ratio is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. Furthermore, from the perspective of cost reduction, the NH3 / HF molar ratio is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0198] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0199] The fluorine-containing platinum hydrate filter cake obtained by the above-mentioned neutralization reaction is decanted using dilute ammonia using a centrifuge, and repeatedly cleaned until the free fluoride ion amount becomes below 100 mg / L, thereby removing fluoride ions from the fluorine-containing platinum hydrate filter cake and obtaining a platinum-containing precipitate. Due to the presence of fluorine compounds such as ammonium fluoride as impurities in the fluorine-containing platinum hydrate filter cake obtained by the above-mentioned neutralization reaction, they are preferably removed. In addition, the cleaning solution for removing fluoride ions is preferably dilute ammonia.

[0200] The molybdenum content of the resulting molybdenum-containing precipitate is calculated by collecting a portion of the molybdenum-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to generate MoO3. The weight of the MoO3 generated in this manner is measured, and the molybdenum content of the molybdenum-containing precipitate can be calculated from this weight.

[0201] Then, a tertiary amine compound and pure water were added to the obtained molybdenum-containing precipitate, and the mixture was stirred for 10 minutes to obtain a molybdenum-containing mixed solution. Thereafter, 35% by mass of hydrogen peroxide was added to the molybdenum-containing mixed solution, and the mixture was stirred for 30 minutes to obtain a molybdate compound-containing solution.

[0202] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the molybdenum-containing mixed solution is 0.1% by mass or more and 30% by mass or less.

[0203] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to molybdenum (H2O2 / Mo) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0204] In addition, it is preferable that the method further comprises a step of removing hydrogen peroxide from the obtained molybdate compound-containing liquid, similarly to the method for producing the tantalate compound-containing liquid.

[0205] The following describes a method for producing a tungstate compound-containing solution containing one of the elements to be mixed with the hafnium oxide compound-containing material of the present invention. The description of the overlap with the method for producing a tantalate compound-containing solution will be omitted.

[0206] First, tungsten or tungsten oxide is reacted with hydrofluoric acid (HF) such as a hydrofluoric acid aqueous solution to form tungsten fluoride (H2MoF6), which is then dissolved in water to obtain a tungsten fluoride aqueous solution as an acidic metal aqueous solution.

[0207] Here, the tungsten fluoride aqueous solution is preferably adjusted to contain 1 to 100 g / L of tungsten in terms of WO3 by adding water (e.g., pure water). In this case, if the tungsten content is 1 g / L or more in terms of WO3, it becomes a tungstate compound hydrate that is easily soluble in water, which is preferred. In consideration of productivity, it is more preferably 10 g / L or more, and further preferably 20 g / L or more. On the other hand, if the tungsten content is 100 g / L or less in terms of WO3, it becomes a tungstate compound hydrate that is easily soluble in water, which is preferred. In order to more reliably synthesize a tungstate compound hydrate that is easily soluble in water, it is more preferably 90 g / L or less, further preferably 80 g / L or less, and particularly preferably 70 g / L or less. In addition, from the perspective of completely dissolving tungsten or tungsten oxide, the pH of the tungsten fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0208] Next, the tungsten fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing tungsten hydrate filter cake. Here, the alkaline aqueous solution used to neutralize the tungsten fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0209] During the neutralization reaction, the amount of NH3 / HF added is preferably a molar ratio of 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a tungstate compound soluble in amine or dilute aqueous ammonia, the molar ratio of NH3 / HF is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. From the perspective of cost reduction, the molar ratio of NH3 / HF is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0210] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0211] The fluorinated tungsten hydrate filter cake obtained by the neutralization reaction is decanted using dilute ammonia water in a centrifuge and repeatedly washed until the amount of free fluoride ions is 100 mg / L or less. This removes fluoride ions from the fluorinated tungsten hydrate filter cake, thereby obtaining a tungsten-containing precipitate. Since fluorinated compounds such as ammonium fluoride are present as impurities in the fluorinated tungsten hydrate filter cake obtained by the neutralization reaction, these are preferably removed. Furthermore, the washing solution used to remove fluoride ions is preferably dilute ammonia water.

[0212] The tungsten content of the resulting tungsten-containing precipitate is calculated by collecting a portion of the tungsten-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce WO3. The weight of the WO3 produced in this manner is measured, and the tungsten content of the tungsten-containing precipitate is calculated from this weight.

