JP2005259556A - Solid electrolyte and its manufacturing method - Google Patents

Solid electrolyte and its manufacturing method Download PDF

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JP2005259556A
JP2005259556A JP2004070181A JP2004070181A JP2005259556A JP 2005259556 A JP2005259556 A JP 2005259556A JP 2004070181 A JP2004070181 A JP 2004070181A JP 2004070181 A JP2004070181 A JP 2004070181A JP 2005259556 A JP2005259556 A JP 2005259556A
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solid electrolyte
heat treatment
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oxygen
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Masaharu Hatano
正治 秦野
Makoto Uchiyama
誠 内山
Mitsugi Yamanaka
貢 山中
Yoshio Akimune
淑雄 秋宗
Masaya Okamoto
正也 岡本
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Nissan Motor Co Ltd
National Institute of Advanced Industrial Science and Technology AIST
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National Institute of Advanced Industrial Science and Technology AIST
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a Sc<SB>2</SB>O<SB>3</SB>-ZrO<SB>2</SB>system solid electrolyte superior in ion conductivity especially in low temperature regions (in the vicinity of 600°C to 800°C), a manufacturing method of the solid electrolyte, and furthermore a solid oxide fuel cell and an oxygen sensor using such solid electrolyte. <P>SOLUTION: By molding a powder having a composition expressed by (1-x)ZrO<SB>2</SB>+xSc<SB>2</SB>O<SB>3</SB>(x=0.03 to 0.15) by an isostatic pressing, and after calcining it within temperature ranges over 1,400°C and below 1,650°C, and by furthermore applying a heat treatment by hot isostatic pressure sintering under high temperature and high pressure atmosphere containing oxygen, a nanocrystal layer of the same component having the thickness of 1 to 10 nm is formed in the crystal grain boundary of the zirconia sinter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、酸素センサや燃料電池などに利用されるジルコニア質固体電解質と、このような固体電解質の製造方法に関するものである。   The present invention relates to a zirconia solid electrolyte used for an oxygen sensor, a fuel cell, and the like, and a method for producing such a solid electrolyte.

1899年にNernstが固体電解質(Solid Electrolyte:SE)を発見した後、1937年にBaurとPreisが1000℃でセラミックス燃料電池を運転して以来,セラミックス固体電解質燃料電池(SOFC:固体酸化物形燃料電池)は進歩を続けており、数kWのジルコニア質セラミックス燃料電池が数千時間の運転実績を積んでいる。
SOFCは、1000℃程度の高温で運転されるため、炭化水素系燃料を電池内で改質(internal reforming)することができ、例えば60%を超えるような高い燃焼効率を得ることが可能であると考えられている。
After Nernst discovered a solid electrolyte (SE) in 1899, Baur and Preis operated a ceramic fuel cell at 1000 ° C in 1937. Batteries) continue to advance, and several kW zirconia ceramic fuel cells have been operating for thousands of hours.
Since the SOFC is operated at a high temperature of about 1000 ° C., the hydrocarbon fuel can be reformed in the cell (internal reforming), and for example, high combustion efficiency exceeding 60% can be obtained. It is believed that.

このようなSOFCは、固体電解質、アノード、カソードから基本的に構成され、これらの間の密着性を高めて性能を向上させたり、耐熱衝撃性を高めて耐久性を向上させたりするために、電極層と電解質層の間に中間層を形成することも行われている。
これら全ての構成材料は、酸化還元性雰囲気に対して安定であって、適度なイオン伝導性を備えている必要がある。また、構成材料の熱膨張係数が互いに接近していると共に、アノードとカソードについては、多孔質体であって、ガス透過性を有していることが要求される。さらに、運転時の安定性の見地からは、導電体の基本要件として同時に焼結された材料系が望ましい。加えて、当然のことながら電池材料としては、強度と靭性に優れ、しかも安価であることが望まれる。
Such SOFC is basically composed of a solid electrolyte, an anode, and a cathode, and in order to improve the performance by improving the adhesion between them, or to improve the durability by improving the thermal shock resistance, An intermediate layer is also formed between the electrode layer and the electrolyte layer.
All these constituent materials are required to be stable with respect to the redox atmosphere and have appropriate ion conductivity. In addition, the thermal expansion coefficients of the constituent materials are close to each other, and the anode and cathode are required to be porous and have gas permeability. Furthermore, from the standpoint of stability during operation, a material system sintered at the same time is desirable as a basic requirement of the conductor. In addition, as a matter of course, the battery material is desired to be excellent in strength and toughness and inexpensive.

