Aluminum magnesium scandium nanometer powder and preparation method thereof

Abstract

The application relates to a kind of scandium aluminate magnesium nano-powder and its preparation method, the preparation method includes the following steps: S1: respectively preparing scandium salt solution, aluminium salt solution, magnesium salt solution and being mixed uniformly according to chemical formula ScAlMgO4 proportioning;S2: using ammonium salt solution or ammonia water to adjust the pH value of the solution after uniform mixing in S1 is 9-12, then hydrothermal reaction is carried out;S3: after hydrothermal reaction, the hydrothermal reaction product is filtered, cleaned, dried, grinded, and scandium aluminate magnesium nano-powder is obtained.Compared with prior art, the present application can produce pure phase ScAlMgO4 nano-powder raw material on a large scale, the whole preparation process does not need to be sintered at high temperature through muffle furnace, which saves energy, reduces cost, and also avoids the change of ScAlMgO4 raw material composition caused by MgO volatilization during high-temperature sintering.

Description

Technical Field

[0001] This invention belongs to the field of scandium aluminate preparation technology, and in particular relates to a scandium aluminate nanopowder and its preparation method. Background Technology

[0002] Since the beginning of the 21st century, third-generation wide-bandgap semiconductor materials (E) represented by gallium nitride (GaN) and zinc oxide (ZnO) have emerged. g Scandium magnesium aluminate (SMA) with a thermal expansion coefficient (TEC) >2.3 eV is gradually becoming a core supporting material for the development of the semiconductor industry. Currently, GaN-based and ZnO-based devices are mainly grown heteroepitaxially on single-crystal Si and sapphire substrates. Due to lattice mismatch and thermal mismatch between the substrate material and the epitaxial layer, a large number of defects and dislocations are generated inside the device, which has a restrictive effect on the device performance. Scandium magnesium aluminate (ScAlMgO4) has relatively small lattice mismatches with GaN and ZnO (mismatch rates of ~1.4% and ~0.09%, respectively) and good matching of thermal expansion coefficients, and is considered a natural substrate material for GaN and ZnO.

[0003] Synthesizing pure-phase ScAlMgO4 raw materials is the primary challenge in growing single crystals. Since ScAlMgO4 is a ternary composite oxide, it requires high-purity Sc2O3, Al2O3, and MgO powders as raw materials. During solid-state sintering, impurity phases are generated between any two components: MgSc2O4 forms above 2270K, ScAlO3 forms at 2000K, and MgAl2O4 can be generated at only 1670K. Even with prolonged high-temperature sintering, it is difficult to synthesize pure-phase ScAlMgO4 raw materials. Sol-gel and co-precipitation methods have been used for the synthesis of pure-phase ScAlMgO4; however, these methods ultimately require high-temperature sintering in a muffle furnace. In large-scale production, this not only causes high-temperature volatilization of MgO leading to compositional changes but also significantly increases costs. This invention employs a hydrothermal method to prepare ScAlMgO4 nanopowder, which can not only synthesize nanoscale powders but also cultivate microcrystals. Furthermore, the preparation process completely avoids high-temperature sintering in a muffle furnace, reducing costs and saving energy.

[0004] CN101693548B discloses a scandium aluminate magnesium oxide nanopowder and its preparation method. This invention uses an aqueous solution of inorganic salts as raw material and citric acid as a chelating agent. The liquid, after cross-linking and chelation with citric acid, is directly heated, and the solution passes through a sol-gel state and is ultimately directly converted into nanocrystalline powder. However, this invention still requires high-temperature calcination at 550-1100℃, which would significantly increase the cost for large-scale production. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a scandium aluminate nanopowder and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The first aspect of this invention provides a method for preparing scandium aluminate magnesium oxide nanopowder, comprising the following steps:

[0008] S1: Prepare scandium salt solution, aluminum salt solution, and magnesium salt solution separately, and mix them evenly according to the chemical formula ScAlMgO4.

[0009] S2: Adjust the pH of the solution after uniform mixing in S1 to 9-12 using ammonium salt solution or ammonia water, and then carry out the hydrothermal reaction.

[0010] S3: After the hydrothermal reaction is completed, the hydrothermal reaction product is filtered, washed, dried and ground to obtain scandium magnesium aluminum oxide nanopowder.

[0011] As a preferred embodiment of the present invention, ammonia is used to adjust the pH in S2, preferably using ammonia with a mass fraction of 20%.

