JP4195931B2 - Scandium compound ultrafine particles and method for producing the same - Google Patents
Scandium compound ultrafine particles and method for producing the same Download PDFInfo
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- 239000011882 ultra-fine particle Substances 0.000 title claims description 72
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 150000003326 scandium compounds Chemical class 0.000 title description 3
- HYXGAEYDKFCVMU-UHFFFAOYSA-N scandium oxide Chemical compound O=[Sc]O[Sc]=O HYXGAEYDKFCVMU-UHFFFAOYSA-N 0.000 claims description 60
- 239000002245 particle Substances 0.000 claims description 33
- NYMLCLICEBTBKR-UHFFFAOYSA-H scandium(3+);tricarbonate Chemical compound [Sc+3].[Sc+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O NYMLCLICEBTBKR-UHFFFAOYSA-H 0.000 claims description 27
- 229910052706 scandium Inorganic materials 0.000 claims description 24
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 16
- -1 scandium ion Chemical class 0.000 claims description 15
- 150000001447 alkali salts Chemical class 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 11
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 238000001354 calcination Methods 0.000 claims description 9
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims description 9
- 150000003839 salts Chemical class 0.000 claims description 9
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 7
- 239000001099 ammonium carbonate Substances 0.000 claims description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000006386 neutralization reaction Methods 0.000 claims description 6
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 5
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- 150000008043 acidic salts Chemical class 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 239000011260 aqueous acid Substances 0.000 claims 1
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- 239000002243 precursor Substances 0.000 description 46
- 230000002776 aggregation Effects 0.000 description 12
- 239000000919 ceramic Substances 0.000 description 11
- 239000000843 powder Substances 0.000 description 11
- 238000004220 aggregation Methods 0.000 description 9
- 239000013078 crystal Substances 0.000 description 9
- 239000002244 precipitate Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- 239000000203 mixture Substances 0.000 description 8
- 239000006185 dispersion Substances 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 6
- 229910052574 oxide ceramic Inorganic materials 0.000 description 6
- 239000011224 oxide ceramic Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000005245 sintering Methods 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- DFCYEXJMCFQPPA-UHFFFAOYSA-N scandium(3+);trinitrate Chemical compound [Sc+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O DFCYEXJMCFQPPA-UHFFFAOYSA-N 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 125000005587 carbonate group Chemical group 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 238000005054 agglomeration Methods 0.000 description 3
- 230000032683 aging Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000003472 neutralizing effect Effects 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 150000003325 scandium Chemical class 0.000 description 3
- 238000000967 suction filtration Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 235000012501 ammonium carbonate Nutrition 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011362 coarse particle Substances 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000011736 potassium bicarbonate Substances 0.000 description 2
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 2
- 235000015497 potassium bicarbonate Nutrition 0.000 description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 description 2
- 235000011181 potassium carbonates Nutrition 0.000 description 2
- 229940086066 potassium hydrogencarbonate Drugs 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 235000017550 sodium carbonate Nutrition 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000000954 titration curve Methods 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- ZPDRQAVGXHVGTB-UHFFFAOYSA-N gallium;gadolinium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Gd+3] ZPDRQAVGXHVGTB-UHFFFAOYSA-N 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- DVMZCYSFPFUKKE-UHFFFAOYSA-K scandium chloride Chemical compound Cl[Sc](Cl)Cl DVMZCYSFPFUKKE-UHFFFAOYSA-K 0.000 description 1
- 229910000346 scandium sulfate Inorganic materials 0.000 description 1
- QHYMYKHVGWATOS-UHFFFAOYSA-H scandium(3+);trisulfate Chemical compound [Sc+3].[Sc+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O QHYMYKHVGWATOS-UHFFFAOYSA-H 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
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- Compositions Of Oxide Ceramics (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
本発明は、スカンジウム化合物超微粒子及びその製造方法に関する。 The present invention relates to scandium compound ultrafine particles and a method for producing the same.
希土類元素であるスカンジウムの酸化物Ｓｃ2Ｏ3粉末はジルコニアセラミックスの安定化剤として、あるいは窒化珪素セラミックスの焼結補助剤として、また、ガドリニウムガリウムガーネット固体レーザーへのドーパントとしてなど、耐火材及び光学材料への添加剤に供せられている。また、酸化スカンジウム粉末は酸化スカンジウムセラミックスの原料として注目されている。 The rare earth element scandium oxide Sc 2 O 3 powder is used as a stabilizer for zirconia ceramics, as a sintering aid for silicon nitride ceramics, and as a dopant for gadolinium gallium garnet solid lasers. It is used as an additive to materials. Further, scandium oxide powder has attracted attention as a raw material for scandium oxide ceramics.
すなわち、酸化スカンジウムは立方晶系であるため光学的異方性がなく、５．７ｅＶと大きなバンドギャップを持ち、２４３０℃という高い融点を持つため、高性能の酸化スカンジウムセラミックスが実現されれば高出力紫外レーザーの母体材料としての応用が切り開かれる可能性がある。酸化スカンジウムは高融点であり、かつ、るつぼとの反応性が高いため引き上げ法や水熱合成法による単結晶育成は困難なため、焼結法によるセラミックスに期待が寄せられているのである。 In other words, since scandium oxide is a cubic system, it has no optical anisotropy, has a large band gap of 5.7 eV, and has a high melting point of 2430 ° C. Therefore, if a high-performance scandium oxide ceramic is realized, There is a possibility that the application of the output ultraviolet laser as a base material will be opened. Since scandium oxide has a high melting point and high reactivity with a crucible, it is difficult to grow a single crystal by a pulling method or a hydrothermal synthesis method. Therefore, there is an expectation for ceramics by a sintering method.
しかし、市販の酸化スカンジウム粉末の粒径は１０μｍ程度と大きいためこれを直接焼結することによりセラミックスを形成するのは困難である。このため、酸化スカンジウムを酸などに溶解し微小サイズのスカンジウム塩を合成し、これを酸化スカンジウムの前駆体とし、この前駆体を仮焼することにより微小サイズの酸化スカンジウム粉末を生成し、この粉末を焼結用の原料として検討する必要がある。 However, since the commercially available scandium oxide powder has a large particle size of about 10 μm, it is difficult to form ceramics by directly sintering it. For this reason, scandium oxide is dissolved in an acid or the like to synthesize a fine sized scandium salt, which is used as a precursor of scandium oxide, and this precursor is calcined to produce a fine sized scandium oxide powder. Must be studied as a raw material for sintering.
