JP6276214B2 - Method for producing gallium oxide aggregate and gallium oxide aggregate - Google Patents
Method for producing gallium oxide aggregate and gallium oxide aggregate Download PDFInfo
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- 229910001195 gallium oxide Inorganic materials 0.000 title claims description 57
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 title claims description 53
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 31
- 229910052733 gallium Inorganic materials 0.000 claims description 31
- 239000002245 particle Substances 0.000 claims description 30
- 239000002243 precursor Substances 0.000 claims description 28
- 230000032683 aging Effects 0.000 claims description 27
- 238000010304 firing Methods 0.000 claims description 18
- 238000006386 neutralization reaction Methods 0.000 claims description 13
- 238000009826 distribution Methods 0.000 claims description 9
- 239000011800 void material Substances 0.000 claims description 8
- 239000003513 alkali Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052753 mercury Inorganic materials 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 3
- 230000002776 aggregation Effects 0.000 claims description 2
- 230000001186 cumulative effect Effects 0.000 claims description 2
- 238000004220 aggregation Methods 0.000 claims 1
- 238000005345 coagulation Methods 0.000 claims 1
- 230000015271 coagulation Effects 0.000 claims 1
- 238000001035 drying Methods 0.000 claims 1
- 239000000843 powder Substances 0.000 description 24
- 238000000034 method Methods 0.000 description 12
- 239000013078 crystal Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- CHPZKNULDCNCBW-UHFFFAOYSA-N gallium nitrate Chemical compound [Ga+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CHPZKNULDCNCBW-UHFFFAOYSA-N 0.000 description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 229910017604 nitric acid Inorganic materials 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000003756 stirring Methods 0.000 description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 description 4
- 229940044658 gallium nitrate Drugs 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000002431 foraging effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 230000005070 ripening Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 241001101998 Galium Species 0.000 description 1
- 102100032849 Sentan Human genes 0.000 description 1
- 101710205302 Sentan Proteins 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004482 other powder Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005019 vapor deposition process Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Description
本発明は、レーザー、蛍光体、発光材料、触媒、半導体接合物の絶縁障壁といったものに好適に使用される酸化ガリウム粒子に関する。 The present invention relates to gallium oxide particles suitably used for lasers, phosphors, luminescent materials, catalysts, insulating barriers for semiconductor junctions, and the like.
酸化ガリウムは、機能性の高い材料として広く研究されており、パワーデバイス用の基板材料としても検討されている。これは、酸化ガリウムの有するバンドギャップが、シリコンの１．１、ＳｉＣ／ＧａＮの３．３〜３．４に比較して、４．７〜４．９と極めて高い値を有し、パワー半導体材料の指標ともいえるバリガー性能指数もシリコンの１に対して、３４４４を示すなど、高い可能性を秘めた材料であることに由来する。（非特許文献１または２参照）
酸化ガリウムの単結晶は、融液成長法により製造することができる。より具体的には、製造方法を説明すれば、酸化ガリウムの原料粉体を単結晶製造装置が備えられたるつぼ等の容器に投入して、これを融解し種結晶に接触させて成長させ単結晶を得るというものである。こうした方法であれば、従来知られているパワーデバイス用材料に比較して、比較的安価に製造が可能であるとされており、結果として次世代のパワーデバイス用材料として大きく期待されている。
酸化ガリウム粉体の製造方法としては、例えば特許文献１では、アンモニア水に対して濃厚な硝酸ガリウム溶液を添加することによって、鱗片状の微粒子が積層した酸化ガリウム粉末とすることができ、こうした粒子によれば、粉砕性を改善させることができるとされている。また、特許文献２では、焼成後の酸化ガリウムについて、６０メッシュ程度の網目の振動篩によって造粒する工程を踏むことで、凝集粒子間空隙の累積容積を調整することで、他の粉末により混合粉末とした際に均一で最密混合性を高めることができる酸化ガリウム粉末が得られうるとしている。
Gallium oxide has been widely studied as a highly functional material and is also being studied as a substrate material for power devices. This is because the band gap of gallium oxide has an extremely high value of 4.7 to 4.9 compared to 1.1 of silicon and 3.3 to 3.4 of SiC / GaN, and is a power semiconductor. The Barriger figure of merit, which can be said to be an index of the material, is derived from the fact that it has a high possibility, such as 3444 for silicon. (See Non-Patent Document 1 or 2)
A single crystal of gallium oxide can be manufactured by a melt growth method. More specifically, the production method will be described. Raw material powder of gallium oxide is put into a container such as a crucible equipped with a single crystal production apparatus, melted, brought into contact with a seed crystal, and grown. It is to obtain crystals. Such a method is considered to be relatively inexpensive to manufacture compared to conventionally known power device materials, and as a result, is highly expected as a next-generation power device material.