また、SOFCにおける単電池の出力は、約1.1Vと限定されているため、高電力を得るには積層構造や並列構造を採ることが必要となることから、このようなセラミックス電池は大型になり、固体電解質やそれを支持するセラミックス材料の製造技術やシステムの選択が非常に難しくなっている。したがって、燃焼器本体などには、例えばフエライト系ステンレスなどの金属部品の有効な利用が望ましく、支持部材としてこのような金属部材を有効に利用するためには、燃料電池の作動温度を低温化することが必要であり、そのためには、低温(600℃〜800℃付近)でのイオン伝導率が高温時と同等に優れた固体電解質材料が望まれている。   In addition, since the output of a single cell in SOFC is limited to about 1.1 V, it is necessary to adopt a laminated structure or a parallel structure in order to obtain high power. Therefore, it is very difficult to select a manufacturing technique and a system for a solid electrolyte and a ceramic material that supports the solid electrolyte. Therefore, effective use of metal parts such as ferrite-based stainless steel is desirable for the combustor body and the like, and in order to effectively use such metal members as support members, the operating temperature of the fuel cell is lowered. For this purpose, a solid electrolyte material having an ionic conductivity at a low temperature (600 ° C. to 800 ° C.) as excellent as that at a high temperature is desired.

このようなSOFCの固体電解質として用いられる材料については、安定化ジルコニア(ZrO)が主流であって、安定化剤としては、CaOやMgOなど2価のアルカリ土類金属酸化物や、ScやYなどの希土類酸化物等が用いられ、例えば、アルカリ土類金属の酸化物であるCaOをドープしたときの特性値としては、800℃で0.01S/cmのイオン伝導性を示す。
また、YやYbなどの希土類酸化物を単独でドープしたときのイオン伝導性については、ある程度の値を示すものの、650℃以下になると大幅に低下することが知られている。なお、希土類酸化物の単独添加による実用的な安定化ジルコニアについては、1970年までにほとんど公知となっている。
For materials used as such SOFC solid electrolytes, stabilized zirconia (ZrO 2 ) is the mainstream, and as stabilizers, divalent alkaline earth metal oxides such as CaO and MgO, Sc 2 Rare earth oxides such as O 3 and Y 2 O 3 are used. For example, the characteristic value when doped with CaO, which is an alkaline earth metal oxide, is 0.01 S / cm ion conduction at 800 ° C. Showing gender.
Moreover, although ion conductivity when rare earth oxides such as Y 2 O 3 and Yb 2 O 3 are doped alone shows a certain value, it is known that the ion conductivity is greatly lowered at 650 ° C. or lower. Yes. Incidentally, practically stabilized zirconia by adding a rare earth oxide alone is almost known by 1970.

一方、最近では、700℃以上で運転する燃料電池用の固体電解質としてスカンジウム酸化物(Sc)で安定化したジルコニアが研究されており、上記のような低温域での運転を行うための固体電解質材料として最も有望であると考えられている。 On the other hand, recently, zirconia stabilized with scandium oxide (Sc 2 O 3 ) has been studied as a solid electrolyte for a fuel cell operating at 700 ° C. or higher. It is considered as the most promising solid electrolyte material.

しかし、Sc安定化ジルコニアにおいては、Scの添加量が6〜9モル%の場合には、立方晶と斜方相が含まれた結晶相が観察され、Y安定化ジルコニアなど他の希土類と同レベルのイオン伝導度を示すのに対し、Sc添加量が10モル%以上の場合には、700℃以上の温度においては、上記のような従来の希土類安定化ジルコニアの値よりも数倍高いイオン伝導度を示すものの、500℃から700℃までの低温域では、ZrSc17で表される結晶相が出現し、従来の希土類安定化ジルコニアの値に較べて、イオン伝導度が2オーダーも低下するとの報告がある(F.M.Spiridonovet al.,J.Solid State Chemistry,2(1970)p.430−438)。 However, in Sc 2 O 3 stabilized zirconia, when the amount of Sc 2 O 3 added is 6 to 9 mol%, a crystal phase including cubic crystals and orthorhombic phases is observed, and Y 2 O 3 While the ion conductivity of the same level as other rare earths such as stabilized zirconia is shown, when the addition amount of Sc 2 O 3 is 10 mol% or more, the conventional ionic compound as described above is used at a temperature of 700 ° C. or more. Although the ionic conductivity is several times higher than the value of the rare earth stabilized zirconia, a crystal phase represented by Zr 7 Sc 2 O 17 appears in the low temperature range from 500 ° C. to 700 ° C. There is a report that the ionic conductivity is reduced by 2 orders of magnitude compared to the value of zirconia (FM Spiritonovet al., J. Solid State Chemistry, 2 (1970) p. 430-). 38).