このような前駆体として従来知られているのはスカンジウムのγ相オキソハイドロオキサイド（γ−ScOOH）である。例えば、非特許文献１では前駆体としてゾルゲル法で合成
されたγ−ScOOHが報告されているが、その形状は扁平なひし形の板状であり、代表的な
形状は６６×３７×４．５ｎｍと記載されている。
Conventionally known as such a precursor is scandium γ-phase oxohydroxide (γ-ScOOH). For example, in Non-Patent Document 1, γ-ScOOH synthesized by a sol-gel method is reported as a precursor, but its shape is a flat rhomboid plate, and a typical shape is 66 × 37 × 4.5 nm. It is described.
これはγ−ScOOHが室温で容易に結晶化し、かつその結晶系が斜方晶系であるためであ
り、扁平な形状は本質的なものである。非特許文献1の３６２頁には、γ−ScOOHを７７３Kで仮焼すると立方晶系のＳｃ2Ｏ3が形成されるがその形状はγ−ScOOHのひし形板状を保っていた旨、記述されている。非特許文献１に示された酸化スカンジウムの応用は光学多層膜であったため、酸化スカンジウム膜に空隙が存在した方が空隙による応力緩和のため応用上の強度を確保できる。このような著しく形状対称性が劣っている形状により酸化スカンジウム膜に空隙ができ所望の応用に供されている。
This is because γ-ScOOH is easily crystallized at room temperature and its crystal system is orthorhombic, and the flat shape is essential. On page 362 of Non-Patent Document 1, it is described that when γ-ScOOH is calcined at 773 K, cubic Sc 2 O 3 is formed, but the shape is maintained as a rhombus plate of γ-ScOOH. ing. Since the application of scandium oxide shown in Non-Patent Document 1 is an optical multilayer film, the presence of voids in the scandium oxide film can ensure the applied strength because stress relaxation due to the voids. Such a shape having extremely inferior shape symmetry creates voids in the scandium oxide film and is used for a desired application.
しかし、セラミックス原料としての目的には形状対称性の劣った形状は空隙を生じやすく不都合である。また、純度を改善するために７００℃から９００℃の高温で仮焼すると４．５ｎｍと薄い板状の酸化スカンジウムは凝集しやすく超微粒子構造を失ってしまう。このように凝集してしまうと焼結はますます困難になり、空隙の少ない高密度の酸化スカンジウムセラミックスは実現困難となる。また、凝集した酸化スカンジウム粉末は添加剤としての応用に関しても母体への均一添加が困難なため好ましくない。このように、従来知られていた酸化スカンジウム粉末及びその前駆体は添加剤やセラミックス原料としての応用に供するには構造的に不都合があった。 However, for the purpose as a ceramic raw material, a shape with inferior shape symmetry tends to cause voids, which is inconvenient. Further, when calcined at a high temperature of 700 ° C. to 900 ° C. in order to improve the purity, the plate-like scandium oxide as thin as 4.5 nm tends to aggregate and lose the ultrafine particle structure. When such agglomeration occurs, sintering becomes more difficult, and high-density scandium oxide ceramics with less voids become difficult to realize. Agglomerated scandium oxide powder is also not preferred for application as an additive because it is difficult to uniformly add to the matrix. Thus, conventionally known scandium oxide powders and their precursors are structurally inconvenient for application as additives and ceramic raw materials.
また、特許文献１には、アルコキシド法及びハライド法により球状のスカンジウム酸化物超微粒子が製造される旨の記載があるが、特許文献１の記載はチタン酸化物とジルコニ
ウム酸化物の超微粒子に関しては詳細な記述があるも、スカンジウム酸化物の超微粒子に関しては製造に関する具体的な記述がない。したがって、スカンジウム超微粒子の存在に関してもその存在は確認されていなかった。
非特許文献１に記載された酸化スカンジウムの前駆体γ−ScOOHは「扁平なひし形板状
の構造形態」をもつという欠点があった。この原因はγ−ScOOHが低温でも結晶化しやす
く、しかも斜方晶系に属するためである。すなわち、斜方晶系特有の扁平な構造形態が現れてしまう。このγ−ScOOHを仮焼して形成される酸化スカンジウムの構造形態はγ−ScOOHの形態を反映して扁平なひし形板状となり、しかも、高温での熱処理によって凝集しやすいという欠点があった。この原因はγ−ScOOHを前駆体としたためであり、また、凝集
しやすいのは、５ｎｍ程度という薄さに起因していると考えられる。
The scandium oxide precursor γ-ScOOH described in Non-Patent Document 1 has a drawback of having a “flat, rhomboid plate-like structure”. This is because γ-ScOOH is easily crystallized even at a low temperature and belongs to the orthorhombic system. That is, a flat structural form peculiar to the orthorhombic system appears. The structural form of scandium oxide formed by calcining this γ-ScOOH has a drawback that it is a flat rhombus plate reflecting the form of γ-ScOOH, and moreover, it tends to aggregate due to heat treatment at high temperature. This is because γ-ScOOH is used as a precursor, and it is considered that the aggregation is likely due to the thinness of about 5 nm.
本発明の目的は、酸化スカンジウム仮焼体超微粒子の前駆体であり、かつ形状対称性に優れた特徴を持つ非晶質塩基性炭酸スカンジウムを主成分とする超微粒子とその製造方法を提供することにある。
さらに、本発明は、上記前駆体を原料として製造される形状対称性に優れた酸化スカンジウム仮焼体超微粒子とその製造方法を提供することを目的としている。
An object of the present invention is to provide ultrafine particles mainly composed of amorphous basic scandium carbonate , which are precursors of scandium oxide calcined ultrafine particles and have excellent shape symmetry, and a method for producing the same. There is.