[0213] Then, a tertiary amine compound and pure water were added to the obtained tungsten-containing precipitate and stirred for 10 minutes to obtain a tungsten-containing mixed solution. Thereafter, 35% by mass of hydrogen peroxide was added to the tungsten-containing mixed solution and stirred for 30 minutes to obtain a tungstate compound-containing solution.

[0214] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the tungsten-containing mixed solution is 0.1 mass % or more and 30 mass % or less.

[0215] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to tungsten (H2O2 / W) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0216] In addition, it is preferable that the method further includes a step of removing hydrogen peroxide from the obtained tungstate compound-containing liquid, similarly to the method for producing the tantalate compound-containing liquid.

[0217] The following describes a method for producing a solution containing a rare earth element acid compound as one of the elements to be mixed with the hafnium oxide compound-containing material of the present invention. The description of any overlaps with the method for producing a solution containing a tantalate oxide compound will be omitted.

[0218] First, a rare earth element or a rare earth element oxide is reacted with hydrofluoric acid (HF) such as a hydrofluoric acid aqueous solution to form rare earth element fluoride, which is then dissolved in water to obtain a rare earth element fluoride aqueous solution as an acidic metal aqueous solution.

[0219] Here, the fluorinated rare earth element aqueous solution is preferably adjusted to contain 1 to 100 g / L of rare earth elements in terms of rare earth element oxide conversion by adding water (e.g., pure water). At this time, if the rare earth element content is 1 g / L or more in terms of rare earth element oxide conversion, it becomes a rare earth element acid compound hydrate that is easily soluble in water, and is therefore preferred. In the case of considering productivity, it is more preferably 10 g / L or more, and further preferably 20 g / L or more. On the other hand, if the rare earth element content is 100 g / L or less in terms of rare earth element oxide conversion, it becomes a rare earth element acid compound hydrate that is easily soluble in water, and is therefore preferred. In order to more reliably synthesize a rare earth element acid compound hydrate that is easily soluble in water, it is more preferably 90 g / L or less, further preferably 80 g / L or less, and particularly preferably 70 g / L or less. In addition, from the perspective of completely dissolving the rare earth element or rare earth element oxide, the pH of the fluorinated rare earth element aqueous solution is preferably 2 or less, and more preferably 1 or less.

[0220] Next, the rare earth element fluoride aqueous solution is neutralized with an alkaline aqueous solution to obtain a fluorine-containing rare earth element hydrate filter cake. The alkaline aqueous solution used to neutralize the rare earth element fluoride aqueous solution is preferably 10% to 30% by mass of ammonia water.

[0221] During the neutralization reaction, the molar ratio of NH3 / rare earth element added is preferably 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the perspective of generating a rare earth element acid compound soluble in amine or dilute aqueous ammonia, the molar ratio of NH3 / HF is preferably 3.0 to 3.0, more preferably 4.0 to 4.0, and even more preferably 5.0 to 5.0. From the perspective of cost reduction, the molar ratio of NH3 / HF is preferably 100 to 100, more preferably 50 to 100, and even more preferably 40 to 10.

[0222] The addition time in the neutralization reaction is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes.

[0223] The fluorinated rare earth element hydrate filter cake obtained by the neutralization reaction is decanted using dilute ammonia water using a centrifuge and repeatedly washed until the amount of free fluoride ions is less than 100 mg / L, thereby removing fluoride ions from the fluorinated rare earth element hydrate filter cake and obtaining a precipitate containing rare earth elements. Since fluorine compounds such as ammonium fluoride are present as impurities in the fluorinated rare earth element hydrate filter cake obtained by the neutralization reaction, they are preferably removed. In addition, the cleaning solution for removing fluoride ions is preferably dilute ammonia water.

[0224] The rare earth element content of the resulting rare earth element-containing precipitate is calculated by collecting a portion of the rare earth element-containing precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce rare earth element oxides. The weight of the resulting rare earth element oxides is measured, and the rare earth element content of the rare earth element-containing precipitate can be calculated from this weight.

[0225] Then, a tertiary amine compound and pure water were added to the resulting rare earth element-containing precipitate, and the mixture was stirred for 10 minutes to obtain a mixed solution containing rare earth elements. Subsequently, 35% by mass of hydrogen peroxide was added to the mixed solution containing rare earth elements, and the mixture was stirred for 30 minutes to obtain a rare earth element acid compound-containing solution.

