Particles having a specific crystal composition of lower-order titanium oxide, a method for producing the same, and a dispersion.

Abstract

The purpose of the present invention is to obtain low-order titanium oxide particles having a novel crystal composition.　The present invention involves a method for producing particles, said method comprising a step for heating a mixture containing TiH2 and TiO2 at a temperature of 700-950°C, wherein the molar ratio of TiO2 to TiH2 contained in the mixture is 5.0-6.8.

Description

[Technical Field]

[0001] This disclosure relates to particles having the crystal compositions of Ti4O7 and γ-Ti3O5, methods for producing the same, and dispersions thereof. [Background technology]

[0002] Lower titanium oxide (also called reduced titanium oxide), obtained by reducing titanium dioxide, exhibits different colors depending on the ratio of titanium to oxygen, which are its constituent elements, and it is known that black can be produced by appropriately adjusting this ratio. Therefore, particles whose surfaces are composed of lower titanium oxide can be used in various applications as pigments such as black pigments. For example, Patent Document 1 discloses a cosmetic product using a pigment that exhibits dichroism, where the appearance color and interference color tones differ, by forming a single layer of lower titanium oxide on plate-like particles. Furthermore, as an application for black pigments, Patent Document 2 discloses black titanium oxide powder prepared using CaH2 as a reducing agent. Patent Document 3 discloses titanium oxynitride powder prepared by reacting titanium oxide with high-temperature ammonia gas. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-280607 [Patent Document 2] Japanese Patent Publication No. 2012-214348 [Patent Document 3] Japanese Patent Publication No. 2010-30842 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Black pigments containing lower-order titanium dioxide exhibit different shades of black, such as reddish blacks and bluish blacks. The shade of black changes not only depending on the composition of lower-order titanium dioxide, as mentioned above, but also on the particle size of the pigment (particles). Furthermore, the same level of blackness can appear lighter or darker depending on the color. For example, with bright colors like red or yellow, the same level of blackness may appear darker with darker colors like blue or green. Therefore, to obtain a black pigment with a desired shade, it may be necessary to adjust physical properties such as particle size. However, such physical properties may be constrained depending on the application of the black pigment, for example. Therefore, it is preferable to obtain the desired shade of black simply by adjusting the composition of lower-order titanium dioxide.

[0005] Therefore, one aspect of the present invention aims to obtain particles of lower-order titanium oxide having a novel crystal composition. [Means for solving the problem]

[0006] The inventors have discovered that when producing particles containing lower-order titanium oxide by heating TiH2 and TiO2, particles with a novel lower-order titanium oxide composition can be obtained by appropriately adjusting the mixing ratio of TiH2 and TiO2 and the heating temperature. These particles have a crystalline composition consisting of specific proportions of Ti4O7 and γ-Ti3O5.

[0007] In other words, one aspect of the present invention is a method for producing particles, comprising the step of heating a mixture containing TiH2 and TiO2 at 700 to 950°C, wherein the molar ratio of TiO2 to TiH2 in the mixture is 5.0 to 6.8. In this step, the mixture may be heated under an Ar gas atmosphere.

[0008] Another aspect of the present invention is a particle having a crystalline composition consisting of Ti4O7 and γ-Ti3O5, with a molar ratio of γ-Ti3O5 to Ti4O7 of 0.01 or more. This particle is L * a * b *In the color space, a * value may be 0.2 or less, and b * value may be 0.0 or less. The total content of Na, K, and P in the particles may be 2000 mass ppm or less.

[0009] Another aspect of the present invention is a dispersion containing the above particles and a dispersion medium.

Advantages of the Invention

[0010] According to one aspect of the present invention, particles of titanium lower oxide having a novel crystal composition can be obtained. Thereby, it becomes easy to adjust the black color of a dispersion containing particles of titanium lower oxide (for example, a resin composition containing particles of titanium lower oxide and a resin).