As a method for producing gallium oxide powder, for example, in Patent Document 1, a gallium oxide powder in which scaly particles are laminated can be obtained by adding a concentrated gallium nitrate solution to ammonia water. According to the above, it is said that the pulverizability can be improved. Moreover, in patent document 2, it mixes with other powder by adjusting the accumulation volume of the space | gap between agglomerated particles by taking the process of granulating the gallium oxide after baking with the vibration sieve of a mesh of about 60 mesh. It is said that a gallium oxide powder that is uniform and can improve close-packing mixing properties when powdered can be obtained.
先行技術文献にも記述されるように酸化ガリウムは、ＩＧＺＯ用のスパッタリングターゲット材料として使用されるため、他の材料と混合して粉砕した時の粉砕性がよいことが望まれている。また、融液にする時には、塊状になっているよりも粉砕性の高い粉末の方が、容易に融液になりやすく、効率よく単結晶の酸化ガリウムを得ることができると期待される。
しかしながら、先行特許文献において繰り返し述べられているように、オキシ水酸化ガリウム等の前駆体を焼成して酸化ガリウムとすると、焼結が進んでしまうため粉砕が極めて行いがたいという問題があった。こうした問題を解決するために、先行文献では前駆体の段階で粉砕を進め、焼結が進みにくくすることを解決手段として採用しているが、製造の途中段階で粉砕工程をいれることは、収率の悪化を招く原因にもなりうるため、適切ではない。
さらに、空隙を大きくすることにより、酸化ガリウム凝集体密度を小さくすることも手段としては考えられる。しかしながら、嵩密度が小さくなっていると容器に詰め輸送した際に、多くの占有面積／体積を必要とするため、輸送コストの増大が起こる可能性がある。
そこで発明者は、粒子内空隙を適切な範囲に設定して、適当な強度を保ちながらも、粉砕が容易であり、かつ輸送時の体積を圧縮することのできる酸化ガリウム凝集体およびその製造することを目的に定めた。
Since gallium oxide is used as a sputtering target material for IGZO as described in the prior art documents, it is desired that pulverizability is good when mixed with other materials and pulverized. In addition, when making a melt, it is expected that a powder with higher grindability is easier to be melted than a lump, and single crystal gallium oxide can be obtained efficiently.
However, as repeatedly described in the prior patent documents, when a precursor such as gallium oxyhydroxide is fired to form gallium oxide, there is a problem that the sintering is extremely difficult because the sintering proceeds. In order to solve these problems, the prior literature adopts as a means to solve the problem that the pulverization proceeds at the precursor stage and makes the sintering difficult to proceed. It is not appropriate because it can cause the rate to deteriorate.
Further, it is conceivable to reduce the density of gallium oxide aggregates by increasing the gap. However, if the bulk density is small, a large occupied area / volume is required when the container is packed and transported, which may increase the transportation cost.
Accordingly, the inventor sets a void in the particle within an appropriate range, and gallium oxide aggregates that can be easily pulverized and can compress the volume during transportation while maintaining an appropriate strength, and the production thereof. It was determined for the purpose.
上述のような課題を解決するために、発明者らが鋭意検討したところ、前駆体を焼成して酸化ガリウムにするとしても、焼成後の酸化ガリウム粉末の焼結部分が適度に空間を有する、ネットワーク構造をとるような粒子とすることで、粒子の機械的強度を小さくすることができ、もって粉砕性が高い粒子とすることができることを見いだし、本発明を完成させた。
その製造方法としては、
ガリウム源を１００ｇ／Ｌ以上の濃度となるように溶解した溶液を、アルカリ溶液に添加して中和により中和物を生成する工程と、
生成した中和物を５０℃未満の温度で熟成する第１熟成工程）と、
８０℃以下の温度で熟成する第２熟成工程と、を備えた工程により前駆体を得て、
この前駆体を焼成することにより酸化ガリウムを製造する方法である。
In order to solve the above-described problems, the inventors have intensively studied, and even if the precursor is fired to gallium oxide, the sintered portion of the gallium oxide powder after firing has a suitable space. It has been found that by using particles having a network structure, the mechanical strength of the particles can be reduced, and thus particles having high grindability can be obtained, and the present invention has been completed.
