JP3007929B2 - High density sintering method for oxide fine particles - Google Patents
High density sintering method for oxide fine particlesInfo
- Publication number
- JP3007929B2 JP3007929B2 JP9127948A JP12794897A JP3007929B2 JP 3007929 B2 JP3007929 B2 JP 3007929B2 JP 9127948 A JP9127948 A JP 9127948A JP 12794897 A JP12794897 A JP 12794897A JP 3007929 B2 JP3007929 B2 JP 3007929B2
- Authority
- JP
- Japan
- Prior art keywords
- sintered body
- oxide
- sintering
- fine particles
- density
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は高密度焼結体の製造
方法に関し、詳しくは、強誘電体、導電体、強磁性体と
して有用な酸化物微粒子の高密度焼結体の製造方法及び
その機能高度化のために好適な焼結方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-density sintered body, and more particularly, to a method for manufacturing a high-density sintered body of oxide fine particles useful as a ferroelectric substance, a conductor, and a ferromagnetic substance. The present invention relates to a sintering method suitable for enhancing functions.
【０００２】[0002]
【従来技術とその課題】現在、電気機器・電子製品等に
用いられているコンデンサ用材料、導電性材料、磁性体
材料として、ペロブスカイト型構造、パイロクロア型構
造、イルメナイト型構造、岩塩型構造、スピネル型構
造、フルオロライト型構造を有する様々な金属酸化物及
びそれらの複合体（コンポジット）が開発・使用されて
いる。これらの酸化物を実用可能な状態にするためには
高密度に焼結させる必要があるが、従来は高温・高圧で
の焼結がなされてきた。2. Description of the Related Art Perovskite-type, pyrochlore-type, ilmenite-type, rock-salt-type, and spinel-type materials are used as capacitor materials, conductive materials, and magnetic materials currently used in electrical equipment and electronic products. Various metal oxides having a mold structure and a fluorolite structure and composites thereof have been developed and used. To make these oxides practicable, it is necessary to sinter them at a high density, but conventionally, sintering at high temperature and high pressure has been performed.
【０００３】この方法では、高密度焼結を達成すること
はできるが、粒径及び誘電特性・導電特性・磁気特性に
大きな影響を与えるドメインサイズを制御できないた
め、高誘電率・高導電率・高磁化率を有する焼結体を安
定に作製できなかった。そのため、粒径・ドメインサイ
ズ制御が可能で、高密度に焼結可能な方法を探索するこ
とが強く求められている。[0003] In this method, high-density sintering can be achieved, but the grain size and the domain size that greatly affects the dielectric properties, conductive properties, and magnetic properties cannot be controlled. A sintered body having a high magnetic susceptibility could not be produced stably. Therefore, there is a strong need to search for a method that can control the particle size and domain size and that can be sintered at high density.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、粒径を制御
しながら短時間で高密度の酸化物焼結体を作製し、高誘
電率・高導電率・高磁化率を有する焼結体を得ることを
主な目的とする。SUMMARY OF THE INVENTION The present invention relates to a sintered compact having a high dielectric constant, a high electrical conductivity, and a high magnetic susceptibility by producing a high-density oxide sintered body in a short time while controlling the particle size. The main purpose is to obtain
【０００５】[0005]
【課題を解決するための手段】本発明者は、上記のよう
な従来技術の問題に鑑みて鋭意研究を重ねた結果、酸化
物微粒子を放電プラズマ焼結機により焼結させ、得られ
る焼結体を高温で熱処理するという２段プロセスを用い
ることにより、高密度で高誘電率・高導電率・高磁化率
の酸化物焼結体が得られることを見出し、本発明を完成
するに至った。Means for Solving the Problems The present inventor has conducted intensive studies in view of the above-mentioned problems of the prior art, and as a result, sintered oxide fine particles with a discharge plasma sintering machine and obtained a sintered material. It has been found that by using a two-stage process of heat-treating the body at a high temperature, an oxide sintered body having a high density, a high dielectric constant, a high conductivity, and a high magnetic susceptibility can be obtained, and the present invention has been completed. .