Brief Description of the Drawings

[0011] [Figure 1] It is the measurement result of X-ray diffraction in Examples 1 to 3 and Comparative Example 1. [Figure 2] It is the measurement result of X-ray diffraction in Examples 4 to 7. [Figure 3] It is the measurement result of X-ray diffraction in Examples 8 to 10 and Comparative Example 2. [Figure 4] It is the measurement result of X-ray diffraction in Examples 11 to 12 and Comparative Examples 3 to 4.

Embodiments for Carrying Out the Invention

[0012] One embodiment of the present invention is a method for producing particles (hereinafter also referred to as "titanium lower oxide particles") having a specific crystal composition (details will be described later) composed of Ti4O7 and γ-Ti3O5. This production method includes a step of heating a mixture containing TiH2 and TiO2 (heating step).

[0013] The mixture used in the heating process includes, for example, powdered TiH2 and powdered TiO2. The mixture may be a powder that is not formed into pellets or the like (containing powdered TiH2 and TiO2 in their original state). The properties of the powdered TiH2 and TiO2 can be selected as appropriate. For example, the particle size of the powdered TiH2 and TiO2 is selected according to the desired particle size of the lower titanium oxide particles. The mixture may contain only TiH2 and TiO2, or only TiH2, TiO2 and unavoidable impurities. Examples of unavoidable impurities include Al2O3, ZrO2, and C (carbon). The total amount of TiH2 and TiO2 in the mixture may be 90% by mass or more, 95% by mass or more, or 99% by mass or more, based on the total amount of the mixture.

[0014] The molar ratio of TiO2 to TiH2 in the mixture (moles of TiO2 / moles of TiH2) is between 5.0 and 6.8. If this molar ratio is less than 5.0, Ti4O7 will not be formed in the resulting particles. In this case, the lower-order titanium oxide particles tend to exhibit a blackish-blue-purple color. If this molar ratio exceeds 6.8, γ-Ti3O5 will not be formed in the resulting particles. In this case, the lower-order titanium oxide particles tend to exhibit a light blackish-blue-green color. There is a tendency for a reddish tint to be present when only γ-Ti3O5 is present, and a lighter black color when only Ti4O7 is present.

[0015] The larger the above molar ratio, the higher the proportion of Ti4O7 and the lower the proportion of γ-Ti3O5 in the resulting particles. The lower limit of the molar ratio may be 5.1 or higher, 5.2 or higher, 5.3 or higher, 5.4 or higher, 5.5 or higher, 5.6 or higher, 5.7 or higher, 5.8 or higher, 5.9 or higher, 6.0 or higher, 6.1 or higher, or 6.2 or higher. The upper limit of the molar ratio may be 6.7 or lower, 6.6 or lower, 6.5 or lower, 6.4 or lower, 6.3 or lower, 6.2 or lower, 6.1 or lower, 6.0 or lower, 5.9 or lower, 5.8 or lower, 5.7 or lower, 5.6 or lower, or 5.5 or lower.

[0016] In the heating process, for example, the mixture is heated to 700-950°C in an electric furnace. This reduces titanium dioxide, and the desired lower titanium oxides (Ti4O7 and γ-Ti3O5) are generated in the resulting particles. If the heating temperature is below 700°C, Ti4O7 and γ-Ti3O5 will not be generated in the resulting particles, for example, Ti n O 2n-1 There is a risk that (n>4) will be generated. If the heating temperature exceeds 950°C, γ-Ti3O5 may not be generated in the resulting particles, and instead, for example, α-Ti3O5 and β-Ti3O5 may be generated. The upper limit of the heating temperature may be 940°C or lower, 930°C or lower, 920°C or lower, 910°C or lower, or 900°C or lower.