As its manufacturing method,
Adding a solution prepared by dissolving a gallium source so as to have a concentration of 100 g / L or more to an alkaline solution to produce a neutralized product by neutralization;
A first aging step for aging the produced neutralized product at a temperature of less than 50 ° C.),
And a second aging step for aging at a temperature of 80 ° C. or lower, to obtain a precursor,
This is a method for producing gallium oxide by firing this precursor.
このような製造方法で得られた酸化ガリウムは、
酸化ガリウム凝集体粉末凝集体の水銀圧入ポロシメータにより測定される対数微分空隙容積分布において、空隙容積径１０μｍ〜３５０μｍの空隙累積が０．５０ｃｍ３／ｇ以上、１．５ｃｍ３／ｇ以下である、酸化ガリウム凝集体である。
さらに加えて、当該酸化ガリウムの嵩密度が０．４５ｇ／ｃｃ以上１．０ｇ／ｃｃ以下である、酸化ガリウムの凝集体である。
さらに、当該凝集体のＤ５０径（乾式法・レーザー回折型粒度分布測定装置による）が０．５μ以上、１５μｍ以下である、第４または第５の構成に記載の構成要素を含む、酸化ガリウム凝集体である。
The gallium oxide obtained by such a manufacturing method is
In log differential void volume distribution measured by a mercury intrusion porosimeter gallium oxide aggregate powder agglomerates, voids cumulative void volume diameter 10μm~350μm is 0.50 cm 3 / g or more and 1.5 cm 3 / g or less, It is a gallium oxide aggregate.
In addition, the gallium oxide aggregate has a bulk density of 0.45 g / cc to 1.0 g / cc.
Furthermore, the gallium oxide containing the component according to the fourth or fifth configuration, in which the D 50 diameter of the aggregate (by a dry method / laser diffraction type particle size distribution analyzer) is 0.5 μm or more and 15 μm or less. Aggregates.
本発明の酸化ガリウム粉末は凝集体内部に空隙が多くなっており、かつ凝集体を構成する個々の粒子の接着が小さいものとなっている。従って、粉末とする際のエネルギーを小さくすることができるので、短時間で効率よく粉末とすることができる。さらに、粒子の嵩密度が大きくなっているため、輸送の際の体積を小さくすることができるため、同一重量の酸化ガリウム凝集体を輸送した際の輸送コスト、及び使用するまでの間の保管コストを低減することができるようになる。 The gallium oxide powder of the present invention has a large number of voids inside the agglomerates, and the adhesion between the individual particles constituting the agglomerates is small. Therefore, since the energy at the time of making into powder can be made small, it can be made into powder efficiently in a short time. Furthermore, since the bulk density of the particles is large, the volume during transportation can be reduced, so the transportation cost when transporting the same weight of gallium oxide aggregates and the storage cost until use Can be reduced.