Furthermore, an object of the present invention is to provide a scandium oxide calcined body ultrafine particle having excellent shape symmetry produced using the precursor as a raw material and a method for producing the same.
本発明の超微粒子は、塩基性炭酸スカンジウムＳｃ（ＯＨ）ＣＯ3を含む、粒径が１０ｎ
ｍ以上６０ｎｍ以下である非晶質の超微粒子であることを特徴としている。
The ultrafine particles of the present invention contain basic scandium carbonate Sc (OH) CO 3 and have a particle size of 10 n
It is characterized by being amorphous ultrafine particles having a diameter of m to 60 nm .
この酸化スカンジウム前駆体の製造法は、スカンジウムの酸性塩水溶液を、炭酸を含む塩基性塩水溶液によって中和反応させることにより、その中和反応沈殿物として合成することを特徴としている。スカンジウムの酸性塩としては塩化塩、硝酸塩、硫酸塩、酢酸塩などの水溶性無機酸塩又は有機酸塩のうち、１種又は２種以上が使用される。炭酸を含む塩基性塩には、炭酸アンモニウム、炭酸ナトリウム、炭酸カリウム又はそれらの炭酸水素塩などの水溶性炭酸塩の１種又は２種以上が使用される。 This method for producing a scandium oxide precursor is characterized in that an acidic salt aqueous solution of scandium is neutralized with a basic salt aqueous solution containing carbonic acid to synthesize it as a neutralization reaction precipitate. As the acid salt of scandium, one or more of water-soluble inorganic acid salts or organic acid salts such as chloride, nitrate, sulfate and acetate are used. As the basic salt containing carbonic acid, one or more water-soluble carbonates such as ammonium carbonate, sodium carbonate, potassium carbonate or hydrogencarbonate thereof are used.
また、この製造方法において、中和反応のために投与される炭酸イオンのモル数の被中和溶液中のスカンジウムイオンのモル数に対する比は２．２ 以上４．０以下に設定され、中和時の反応温度は２５℃ 以上６０℃ 以下に制御するとよい。本発明の第２ の目的である酸化スカンジウム超微粒子は、１０ｎｍ以上６０ｎｍ以下の粒径をもち、かつ球状又は多面体状の外形形状を有することを特徴とする。
In this production method, the ratio of the number of moles of carbonate ions administered for the neutralization reaction to the number of moles of scandium ions in the solution to be neutralized is set to 2.2 or more and 4.0 or less. The reaction temperature at that time is preferably controlled to 25 ° C. or more and 60 ° C. or less. The scandium oxide ultrafine particles, which is the second object of the present invention, have a particle diameter of 10 nm to 60 nm and have a spherical or polyhedral outer shape.
本発明による酸化スカンジウム仮焼体超微粒子の製造方法は、塩基性炭酸スカンジウムを主成分とする超微粒子を７００℃以上９００℃以下の温度で酸素雰囲気中で仮焼する工程を含むことを特徴としている。
The method for producing scandium oxide calcined ultrafine particles according to the present invention includes a step of calcining ultrafine particles mainly composed of basic scandium carbonate in an oxygen atmosphere at a temperature of 700 ° C. or higher and 900 ° C. or lower. Yes.
本発明による酸化スカンジウム仮焼体超微粒子の形状として球状又は多面体状と規定したのは、仮焼中に立方晶系の晶癖出現により球状の形状が歪む理由による。多面体に変形しても形状対称性がよいため球状の超微粒子と同等の焼結性を示す。酸化スカンジウム仮焼体超微粒子の製造法として酸素雰囲気中で７００℃以上９００℃以下と規定したのは、７００℃未満では不純物の含有が除去されないためであり、９００℃以下としたのは酸化スカンジウム仮焼体超微粒子の凝集を防止するためである。
The reason why the shape of the ultrafine particles of the scandium oxide calcined body according to the present invention is defined as spherical or polyhedral is because the spherical shape is distorted due to the appearance of cubic crystal habits during calcination. Even if it is deformed into a polyhedron, the shape symmetry is good, so that it exhibits sinterability equivalent to that of spherical ultrafine particles. The reason why the ultrafine particles of scandium oxide calcined body are defined as 700 ° C. or higher and 900 ° C. or lower in an oxygen atmosphere is that the inclusion of impurities is not removed below 700 ° C., and the scan temperature is 900 ° C. or lower. This is to prevent aggregation of the calcined body ultrafine particles.
［作用］
本発明の目的である、酸化スカンジウム仮焼体超微粒子の前駆体でありかつ形状対称性に優れた特徴を持つ非晶質塩基性炭酸スカンジウムを主成分とする超微粒子は、非特許文献１などに記載された従来の前駆体γ−SｃＯＯＨとは全く組成が異なるゆえに、球状の超微粒子構造を示す。
[Action]
Non-Patent Document 1 and the like are ultrafine particles mainly composed of amorphous basic scandium carbonate, which are precursors of scandium oxide calcined ultrafine particles, which are the object of the present invention, and have excellent shape symmetry. Since the composition is completely different from the conventional precursor γ-ScOOH described in 1), it shows a spherical ultrafine particle structure.
本発明による非晶質のスカンジウム化合物前駆体は、非晶質であるため晶癖をもたず、球状の超微粒子の形状を示す。組成として塩基性炭酸スカンジウムを含むことによりこのような超微粒子形状が得られる。酸性スカンジウム塩水溶液に加える中和剤として炭酸基を含む塩基性塩水溶液を採用する製造方法を適用することにより前駆体中に炭酸イオン及び塩基性イオンが導入される。 Since the amorphous scandium compound precursor according to the present invention is amorphous, it has no crystal habit and exhibits the shape of spherical ultrafine particles. By including basic scandium carbonate as a composition, such an ultrafine particle shape can be obtained. By applying a production method that employs a basic salt aqueous solution containing a carbonate group as a neutralizing agent added to the acidic scandium salt aqueous solution, carbonate ions and basic ions are introduced into the precursor.