一方、特許文献1には、Scに加えてInやGa、Tiなどの副ドーパントを添加することによって、相構造を安定なものとし、構造変化に基づく膨張率差による破壊を防止することが提案されている。さらに、特許文献2には、ゾルゲル法を適用することによって、イオン伝導度に優れたSc、Al添加ZrO系電解質膜を薄膜化し、発電効率を向上させることが記載されている。
また、熱間静水圧プレスを利用した焼結方法によってSc安定化ジルコニアをアルゴン雰囲気下で再焼結して空孔を縮小させ、もって強度および伝導度を向上させる手法が報告されている(非特許文献2参照)。
特開平06−150943号公報 特開平10−097860号公報 平野、他,Solid State Ionics,133(2000)p.1−9
On the other hand, Patent Document 1 proposes that by adding a sub-dopant such as In, Ga, or Ti in addition to Sc, the phase structure is stabilized and the destruction due to the difference in expansion coefficient based on the structural change is prevented. Has been. Furthermore, Patent Document 2 describes that by applying the sol-gel method, the Sc 2 O 3 and Al 2 O 3 -added ZrO 2 -based electrolyte film excellent in ionic conductivity is thinned to improve power generation efficiency. ing.
Also reported is a method of reducing the pores by re-sintering Sc 2 O 3 stabilized zirconia in an argon atmosphere by a sintering method using a hot isostatic press, thereby improving strength and conductivity. (See Non-Patent Document 2).
Japanese Patent Laid-Open No. 06-150943 Japanese Patent Laid-Open No. 10-097860 Hirano et al., Solid State Ionics, 133 (2000) p. 1-9

しかしながら、上記特許文献及び非特許文献に記載された技術では、必ずしも十分にイオン伝導度を向上させることはできず、固体電解質の低温域(600℃〜800℃付近)におけるイオン伝導性のさらなる向上が求められている。   However, the techniques described in the above-mentioned patent documents and non-patent documents cannot sufficiently improve the ion conductivity, and further improve the ion conductivity in the low temperature region (around 600 ° C. to 800 ° C.) of the solid electrolyte. Is required.

本発明は、従来のSc安定化ジルコニアにおける上記課題に鑑みてなされたものであって、特に600℃〜800℃付近におけるイオン伝導性に優れ、固体酸化物形燃料電池の低温作動化に寄与するSc−ZrO系固体電解質と、このような固体電解質の製造方法、さらには、当該固体電解質を用いた固体酸化物形燃料電池及び酸素センサを提供することを目的としている。 The present invention has been made in view of the above-mentioned problems in conventional Sc 2 O 3 stabilized zirconia, and is excellent in ion conductivity particularly in the vicinity of 600 ° C. to 800 ° C., and enables low-temperature operation of a solid oxide fuel cell. It is an object of the present invention to provide a Sc 2 O 3 —ZrO 2 -based solid electrolyte that contributes to the above, a method for producing such a solid electrolyte, and a solid oxide fuel cell and an oxygen sensor using the solid electrolyte. .

本発明者らは、Y安定化ジルコニアにおいては、粒内のバルク伝導度に対して、粒界におけるイオン伝導度が約2オーダー低いとの報告(Acta Materialia51(2003)p.2539−2547)に着目し、Sc安定化ジルコニアの粒界にもイオン伝導を阻害する抵抗層が介在しているのではないかとの推定に基づき、このような伝導阻害層を消滅させるべく、材料組成や出発原料、焼成条件や熱処理などについて鋭意検討を重ねた結果、焼成後のSc−ZrO材料に、酸素を含有する高温高圧雰囲気下で熱間静水圧焼結による熱処理を施すことによって、粒界に極めて薄いナノ結晶層が生成され、熱処理前に較べてイオン伝導度が向上することを見出し、本発明を完成するに到った。 The present inventors have reported that in Y 2 O 3 -stabilized zirconia, the ionic conductivity at the grain boundary is about 2 orders of magnitude lower than the bulk conductivity in the grains (Acta Materia 51 (2003) p. 2539-). 2547), based on the assumption that a resistance layer that inhibits ionic conduction is also present at the grain boundaries of Sc 2 O 3 stabilized zirconia, in order to eliminate such a conduction-inhibiting layer, As a result of intensive investigations on material composition, starting materials, firing conditions, heat treatment, etc., heat treatment by hot isostatic pressing was performed on the fired Sc 2 O 3 —ZrO 2 material in a high temperature and high pressure atmosphere containing oxygen. As a result, a very thin nanocrystal layer was formed at the grain boundary, and the ionic conductivity was found to be improved as compared with that before the heat treatment, and the present invention was completed.

本発明は上記知見に基づくものであって、本発明の固体電解質は、一般式:(1−x)ZrO+xSc(式中のxは、0.03〜0.15)で表わされる組成を有するジルコニア焼結体から成り、結晶粒界に1〜10nmの厚さを有する同成分のナノ結晶層を備えていることを特徴としている。
また、本発明の固体電解質の製造方法においては、上記成分を有する粉末を静水圧プレスにより成形し、1400℃を超え1650℃未満の温度範囲で焼成した後、さらに酸素を含む雰囲気中において熱間静水圧焼結による熱処理を施すようにしている。
The present invention is based on the above findings, and the solid electrolyte of the present invention is represented by the general formula: (1-x) ZrO 2 + xSc 2 O 3 (wherein x is 0.03 to 0.15). It is characterized by comprising a nanocrystal layer of the same component having a thickness of 1 to 10 nm at a grain boundary.
In the method for producing a solid electrolyte of the present invention, the powder having the above components is formed by isostatic pressing, fired in a temperature range of more than 1400 ° C. and less than 1650 ° C., and then hot in an atmosphere containing oxygen. Heat treatment is performed by isostatic pressing.