[0017] The mixture is heated, for example, under an inert gas atmosphere or under vacuum. The inert gas may be Ar gas or N2 gas, which makes it easier to obtain lower-order titanium oxide particles having the desired crystal composition (for example, TiO in lower-order titanium oxide particles). x From the viewpoint of further suppressing the generation of (x≧1.75), Ar gas is preferred. If the mixture is heated under vacuum, the degree of vacuum may be, for example, 500 Pa or less.

[0018] The heating time may be, for example, 1 hour or more, 2 hours or more, or 4 hours or more, from the viewpoint of allowing the reduction reaction to proceed sufficiently, and may be, for example, 24 hours or less, 18 hours or less, or 12 hours or less, from the viewpoint of moderately suppressing the growth of lower-order titanium oxide particles and making it easier to recover in powder form.

[0019] In one embodiment, this manufacturing method may further include a step of washing the lower-order titanium oxide particles (washing step). The washing step can remove impurities. Washing is carried out by, for example, at least one selected from the group consisting of hot water, alcohol, and organic acid. The alcohol may be, for example, methanol, ethanol, or a mixture thereof. The organic acid may be, for example, acetic acid. Washing with an organic acid is preferable from the viewpoint of suppressing the incorporation of ionic impurities such as halide ions into the lower-order titanium oxide powder.

[0020] This manufacturing method preferably further comprises a step of grinding the lower titanium oxide particles after the heating step (grinding step). Examples of grinding methods in the grinding step include methods using various grinding machines such as mortars, ball mills, jet mills, and fine mills. The grinding step may be performed once or two or more times. If the grinding step is performed two or more times, the grinding methods used in each grinding step may be different. By performing the grinding step, the chromaticity and specific surface area of ​​the lower titanium oxide particles can be adjusted.

[0021] If this manufacturing method includes a washing step and a grinding step, the order of these steps is arbitrary. That is, this manufacturing method may include a heating step, a washing step, and a grinding step in this order, or it may include a heating step, a grinding step, and a washing step in this order. In the former case, a step of drying the lower titanium oxide particles (drying step) may be further carried out between the washing step and the grinding step. The drying temperature in the drying step may be, for example, 100°C or higher and 200°C or lower. The drying time may be, for example, 10 hours or higher and 20 hours or lower.

[0022] The lower-order titanium oxide particles obtained by the manufacturing method described above have a crystalline composition consisting of Ti4O7 and γ-Ti3O5. A crystalline composition consisting of Ti4O7 and γ-Ti3O5 means that the crystalline composition contains substantially only Ti4O7 and γ-Ti3O5. The fact that the lower-order titanium oxide particles have a crystalline composition consisting of Ti4O7 and γ-Ti3O5 can be confirmed by measuring the crystalline composition of the lower-order titanium oxide particles by X-ray diffraction (XRD) and observing diffraction peaks substantially attributable to Ti4O7 and γ-Ti3O5, respectively. These lower-order titanium oxide particles may consist of a mixed phase comprising two crystalline phases, Ti4O7 and γ-Ti3O5, within a single particle.

[0023] In the crystal composition of the low-order titanium oxide particles, the molar ratio of γ-Ti3O5 to Ti4O7 (content of γ-Ti3O5 (mol) / content of Ti4O7 (mol)) is 0.01 or more. The molar ratio may be 0.05 or more, 0.20 or more, 0.70 or more, or 1.0 or more, and may also be 99 or less, 50 or less, 20 or less, 10 or less, or 5 or less. The molar ratio is calculated by the following formula. Molar ratio (γ-Ti3O5 / Ti4O7) = (M1 / F1) / (M2 / F2) In the formula, M1 represents the mass fraction of γ-Ti3O5 in the low-order titanium oxide particles, F1 represents the formula weight of γ-Ti3O5 (=223.60), M2 represents the mass fraction of Ti4O7 in the low-order titanium oxide particles, and F2 represents the formula weight of Ti4O7 (=303.46).