[0226] The tertiary amine compound is preferably mixed so that the content of the tertiary amine compound in the mixed solution containing the rare earth element is 0.1% by mass or more and 30% by mass or less.

[0227] The hydrogen peroxide content of the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, hydrogen peroxide is preferably added so that the molar ratio of hydrogen peroxide to the rare earth element (H2O2 / Hf) is 0.6 to 1.5. Since hydrogen peroxide may decompose during mixing, it is more preferably 0.7 to 1.2.

[0228] In addition, it is preferable that the method further includes the step of removing hydrogen peroxide from the obtained rare earth element acid compound-containing liquid, similarly to the method for producing the tantalate compound-containing liquid.

[0229] Furthermore, the composite hafnic acid film of the present invention is characterized by containing composite hafnic acid particles contained in the composite hafnic acid compound-containing material of the present invention.

[0230] The composite hafnic acid film of the present invention contains composite hafnic acid particles contained in the composite hafnic acid compound-containing material of the present invention.

[0231] The method for producing a composite hafnic acid film of the present invention is characterized by comprising the steps of applying a composite hafnic acid compound-containing material produced by the method for producing a composite hafnic acid compound-containing material of the present invention, and drying and / or firing the coating to produce a composite hafnic acid film.

[0232] The method for producing the dry composite hafnic acid film of the present invention among the composite hafnic acid films of the present invention comprises, in the same manner as the method for producing the dry composite hafnic acid compound film of the present invention, a coating step of coating the composite hafnic acid compound-containing material of the present invention on the surface of a substrate; and a film drying step of drying the composite hafnic acid compound-containing material coated on the surface of the substrate to obtain a dry film.

[0233] The method for manufacturing the composite hafnic acid fired film of the present invention among the composite hafnic acid films of the present invention is the same as the method for manufacturing the hafnic acid compound fired film of the present invention, including: a coating step of coating the composite hafnic acid compound-containing material of the present invention on the surface of a substrate; a film drying step of drying the composite hafnic acid compound-containing material coated on the surface of the substrate to obtain a dry film; and a film firing step of firing the dry film in the atmosphere at a firing temperature of 300°C to 1200°C and a firing time of 1 hour to 12 hours to obtain a fired film.

[0234] In this specification, the expression "X to Y" (X and Y are arbitrary numbers) includes, unless otherwise specified, the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, the expression "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number) also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0235] Effects of the Invention

[0236] The hafnic acid compound-containing material of the present invention is alkaline and has excellent dispersibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0237] Figure 1 This is a table showing the physical property values ​​and measurement results of hafnium oxide compound-containing materials of Examples 1 to 5 of the present invention and Comparative Example 1.

[0238] Figure 2 This is a graph showing the transmittance of hafnic acid compound-containing materials of Examples 1 to 5 of the present invention and Comparative Example 1.

[0239] Figure 3 This is a diagram showing the measurement results of the XRD spectrum of the hafnium oxide compound-containing material of Example 4 of the present invention. DETAILED DESCRIPTION

[0240] The hafnium oxide compound-containing material according to the embodiment of the present invention is further described below with reference to the following examples. However, the following examples are not intended to limit the present invention.

[0241] (Example 1)

[0242] 105.1 g of 55% by mass hydrofluoric acid and 796.9 g of pure water were added to 76.0 g of hafnium oxide (98% purity, powder, manufactured by High Purity Science Laboratory Co., Ltd.), heated to 80°C in a water bath, and stirred for 24 hours to dissolve the mixture, thereby obtaining a hydrofluoric acid solution of the hafnium compound. To 60 g of this hydrofluoric acid solution of the hafnium compound, 2.2 g of 35% by mass hydrogen peroxide solution was added to obtain an aqueous hafnium complex solution (H₂O₂ / Hf molar ratio = 1.0). After stirring for 5 minutes, 377.2 g of 25% by mass ammonia water (NH₃ / Hf molar ratio = 250) was slowly added. The mixture was then stirred for 5 minutes to obtain a neutralized reaction solution containing hafnium hydroxide as a precipitate.

[0243] Next, the neutralized reaction solution was decanted using a centrifuge to recover the precipitate (including hafnium hydroxide). The recovered precipitate was mixed with 200 g of 25% by mass ammonia water to form a slurry, and then decanted again to recover the precipitate. This decantation and precipitate (including hafnium hydroxide) recovery process was repeated three times.