さらに、本発明の固体酸化物形燃料電池及び酸素センサにおいては、本発明の上記固体電解質を使用したことを特徴とするものである。   Furthermore, in the solid oxide fuel cell and the oxygen sensor of the present invention, the solid electrolyte of the present invention is used.

本発明の固体電解質は、(1−x)ZrO+xSc(式中のxは、0.03〜0.15)で表わされる組成を有するジルコニア焼結体から成り、その結晶粒界に厚さが1〜10nmのナノ結晶層を備え、当該ナノ結晶層は、結晶粒内と同じ組成を有し、粒界におけるイオン伝導度を阻害することがなく、固体電解質全体のイオン伝導度を向上させることができる。
また、本発明の固体電解質製造方法においては、上記成分を有する粉末を静水圧プレス成形し、1400℃を超え1650℃未満の温度で焼成した後、酸素を含む高温高圧の雰囲気下で熱間静水圧焼結による熱処理を施すようにしており、当該熱処理により焼成体の結晶粒界に酸素が導入されることによって、イオン伝導の阻害要因である粒界に、粒界抵抗を緩衝するナノ結晶層を成長させることができ、特に600℃〜800℃付近におけるイオン伝導性に優れたSc−ZrO系固体電解質を得ることができる。
The solid electrolyte of the present invention comprises a zirconia sintered body having a composition represented by (1-x) ZrO 2 + xSc 2 O 3 (wherein x is 0.03 to 0.15), and the grain boundaries thereof The nanocrystal layer having a thickness of 1 to 10 nm, the nanocrystal layer having the same composition as that in the crystal grains, and without inhibiting the ionic conductivity at the grain boundary, the ionic conductivity of the entire solid electrolyte Can be improved.
In the solid electrolyte production method of the present invention, the powder having the above components is subjected to isostatic pressing, fired at a temperature exceeding 1400 ° C. and less than 1650 ° C., and then hot isostatically in a high temperature and high pressure atmosphere containing oxygen. A nanocrystalline layer that bufferes the grain boundary resistance at the grain boundaries that are an impediment to ionic conduction by introducing heat treatment into the grain boundaries of the fired body through the heat treatment by hydrostatic sintering. In particular, it is possible to obtain a Sc 2 O 3 —ZrO 2 -based solid electrolyte excellent in ionic conductivity at around 600 ° C. to 800 ° C.

このような固体電解質は、燃料電池や酸素センサなどに好適に使用することができ、特に当該固体電解質を固体酸化物形燃料電池に適用した場合には、作動温度の低温化を可能なものとし、電池要素のみならず、周辺部材の耐久性向上及びコスト低減に大きく寄与することができる。   Such a solid electrolyte can be suitably used for a fuel cell, an oxygen sensor, and the like. In particular, when the solid electrolyte is applied to a solid oxide fuel cell, the operating temperature can be lowered. In addition to the battery element, it can greatly contribute to the improvement of durability and cost reduction of peripheral members.

以下、本発明の実施の形態について具体的に説明する。   Hereinafter, embodiments of the present invention will be specifically described.

本発明の固体電解質は、上記のように(1−x)ZrO+xScで表わされる組成(式中のxは、0.03〜0.15)を有するジルコニア焼結体から成り、その結晶粒界に厚さが1〜10nmのナノ結晶層を備えており、このようなナノ結晶層は、例えば、上記成分の粉末材料を成形及び焼成した後、酸素を含む高温高圧雰囲気下における熱間静水圧焼結処理を施すことによって得ることができる。 The solid electrolyte of the present invention comprises a zirconia sintered body having a composition represented by (1-x) ZrO 2 + xSc 2 O 3 as described above (wherein x is 0.03 to 0.15), The crystal grain boundary is provided with a nanocrystal layer having a thickness of 1 to 10 nm. Such a nanocrystal layer is formed, for example, in a high-temperature and high-pressure atmosphere containing oxygen after molding and baking the powder material of the above components. It can be obtained by applying a hot isostatic pressing process.