本発明は、酸化ガリウム粉末を製造する際における各工程で特徴を有する。すなわち、ガリウム源とアルカリを反応させる中和工程、中和により得られた前駆体を成長させる熟成工程、得られた前駆体を焼成することで酸化ガリウムとする焼成工程にそれぞれ特徴があるので、順を追い説明する。
＜ガリウム源＞
酸化ガリウムとなるガリウム源は、ガリウム溶液が好ましい。さらには硝酸ガリウムが好ましい。硝酸ガリウムの濃度は１００ｇ／Ｌ以上である方が、大量生産の面で好ましい。ガリウム濃度として１００ｇ／Ｌ以下の溶液としてしまうと、前駆体形成後の固液分離の際に大量の廃液が発生することになるので、環境面でも好ましくない。硝酸ガリウムの不純物は、ガリウムに対して全１質量％以下であれば問題なく、数ｐｐｍの元素の影響は、実質ない。前駆体の組成が均質で、安定して生成できるからである。他にも酸化ガリウム、そのスクラップ、ガリウム金属の固体金属であってもアルカリと反応し、溶解できるものであれば良い。
＜中和工程＞
酸化ガリウムの前駆体となる中和物は、アルカリ源に対してガリウムを添加するいわゆる逆中和法により生成させる。こうすることで、焼成後して凝集体化する際に崩れやすい形態となりやすいので好ましい。この中和物は、オキシ水酸化ガリウムが主な組成である。
中和の際には、中和熱が発生するので、この温度が高くなってしまうと、前駆体の形態がいびつになり、ひいては酸化ガリウムの形態にも影響が及ぶので好ましくない。中和時の温度は第１の中和温度以下、好ましくは３０℃以下となるように調整するのが良い。
中和に用いるアルカリは、公知のアルカリ剤はいずれも使用できると考えられるが、高純度の酸化ガリウムを得るには、アンモニア水とするのが適当である。
＜熟成工程＞
本発明の特徴として、熟成工程を２段階以上にすることがある。第１の熟成工程により、前駆体の核を形成させ、昇温後の第２熟成工程で前駆体を成長させる。このときの雰囲気は大気中で行うのがよい。雰囲気を限定するものではない。
第１熟成工程と第２熟成工程との間の温度差は５℃以上、好ましくは１０℃以上幅があるのがよく、幅は４０℃以内、好ましくは３０℃以内、一層好ましくは２０℃以内とするのが良い。
第１熟成工程における温度は５０℃未満、下限の温度としては室温以上、好ましくは３０℃以上、より好ましくは３５℃以上とするのがよい。熟成の時間には、そのスケールにより調整することができるので、特段の制限はないが５分以上とするのが適当である。
第２熟成工程における温度は８０℃以下、好ましくは７０℃以下、一層好ましくは６０℃以下とするのがよい。第２の熟成は粒子の大きさにも影響するので、できるだけ時間をかけて行うのがよく、熟成時間は１時間以上、好ましくは３時間以上、一層好ましくは５時間以上とするのが良い。
こうして得られた前駆体は、大気中で常法によりろ過による固液分離を行った上で、前駆体乾燥粉とする。場合によっては不純物をできるだけ残さないために、ろ過後に導電率計の数値を見ながら、水洗などを行うのも好ましい構成である。なお、熟成工程における開始、終了時点は、所定温度に達した時を始期とし、所定温度より降温が連続的始まった時点を終期とする。
＜焼成工程＞
焼成工程は、前駆体を酸化ガリウムに変化させる工程である。ここで特に重要とするのは焼成時の温度であり、焼成炉内の温度を９００℃以下、好ましくは８５０℃以下、一層好ましくは８００℃以下とする必要がある。温度があまりに高すぎると、よく知られている様に焼成後に収縮が著しく、解砕が行いがたいという問題が生じるとともに、本発明の特徴である、粒子内部の空孔が生じがたくなるので好ましくない。ただ、焼成温度が低すぎると、酸化ガリウムの結晶系が異なったものが生じてくるので好ましくない。
焼成も熟成工程と同じく、処理温度までの時間を長くとり緩やかに昇温するのが好ましい。昇温時間は５００℃／時間以下、好ましくは３００℃／時間以下、一層好ましくは１５０℃／時間以下とするのが良い。
こうして得られた酸化ガリウム凝集体は、場合により粉砕工程を経て、粉末とすることもできる。粉末とする方法には特段限定はなく、公知の方法をいずれも使用することができる。
上記のようにして得られた酸化ガリウム粉末は、粒子間の空隙が比較的大きいにもかかわらず、嵩密度が高く、粉末としての密度が高いので、体積を低減することができる。こうした効果を得るには、酸化ガリウム凝集体粉末凝集体の水銀圧入ポロシメータにより測定される対数微分空隙容積分布において、空隙容積径１０μｍ〜３５０μｍの範囲における空隙累積が０．５０ｃｍ３／ｇ以上、好ましくは０．６０ｃｍ３／ｇ以上となっていることが好ましく、１．５ｃｍ３／ｇ以下、好ましくは１．０ｃｍ３／ｇ以下であることがより好ましい。この範囲となることで、酸化ガリウム粒子の流動性が向上するため適当である。
また、嵩密度は下限が０．４５ｇ／ｃｃ以上、好ましくは０．５０ｇ／ｃｃ以上、一層好ましくは０．６０ｇ／ｃｃ以上であって、上限が１．００ｇ／ｃｃ以下、好ましくは０．９０ｇ／ｃｃ以下、一層好ましくは０．８０ｇ／ｃｃ以下とするのが良い。０．４５ｇ／ｃｃ以上である酸化ガリウム凝集体であれば、従来の酸化ガリウム凝集体と同一重量であっても、体積が抑えられるため、輸送コストの低減が期待できるので好ましい。
The present invention is characterized by each step in producing a gallium oxide powder. That is, the neutralization step of reacting the gallium source with the alkali, the aging step of growing the precursor obtained by neutralization, and the firing step of gallium oxide by firing the obtained precursor, respectively, Explain in order.