[0012] Further, in S1, the scandium salt solution is one or more of scandium chloride, scandium nitrate, scandium sulfate, scandium hydroxide, or scandium fluoride.

[0013] In a preferred embodiment of the present invention, in S1, the scandium salt solution is selected as scandium nitrate.

[0014] It should be noted that the scandium salt solution mentioned above includes Sc2O3 added to acid and heated and stirred to dissolve, such as Sc2O3 added to hydrochloric acid and heated and stirred to dissolve to obtain scandium chloride.

[0015] Furthermore, in S1, the concentration of the scandium salt solution is 0.01–5 mol / L.

[0016] Further, in S1, the aluminum salt solution is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum hydroxide, or aluminum fluoride.

[0017] In a preferred embodiment of the present invention, in S1, the aluminum salt solution is selected as aluminum nitrate.

[0018] It should be noted that the aluminum salt solution mentioned above includes Al2O3 added to acid and heated and stirred to dissolve it, such as Al2O3 added to hydrochloric acid and heated and stirred to dissolve it to obtain aluminum chloride.

[0019] Furthermore, in S1, the concentration of the aluminum salt solution is 0.01–5 mol / L.

[0020] Further, in S1, the magnesium salt solution is one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium hydroxide, or magnesium fluoride.

[0021] In a preferred embodiment of the present invention, in S1, the magnesium salt solution is selected as magnesium nitrate.

[0022] It should be noted that the magnesium salt solution mentioned above includes MgO added to acid and heated and stirred to dissolve it, such as MgO added to hydrochloric acid and heated and stirred to dissolve it to obtain magnesium chloride.

[0023] Furthermore, in S1, the concentration of the magnesium salt solution is 0.01–5 mol / L.

[0024] Furthermore, in S2, the mass fraction of the ammonium salt solution used to adjust the pH is 10-30%.

[0025] Furthermore, in S3, the specific conditions for the hydrothermal reaction are: reaction temperature 70-200℃, reaction time 10-40h.

[0026] In a preferred embodiment of the present invention, in step S3, the reaction temperature is 70°C and the reaction time is 20 hours.

[0027] A second aspect of the present invention provides a scandium aluminate nanoparticle, which is obtained by the above-described preparation method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The preparation method of the present invention can produce pure phase ScAlMgO4 nanopowder raw materials on a large scale. The entire preparation process does not require high-temperature sintering in a muffle furnace, which saves energy, reduces costs, and avoids the volatilization of MgO caused by high-temperature sintering, which would cause changes in the composition of the synthesized ScAlMgO4 raw materials.

[0030] (2) The ScAlMgO4 nanopowder prepared by the hydrothermal method of this invention has a more uniform morphology and is suitable for the preparation and research of microstructure.

[0031] (3) The ScAlMgO4 nanopowder prepared by the hydrothermal method of the present invention has a more uniform morphology and can be applied to multiple fields, such as the preparation of artificial crystals, thin films, ceramics, glass and other raw materials, and can also be used as a doping material for fluorescent nanopowders.

[0032] (4) The present invention uses ammonia or ammonium salt to adjust the pH. If sodium hydroxide is used for adjustment, the generated ScAlMgO4 raw material contains Na element impurities, and the purity of the raw material is greatly reduced. Therefore, the present invention has no performance impact on the subsequent preparation of artificial crystals, thin films, ceramics, glass and fluorescent nanopowders. Attached Figure Description

[0033] Figure 1The images show the XRD patterns of the raw material powders synthesized in Example 1 and Comparative Example 1 of this invention, as well as the ScAlMgO4 standard card.

[0034] Figure 2 This is a SEM image of the raw material synthesized in Example 1 of the present invention.

[0035] Figure 3 This is the EDS energy spectrum of the raw material synthesized in Example 1 of the present invention.

[0036] Figure 4 This is a SEM image of ScAlMgO4 synthesized in Comparative Example 2 of this invention. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Unless otherwise specified, all raw materials used in this invention are commercially available or can be prepared using conventional methods in the art.

[0039] Example 1

[0040] Weigh out Sc2O3, Al2O3, and MgO raw materials with a purity of 5N according to stoichiometric ratios, and place them in their respective beakers. Add nitric acid with a mass fraction of 68% and a volume five times that of the powder, and heat to 70°C on a magnetic stirrer until homogeneous. After the powder raw materials are completely dissolved in the acid and the solution becomes clear, cool to room temperature. Using a burette, add a 20% ammonia solution dropwise to the room temperature solution at a rate of 3 mL / min, stirring constantly, and adjust the pH to 10. Transfer the entire suspension in the beaker to a polytetrafluoroethylene high-pressure reactor, heat to 70°C, and let stand for 20 hours. Remove the reacted raw materials, filter, wash three times with deionized water and alcohol respectively, dry, and grind into powder. The resulting white powder is the synthesized ScAlMgO4 nanoparticles.