[0024] The mass fraction (M1) of γ-Ti3O5 and the mass fraction (M2) of Ti4O7 in the low-order titanium oxide particles are calculated by performing Rietveld analysis on the X-ray diffraction pattern. Specifically, using Rietveld method software (for example, PDXL2, integrated powder X-ray analysis software manufactured by Rigaku Corporation), and using crystal structure data from the crystal structure database (Pearson's Crystal Data), 1250094 for Ti4O7 (Journal of Solid State Chemistry 3, 340(1971)) and 1900755 for γ-Ti3O5 (Journal of Solid State Chemistry 20, 29(1977)), the above mass fractions are calculated.

[0025] Due to having the above crystal composition, the low-order titanium oxide particles exhibit black with a predetermined chromaticity. The L * a * b * value in the color space of L * is preferably 13.0 or less, more preferably 12.0 or less, still more preferably 11.0 or less, and may be, for example, 4.0 or more, 5.0 or more, or 6.0 or more. The L * a * b *a in color space * The value is preferably -3.0 or higher, more preferably -2.0 or higher, preferably 0.2 or lower, and even more preferably 0.0 or lower. L of lower titanium oxide particles * a * b * b in color space * The value is preferably -8.0 or higher, more preferably -6.0 or higher, even more preferably -4.0 or higher, preferably 0.0 or lower, and more preferably -2.0 or lower.

[0026] L * a * b * L in color space * value, a * Value and b * The values ​​are measured using a colorimeter (e.g., ZE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.)). More specifically, after zeroing with a dark-field cylinder, standard calibration is performed using a standard white plate (X=91.71, Y=93.56, Z=110.52). Then, approximately 3g of low-order titanium oxide particles are placed in a 35φ×15H round cell and measured.

[0027] The specific surface area of ​​lower-order titanium oxide particles is 0.25 m². 2 / g or more, 1m 2 / g or more, 2m 2 / g or more, 3m 2 / g or more, or 4m 2 / g or more, 20m 2 / g or less, 10m 2 / g or less, or 8m 2 The value may be less than or equal to / g. The specific surface area of ​​the lower-order titanium oxide particles is measured using a specific surface area analyzer (e.g., Macsorb HM model-1201, manufactured by Mountech). Degassing is performed at 200°C for 10 minutes using nitrogen gas flow (atmospheric pressure), and the specific surface area is measured under the condition of n=2 with an equilibrium relative pressure of approximately 0.3 by nitrogen gas adsorption.

[0028] The lower the amount of impurities in the lower titanium oxide particles, the better. The Al content in the lower titanium oxide particles is preferably 200 ppm by mass or less, 50 ppm by mass or less, or 20 ppm by mass or less. The B content in the lower titanium oxide particles is preferably 50 ppm by mass or less, 30 ppm by mass or less, or 10 ppm by mass or less. The Ba content in the lower titanium oxide particles is preferably 50 ppm by mass or less, 10 ppm by mass or less, or 5 ppm by mass or less. The Ca content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 50 ppm by mass or less, or 10 ppm by mass or less. The Cd content in the lower titanium oxide particles is preferably 10 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Co content in the lower titanium oxide particles is preferably 10 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Cr content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 10 ppm by mass or less, or 5 ppm by mass or less. The Cu content in the lower titanium oxide particles is preferably 200 ppm by mass or less, 50 ppm by mass or less, or 10 ppm by mass or less. The Fe content in the lower titanium oxide particles is preferably 200 ppm by mass or less, 50 ppm by mass or less, or 10 ppm by mass or less. The K content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 5 ppm by mass or less, or 1 ppm by mass or less. The Li content in the lower titanium oxide particles is preferably 20 ppm by mass or less, 2 ppm by mass or less, or 0.5 ppm by mass or less.