<Galium source>
The gallium source to be gallium oxide is preferably a gallium solution. Furthermore, gallium nitrate is preferable. The concentration of gallium nitrate is preferably 100 g / L or more in terms of mass production. If the solution has a gallium concentration of 100 g / L or less, a large amount of waste liquid is generated at the time of solid-liquid separation after the precursor is formed, which is not preferable in terms of environment. The impurities of gallium nitrate have no problem as long as the total is 1% by mass or less with respect to gallium, and there is substantially no influence of an element of several ppm. This is because the composition of the precursor is homogeneous and can be stably generated. In addition, gallium oxide, its scrap, or a solid metal of gallium metal may be used as long as it can react with alkali and dissolve.
<Neutralization process>
The neutralized product that becomes the precursor of gallium oxide is generated by a so-called reverse neutralization method in which gallium is added to an alkali source. This is preferable because it tends to collapse when it is aggregated after firing. This neutralized product is mainly composed of gallium oxyhydroxide.
During the neutralization, heat of neutralization is generated. Therefore, if this temperature is increased, the form of the precursor becomes distorted, and the form of gallium oxide is also affected. The temperature at the time of neutralization is adjusted to be not higher than the first neutralization temperature, preferably not higher than 30 ° C.
As the alkali used for neutralization, any known alkali agent can be used, but ammonia water is suitable for obtaining high-purity gallium oxide.
<Aging process>
As a feature of the present invention, the aging process may include two or more stages. Precursor nuclei are formed in the first aging step, and the precursor is grown in the second aging step after the temperature rise. The atmosphere at this time is preferably performed in the air. It does not limit the atmosphere.
The temperature difference between the first aging step and the second aging step should be 5 ° C. or more, preferably 10 ° C. or more, and the width is within 40 ° C., preferably within 30 ° C., more preferably within 20 ° C. It is good to do.
The temperature in the first aging step is less than 50 ° C., and the lower limit temperature is room temperature or higher, preferably 30 ° C. or higher, more preferably 35 ° C. or higher. The aging time can be adjusted according to the scale, and is not particularly limited, but is suitably 5 minutes or longer.
The temperature in the second aging step is 80 ° C. or lower, preferably 70 ° C. or lower, more preferably 60 ° C. or lower. Since the second aging also affects the size of the particles, it is preferable to take as much time as possible, and the aging time is 1 hour or longer, preferably 3 hours or longer, more preferably 5 hours or longer.
The precursor thus obtained is subjected to solid-liquid separation by filtration in the air in the usual manner, and then used as a precursor dry powder. In some cases, in order to leave as little impurities as possible, it is also preferable to perform washing with water while monitoring the numerical value of the conductivity meter after filtration. The start and end time points in the ripening process start from the time when the temperature reaches a predetermined temperature, and end when the temperature decrease starts from the predetermined temperature continuously.
<Baking process>
The firing step is a step of changing the precursor to gallium oxide. Particularly important here is the temperature during firing, and the temperature in the firing furnace needs to be 900 ° C. or lower, preferably 850 ° C. or lower, more preferably 800 ° C. or lower. If the temperature is too high, as is well known, shrinkage is remarkable after firing, causing problems that it is difficult to disintegrate, and it is difficult to generate pores inside the particles, which is a feature of the present invention. It is not preferable. However, if the firing temperature is too low, gallium oxide crystal systems differ, which is not preferable.