[0244] Then, 31.1 g of 25% by mass TMAH was added to the recovered precipitate (containing hafnium hydroxide) to obtain a mixed solution. Pure water was added until the total weight of the mixed solution became 77.7 g in such a way that the final hafnium content was 6% by mass in terms of HfO2 conversion, and the mixed solution was stirred for 6 hours to obtain the colorless and transparent hafnium acid compound-containing liquid of Example 1. The pH of the hafnium acid compound-containing liquid of Example 1 was 14.8. In addition, the hafnium acid compound-containing liquid of Example 1 was dried, and the XRD maximum intensity (Ia) of the obtained dry powder at a diffraction angle of 2θ = 31° or more and 33° or less was 478.333, and the XRD maximum intensity (Ib) at a diffraction angle of 2θ = 5° or more and 6° or less was 1255.00. Furthermore, the ratio Ib / Ia of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 2.62.

[0245] (Example 2)

[0246] In Example 2, instead of adding 31.1 g of 25% by mass TMAH, 22.2 g of 35% by mass TEAH was added to the recovered precipitate (containing hafnium hydroxide) to obtain a mixed solution. The same manufacturing method as in Example 1 was implemented to obtain a colorless and transparent hafnium oxide compound-containing liquid of Example 2. The pH of the hafnium oxide compound-containing liquid of Example 2 obtained was 14.3. In addition, the hafnium oxide compound-containing liquid of Example 2 was dried, and the XRD maximum intensity (Ia) of the obtained dry powder at a diffraction angle of 2θ = 31° or more and 33° or less was 523.333, and the XRD maximum intensity (Ib) at a diffraction angle of 2θ = 5° or more and 6° or less was 785.000. In addition, the ratio of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 1.50.

[0247] (Example 3)

[0248] In Example 3, the same production method as in Example 1 was followed, except that 19.4 g of 40% benzyltrimethylammonium hydroxide was added to the recovered precipitate (containing hafnium hydroxide) instead of 31.1 g of 25% by mass TMAH to obtain a mixed solution. A colorless, transparent hafnium oxide compound-containing solution of Example 3 was obtained. The pH of the hafnium oxide compound-containing solution of Example 3 was 14.4. Furthermore, the hafnium oxide compound-containing solution of Example 3 was dried, and the resulting dry powder had an XRD maximum intensity (Ia) of 440.000 at a diffraction angle of 2θ = 31° to 33°, and an XRD maximum intensity (Ib) of 1083.33 at a diffraction angle of 2θ = 5° to 6°. Furthermore, the ratio (Ib / Ia) of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 2.46.

[0249] (Example 4)

[0250] In Example 4, the same manufacturing method as in Example 1 was followed, except that 16.2 g of 47-50 mass% choline was added to the recovered precipitate (containing hafnium hydroxide) to obtain a mixed solution, rather than 31.1 g of 25 mass% TMAH. A colorless, transparent hafnium oxide compound-containing solution of Example 4 was obtained. The pH of the hafnium oxide compound-containing solution of Example 4 was 14.5. Furthermore, the hafnium oxide compound-containing solution of Example 4 was dried, and the resulting dry powder had an XRD maximum intensity (Ia) of 600.000 at a diffraction angle of 2θ of 31° to 33°, and an XRD maximum intensity (Ib) of 701.667 at a diffraction angle of 2θ of 5° to 6°. Furthermore, the ratio (Ib / Ia) of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 1.17.

[0251] (Example 5)

[0252] In Example 5, instead of adding 31.1 g of 25% by mass TMAH, 11.6 g of 47 to 50% by mass choline was added to the recovered precipitate (containing hafnium hydroxide) to obtain a mixed solution, and pure water was added so that the final hafnium content was 10% by mass in terms of HfO2. The same manufacturing method as in Example 1 was followed to obtain a colorless, transparent hafnium oxide compound-containing solution of Example 5. The pH of the hafnium oxide compound-containing solution of Example 5 was 14.5. Furthermore, the hafnium oxide compound-containing solution of Example 5 was dried, and the obtained dry powder had an XRD maximum intensity (Ia) of 718.333 at a diffraction angle of 2θ = 31° to 33°, and an XRD maximum intensity (Ib) of 521.667 at a diffraction angle of 2θ = 5° to 6°. Furthermore, the ratio Ib / Ia of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 1.38.