[0029] The Mg content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 10 ppm by mass or less, or 1 ppm by mass or less. The Mn content in the lower titanium oxide particles is preferably 10 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Mo content in the lower titanium oxide particles is preferably 10 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Na content in the lower titanium oxide particles is preferably 50 ppm by mass or less, 10 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Ni content in the lower titanium oxide particles is preferably 50 ppm by mass or less, 20 ppm by mass or less, or 10 ppm by mass or less. The P content in the lower titanium oxide particles is preferably 200 ppm by mass or less, 30 ppm by mass or less, 10 ppm by mass or less, or 5 ppm by mass or less. The Pb content in the lower titanium oxide particles is preferably 50 ppm by mass or less, 5 ppm by mass or less, or 2 ppm by mass or less. The Sb content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 20 ppm by mass or less, 10 ppm by mass or less, or 2 ppm by mass or less. The Si content in the lower titanium oxide particles is preferably 1000 ppm by mass or less, 100 ppm by mass or less, 30 ppm by mass or less, 20 ppm by mass or less, or 2 ppm by mass or less. The Zn content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 10 ppm by mass or less, or 2 ppm by mass or less. The Zr content in the lower titanium oxide particles is preferably 100 ppm by mass or less, 20 ppm by mass or less, or 2 ppm by mass or less.

[0030] The total content of Na, K, and P in the lower titanium oxide particles is preferably 2000 ppm by mass or less, 1000 ppm by mass or less, 500 ppm by mass or less, or 100 ppm by mass or less. For example, the total content of Pb, Cd, and Cr is preferably 200 ppm by mass or less, 100 ppm by mass or less, 50 ppm by mass or less, or 30 ppm by mass or less. The amount of impurities in the lower titanium oxide particles is measured using Agilent 5110 ICP-OES (manufactured by Agilent Technologies, Inc.).

[0031] The aforementioned low-grade titanium oxide particles are suitably used as pigments (coloring fillers) such as black pigments. Such pigments (coloring fillers) are suitably used as colorants in cosmetics, electronic components such as semiconductors, and coatings such as paints and inks.

[0032] When lower-order titanium oxide particles are used in the applications described above, they are used dispersed in a dispersion medium, for example. That is, another embodiment of the present invention is a dispersion containing the lower-order titanium oxide particles described above and a dispersion medium for dispersing the lower-order titanium oxide particles.

[0033] The dispersion medium is appropriately selected according to the application of the dispersion and may be, for example, water, alcohol, ketone, ester, resin, etc. Examples of resins include epoxy resin, silicone resin, phenolic resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, fully aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS (acrylonitrile butadiene styrene) resin, AAS (acrylonitrile acrylic rubber styrene) resin, AES (acrylonitrile ethylene propylene diene rubber styrene) resin, etc.

[0034] The content of lower-order titanium oxide particles in the dispersion is appropriately selected depending on the application of the dispersion, and may be, for example, 5% by mass or more and 90% by mass or less, based on the total amount of the dispersion. The content of the dispersion medium in the dispersion is appropriately selected depending on the application of the dispersion, and may be, for example, 10% by mass or more and 95% by mass or less, based on the total amount of the dispersion. [Examples]

[0035] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0036] <Production of lower-order titanium oxide particles> [Example 1] 10g of TiO2 powder (Toho Titanium Co., Ltd., HT0514: 99.9% purity) and 1.249g of TiH2 powder (Toho Tech Co., Ltd., TCH450: 99.8% purity) (TiO2 / TiH2 = 5.0 / 1 (molar ratio)) were mixed in an Eich mixer (manufactured by Nippon Eich Co., Ltd.) to obtain a mixture. This mixture was transferred to an alumina crucible and heated in an electric furnace (Fuji Denpa Kogyo Co., Ltd., High Multi 10000) under an Ar atmosphere at a rate of 10°C / min to 900°C for 12 hours. After heating, the obtained powder was ground in a mortar for 5 minutes to obtain black lower-order titanium oxide particles.

[0037] [Examples 2-10] Black lower-order titanium oxide particles were obtained in the same manner as in Example 1, except that the amount of TiH2 powder was changed so that the molar ratio of TiO2 to TiH2 (TiO2 / TiH2) was as shown in Table 1.