As with the ripening step, it is preferable to increase the temperature gradually by increasing the time until the treatment temperature. The temperature raising time is 500 ° C./hour or less, preferably 300 ° C./hour or less, more preferably 150 ° C./hour or less.
The gallium oxide aggregate obtained in this way can be made into a powder through a pulverization step. There is no particular limitation on the method of forming a powder, and any known method can be used.
The gallium oxide powder obtained as described above has a high bulk density and a high density as a powder, although the voids between the particles are relatively large, the volume can be reduced. In order to obtain such an effect, in the logarithmic differential void volume distribution measured by a mercury intrusion porosimeter of the gallium oxide aggregate powder aggregate, the void accumulation in the range of the void volume diameter of 10 μm to 350 μm is 0.50 cm 3 / g or more, preferably Is preferably 0.60 cm 3 / g or more, 1.5 cm 3 / g or less, more preferably 1.0 cm 3 / g or less. This range is appropriate because the fluidity of the gallium oxide particles is improved.
The lower limit of the bulk density is 0.45 g / cc or more, preferably 0.50 g / cc or more, more preferably 0.60 g / cc or more, and the upper limit is 1.00 g / cc or less, preferably 0.90 g. / Cc or less, more preferably 0.80 g / cc or less. A gallium oxide aggregate of 0.45 g / cc or more is preferable because the volume can be suppressed even if the weight is the same as that of the conventional gallium oxide aggregate, and a reduction in transportation cost can be expected.
＜得られた粉末の評価＞
得られた酸化ガリウム粉末の物性などは、下記の方法を用いて評価した。
＜細孔分布測定＞
凝集体における細孔容積は、試料０．３〜０．５ｇを水銀圧入法（Ｍｉｃｒｏｍｅｔｉｔｉｃｓ Ｉｎｓｔｒｕｍｅｎｔ Ｃｏｒｐｏｒａｔｉｏｎ 社製のＡｕｔｏＰｏｒｅ ＩＶ ９５００型）を用いて測定した。
＜粒子径測定／粒度分布＞
凝集体の平均粒子径および粒度分布は、レーザー回折型粒度分布測定装置（ＳＹＭＰＡＴＥＣ株式会社製 ＨＥＬＯＳ＆ＲＯＤＯＳ−ＫＦ型）を用いて測定した。
＜嵩密度＞
嵩密度は、ＪＩＳ Ｋ−５１０１：２００４「顔料試験方法」に準拠して、蔵持科学機械製作所製カサ比重測定器を使用して測定した。
＜粒子形状＞
粒子形状は、粉末試料を樹脂で埋め込んで、研磨により作成した試料を、走査型電子顕微鏡を用いて、観察した。このとき導通を取るために、白金蒸着処理を行っている。
<Evaluation of the obtained powder>
The physical properties and the like of the obtained gallium oxide powder were evaluated using the following methods.
<Measurement of pore distribution>
The pore volume in the aggregate was measured by using a mercury intrusion method (AutoPore IV 9500 type manufactured by Micrometrics Instrument Corporation) for 0.3 to 0.5 g of the sample.
<Particle size measurement / particle size distribution>
The average particle size and particle size distribution of the aggregates were measured using a laser diffraction particle size distribution analyzer (HELOS & RODOS-KF type manufactured by SYMPATEC Corporation).
<Bulk density>
The bulk density was measured in accordance with JIS K-5101: 2004 “Pigment Test Method” using a Kasa Denshi Machine Mfg.
<Particle shape>
For the particle shape, a powder sample was embedded with resin and a sample prepared by polishing was observed using a scanning electron microscope. At this time, a platinum vapor deposition process is performed in order to obtain conduction.