また、投与される炭酸イオンのモル数の被投与溶液中のスカンジウムイオンのモル数に対する比を２．２以上に設定し、中和時の反応温度は２５℃以上６０℃以下に制御することにより形状分散の少ない超微粒子が製造される。形成された超微粒子は球状で粒径の分散が少なく、かつ凝集は極めて少なかった。このため吸引濾過は容易であり、かつ乾燥物の粉砕も容易であった。 Further, the ratio of the number of moles of carbonate ions to be administered to the number of moles of scandium ions in the solution to be administered is set to 2.2 or more, and the reaction temperature during neutralization is controlled to 25 ° C. or more and 60 ° C. or less. Ultrafine particles with little shape dispersion are produced. The formed ultrafine particles were spherical, had little dispersion in particle size, and had very little aggregation. For this reason, the suction filtration was easy, and the dried product was easily pulverized.
酸性スカンジウム塩水溶液に加える中和剤として炭酸基を含む塩基性塩水溶液がアンモニウム基を含む場合は、投与される炭酸イオンのモル数の被投与溶液中のスカンジウムイオンのモル数に対する比を２．２以上に設定した場合であっても、この比の増大とともに、製造される塩基性炭酸スカンジウム超微粒子中にアンモニウム基を含む炭酸スカンジウム塩（ＮＨ4）Ｓｃ（ＣＯ3）2の粒子が混入する。混入したアンモニウム基を含む炭酸ス
カンジウム粒子の体積が製造される前駆体の体積の５０％未満であれば、発明の効果は損なわれず、空隙の少ない酸化スカンジウムセラミックスが実現する。
When the basic salt aqueous solution containing a carbonate group as a neutralizing agent added to the acidic scandium salt aqueous solution contains an ammonium group, the ratio of the number of moles of carbonate ions to be administered to the number of moles of scandium ions in the solution to be administered is 2. Even when the ratio is set to 2 or more, as the ratio increases, the scandium carbonate carbonate salt (NH 4 ) Sc (CO 3 ) 2 particles containing ammonium groups are mixed in the manufactured basic scandium carbonate ultrafine particles. . If the volume of the mixed scandium carbonate particles containing ammonium groups is less than 50% of the volume of the precursor to be produced, the effect of the invention is not impaired and a scandium oxide ceramic with fewer voids is realized.
本発明の前駆体は、γ−SｃＯＯＨとは異なって凝集しにくい。前駆体である非晶質塩基性炭酸スカンジウムを主成分とする超微粒子が、粒径が１ｎｍから１００ｎｍの範囲にあれば、従来の前駆体であるγ−SｃＯＯＨに比べて形状対称性に優れているため、７００℃ 以上９００℃以下の仮焼によっても凝集の少ない酸化スカンジウム仮焼体超微粒子が形成できる。
Unlike the γ-ScOOH, the precursor of the present invention hardly aggregates. Ultrafine particles mainly composed of amorphous basic carbonate scandium is precursor, range particle size from 1nm to 100nm near-lever, excellent shape symmetry compared to γ-ScOOH a conventional precursor Therefore, scandium oxide calcined body ultrafine particles with little aggregation can be formed even by calcining at 700 ° C. or higher and 900 ° C. or lower.
しかしながら、前駆体の一次粒子の粒径が１０ｎｍ未満の場合は本発明による前駆体であっても凝集する可能性があり、前駆体粒径が６０ｎｍを超すと仮焼によって生成される酸化スカンジウムも粒径が６０ｎｍを超え、その後の焼成工程によって作成されるセラミックスの焼結性が低下し、密度も低下する。そのため、粒径として１０ｎｍ以上６０ｎｍ以下が望ましい。 However, when the particle size of the primary particles of the precursor is less than 10 nm, the precursor according to the present invention may aggregate, and when the particle size of the precursor exceeds 60 nm, scandium oxide generated by calcination is also present. The particle size exceeds 60 nm, the sinterability of the ceramics produced by the subsequent firing step is lowered, and the density is also lowered. Therefore, the particle size is desirably 10 nm or more and 60 nm or less.
すなわち、非晶質塩基性炭酸スカンジウムを主成分とする超微粒子及び酸化スカンジウム仮焼体超微粒子としては、高分解能走査顕微鏡観察により測定した一次粒子の粒径が１０ｎｍから６０ｎｍの範囲に分布し、数平均で定義された平均粒径が３０から５０ｎｍであることが望ましい。また、非晶質塩基性炭酸スカンジウムを主成分とする超微粒子としては、アンモニウム基を含む炭酸スカンジウム粒子を体積比で５０％ 未満混在したものでも本発明の作用は失われない。
That is, as ultrafine particles mainly composed of amorphous basic scandium carbonate and scandium oxide calcined body ultrafine particles, the primary particle diameter measured by high-resolution scanning microscope observation is distributed in the range of 10 nm to 60 nm, The average particle size defined by the number average is preferably 30 to 50 nm. In addition, as the ultrafine particles containing amorphous basic scandium carbonate as a main component, even if scandium carbonate particles containing ammonium groups are mixed in a volume ratio of less than 50%, the effect of the present invention is not lost.
本発明により、酸化スカンジウム仮焼体超微粒子の前駆体であり、かつ形状対称性に優れた特徴を持つ非晶質スカンジウムを主成分とする超微粒子が提供され、さらに、従来の酸化スカンジウム粉末に比べて粒径がはるかに小さく、形状対称性に優れ、かつ形状分散の少ない酸化スカンジウム仮焼体超微粒子が提供される。この酸化スカンジウム仮焼体超微粒子を用いて空隙の少ないセラミックスの焼結が可能となる。
The present invention is a precursor of scandium oxide calcined ultrafine particles, and ultrafine particles mainly composed of amorphous Shitsusu Kanjiumu with superior characteristics in a shape symmetry are provided, further, conventional scandium oxide powder Compared to the above, scandium oxide calcined body ultrafine particles having a much smaller particle size, excellent shape symmetry, and little shape dispersion are provided. By using the scandium oxide calcined body ultrafine particles, ceramics with few voids can be sintered.