このように、本発明の固体電解質は、上記ジルコニア焼結体の結晶粒界に1〜10nm厚さのナノ結晶層を備えたものであって、当該固体電解質におけるナノ結晶層は、透過型電子顕微鏡(200kV以上)を用いて、10万倍以上の倍率で観察することができ、その成分は1〜5nmに絞った電子ビームを照射したEDS分析により確認することができる。   Thus, the solid electrolyte of the present invention is provided with a nanocrystal layer having a thickness of 1 to 10 nm at the crystal grain boundary of the zirconia sintered body, and the nanocrystal layer in the solid electrolyte is a transmission electron. Using a microscope (200 kV or more), it can be observed at a magnification of 100,000 times or more, and its components can be confirmed by EDS analysis irradiated with an electron beam focused to 1 to 5 nm.

以下、本発明の固体電解質の製造方法について、工程順に説明する。
当該固体電解質の製造工程は、従来法と同じく、原料の混合工程、合成工程、粉砕工程、焼結工程及び成形工程を経るものであるが、通常の焼成後、酸素を含有する高温高圧の雰囲気中に熱間静水圧焼結処理を行うことを特徴としている。
Hereafter, the manufacturing method of the solid electrolyte of this invention is demonstrated in order of a process.
The manufacturing process of the solid electrolyte is the same as the conventional method through the raw material mixing process, the synthesis process, the pulverization process, the sintering process, and the molding process, but after normal firing, an oxygen-containing high-temperature and high-pressure atmosphere It is characterized by performing hot isostatic pressing.

(1−x)ZrO+xSc(x=0.03〜0.15)の一般式で表される組成成分を有する固体電解質の出発原料としては、Zr及びScのクエン酸水溶液から製造した粉末を用いることが望ましい。ここで、xの値を上記範囲内にするのは、xが上記値0.03よりも小さい、すなわちジルコニア系固体電解質中におけるSc含有量が3モル%に満たないと、イオン伝導性の低い単斜相が増加する一方、0.15よりも大きい、すなわち当該電解質中のSc含有量が15モル%を超えると、イオン伝導性に優れる高温相が安定して得られなくなることによる。 (1-x) ZrO 2 + xSc 2 O 3 (x = 0.03 to 0.15) As a starting material for a solid electrolyte having a composition represented by the general formula, it is produced from an aqueous citric acid solution of Zr and Sc. It is desirable to use the prepared powder. Here, the value of x falls within the above range when the value of x is smaller than 0.03, that is, when the Sc 2 O 3 content in the zirconia solid electrolyte is less than 3 mol%, On the other hand, when the monoclinic phase having low conductivity is increased, the temperature is higher than 0.15, that is, when the content of Sc 2 O 3 in the electrolyte exceeds 15 mol%, a high-temperature phase excellent in ion conductivity can be stably obtained. By disappearing.

先ず、上記Zr及びScのクエン酸塩を900℃から1000℃程度の温度で仮焼し上記の組成物を得る。さらに、その仮焼生成物をアルコール中でボールミルを使用して24時間程度の粉砕を行った後、ロータリーエバボレータを用いて乾燥する。この仮焼粉末の粉砕は、粉末粒経が0.5μm以下となるように行うことが好ましい。すなわち、粉末の粒子径が0.5μm超えると、後工程での焼結が困難になる傾向がある。   First, the citrate salt of Zr and Sc is calcined at a temperature of about 900 ° C. to 1000 ° C. to obtain the above composition. Further, the calcined product is pulverized in alcohol for about 24 hours using a ball mill, and then dried using a rotary evaporator. The calcination powder is preferably pulverized so that the particle size of the calcined powder is 0.5 μm or less. That is, when the particle diameter of the powder exceeds 0.5 μm, sintering in the subsequent process tends to be difficult.

次に、上記成分の粉末を静水圧プレスによって、98MPaから196MPa程度の圧力で成形した後、当該成形体に1400℃を超え1650℃未満の温度範囲の大気中において1時間から8時間程度の焼成を施す。   Next, the powder of the above component is molded by a hydrostatic pressure press at a pressure of about 98 MPa to 196 MPa, and then the molded body is fired for about 1 to 8 hours in the air in a temperature range of over 1400 ° C. and less than 1650 ° C. Apply.

上記温度範囲での焼成が施された成形体には、さらに酸素含有雰囲気下において熱間静水圧焼結による熱処理が施されることになるが、当該熱処理は、酸素分圧が5〜20%、圧力が0.9〜200MPa、温度が1200℃を超え1650℃未満の高温高圧酸素雰囲気中に30〜240分程度保持することによって行うのが好ましい。   The molded body that has been fired in the above temperature range is further subjected to a heat treatment by hot isostatic pressing in an oxygen-containing atmosphere, and the heat treatment has an oxygen partial pressure of 5 to 20%. It is preferably carried out by maintaining in a high-temperature high-pressure oxygen atmosphere at a pressure of 0.9 to 200 MPa and a temperature of more than 1200 ° C. and less than 1650 ° C. for about 30 to 240 minutes.