【０００６】本発明は、酸化物微粒子を放電プラズマ焼
結する酸化物微粒子の焼結方法にある。本発明は、一種
又は二種以上の酸化物微粒子を放電プラズマ焼結して
（具体的には、放電プラズマ焼結機を用いて粒成長を起
こさせずに焼結させ、得られた焼結体を熱処理して）酸
化物焼結体（特に、ペロブスカイト型構造、パイロクロ
ア型構造、イルメナイト型構造、岩塩型構造、スピネル
型構造又はフルオロライト型構造を有する酸化物焼結
体）又は酸化物／酸化物複合体の焼結体（特に、高誘電
率、高導電率、高磁化率を有する焼結体）を作製する高
密度焼結体の製造方法にある。The present invention is a method for sintering oxide fine particles by spark plasma sintering the oxide fine particles. In the present invention, one or more oxide fine particles are subjected to discharge plasma sintering (specifically, sintering without causing grain growth using a discharge plasma sintering machine). Heat-treated body) oxide sintered body (particularly oxide sintered body having perovskite type structure, pyrochlore type structure, ilmenite type structure, rock salt type structure, spinel type structure or fluorolite type structure) or oxide / The present invention relates to a method for producing a high-density sintered body for producing a sintered body of an oxide composite (particularly, a sintered body having a high dielectric constant, a high electrical conductivity, and a high magnetic susceptibility).
【０００７】[0007]
【発明の実施の形態】酸化物微粒子 出発原料である酸化物微粒子は特に限定されるものでは
なく、各種の金属酸化物の微粒子を原料粉末として使用
できる。金属酸化物としては、チタン酸バリウム（Ｂａ
ＴｉＯ3）、チタン酸鉛（ＰｂＴｉＯ3）、チタン酸カル
シウム（ＣａＴｉＯ3）、チタン酸ストロンチウム（Ｓ
ｒＴｉＯ3）、ジルコン酸バリウム（ＢａＺｒＯ3）、ジ
ルコン酸鉛（ＰｂＺｒＯ3）、ジルコン酸カルシウム
（ＣａＺｒＯ3）、ジルコン酸ストロンチウム（ＳｒＺ
ｒＯ3）、及びこれらの固溶体、ＮａＺｒ2（ＰＯ4）3及
びＮａ4Ｚｒ2（ＳｉＯ4）3をはじめとするＮＡＳＩＣＯ
Ｎ酸化物（Ｎａ1+xＺｒ2Ｐ3-xＳｉxＯ12；ｘは化合物中
のリンに対するシリコンの添加比を示す（０≦ｘ≦
３））を例示することができる。酸化物微粒子の調製方
法については、特に限定されるものではなく、例えば、
固体反応法、加水分解法、ゾルゲル法等の合成手法によ
り調製することができる。BEST MODE FOR CARRYING OUT THE INVENTION The oxide fine particles as a starting material for oxide fine particles are not particularly limited, and fine particles of various metal oxides can be used as a raw material powder. As the metal oxide, barium titanate (Ba)
TiO 3 ), lead titanate (PbTiO 3 ), calcium titanate (CaTiO 3 ), strontium titanate (S
rTiO 3 ), barium zirconate (BaZrO 3 ), lead zirconate (PbZrO 3 ), calcium zirconate (CaZrO 3 ), strontium zirconate (SrZ)
rO 3 ) and their solid solutions, NASICO including NaZr 2 (PO 4 ) 3 and Na 4 Zr 2 (SiO 4 ) 3
N-oxide (Na 1 + x Zr 2 P 3-x Si x O 12; x represents an addition ratio of silicon to phosphorus in the compound (0 ≦ x ≦
3)) can be exemplified. The method for preparing the oxide fine particles is not particularly limited, for example,
It can be prepared by a synthesis method such as a solid reaction method, a hydrolysis method, a sol-gel method and the like.
【０００８】本発明の焼結方法は、ペロブスカイト型、
パイロクロア型、イルメナイト型、岩塩型、スピネル型
又はフルオライト型の結晶構造を有する酸化物焼結体を
製造するために好適である。従って、本発明の高密度焼
結体の製造方法は、これらの結晶構造を形成することが
できる金属酸化物の微粒子を出発原料として用いて焼結
体を製造するために好適である。[0008] The sintering method of the present invention comprises a perovskite type,
It is suitable for producing an oxide sintered body having a pyrochlore type, ilmenite type, rock salt type, spinel type or fluorite type crystal structure. Therefore, the method for producing a high-density sintered body of the present invention is suitable for producing a sintered body using metal oxide fine particles capable of forming these crystal structures as starting materials.
【０００９】本発明によれば、粒成長を起こさせずに酸
化物微粒子を焼結させることができるので、原料に用い
る酸化物微粒子の粒径を調節することにより、得られる
焼結体の粒径を制御することができる。原料に用いる酸
化物微粒子の粒径の調節には、その調製方法により、公
知の方法を使用できる。According to the present invention, the oxide fine particles can be sintered without causing grain growth. Therefore, by adjusting the particle size of the oxide fine particles used as a raw material, the particles of the obtained sintered body can be sintered. The diameter can be controlled. A known method can be used to adjust the particle size of the oxide fine particles used as a raw material, depending on the preparation method.