[0253] (Comparative Example 1)

[0254] The hafnic acid compound of Comparative Example 1 was obtained through the following steps.

[0255] First, 634 g of ion-exchanged water was added to 333 g of hafnium hydroxide (containing 45% by weight as HfO2) to obtain a hafnium hydroxide aqueous solution. While stirring the obtained hafnium hydroxide aqueous solution, 33 g of 67.5% by weight nitric acid was added to the hafnium hydroxide aqueous solution to obtain a slurry. The hafnium content of the slurry was 15% by weight as HfO2, and the nitric acid content was such that 0.5 g equivalent of nitric acid was contained per 1 mol of hafnium.

[0256] Next, the slurry was heated to 150°C, held for 24 hours, allowed to stand, and then cooled naturally, thereby obtaining the crystalline hafnium dioxide sol of Comparative Example 1. Furthermore, the crystalline hafnium dioxide sol of Comparative Example 1 was dried, and the resulting dry powder had an XRD maximum intensity (Ia) of 1050.00 at a diffraction angle of 2θ = 31° to 33°, and an XRD maximum intensity (Ib) of 418.333 at a diffraction angle of 2θ = 5° to 6°. Furthermore, the ratio (Ib / Ia) of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia) was 0.40.

[0257] Then, the following physical properties were measured for the hafnic acid compound-containing solutions of Examples 1 to 5 and the crystalline hafnium dioxide sol of Comparative Example 1. The measured physical property values ​​and their measuring methods are shown below, and the measurement results are shown in Figure 1 .

[0258] <Elemental Analysis>

[0259] The sample is moderately diluted with dilute hydrochloric acid according to requirements, and the Hf weight fraction in terms of HfO2 conversion is measured by ICP emission analysis (manufactured by Agilent Technologies: AG-5110).

[0260] <pH measurement>

[0261] The electrode of the pH meter (manufactured by HORIBA: glass electrode type hydrogen ion concentration indicator D-51) (manufactured by HORIBA: standard ToupH electrode 9615S-10D) is immersed in the hafnium acid compound-containing liquids of Examples 1 to 5 and the crystalline hafnium dioxide sol of Comparative Example 1. After confirming that the liquid temperature is stable at 25 °C, the pH is measured. Figure 1 The "initial pH" refers to the pH of the hafnium acid compound-containing liquid adjusted to a liquid temperature of 25 °C immediately after generation. Additionally, Figure 1 the "pH over time" refers to the pH of the hafnium acid compound-containing liquid after standing for 1 month in a thermostat set at room temperature of 25 °C. Furthermore, for the crystalline hafnium dioxide sol of Comparative Example 1, crystalline hafnium dioxide particles were precipitated, so it was difficult to measure the "pH over time".

[0262] <Transmittance measurement>

[0263] 4 ml of the hafnium acid compound-containing liquids of Examples 1 to 5 is placed in a quartz cell with an optical path length of 5.0 mm. The transmittances of the hafnium acid compound-containing liquids of Examples 1 to 5 at wavelengths of 550 nm, 600 nm, 650 nm, and 700 nm are measured using a spectrophotometer according to the above transmittance measurement conditions. Then, those with a transmittance of 70% T or more at wavelengths of 550 nm, 600 nm, 650 nm, and 700 nm are evaluated as "〇 (good)", and those less than 70% T are evaluated as "× (poor)". Figure 1 The "initial transmittance" refers to the transmittance of the hafnium acid compound-containing liquid adjusted to a liquid temperature of 25 °C immediately after generation. Additionally, Figure 1 the "transmittance over time" refers to the transmittance of the hafnium acid compound-containing liquid after standing for 1 month in a thermostat set at room temperature of 25 °C. Moreover, Figure 2 is a graph showing the transmittances of the hafnium acid compound-containing liquids of Examples 1 to 5 and the crystalline hafnium dioxide sol of Comparative Example 1.