本発明の実施の形態について詳細に説明する。塩基性炭酸スカンジウムを主成分とする超微粒子の合成には、まずスカンジウムの酸性塩水溶液を、炭酸を含む塩基性塩水溶液で中和して沈殿物を生成する。スカンジウムの酸性塩としては塩化塩、硝酸塩、硫酸塩、酢酸塩などの水溶性無機酸塩又は有機酸塩のうち、１種又は２種以上が使用される。炭酸を含む塩基性塩には、炭酸アンモニウム、炭酸ナトリウム、炭酸カリウム又はそれらの炭酸水素塩などの水溶性炭酸塩の１種又は２種以上が使用される。
Embodiments of the present invention will be described in detail. In order to synthesize ultrafine particles containing basic scandium carbonate as a main component, an acidic salt aqueous solution of scandium is first neutralized with a basic salt aqueous solution containing carbonic acid to generate a precipitate. As the acid salt of scandium, one or more of water-soluble inorganic acid salts or organic acid salts such as chloride, nitrate, sulfate and acetate are used. As the basic salt containing carbonic acid, one or more water-soluble carbonates such as ammonium carbonate, sodium carbonate, potassium carbonate or hydrogencarbonate thereof are used.
中和反応時の温度は２５℃以上６０℃以下が適切である。６０℃を超える温度では水溶性炭酸塩の分解が生じることと、生成される塩基性炭酸スカンジウムの粒径が６０ｎｍを越えてしまうため望ましくなく、２５℃未満では中和反応の進行が遅くなることと、生成される塩基性炭酸スカンジウムの粒径として１０ｎｍ未満のものが生成されるため望ましくない。 The temperature during the neutralization reaction is suitably from 25 ° C to 60 ° C. Decomposition of water-soluble carbonate occurs at temperatures above 60 ° C, and the particle size of the basic scandium carbonate produced exceeds 60 nm, which is undesirable, and below 25 ° C, the progress of the neutralization reaction is slow. In addition, since the basic scandium carbonate produced has a particle size of less than 10 nm, it is not desirable.
沈殿物が生成された溶液は、攪拌しながら熟成する。熟成時間は２５℃ から６０℃ の範囲の温度下では１時間で十分であるが、１２時間以上熟成してもさしつかえない。この熟成後、沈殿物を吸引ポンプで濾過し、蒸留水と無水アルコールで洗浄した後に窒素ガス中で室温乾燥させる。乾燥物は粉砕したのち酸化スカンジウム仮焼体超微粒子の前駆体として供せられる。
The solution in which the precipitate is formed is aged with stirring. An aging time of 1 hour is sufficient at a temperature in the range of 25 ° C. to 60 ° C., but an aging time of 12 hours or longer is acceptable. After this aging, the precipitate is filtered with a suction pump, washed with distilled water and anhydrous alcohol, and then dried in nitrogen gas at room temperature. The dried product is pulverized and then used as a precursor of scandium oxide calcined ultrafine particles.
本発明による酸化スカンジウム仮焼体超微粒子は、本発明による非晶質塩基性炭酸スカンジウムを主成分とする超微粒子を仮焼することにより形成される。仮焼工程は、酸素雰囲気中での７００℃以上９００℃以下の加熱によって構成される。酸素雰囲気は化学量論的組成を持つＳｃ２Ｏ３を得るために必要である。７００℃以上としたのは酸化スカンジウム中に含まれる揮発性の微量不純物の除去に望ましいからであり、９００℃以下としたのは、この温度を超えると温度では酸化スカンジウム仮焼体超微粒子の凝集が開始するため望ましくないからである。加熱時間は、１時間以上が望ましい。しかし、９００℃を超える温度で２４時間以上加熱すると凝集が進行した。したがって、過度に長い加熱は避けた方がよい。
Scandium oxide calcined ultrafine particles according to the present invention is formed by the ultrafine particles to the amorphous salts based carbonate scandium according to the invention as a main component is calcined. The calcination step is constituted by heating at 700 ° C. or higher and 900 ° C. or lower in an oxygen atmosphere. An oxygen atmosphere is necessary to obtain Sc 2 O 3 having a stoichiometric composition. Was set to 700 ° C. or higher is because desirable for the removal of volatile trace impurities contained in the scandium oxide, what was 900 ° C. or less, above this temperature the agglomeration of scandium oxide calcined body ultrafine particles at a temperature This is because it is not desirable. The heating time is preferably 1 hour or longer. However, agglomeration progressed when heated at a temperature exceeding 900 ° C. for 24 hours or more. Therefore, it is better to avoid excessively long heating.
以下では、スカンジウムの酸性塩として硝酸塩を、炭酸を含む塩基性塩として炭酸水素アンモニウムを選択した。これ以外の組み合わせであっても前述の組み合わせであれば塩基性炭酸スカンジウム超微粒子は合成される。硝酸塩水溶液は、市販の酸化スカンジウム粉末（純度９９．９％以上、平均粒径１０μｍ以上）を８０℃で過剰量の硝酸に溶解させたのち、過剰量の硝酸を蒸発させることにより作成した。 In the following, nitrate was selected as the acid salt of scandium, and ammonium hydrogen carbonate was selected as the basic salt containing carbonic acid. Even in other combinations, the basic scandium carbonate ultrafine particles are synthesized as long as the above-described combinations are used. The aqueous nitrate solution was prepared by dissolving a commercially available scandium oxide powder (purity 99.9% or more, average particle size 10 μm or more) in an excess amount of nitric acid at 80 ° C., and then evaporating the excess amount of nitric acid.