[0038] [Example 11] Black lower-order titanium oxide particles were obtained in the same manner as in Example 6, except that the heating time was changed to 4 hours.

[0039] [Example 12] Black lower-order titanium oxide particles were obtained in the same manner as in Example 6, except that the heating temperature was changed as shown in Table 1.

[0040] [Comparative Examples 1, 2] Particles were obtained in the same manner as in Example 1, except that the amount of TiH2 powder was changed so that the molar ratio of TiO2 to TiH2 (TiO2 / TiH2) was as shown in Table 1.

[0041] [Comparative Examples 3, 4] Particles were obtained in the same manner as in Example 6, except that the heating temperature was changed as shown in Table 1.

[0042] <X-ray Diffraction Measurement> Powder X-ray diffraction measurements were performed on each of the particles of the above Examples and Comparative Examples. Specifically, using a sample horizontal multi-purpose X-ray diffractometer (manufactured by Rigaku Corporation, RINT-UltimaIV), diffraction patterns were measured under the following measurement conditions. The obtained X-ray diffraction patterns are shown in FIGS. 1 to 4. (Measurement Conditions) X-ray source: Cu-Kα ray (λ = 1.54184 Å) Tube voltage: 40 kV, tube current: 40 mA Optical conditions during measurement: Divergence slit = 2 / 3° Scattering slit: 8 mm Receiving slit = 0.15 mm Position of diffraction peak = 2θ (diffraction angle) Scan speed: 4.0° (2θ) / min, continuous scan Measurement range: 2θ = 10° to 80°

[0043] Subsequently, the mass fractions (mass %) of Ti4O7 and γ-Ti3O5 in the obtained particles were calculated using Rietveld method software (manufactured by Rigaku Corporation, integrated powder X-ray analysis software PDXL2). The crystal structure was obtained from the crystal structure database (Pearson's Crystal Data), using 1250094 for Ti4O7 (Journal of Solid State Chemistry 3, 340 (1971) ), and 1900755 for γ-Ti3O5 (Journal of Solid State Chemistry 20, 29 (1977)). Also, the mass fraction M1 of γ-Ti3O5 and the mass fraction M of Ti4O7 From 2, the molecular weight of γ-Ti3O5 F1 (=223.60) and the molecular weight of Ti4O7 F2 (=303.46), the molar ratio of γ-Ti3O5 to Ti4O7 (γ-Ti3O5 / Ti4O7) is given by the following formula: Molar ratio (γ-Ti3O5 / Ti4O7) = (M1 / F1) / (M2 / F2) The calculation was performed using the method described below. The results are shown in Table 1.

[0044] <Measurement of chromaticity> For each particle in the above examples and comparative examples, the chromaticity (L) was measured using a colorimeter ZE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). * a * b * L in color space * value, a * Value and b * The chromaticity was measured. More specifically, first, zero correction was performed using a dark-field cylinder, and then standardization was performed using a standard white plate (X=91.71, Y=93.56, Z=110.52). Next, approximately 3g of particles were placed in a 35φ×15H round cell, and the chromaticity was measured. The results are shown in Table 1. As can be seen from the results of this test, by controlling the molar ratio of γ-Ti3O5 to Ti4O7 (γ-Ti3O5 / Ti4O7) within an appropriate range, it was possible to adjust to black of various chromaticities.