なお、熱間静水圧焼結による熱処理における酸素以外の雰囲気ガスについては、通常、不活性ガスとしてアルゴンを用いるが、腐食性や可燃性のないものである限り、特に限定されることはなく、例えば窒素ガスなどを用いることも可能である。
また、酸素分圧及び焼結圧力の上限値については、装置上の制約がない限り、特に限定されるものではなく、このような高圧・高酸素濃度雰囲気を用いることによって処理時間の短縮が可能になるものと予測されるが、このような焼結処置が可能な装置は、製造コストや運転コストが嵩むものと考えられることから、それぞれ20%及び200MPa以下とすることが望ましい。
As for the atmospheric gas other than oxygen in the heat treatment by hot isostatic pressing, argon is usually used as an inert gas, but is not particularly limited as long as it is not corrosive or flammable, For example, nitrogen gas or the like can be used.
In addition, the upper limit values of the oxygen partial pressure and sintering pressure are not particularly limited as long as there are no restrictions on the apparatus, and the processing time can be shortened by using such a high pressure / high oxygen concentration atmosphere. However, since an apparatus capable of such a sintering treatment is considered to increase manufacturing costs and operating costs, it is desirable that the apparatus be 20% and 200 MPa or less, respectively.

このようにして得られた固体電解質の微細構造、すなわち1〜10nm厚さを有するナノ結晶層の存在は、上記したように、透過型電子顕微鏡(200kV以上)を用いて、イオンミリングなどによって薄膜化した試料を10万倍以上の倍率で観察することにより確認することができ、その成分は1〜5nmに絞った電子ビームを照射したEDS分析によって求めることができる。   The fine structure of the solid electrolyte thus obtained, that is, the presence of the nanocrystal layer having a thickness of 1 to 10 nm, is thin as described above by ion milling using a transmission electron microscope (200 kV or more). The observed sample can be confirmed by observing the sample at a magnification of 100,000 times or more, and its component can be obtained by EDS analysis irradiated with an electron beam focused to 1 to 5 nm.

以下、本発明を実施例に基づいて具体的に説明するが、本発明は、これら実施例によって何ら限定されるものではない。   EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by these Examples.

(実施例1)
(1−x)ZrO+xScの一般式で表される組成成分において、Scのモル比xが0.05となるような固体電解質材料をクエン酸塩からの仮焼結によって得た後、当該仮焼生成物をアルコール中でボールミルを用いて24時間粉砕し、その後ロータリーエバボレータを用いて乾燥した。
次に、上記粉末を100MPa程度の圧力で成型した後、1450℃の大気中で6時間の焼成を行なった。
(Example 1)
In the composition component represented by the general formula (1-x) ZrO 2 + xSc 2 O 3 , a solid electrolyte material in which the molar ratio x of Sc 2 O 3 is 0.05 is temporarily sintered from citrate. After that, the calcined product was pulverized in alcohol using a ball mill for 24 hours, and then dried using a rotary evaporator.
Next, the powder was molded at a pressure of about 100 MPa, and then fired in the atmosphere at 1450 ° C. for 6 hours.

焼成後の上記成形体に、酸素分圧:20%(バランス:Ar)、圧力:1.0MPa、温度:1300℃の雰囲気下において、熱間静水圧焼結による2時間の熱処理を施し、得られたSc−ZrO系固体電解質について、密度や粒子径、立方晶率を調査すると共に、600℃及び800℃におけるイオン伝導度を測定した。さらに、イオンミリングによって薄膜化した試料について、透過型電子顕微鏡による組織観察を行ない、ナノ結晶層の存在を確認した。
これらの結果をその製造条件と共に表1に示す。
The molded body after firing was subjected to a heat treatment for 2 hours by hot isostatic pressing in an atmosphere of oxygen partial pressure: 20% (balance: Ar), pressure: 1.0 MPa, temperature: 1300 ° C. The obtained Sc 2 O 3 —ZrO 2 solid electrolyte was examined for density, particle diameter, and cubic rate, and ion conductivity at 600 ° C. and 800 ° C. was measured. Furthermore, the structure of the sample thinned by ion milling was observed with a transmission electron microscope to confirm the presence of the nanocrystal layer.
These results are shown in Table 1 together with the production conditions.

(実施例2)
Scのモル比xが0.07となるように固体電解質材料を調製し、圧力を98MPaとしたことを除いて、上記実施例1と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
なお、本発明実施例の代表例として、当該実施例2に係わる固体電解質の透過型電子顕微鏡による微細組織写真(60万倍)を図1に示す。
(Example 2)
The solid electrolyte material was prepared so that the molar ratio x of Sc 2 O 3 was 0.07, and the same operation as in Example 1 was repeated except that the pressure was 98 MPa. Obtained. And the same investigation and measurement were performed, and the results are also shown in Table 1.
As a representative example of the embodiment of the present invention, a microstructural photograph (600,000 times) of the solid electrolyte according to the second embodiment by a transmission electron microscope is shown in FIG.