図１は、０．１モル濃度の硝酸スカンジウム溶液に１モル濃度の炭酸水素アンモニウム溶液を沈殿剤として加えたときの滴定曲線であり、横軸は反応系に含有される炭酸水素アンモニウムモル量のスカンジウムイオンのモル量に対する比Ｒ（すなわちＮＨ4ＨＣＯ3／Ｓｃ3+）である。縦軸はそのときの反応系のｐＨ値である。また、図中には沈殿反応の開始点と終了点を示した。図１より沈殿はＲが０．７５（ｐＨは４．４）から開始し、Ｒが２．２（ｐＨは５）で終了している。したがって、溶液中のＳｃイオンを完全に沈殿させるにはＲを２．２以上とする必要がある。 FIG. 1 is a titration curve when a 1 molar ammonium bicarbonate solution is added as a precipitant to a 0.1 molar scandium nitrate solution, and the horizontal axis represents the molar amount of ammonium bicarbonate contained in the reaction system. It is the ratio R to the molar amount of scandium ions (ie NH 4 HCO 3 / Sc 3+ ). The vertical axis represents the pH value of the reaction system at that time. In the figure, the start and end points of the precipitation reaction are shown. From FIG. 1, precipitation starts when R is 0.75 (pH is 4.4) and finishes when R is 2.2 (pH is 5). Therefore, R needs to be 2.2 or more in order to completely precipitate Sc ions in the solution.
沈殿によって得られた前駆体の組成分析を行ったところ、Ｒが２．２以上３．０以下（ｐＨは７．８以下）の条件で形成された前駆体は塩基性炭酸スカンジウムＳｃ（ＯＨ）ＣＯ3・Ｈ2Ｏと同定された。同定に当たって、スカンジウム量は誘導結合型プラズマ分光光度計で決定し、炭素量は炭素／硫黄同時決定計で決定した。この結果、前駆体中のスカンジウムと炭素の比は１：１であることが判明した。 When the composition analysis of the precursor obtained by precipitation was performed, the precursor formed under the condition of R of 2.2 or more and 3.0 or less (pH is 7.8 or less) is a basic scandium carbonate Sc (OH). It was identified as CO 3 .H 2 O. In identification, the amount of scandium was determined by an inductively coupled plasma spectrophotometer, and the amount of carbon was determined by a simultaneous carbon / sulfur determination meter. As a result, it was found that the ratio of scandium to carbon in the precursor was 1: 1.
炭素は価数−２の炭酸基ＣＯ3によるものであり、スカンジウムイオンの価数が＋３で
あることを考慮すると価数−１のＯＨ基の存在が不可欠であり、したがって、Ｓｃ（ＯＨ）ＣＯ3が前駆体の主成分と推定された。なお、アンモニウムイオンは蒸留滴定法で定量
し、硝酸イオンは分光光度計で定量したが前駆体には含まれていなかった。結晶水Ｈ2Ｏ
の量は以上の結果と前駆体の重量との違いから推定した。前駆体を仮焼するとＳｃ2Ｏ3に変化する。この変化に伴う重量変化は、前駆体組成の前記同定結果が正しいことを裏付けていた。
Carbon is due to the valence-2 carbonate group CO 3 , and the presence of the valence -1 OH group is indispensable considering the valence of the scandium ion is +3. Therefore, Sc (OH) CO 3 was estimated as the main component of the precursor. Ammonium ions were quantified by distillation titration, and nitrate ions were quantified with a spectrophotometer, but were not included in the precursor. Crystal water H 2 O
The amount of was estimated from the difference between the above results and the weight of the precursor. When the precursor is calcined, it changes to Sc 2 O 3 . The weight change accompanying this change confirmed that the identification result of the precursor composition was correct.
この前駆体のＸ線回折は非晶質を示すブロードな背景回折を示すのみであった。図２にこの前駆体の高分解能走査電子顕微鏡像を示す。粒径は１０ｎｍ以上６０ｎｍ以下に分布するが３０ｎｍから４０ｎｍに分布（数平均分布）が集中する分散の少ない球状超微粒子構造が認められた。また、図２は凝集の程度が小さいことを示している。 X-ray diffraction of this precursor only showed a broad background diffraction indicating amorphous. FIG. 2 shows a high-resolution scanning electron microscope image of this precursor. A spherical ultrafine particle structure with small dispersion in which the particle size is distributed from 10 nm to 60 nm but the distribution (number average distribution) is concentrated from 30 nm to 40 nm was observed. FIG. 2 shows that the degree of aggregation is small.
一方、Ｒが４を超す条件で形成された前駆体の組成を同様な同定手法で決定したところ、（ＮＨ4）Ｓｃ（ＣＯ3）2・Ｈ2Ｏの組成と判明した。そのＸ線回折には明瞭な回折ピークが多数見られており、前駆体は結晶化していることがわかった。また、Ｒが３と４の間の条件で形成された前駆体は、Ｓｃ（ＯＨ）ＣＯ3・Ｈ2Ｏと（ＮＨ4）Ｓｃ（ＣＯ3）2・
Ｈ2Ｏの混合物であった。Ｒが４以下では、（ＮＨ4）Ｓｃ（ＣＯ3）2・Ｈ2Ｏの存在は体
積比で５０％未満であった。Ｒが３より大きい条件で形成された前駆体の高分解走査顕微鏡観察を行ったが、その凝集の程度はいずれもγ−ＳｃＯＯＨよりは小さく、したがって従来の前駆体であるγ−ＳｃＯＯＨより形状が優れていた。
On the other hand, when the composition of the precursor formed under the condition that R exceeds 4 was determined by the same identification method, it was found to be the composition of (NH 4 ) Sc (CO 3 ) 2 .H 2 O. In the X-ray diffraction, many clear diffraction peaks were observed, and it was found that the precursor was crystallized. Precursors formed under conditions where R is between 3 and 4 are Sc (OH) CO 3 .H 2 O and (NH 4 ) Sc (CO 3 ) 2.
It was a mixture of H 2 O. When R was 4 or less, the presence of (NH 4 ) Sc (CO 3 ) 2 .H 2 O was less than 50% by volume. The precursors formed under conditions where R was greater than 3 were observed with a high-resolution scanning microscope. However, the degree of aggregation was smaller than that of γ-ScOOH, and thus the shape was smaller than that of γ-ScOOH, which is a conventional precursor. It was excellent.