[0264] <XRD maximum intensity ratio measurement>

[0265] The hafnic acid compound-containing solutions of Examples 1 to 5 were dried at 150°C for 15 hours under a vacuum environment to obtain dry powders. The resulting dry powders were used as samples and subjected to powder X-ray diffraction measurement under the aforementioned conditions to measure the XRD maximum intensity ratio. Specifically, the XRD maximum intensity (Ia) at a diffraction angle of 2θ = 31° to 33° and the XRD maximum intensity (Ib) at a diffraction angle of 2θ = 5° to 6° were measured. The ratio of the XRD maximum intensity (Ib) to the XRD maximum intensity (Ia), Ib / Ia, was then calculated.

[0266] <Film uniformity test>

[0267] The appearance evaluation of the coating formed on the surface of the glass substrate as a substitute for the collector plate was performed by observation with an optical microscope. The hafnium acid compound-containing liquid of Examples 1 to 5 was dropped onto a 15 mm × 15 mm glass substrate using a syringe and applied by spin coating (1500 rpm, 30 seconds). Then, a coating was formed on the glass substrate by drying the coated portion at 60 ° C for 30 minutes. The formed coating was observed at 100 times using an optical microscope, and the coating in which no coarse particles and no bubbles, uneven coating, or cracks were present was evaluated as “00 (excellent)”, the coating in which no coarse particles but bubbles, uneven coating, or at least one of cracks were present was evaluated as “0 (good)”, and the coating in which coarse particles and bubbles, uneven coating, or at least one of cracks were present was evaluated as “× (poor)”. Figure 1 The "initial film uniformity" refers to the film uniformity of the coating film formed by the hafnic acid compound-containing liquid immediately after it is generated. Figure 1 The "film uniformity over time" refers to the film uniformity of a coating film formed after a hafnic acid compound-containing solution immediately after formation is allowed to stand in a thermostat set at room temperature of 25°C for one month.

[0268] like Figure 1 As shown, regarding the hafnium oxide compound-containing liquids of Examples 1 to 5, if the ratio Ib / Ia of the XRD maximum intensity (Ib) at a diffraction angle 2θ = 5° or more and 6° or less of the dry powder obtained by drying these hafnium oxide compound-containing liquids at 150°C for 15 hours is 1.1 or more to the XRD maximum intensity (Ia) at a diffraction angle 2θ = 31° or more and 33° or less is 1.1, the solubility in the solvent is excellent. Here, Figure 3 This is a graph showing the measurement results of the XRD spectrum of the hafnium oxide compound-containing liquid of Example 4. The pattern appearing at a diffraction angle of 2θ = 31° or more and 33° or less is the XRD maximum intensity (Ia), and the pattern appearing at a diffraction angle of 2θ = 5° or more and 6° or less is the XRD maximum intensity (Ib).

[0269] The hafnic acid compound-containing liquids of Examples 1 to 5 have excellent dispersibility when the maximum value of the transmittance in the wavelength range of 550 nm to 700 nm is 70%T or more.

[0270] The hafnium oxide compound-containing liquids of Examples 1 to 5 have good stability if the hafnium content in the hafnium oxide compound-containing liquid is greater than 0 mass % and not less than 10 mass % in terms of HfO 2 .

[0271] If the organic nitrogen compound contained in the hafnic acid compound-containing liquid of Examples 1 to 5 is a quaternary ammonium compound, especially one or more selected from tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), choline, and benzyltrimethylammonium hydroxide, not only will the solubility be high, but high crystallization and high solubility can also be suppressed.

[0272] The hafnic acid compound-containing solutions of Examples 1 to 5 are alkaline when the pH is greater than 7, and have excellent stability over time.

[0273] Regarding the hafnium oxide compound-containing solutions of Examples 1 to 5, coating films formed therefrom were observed using an optical microscope at 100 times magnification. The coating films had excellent film uniformity.

[0274] In addition to the configurations of each invention or embodiment, the invention disclosed in this specification also includes, within the scope of applicability, the following: those obtained by changing these partial configurations into other configurations disclosed in this specification and specifying them; or those obtained by adding other configurations disclosed in this specification to these above-mentioned configurations and specifying them; or those obtained by deleting these partial configurations and specifying them as a higher-level concept within the limit of obtaining some effects.

[0275] Industrial applicability

[0276] The hafnium acid compound-containing material of the present invention is alkaline and has high dispersibility, and is suitable as a coating material or composite material with high film adhesion or film uniformity. In addition, the hafnium acid compound-containing material of the present invention has excellent storage stability, and can suppress the incidence of defective products caused by sediment due to time changes, thereby reducing waste, and the energy cost when treating waste can also be reduced. Furthermore, the hafnium acid compound-containing material of the present invention is also good because the formation of the coating film is also good, so in the coated coating material, waste can also be reduced, and the incidence of defective products can be suppressed. From these viewpoints, sustainable management of natural resources and efficient advantages and decarbonization (carbon neutralization) can be achieved.