金属ガリウム（ＤＯＷＡエレクトロニクス株式会社製）をガリウム濃度１０５ｇ／Ｌになるように硝酸に溶解し、ガリウムの硝酸溶液１９０．９ｇを作成した。アンモニア水７９．９ｇを純水３５４．７ｇに添加して希釈し、そこへ先に作成したガリウムの硝酸溶液を添加して、中和してガリウム中和物を生成した。
第１熟成工程として、当該ガリウム中和物を形成してから大気中４０℃にて、緩やかに攪拌しながら１０分間熟成を行った。そののち、１．５時間かけて６０℃まで昇温させた。そうして、第２熟成工程として、６０℃に昇温し、８時間攪拌を継続して前駆体を形成させた。得られた前駆体は、ろ過、水洗、乾燥を経て乾燥凝集体とした。
当該前駆体を箱形焼成炉にアルミナのバット上に広げて静置し、室温から８００℃まで昇温させ、その後８時間焼成してβ酸化ガリウム凝集体を得た。得られた粉末の断面写真を図１および図２に示し、物性を表１に示す。
Metal gallium (manufactured by DOWA Electronics Co., Ltd.) was dissolved in nitric acid so as to have a gallium concentration of 105 g / L to prepare 190.9 g of a gallium nitric acid solution. Ammonia water 79.9g was added to 354.7g of pure water for dilution, and the gallium nitric acid solution prepared previously was added thereto and neutralized to produce a neutralized gallium product.
As the first aging step, the gallium neutralized product was formed, and then aging was performed for 10 minutes at 40 ° C. in the atmosphere with gentle stirring. After that, the temperature was raised to 60 ° C. over 1.5 hours. Then, as a second aging step, the temperature was raised to 60 ° C., and stirring was continued for 8 hours to form a precursor. The obtained precursor was filtered, washed with water, and dried to obtain a dry aggregate.
The precursor was spread on an alumina bat in a box-type firing furnace, allowed to stand, heated from room temperature to 800 ° C., and then fired for 8 hours to obtain β-gallium oxide aggregates. Cross-sectional photographs of the obtained powder are shown in FIG. 1 and FIG. 2, and physical properties are shown in Table 1.
（比較例１）
金属ガリウム（ＤＯＷＡエレクトロニクス株式会社製）をガリウム濃度１０３ｇ／Ｌになるように硝酸に溶解し、ガリウムの硝酸溶液６６．３ｇを作成した。アンモニア水２６．８ｇを純水８６０．８ｇに添加して希釈し、そこへ先に作成したガリウムの硝酸溶液を添加して、中和してガリウム中和物を生成させた。
第１熟成工程として、当該ガリウム中和物を形成してから大気中３０℃にて、緩やかに攪拌しながら５分間熟成を行った。そののち、６０℃まで昇温させた。そうして、第２熟成工程として、６０℃に維持し、６時間攪拌を継続して前駆体を形成させた。得られた前駆体は、ろ過、水洗、乾燥を経て乾燥凝集体とした。
得られた前駆体を箱形焼成炉にアルミナのバット上に広げて静置し、室温から８００℃まで昇温させ、その後８時間焼成してβ酸化ガリウム凝集体を得た。得られた粉末の断面写真を図３および図４に示し、物性を表１に示す。
(Comparative Example 1)
Metal gallium (manufactured by DOWA Electronics Co., Ltd.) was dissolved in nitric acid so as to have a gallium concentration of 103 g / L to prepare 66.3 g of a gallium nitric acid solution. 26.8 g of ammonia water was added to 860.8 g of pure water for dilution, and the gallium nitric acid solution prepared previously was added thereto to neutralize it to produce a neutralized gallium product.
In the first aging step, the gallium neutralized product was formed, and then aging was performed at 30 ° C. in the atmosphere for 5 minutes with gentle stirring. Thereafter, the temperature was raised to 60 ° C. Then, as a second aging step, the temperature was maintained at 60 ° C., and stirring was continued for 6 hours to form a precursor. The obtained precursor was filtered, washed with water, and dried to obtain a dry aggregate.
The obtained precursor was spread on an alumina bat in a box-type firing furnace, allowed to stand still, heated from room temperature to 800 ° C., and then fired for 8 hours to obtain a β-gallium oxide aggregate. Cross-sectional photographs of the obtained powder are shown in FIGS. 3 and 4, and physical properties are shown in Table 1.