しかし、図２のような粒径分散の少ない球状超微粒子構造だけで構成される構造ではなく、数ミクロンに凝集した構造体を含んでいた。特に、Ｒが４を超える値の前駆体では凝集した構造体が大部分（体積比で５０％以上）を占めていた。したがって、Ｒの値としては２．２以上３．０以下が理想的な条件である。３．０以上４．０以下の場合も非晶質の球状超微粒子が多数含まれているので実用的な条件の範疇に含まれる。 However, it is not a structure composed only of spherical ultrafine particle structures with small particle size dispersion as shown in FIG. 2, but includes a structure aggregated to several microns. In particular, in the precursor having a value of R exceeding 4, most of the aggregated structures accounted for 50% or more by volume ratio. Therefore, the ideal value of R is 2.2 or more and 3.0 or less. The case of 3.0 or more and 4.0 or less is also included in the category of practical conditions because it contains many amorphous spherical ultrafine particles.
Ｒが４．０を超える値では凝集した構造体が多いため実用的な条件とはいい難い。このようなＲ依存性は、炭酸を含む塩基性塩として炭酸水素アンモニウムのようにアンモニウム基を含むものを採用した場合に現れる現象であって、アンモニウム基を含まない炭酸を含む塩基性塩を採用した場合には、結晶化する前駆体は形成されないので、Ｒ（ただし、この場合のＲは、炭酸イオンのモル量のスカンジウムイオンのモル量に対する比と定義される）が２．２以上という条件で十分である。 When R exceeds 4.0, there are many aggregated structures, and it is difficult to say that it is a practical condition. Such R dependence is a phenomenon that appears when a basic salt containing carbonic acid, such as ammonium hydrogen carbonate, containing an ammonium group is used, and a basic salt containing carbonic acid not containing an ammonium group is adopted. In this case, since the precursor to be crystallized is not formed, the condition that R (where R is defined as the ratio of the molar amount of carbonate ions to the molar amount of scandium ions) is 2.2 or more Is enough.
以上のとおり、スカンジウムの酸性塩水溶液を、炭酸を含む塩基性塩水溶液で中和して沈殿物を生成することにより非晶質塩基性炭酸スカンジウムを主成分とする超微粒子が合成された。特に、炭酸イオンのモル量のスカンジウムイオンのモル量に対する比を２．２ 以上４．０以下に制御すれば約５０ｎｍの粒径にそろった凝集の小さい非晶質塩基性炭酸スカンジウムを主成分とする超微粒子が得られた。以上では前駆体をつくるための母塩として硝酸スカンジウムを採用したが、母塩として塩化スカンジウムあるいは硫酸スカンジウムを用いた場合の結果も、母塩を硝酸スカンジウムとした場合と変わりはなかった。
As described above, ultrafine particles mainly composed of amorphous basic scandium carbonate were synthesized by neutralizing an aqueous salt solution of scandium with an aqueous basic salt solution containing carbonic acid to produce a precipitate. In particular, when the ratio of the molar amount of carbonate ion to the molar amount of scandium ion is controlled to 2.2 or more and 4.0 or less , amorphous basic scandium carbonate having a small aggregation and having a particle size of about 50 nm is the main component. The resulting ultrafine particles were obtained. In the above, scandium nitrate was used as the mother salt for producing the precursor, but the results when scandium chloride or scandium sulfate was used as the mother salt were the same as when the mother salt was scandium nitrate.
実施例１ で製造した非晶質塩基性炭酸スカンジウムを主成分とする超微粒子を酸素雰囲気中で７００℃、２時間仮焼した。図３は、得られた超微粒子の高分解能走査電子顕微鏡像である。明らかに超微粒子構造を示しており、粒径は１０ｎｍ以上６０ｎｍ以下に分布するが３０ｎｍから４０ｎｍ に分布（ 数平均分布） が集中する分散の少ない超微粒子構造となっている。超微粒子の形状はほぼ球状であるが、一部、立方晶系の晶癖を反映した多面体形状の超微粒子も混在していた。
The ultrafine particles mainly composed of amorphous basic scandium carbonate produced in Example 1 were calcined at 700 ° C. for 2 hours in an oxygen atmosphere. FIG. 3 is a high-resolution scanning electron microscope image of the obtained ultrafine particles. The ultrafine particle structure is clearly shown, and the particle diameter is distributed from 10 nm to 60 nm, but the distribution (number average distribution) is concentrated from 30 nm to 40 nm, and the dispersion is small and the ultrafine particle structure is small. The shape of the ultrafine particles was almost spherical, but some polyhedral ultrafine particles reflecting a cubic crystal habit were also mixed.
Ｘ線回折は立方晶系の酸化スカンジウムからの回折のみを示した。背景散乱はほとんどなく、ほぼ完全に結晶化していることが判明した。透過電子顕微鏡観察から、多面体形状の超微粒子も含めて、これらの超微粒子は多結晶粒であることが判明した。仮焼温度と時間を選ぶことにより、単結晶化させることは可能であるが、同時に凝集が進行するので焼結用原料の目的には多結晶の状態で十分である。酸化スカンジウムの（２２２）回折線幅から計算した粒径は２８ｎｍであり、窒素吸着量から測定した表面積（グラムあたり４９ｍ2）から球状を仮定して計算した粒径は３２ｎｍであった。これらの粒径の値は、図２
の形状とよく一致する。
X-ray diffraction showed only diffraction from cubic scandium oxide. It was found that there was almost no background scattering and almost complete crystallization. Observation with a transmission electron microscope revealed that these ultrafine particles, including polyhedral ultrafine particles, were polycrystalline. By selecting the calcination temperature and time, it is possible to make a single crystal, but since aggregation proceeds simultaneously, a polycrystalline state is sufficient for the purpose of the raw material for sintering. The particle diameter calculated from the (222) diffraction line width of scandium oxide was 28 nm, and the particle diameter calculated from the surface area measured from the amount of nitrogen adsorption (49 m 2 per gram) assuming a spherical shape was 32 nm. These particle size values are shown in FIG.
It matches the shape of.