【００１０】放電プラズマ焼結 原料粉末を放電プラズマ焼結することにより、粒成長を
起こさせずに焼結させることができ、高密度の焼結体、
即ち、原料粉末よりも高密度の焼結体を製造することが
できる。原料粉末を加圧しながら高温に加熱し、数分間
電圧を印加することにより放電プラズマ焼結を進行させ
ることができる。[0010] By spark plasma sintering of the discharge plasma sintering raw material powder, sintering can be performed without causing grain growth.
That is, a sintered body having a higher density than the raw material powder can be manufactured. The raw material powder is heated to a high temperature while being pressurized, and discharge plasma sintering can be advanced by applying a voltage for several minutes.
【００１１】好ましい実施の形態では、放電プラズマ焼
結装置を用いて酸化物微粒子の焼結を行う。放電プラズ
マ焼結、放電焼結及び通電焼結などのＯＮ−ＯＦＦパル
ス通電による焼結法を用いて粉体を圧縮して圧粉体と
し、この圧粉体にパルス状電流を通電すると共に、その
ピーク電流とパルス幅とを制御して材料温度を制御しつ
つ圧縮焼結することができる。粉体粒子間隙に生ずる放
電現象を利用し放電プラズマ、放電衝撃圧力などによる
粒子表面の浄化活性化作用及び電場に生ずる電解拡散効
果やジュール熱による熱拡散効果、加圧による塑性変形
力などが焼結の駆動力となり焼結を促進するものであ
る。In a preferred embodiment, the oxide fine particles are sintered using a spark plasma sintering apparatus. Using a sintering method with ON-OFF pulse conduction such as discharge plasma sintering, discharge sintering, and electric sintering, the powder is compressed into a green compact, and a pulsed current is applied to the green compact, The compression sintering can be performed while controlling the material temperature by controlling the peak current and the pulse width. Utilizing discharge phenomena generated in the gaps between powder particles, the activation of purification of the particle surface by discharge plasma, discharge impact pressure, etc., the electrolytic diffusion effect generated by an electric field, the thermal diffusion effect caused by Joule heat, and the plastic deformation force caused by pressurization are ignited. It serves as a driving force for sintering and promotes sintering.
【００１２】放電プラズマ焼結機としては、原料粉末の
加熱・冷却および加圧が可能で、放電を起こすだけの電
圧が印加できるものなどを使用できる。すなわち、加熱
・冷却装置、加圧装置及び放電装置並びに原料粉末を収
納する治具を備えた放電プラズマ焼結機により、原料粉
末を放電プラズマ焼結することができる。治具としては
グラファイトが適している。As the discharge plasma sintering machine, one capable of heating, cooling and pressurizing the raw material powder and applying a voltage sufficient to generate a discharge can be used. That is, the raw material powder can be subjected to discharge plasma sintering by a discharge plasma sintering machine equipped with a heating / cooling device, a pressurizing device, a discharge device, and a jig for storing the raw material powder. Graphite is suitable as a jig.
【００１３】図１に放電プラズマ焼結装置の概略構成を
示す。放電プラズマ焼結装置（１）は粉体（２）を装填
する成形用のダイ（３）及び上下一対の圧縮通電用パン
チ（４、５）を有している。パンチ（４、５）は加圧機
構（１３）により駆動される冷却水路（９、９’）を内
蔵する上下一対の通電加圧パンチ電極（６、７）により
パルス電流が供給される。FIG. 1 shows a schematic configuration of a spark plasma sintering apparatus. The spark plasma sintering apparatus (1) has a molding die (3) for loading the powder (2) and a pair of upper and lower compression energizing punches (4, 5). The punches (4, 5) are supplied with a pulse current by a pair of upper and lower energized pressurized punch electrodes (6, 7) including cooling water channels (9, 9 ') driven by a pressurizing mechanism (13).