Claims

1. A hafnium oxide compound-containing substance, characterized in that: The hafnium acid compound contains hafnium, an organic nitrogen compound and a solvent. The hafnic acid compound-containing material is dried at 150°C for 15 hours under a vacuum environment, and the ratio Ib / Ia of the XRD maximum intensity (Ib) at a diffraction angle 2θ = 5° or more and 6° or less to the XRD maximum intensity (Ia) at a diffraction angle 2θ = 31° or more and 33° or less is 1.1 or more.

2. A hafnium oxide compound-containing substance, characterized in that: The hafnium acid compound contains hafnium, an organic nitrogen compound and a solvent. The hafnic acid compound-containing material has a maximum transmittance of 70%T or more in a wavelength range of 550 nm to 700 nm.

3. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The hafnium content in the hafnium oxide compound-containing material is greater than 0 mass % and less than or equal to 10 mass % in terms of HfO 2 .

4. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The hafnic acid compound-containing substance contains hydrogen peroxide.

5. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The hafnic acid compound-containing substance contains water.

6. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The organic nitrogen compound is a quaternary ammonium compound.

7. The hafnium oxide compound-containing material according to claim 6, wherein The quaternary ammonium is one or more selected from tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), choline, and benzyltrimethylammonium hydroxide.

8. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The pH of the hafnic acid compound-containing material is greater than 7.

9. The hafnium oxide compound-containing material according to claim 1 or 2, wherein The hafnic acid compound-containing material has a maximum transmittance of 90%T or more in a wavelength range of 550 nm to 700 nm.

10. A method for producing a material containing a hafnium oxide compound, characterized in that: It includes the following steps: adding an acidic hafnium aqueous solution containing hafnium to an alkaline aqueous solution to generate a hafnium-containing precipitate; and The step of adding an organic nitrogen compound to the hafnium-containing precipitate slurry after the hafnium-containing precipitate is slurried to generate a hafnium acid compound-containing material.

11. A hafnium oxide compound powder, characterized in that: The hafnic acid compound-containing material comprises hafnic acid particles contained in the hafnic acid compound-containing material according to claim 1 or 2.

12. A method for producing hafnium oxide compound powder, characterized in that: The method comprises the steps of drying and / or calcining the hafnium oxide compound-containing material according to claim 1 or 2 to generate hafnium oxide powder.

13. A hafnium oxide compound film, characterized in that: The hafnic acid compound-containing material comprises hafnic acid particles contained in the hafnic acid compound-containing material according to claim 1 or 2.

14. A method for producing a hafnium oxide compound film, characterized in that: The hafnic acid compound-containing material according to claim 1 or 2 is applied, and then dried and / or fired.

15. A composite hafnic acid compound-containing material, characterized in that: The invention comprises: the hafnium oxide compound-containing material according to claim 1 or 2; and at least one element selected from the group consisting of Si, Al, Ti, Zn, Sn, Y, Ce, Ba, Sr, P, S, La, Gd, Nd, Eu, Dy, Yb, Nb, Li, Na, K, Mg, Ca, Zr, Mo, Ta, V, Ga, Ge, and W.

16. A method for producing a composite hafnium oxide compound-containing material, characterized in that: The method comprises the steps of mixing the hafnium oxide compound-containing material produced by the method for producing the hafnium oxide compound-containing material according to claim 10 with at least one element selected from the group consisting of Si, Al, Ti, Zn, Sn, Y, Ce, Ba, Sr, P, S, La, Gd, Nd, Eu, Dy, Yb, Nb, Li, Na, K, Mg, Ca, Zr, Mo, Ta, V, Ga, Ge and W to produce a composite hafnium oxide compound-containing material.

17. A composite hafnium oxide compound film, characterized in that: The composite hafnic acid particle comprises the composite hafnic acid compound-containing material according to claim 15 .

18. A method for producing a composite hafnium oxide compound film, characterized in that: The composite hafnic acid compound-containing material produced by the method for producing the composite hafnic acid compound-containing material according to claim 16 is applied and then dried and / or fired.

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