図３に示した酸化スカンジウム仮焼体超微粒子を室温で２００メガパスカルの圧力を用いて圧縮したのち、圧力印加のない状態で空気中で１５００℃ ２時間焼結させたところ、密度が理論値の９９％ 以上の高密度酸化スカンジウムセラミックスが得られた。
比較例１
硝酸スカンジウムに加える沈殿剤として炭酸基を含まないアンモニア水を用いた。２５℃ 以上７０℃以下の温度に保たれた硝酸スカンジウム含有溶液を攪拌しながら沈殿剤であるアンモニア水を滴下することにより沈殿物を生成させた。この生成沈殿物を吸引ろ過したのち蒸留水及び無水アルコールで洗浄し、乾燥させた。乾燥物は破砕して粉末状の形状とした。沈殿物は、強度にゲル化したため吸引ろ過は容易ではなかった。また、乾燥工程中に試料は激しく凝集したので、その粉砕も容易ではなかった。
When the scandium oxide calcined ultrafine particles shown in FIG. 3 were compressed at room temperature using a pressure of 200 megapascals and sintered in air at 1500 ° C. for 2 hours without applying pressure, the density was the theoretical value. 99% or more of the above high density scandium oxide ceramics was obtained.
Comparative Example 1
Ammonia water containing no carbonate group was used as a precipitant to be added to scandium nitrate. A precipitate was generated by dropping ammonia water as a precipitant while stirring the scandium nitrate-containing solution kept at a temperature of 25 ° C. or higher and 70 ° C. or lower. The produced precipitate was subjected to suction filtration, washed with distilled water and anhydrous alcohol, and dried. The dried product was crushed into a powdery shape. Since the precipitate was strongly gelled, suction filtration was not easy. Further, since the sample was agglomerated during the drying process, the pulverization was not easy.
このようにして形成された前駆体粉末をX線回折により解析した。回折スペクトルはブ
ロードであったがγ−ScOOHを特徴づける多数の明瞭な回折ピークを示し、前駆体はγ−ScOOHであることが同定された。（０２０）回折ピークの線幅を解析した結果、γ−ScOOH
は（０２０）回折線に規定される空間軸方向に対し約６ｎｍのサイズを持つことが判明した。この値は非特許文献１に記載されたγ−ScOOHのひし形板片の板片厚４．５ｎｍに近
い値である。また、乾燥中に激しく凝集したため走査型顕微鏡で観察される形態は、数μｍ程度サイズの粗い粒子であった。すなわち、γ−ScOOHは激しい凝集のため粒径の揃っ
た超微粒子の形状を呈することはない。
比較例２
比較例１で得られた粒子を前駆体として７００℃で仮焼した。得られた酸化スカンジウムは、その（２２２）Ｘ線回折線幅から見積もられた結晶粒径は３８ｎｍであったが、走査顕微鏡で観察される形態は、γ−ScOOHの形状を反映して数μｍ程度の粗い粒子であっ
た。また、窒素ガスの吸着量から計算された１グラムあたりの表面積は０．７ｍ2であっ
た。この表面積から球形を仮定して計算して求めた粒径は２．２μｍとなり、走査顕微鏡観察結果を裏付けている。このような形状の酸化スカンジウムを焼成しても酸化スカンジウムの理想密度の８３％のセラミックスしか得られなかった。ただし、ここで理想密度とは単結晶酸化スカンジウムから計算される密度をいう。このような低密度のセラミックスは光学的応用に供することができない。
The precursor powder thus formed was analyzed by X-ray diffraction. The diffraction spectrum was broad but showed a number of distinct diffraction peaks characterizing γ-ScOOH, and the precursor was identified as γ-ScOOH. As a result of analyzing the line width of the (020) diffraction peak, γ-ScOOH
Was found to have a size of about 6 nm with respect to the spatial axis direction defined by the (020) diffraction line. This value is close to the plate thickness of 4.5 nm of the γ-ScOOH rhomboid plate described in Non-Patent Document 1. Further, since the particles aggregated vigorously during drying, the morphology observed with a scanning microscope was coarse particles having a size of about several μm. That is, γ-ScOOH does not exhibit the shape of ultrafine particles having a uniform particle diameter due to intense aggregation.
Comparative Example 2
The particles obtained in Comparative Example 1 were calcined at 700 ° C. as a precursor. The obtained scandium oxide had a crystal grain size estimated from its (222) X-ray diffraction line width of 38 nm, but the morphology observed with a scanning microscope reflects the shape of γ-ScOOH. It was a coarse particle of about μm. The surface area per gram calculated from the amount of nitrogen gas adsorbed was 0.7 m 2 . The particle diameter calculated by assuming a spherical shape from this surface area is 2.2 μm, confirming the scanning microscope observation result. Even when the scandium oxide having such a shape was fired, only 83% of the ideal density of scandium oxide was obtained. Here, the ideal density means a density calculated from single-crystal scandium oxide. Such low density ceramics cannot be used for optical applications.
以上の結果は、γ−SｃOOHを前駆体とした場合には粒径の揃った酸化スカンジウム仮焼体超微粒子は実現せず、したがって、焼成法によっては応用に供することの可能な酸化スカンジウムセラミックスは実現できないことを示している。
The above results show that when γ-ScOOH is used as a precursor, scandium oxide calcined ultrafine particles having a uniform particle size are not realized. Therefore, depending on the firing method, scandium oxide ceramics that can be used for application are Indicates that it cannot be realized.
本発明によれば、形状対称性に優れ、かつ形状分散の少ない酸化スカンジウム仮焼体超微粒子が提供され、従来の酸化スカンジウム粉末に比べて粒径がはるかに小さいので、耐火性セラミックスや固体レーザー材料への均一なスカンジウム添加が容易になる。また、従来の酸化スカンジウム粉末に比べて粒径がはるかに小さいので、空隙の少ないセラミックスの焼結が可能となり、高出力紫外レーザーの母体材料としての応用が可能な高密度なスカンジウムセラミックス合成も可能になる。
According to the present invention, scandium oxide calcined ultrafine particles having excellent shape symmetry and little shape dispersion are provided, and the particle size is much smaller than that of conventional scandium oxide powder. Uniform scandium addition to the material is facilitated. In addition, since the particle size is much smaller than that of conventional scandium oxide powder, it is possible to sinter ceramics with less voids and to synthesize high-density scandium ceramics that can be used as a base material for high-power ultraviolet lasers. become.
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