（比較例２）
金属ガリウム（ＤＯＷＡエレクトロニクス株式会社製）をガリウム濃度３０ｇ／Ｌになるように塩酸に溶解し、ガリウムの硝酸溶液１３４Ｌを作成した。５．６％アンモニア９．４ｋｇを準備して、先に作成しておいたガリウムの塩酸溶液へ添加して、中和してガリウム中和物を生成した。第１熟成工程として、当該ガリウム中和物を形成してから大気中３０℃にて、約２０時間攪拌を継続して前駆体を形成させた。得られた前駆体は、ろ過、水洗、乾燥を経て乾燥凝集体とした。
得られた前駆体を箱形焼成炉にアルミナのバット上に広げて静置し、室温から６４０℃まで昇温させ、その後４時間焼成してβ酸化ガリウム凝集体を得た。得られた粉末の断面写真を図５および図６に示し、物性を表１に示す。
(Comparative Example 2)
Metallic gallium (manufactured by DOWA Electronics Co., Ltd.) was dissolved in hydrochloric acid so as to have a gallium concentration of 30 g / L to prepare a gallium nitric acid solution 134L. 5.4 kg of 5.6% ammonia was prepared, added to the previously prepared gallium hydrochloric acid solution, and neutralized to produce a neutralized gallium product. As a first aging step, after the formation of the neutralized gallium product, stirring was continued for about 20 hours at 30 ° C. in the atmosphere to form a precursor. The obtained precursor was filtered, washed with water, and dried to obtain a dry aggregate.
The obtained precursor was spread on an alumina bat in a box-type firing furnace, allowed to stand, heated from room temperature to 640 ° C., and then fired for 4 hours to obtain a β-gallium oxide aggregate. Cross-sectional photographs of the obtained powder are shown in FIGS. 5 and 6, and physical properties are shown in Table 1.
以上の通り、順中和による従来の方法（比較例）では、空隙が狭くなりすぎており、流動性が必ずしも高いものとはいえなかった。また、逆中和による比較例１では嵩密度も低くなってしまう様なものになってしまった。一方で本願発明に従うものの場合では、嵩密度が高く、流動性に優れた酸化ガリウム凝集体が得られていることがわかる。β酸化ガリウムは、結晶形状が板状であること、この板状結晶はナノレベルサイズで生成されることも知られている。板状結晶は、長手方向に成長するが、その成長するより早く、凝集させやすい前駆体とすることにより、成長より凝集が早くなり、内部は微少な酸化ガリウム結晶粒子からなり、空隙を有した酸化ガリウム粒子による粉末を得られる。 As described above, in the conventional method (comparative example) by forward neutralization, the voids are too narrow and the fluidity is not necessarily high. Further, in Comparative Example 1 by reverse neutralization, the bulk density was lowered. On the other hand, in the case according to the present invention, it can be seen that a gallium oxide aggregate having a high bulk density and excellent fluidity is obtained. It is also known that β-gallium oxide has a plate-like crystal shape and the plate-like crystal is generated at a nano-level size. The plate-like crystal grows in the longitudinal direction, but by making it a precursor that is easier to agglomerate faster than the growth, the agglomeration is faster than the growth, and the inside is composed of fine gallium oxide crystal particles and has voids A powder of gallium oxide particles can be obtained.
Claims (5)
当該ガリウム中和物を３５℃以上且つ５０℃未満の温度で熟成する第１熟成工程と、
第１熟成工程後に、第１熟成工程温度よりも高い温度且つ８０℃以下の温度で熟成し、前駆体を生成する第２熟成工程と、
当該前駆体を固液分離後、焼成し、酸化ガリウムを生成する焼成工程と、を備えた、酸化ガリウム製造方法。 Adding a gallium source to an alkali to produce a neutralized gallium product by a neutralization reaction;
A first aging step of aging the gallium neutralized product at a temperature of 35 ° C. or higher and lower than 50 ° C .;
After the first aging step, aging at a temperature higher than the first aging step temperature and at a temperature of 80 ° C. or less, a second aging step for generating a precursor;
And a firing step of firing the precursor after solid-liquid separation and firing to produce gallium oxide.
D 50 diameter of the aggregates (by dry process, a laser diffraction type particle size distribution measuring apparatus) is 0.5μm or more and 15μm or less, gallium oxide aggregate according to claim 3 or 4.
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