【００１４】粉体（２）にパルス電流を供給するため成
形用ダイ（３）及びパンチ（４、５）は導電性部材で構
成されており、パンチ（４、５）は加圧パンチ電極
（６、７）内に設けられた図示しない給電端子を介して
焼結用電源（１１）に接続されている。焼結用電源（１
１）により発生したパルス電流が成形用ダイ（３）、パ
ンチ（４、５）を介して粉体（２）を流れるように構成
されている。この通電部は水冷真空チャンバー（８）に
収容されており、チャンバー内部は雰囲気制御機構（１
５）により所定の真空度を維持するか、アルゴンガス等
の不活性ガス雰囲気、大気雰囲気としても良い。In order to supply a pulse current to the powder (2), the molding die (3) and the punches (4, 5) are made of a conductive material, and the punches (4, 5) are formed by pressurized punch electrodes (4). 6, 7) are connected to a sintering power supply (11) via a power supply terminal (not shown) provided in the apparatus. Power supply for sintering (1
The pulse current generated in 1) flows through the powder (2) via the molding die (3) and the punches (4, 5). This current-carrying part is housed in a water-cooled vacuum chamber (8), and the inside of the chamber is controlled by an atmosphere control mechanism (1).
The predetermined degree of vacuum may be maintained according to 5), or an inert gas atmosphere such as an argon gas atmosphere or an air atmosphere may be used.
【００１５】成形用ダイ（３）及びパンチ（４、５）は
所望の焼結体形状に応じた形状に構成することができる
が、ここでは成形用ダイ及びパンチは円柱状に構成され
ており、本実施形態では円柱ペレット状の焼結体が得ら
れる。成形用ダイ（３）及びパンチ（４、５）は導電性
を持つグラファイトで構成されているが、導電性と耐熱
性及び加圧に耐え得る強度を持つものであれば他の材
質、例えば導電性セラミックス等で構成しても良い。The forming die (3) and the punches (4, 5) can be formed in a shape corresponding to a desired sintered body shape. Here, the forming die and the punch are formed in a cylindrical shape. In this embodiment, a cylindrical pellet-shaped sintered body is obtained. The molding die (3) and the punches (4, 5) are made of graphite having conductivity. However, other materials such as conductive materials having conductivity, heat resistance and strength enough to withstand pressure are used. It may be made of conductive ceramics or the like.
【００１６】図１に示す制御装置（１２）は加圧機構
（１３）、焼結用電源（１１）、雰囲気制御機構（１
５）、水冷却機構（１６、１０）、及び温度計測装置
（１７）を駆動制御するものである。制御装置（１２）
は加圧機構（１３）を駆動し、パンチ（４、５）が所定
の圧縮圧力で粉体（２）を圧縮するよう構成されてい
る。圧粉体（２）の温度は成形用ダイ（３）に取り付け
られた図示しない熱電対又は放射温度計などにより検出
される。検出値は制御装置（１２）に入力され所定の制
御プログラムに基づいて焼結用電源（１１）を駆動しパ
ルス電流を発生させる。The control device (12) shown in FIG. 1 includes a pressurizing mechanism (13), a sintering power supply (11), and an atmosphere control mechanism (1).
5) Drive control of the water cooling mechanisms (16, 10) and the temperature measuring device (17). Control device (12)
Is configured to drive the pressing mechanism (13) so that the punches (4, 5) compress the powder (2) at a predetermined compression pressure. The temperature of the green compact (2) is detected by a thermocouple or a radiation thermometer (not shown) attached to the molding die (3). The detected value is input to the controller (12) and drives the sintering power supply (11) based on a predetermined control program to generate a pulse current.
【００１７】パルス電流の周期は３００Ｈｚ乃至３０Ｋ
Ｈｚとすることができるが電源価格の点から低周波電源
が推奨される。加熱温度は適宜調整する必要があり原料
粉末の種類により異なるが通常は数百〜１０００℃以
上、好ましくは５００〜１５００℃、更に好ましくは８
００〜１３００℃程度とする。制御装置（１２）は圧粉
体（２）の温度検出値が予め設定された昇温曲線と一致
するよう電流、電圧値を調節するよう構成されている。The cycle of the pulse current is 300 Hz to 30 K
Hz, but a low-frequency power source is recommended in terms of power source price. The heating temperature must be appropriately adjusted and varies depending on the type of the raw material powder, but is usually several hundred to 1000 ° C. or higher, preferably 500 to 1500 ° C., and more preferably 8 to 1000 ° C.
It is set to about 00 to 1300 ° C. The control device (12) is configured to adjust the current and voltage values so that the temperature detection value of the green compact (2) matches a preset temperature rising curve.