(実施例3)
Scのモル比xが0.08となるように固体電解質材料を調製し、圧力を126MPaとしたことを除いて、上記実施例1と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
(Example 3)
The solid electrolyte material was prepared so that the molar ratio x of Sc 2 O 3 was 0.08, and the same operation as in Example 1 was repeated except that the pressure was 126 MPa. Obtained. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例4)
Scのモル比xが0.07となるように固体電解質材料を調製し、成形体の焼成温度及び熱間静水圧焼結による熱処理温度をそれぞれ1500℃としたことを除いて、上記実施例1と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
Example 4
The solid electrolyte material was prepared so that the molar ratio x of Sc 2 O 3 was 0.07, except that the firing temperature of the molded body and the heat treatment temperature by hot isostatic pressing were 1500 ° C., respectively. The same operation as in Example 1 was repeated to obtain a solid electrolyte of this example. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例5)
熱間静水圧焼結による熱処理雰囲気の酸素分圧を5%とし、圧力を10MPaとしたことを除いて、上記実施例4(モル比x=0.07)と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
(Example 5)
The same operation as in Example 4 (molar ratio x = 0.07) was repeated except that the oxygen partial pressure in the heat treatment atmosphere by hot isostatic pressing was 5% and the pressure was 10 MPa. A solid electrolyte was obtained. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例6)
成形体の焼成温度を1550℃とし、圧力を49MPaとしたことを除いて、上記実施例4と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
(Example 6)
Except that the calcining temperature of the compact was 1550 ° C. and the pressure was 49 MPa, the same operation as in Example 4 was repeated to obtain a solid electrolyte of this example. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例7)
熱間静水圧焼結による熱処理雰囲気圧力を48MPaとしたことを除いて、上記実施例6(モル比x=0.07)と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
(Example 7)
The same operation as in Example 6 (molar ratio x = 0.07) was repeated except that the heat treatment atmosphere pressure by hot isostatic pressing was 48 MPa to obtain a solid electrolyte of this example. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例8)
成形体の焼成温度を1600℃とし、圧力を196MPaとしたことを除いて、上記実施例4と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
(Example 8)
Except that the firing temperature of the molded body was 1600 ° C. and the pressure was 196 MPa, the same operation as in Example 4 was repeated to obtain a solid electrolyte of this example. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(実施例9)
熱間静水圧焼結による熱処理雰囲気の酸素分圧を5%としたことを除いて、上記実施例8(モル比x=0.07)と同様の操作を繰り返し、本例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
Example 9
Except that the oxygen partial pressure of the heat treatment atmosphere by hot isostatic pressing was set to 5%, the same operation as in Example 8 (molar ratio x = 0.07) was repeated to obtain a solid electrolyte of this example. It was. And the same investigation and measurement were performed, and the results are also shown in Table 1.

(比較例1)
(1−x)ZrO+xScの一般式で表される組成成分において、Scのモル比xが0.07となるような固体電解質材料をクエン酸塩からの仮焼結によって得た後、当該仮焼生成物をアルコール中でボールミルを用いて24時間粉砕し、その後ロータリーエバボレータを用いて乾燥した。
次に、上記粉末を100MPa程度の圧力で成型した後、1450℃の大気中で6時間の焼成を行なうことにより、熱間静水圧焼結による熱処理を施すことなく、本比較例の固体電解質を得た。そして、同様の調査及び測定を行い、その結果を表1に併せて示す。
また、当該比較例1に係わる固体電解質の透過型電子顕微鏡による微細組織写真(30万倍)を図2に示す。
(Comparative Example 1)
In the composition component represented by the general formula of (1-x) ZrO 2 + xSc 2 O 3 , a solid electrolyte material in which the molar ratio x of Sc 2 O 3 is 0.07 is temporarily sintered from citrate. After that, the calcined product was pulverized in alcohol using a ball mill for 24 hours, and then dried using a rotary evaporator.
Next, the powder is molded at a pressure of about 100 MPa, and then fired in the atmosphere at 1450 ° C. for 6 hours, so that the solid electrolyte of this comparative example is not subjected to heat treatment by hot isostatic pressing. Obtained. And the same investigation and measurement were performed, and the results are also shown in Table 1.
Moreover, the fine structure photograph (300,000 times) of the solid electrolyte concerning the said comparative example 1 by the transmission electron microscope is shown in FIG.