[0041] like Figure 1 As shown, the synthesized ScAlMgO4 nanopowder phases correspond one-to-one with the ScAlMgO4 standard card (PDF 40-1393), with no impurity phases generated.

[0042] like Figure 2 As shown, the synthesized ScAlMgO4 nanoparticles exhibit a nanoscale morphology (approximately 50 nm) under SEM, and the morphology is uniform and spherical.

[0043] like Figure 3As shown, the EDS energy spectrum of the synthesized ScAlMgO4 nanoparticles showed no other impurity elements, and the atomic percentages of Mg, Al, and Sc were 4.72±0.5 at.%, 5.17±0.5 at.%, and 5.86±0.6 at.%, respectively.

[0044] Example 2

[0045] The majority of the content is as described in Example 1, except that Sc(NO3)3, Al(NO3)3 and Mg(NO3)2 with a purity of 5N are weighed according to the stoichiometric ratio, and the raw materials are dissolved in deionized water with a volume fraction of 5 times that of the raw materials to obtain a salt solution of Sc ions, Al ions and Mg ions.

[0046] Example 3

[0047] The majority of the results were as described in Example 1, except that the solution used to adjust the pH was a 30% (w / w) aqueous solution of NH4NO3.

[0048] Example 4

[0049] The majority of the solution used to adjust the pH value was as described in Example 1, except that the solution used was a 100% aqueous solution of NH4NO3.

[0050] Example 5

[0051] The majority of the results are as described in Example 1, except that the polytetrafluoroethylene high-pressure reactor is kept at 150°C for 10 hours.

[0052] Example 6

[0053] The majority of the results are as described in Example 1, except that the polytetrafluoroethylene high-pressure reactor is kept at 200°C for 40 hours.

[0054] Comparative Example 1

[0055] The majority of the solutions were as described in Example 1, except that the pH of the solution was adjusted to 8.

[0056] like Figure 1 As shown, the main phase in the raw materials synthesized in Comparative Example 1 is the ScAlMgO4 phase (marked as phase A in the figure). In addition, spinel MgAl2O4 phase (marked as phase B in the figure) and Sc2O3 phase (marked as phase C in the figure) are also synthesized.

[0057] Comparative Example 2

[0058] The majority of the reactions were as described in Example 1, except that the hydrothermal reaction was replaced with calcination at 800°C for 2 hours in a muffle furnace.

[0059] Compared to hydrothermal reactions in a polytetrafluoroethylene high-pressure reactor, the SME photograph of ScAlMgO4 after high-temperature sintering in a muffle furnace is shown below. Figure 4 As shown, the morphology is irregular and mostly submicron in size, with numerous cluster structures. This process significantly impacts the performance of subsequent fluorescent nanopowder preparation and microstructure. Furthermore, the use of a high-temperature muffle furnace greatly increases the cost of large-scale production of ScAlMgO4 raw materials.

[0060] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing scandium aluminate magnesium oxide nanopowder, characterized in that, Includes the following steps: S1: Prepare scandium salt solution, aluminum salt solution, and magnesium salt solution separately, and mix them evenly according to the chemical formula ScAlMgO4. S2: Adjust the pH of the solution after uniform mixing in S1 to 9-12 using ammonium salt solution or ammonia water, and then carry out a hydrothermal reaction at a reaction temperature of 70 ℃ for 10-40 h. S3: After the hydrothermal reaction is completed, the hydrothermal reaction product is filtered, washed, dried and ground to obtain scandium magnesium aluminum oxide nanopowder; In S1, the scandium salt solution is one or more of scandium chloride, scandium nitrate, scandium sulfate, or scandium fluoride; In S1, the concentration of the scandium salt solution is 0.01~5 mol / L; In S1, the aluminum salt solution is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, or aluminum fluoride; In S1, the concentration of the aluminum salt solution is 0.01~5 mol / L; In S1, the magnesium salt solution is one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, or magnesium fluoride; In S1, the concentration of the magnesium salt solution is 0.01~5 mol / L; In S2, the mass fraction of the ammonium salt solution used to adjust the pH is 10-30%.

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