[0045] <Elemental analysis> Elemental analysis was also performed on each particle in Examples 1 to 12 using Agilent 5110 ICP-OES (manufactured by Agilent Technologies, Inc.). Specifically, 0.1 g of particles was weighed into a platinum crucible, 1 ml each of HF and HCl were added, and pressurized acid decomposition was carried out at 150°C for 4 hours. After that, the volume was reduced to 6 ml, and after confirming that there were no unwanted residues, ICP emission spectroscopy was performed. The results are shown in Table 2. In Table 2, "ND" means that the result was below the detection limit, and the number in parentheses means that the result was below the quantification limit. The detection limit and quantification limit are as follows. (Detection limit) Li, Na, Mg, K, and Ca: 0.5 ppm by mass P:5 mass ppm Other elements: 2 ppm by mass (lower limit of quantification) Li, Na, Mg, K, and Ca: 2 ppm by mass P: 10 mass ppm Other elements: 5 ppm by mass

[0046] [Table 1]

[0047] [Table 2]

Claims

1. Ti ４ O ７ and γ-Ti ３ O ５ Having a crystalline composition consisting of the Ti ４ O ７ The γ-Ti ３ O ５ A method for producing particles in which the molar ratio is 0.01 or greater, TiH ２ and TiO ２ comprising a step of heating a mixture containing the same at 700 to 950 ° C in an Ar gas atmosphere, The TiH contained in the mixture ２ The TiO ２ The molar ratio is 5.0 to 6.

8. The aforementioned molar ratio is obtained by performing Rietveld analysis on the X-ray diffraction pattern. ４ O ７ Let M2 be the mass fraction of the γ-Ti ３ O ５ When the mass fraction of is M1, it is a value calculated from the following formula: Molar ratio (γ-Ti ３ O ５ / Ti ４ O7) = (M1 / 223.60) / (M2 / 303.46) The aforementioned Rietveld analysis was performed using the integrated powder X-ray analysis software PDXL2, with the crystal structure database being Pearson's Crystal Data, reference number 1250094, Ti ４ O ７ , and γ-Ti of reference number 1900755 ３ O ５ A method for manufacturing particles using crystal structure data.

2. Ti ４ O ７ and γ-Ti ３ O ５ It has a crystalline composition consisting of, The Ti ４ O ７ The γ-Ti ３ O ５ A particle having a molar ratio of 0.01 or greater, In the L*a*b* color space, the a* value is 0.2 or less, and the b* value is 0.0 or less. The aforementioned molar ratio is obtained by performing Rietveld analysis on the X-ray diffraction pattern. ４ O ７ Let M2 be the mass fraction of the γ-Ti ３ O ５ When the mass fraction of is M1, it is a value calculated from the following formula: Molar ratio (γ-Ti ３ O ５ / Ti ４ O7) = (M1 / 223.60) / (M2 / 303.46) The aforementioned Rietveld analysis was performed using the integrated powder X-ray analysis software PDXL2, with the crystal structure database being Pearson's Crystal Data, reference number 1250094, Ti ４ O ７ , and γ-Ti of reference number 1900755 ３ O ５ Particles using crystal structure data.

3. The particle according to claim 2, wherein the total content of Na, K, and P in the particle is 2000 ppm by mass or less.

4. A mixture comprising particles and a dispersion medium, The particles have a crystalline composition consisting of Ti₄O₃ and γ-Ti₃O₅. A particle having a molar ratio of γ-Ti3O5 to Ti4O7 of 0.01 or more, The aforementioned molar ratio is a value calculated from the following formula, where M2 is the mass fraction of Ti4O7 obtained by Rietveld analysis of the X-ray diffraction pattern, and M1 is the mass fraction of γ-Ti3O5. Molar ratio (γ-Ti 3 O 5 / Ti 4 O7) = (M1 / 223.60) / (M2 / 303.46) The Rietveld analysis described above uses the integrated powder X-ray analysis software PDXL2 and the crystal structure data of Ti₄O₃ (reference number 1250094) and γ-Ti₃O₅ (reference number 1900755) from Pearson's Crystal Data as the crystal structure database for the dispersion.

5. The dispersion according to claim 4, wherein in the L*a*b* color space, the a* value is 0.2 or less and the b* value is 0.0 or less.

6. The dispersion according to claim 4 or 5, wherein the total content of Na, K, and P in the particles is 2000 ppm by mass or less.

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