Figure 2005259556
Figure 2005259556

表1の記載から明らかなように、実施例1〜9の固体電解質においては、図1に代表例として示したように、その結晶粒界に1〜10nm幅のナノ結晶層の存在が確認され、低温域(600℃〜800℃付近)においても、良好なイオン伝導性を示すことが確認された。
これに対して、熱間静水圧焼結による熱処理が施されていない比較例のしていない固体電解質においては、図2に示したように、上記のようなナノ結晶層が認められず、600℃及び800℃におけるイオン伝導度についても、上記実施例に較べて1割程度低い値となっていることが判明した。
As is apparent from the description in Table 1, in the solid electrolytes of Examples 1 to 9, as shown as a representative example in FIG. 1, the presence of a nanocrystal layer having a width of 1 to 10 nm was confirmed at the crystal grain boundary. In addition, it was confirmed that good ion conductivity was exhibited even in a low temperature range (around 600 ° C. to 800 ° C.).
On the other hand, in the solid electrolyte which is not subjected to the heat treatment by hot isostatic pressing, the nanocrystal layer as described above is not recognized as shown in FIG. It was also found that the ionic conductivity at ℃ and 800 ℃ was about 10% lower than that in the above example.

本発明の実施例2に係わる固体電解質における微細構造を示す透過型電子顕微鏡写真である。It is a transmission electron micrograph which shows the fine structure in the solid electrolyte concerning Example 2 of this invention. 熱間静水圧焼結による熱処理が施されていない比較例1に係わる固体電解質の微細構造を示す透過型電子顕微鏡写真である。It is a transmission electron micrograph which shows the fine structure of the solid electrolyte concerning the comparative example 1 which has not been heat-processed by hot isostatic pressing.

Claims (5)

次の一般式(1)
(1−x)ZrO+xSc・・・(1)
(式中のxは、0.03〜0.15)で表わされる組成を有するジルコニア焼結体から成り、結晶粒界に1〜10nmの厚さを有する同成分のナノ結晶層を備えていることを特徴とする固体電解質。
The following general formula (1)
(1-x) ZrO 2 + xSc 2 O 3 (1)
(Wherein x is 0.03 to 0.15), and is composed of a zirconia sintered body having a composition represented by the following formula, and has a nanocrystalline layer of the same component having a thickness of 1 to 10 nm at a grain boundary. A solid electrolyte characterized by that.
請求項1に記載の固体電解質を製造するに際し、上記成分を有する粉末を静水圧プレスにより成形した後、1400℃を超え1650℃未満の温度範囲で焼成し、さらに酸素含有雰囲気下において熱間静水圧焼結による熱処理を施すことを特徴とする固体電解質の製造方法。   In producing the solid electrolyte according to claim 1, the powder having the above components is molded by a hydrostatic pressure press, fired in a temperature range of more than 1400 ° C. and less than 1650 ° C., and further hot-static under an oxygen-containing atmosphere. A method for producing a solid electrolyte, characterized by performing a heat treatment by hydrostatic sintering. 熱間静水圧焼結による熱処理工程において、酸素分圧が5〜20%、圧力が0.9〜200MPaであって、1200℃を超え1650℃未満の温度範囲の雰囲気に30〜240分保持することを特徴とする請求項2に記載の固体電解質の製造方法。   In the heat treatment step by hot isostatic pressing, the oxygen partial pressure is 5 to 20%, the pressure is 0.9 to 200 MPa, and the temperature is maintained in an atmosphere in the temperature range of more than 1200 ° C. and less than 1650 ° C. for 30 to 240 minutes. The method for producing a solid electrolyte according to claim 2. 請求項1に記載の固体電解質を用いたことを特徴とする固体酸化物形燃料電池。   A solid oxide fuel cell comprising the solid electrolyte according to claim 1. 請求項1に記載の固体電解質を用いたことを特徴とする酸素センサ。
An oxygen sensor using the solid electrolyte according to claim 1.
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Publication number Priority date Publication date Assignee Title
WO2017034058A1 (en) * 2015-08-27 2017-03-02 (주)화인테크 Β-alumina solid electrolyte obtained by hot isostatic pressing method, and preparation method therefor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06116026A (en) * 1992-09-29 1994-04-26 Kyocera Corp Zirconia solid electrolyte
JPH08503193A (en) * 1992-11-17 1996-04-09 ローベルト ボツシユ ゲゼルシヤフト ミツト ベシユレンクテル ハフツング Sintered solid electrolyte with high oxygen ion conductivity
JPH08119732A (en) * 1994-10-28 1996-05-14 Kyocera Corp Production of solid electrolyte

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06116026A (en) * 1992-09-29 1994-04-26 Kyocera Corp Zirconia solid electrolyte
JPH08503193A (en) * 1992-11-17 1996-04-09 ローベルト ボツシユ ゲゼルシヤフト ミツト ベシユレンクテル ハフツング Sintered solid electrolyte with high oxygen ion conductivity
JPH08119732A (en) * 1994-10-28 1996-05-14 Kyocera Corp Production of solid electrolyte

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017034058A1 (en) * 2015-08-27 2017-03-02 (주)화인테크 Β-alumina solid electrolyte obtained by hot isostatic pressing method, and preparation method therefor

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