【００１８】このようなパルス通電法を用いた放電プラ
ズマ焼結装置などの通電焼結法は圧粉体自体の自己発熱
となるジュール熱を直接利用しているため、誘導加熱あ
るいは輻射加熱を用いた従来焼結法に比べ高い熱効率を
有している。またパルス状電圧・電流を印可することに
よって粉体粒子間の空隙で放電現象を生じさせ放電に伴
う局所的な高温により粒子間のネック形成を促進させ、
かつ粒成長を抑制することが可能である。そのため通常
の直流・交流を用いた焼結方法により、高効率かつ短時
間で焼結体を作製することができる。In the current sintering method such as the discharge plasma sintering apparatus using the pulse current method, since the Joule heat which is the self-heating of the green compact itself is directly used, induction heating or radiant heating is used. It has higher thermal efficiency than the conventional sintering method. In addition, by applying pulsed voltage and current, a discharge phenomenon occurs in the gap between the powder particles, and a local high temperature accompanying the discharge promotes the formation of a neck between the particles,
In addition, it is possible to suppress grain growth. Therefore, a sintered body can be manufactured with high efficiency and in a short time by a normal sintering method using DC / AC.
【００１９】熱処理 例えば、治具としてグラファイトを用いた場合、得られ
る焼結体は治具の成分であるグラファイトを含み、導電
性がある。焼結体に含まれるグラファイト等の不純物
は、この後、熱処理する２段プロセスにより、取除くこ
とができる。具体的には、通常の電気炉を用い、大気雰
囲気下、または制御雰囲気下、放電プラズマ焼結の焼結
温度と同程度の温度、即ち、数百〜１０００℃以上、好
ましくは５００〜１５００℃、更に好ましくは８００〜
１３００℃程度で数十分〜数時間程度加熱することによ
り、グラファイト等を取除くことができ、高密度焼結体
を得ることができる。 Heat treatment For example, when graphite is used as a jig, the obtained sintered body contains graphite which is a component of the jig and has conductivity. Impurities such as graphite contained in the sintered body can be removed by a two-step process in which heat treatment is performed thereafter. Specifically, using a normal electric furnace, under the air atmosphere or under a controlled atmosphere, a temperature approximately equal to the sintering temperature of spark plasma sintering, that is, several hundred to 1,000 ° C. or higher, preferably 500 to 1500 ° C. , More preferably 800 to
By heating at about 1300 ° C. for several tens of minutes to several hours, graphite or the like can be removed, and a high-density sintered body can be obtained.
【００２０】熱処理の際、焼結体は、それと反応しない
通常のアルミナ等のルツボに入れ、昇温・降温速度は数
〜数十℃／ｍｉｎ、好ましくは５〜１５℃／ｍｉｎ程度
で行う。一回のプラズマ焼結により、焼結できる原料粉
末の量（使用量）は、装置の性能等に応じて適宜選択す
る必要があり、原料粉末の種類により異なるが、通常数
ｇ程度を用いる。During the heat treatment, the sintered body is placed in a crucible made of ordinary alumina or the like which does not react with the sintered body, and the temperature is raised and lowered at a rate of several to several tens of degrees Celsius / min, preferably about 5 to 15 degrees Celsius / min. The amount (use amount) of the raw material powder that can be sintered by one plasma sintering needs to be appropriately selected according to the performance of the apparatus and the like, and varies depending on the type of the raw material powder.
【００２１】[0021]
【実施例】以下、チタン酸バリウムを対象とした実施例
を示し、本発明の特徴とするところをより明確にする。EXAMPLES Examples of barium titanate will be described below to clarify the features of the present invention.
【００２２】実施例１ （チタン酸バリウム微粒子の合成）焼結に用いるチタン
酸バリウム微粒子の合成は、原料、条件などの点で特に
限定されるものではないが、通常以下の様にして合成す
ることができる。まず８０℃の０．４５Ｍ Ｂａ（Ｏ
Ｈ）2水溶液にＴｉ［ＯＣＨ（ＣＨ3）2］4を滴下して加
水分解反応を行い、ＢａＴｉＯ3沈澱を得る。反応はＢ
ａＣＯ3の生成を防ぐために窒素雰囲気下で行う。得ら
れた沈澱物を１２００℃で２時間焼成することにより平
均粒径約０．６μｍの粉末を得ることができる。 Example 1 (Synthesis of Barium Titanate Fine Particles) The synthesis of barium titanate fine particles used for sintering is not particularly limited in terms of raw materials, conditions, etc., but is usually performed as follows. be able to. First, 0.45M Ba (O
H) 2 aqueous Ti [OCH (CH 3) 2 ] 4 was added dropwise and subjected to hydrolysis reaction to obtain a BaTiO 3 precipitate. The reaction is B
This is performed in a nitrogen atmosphere to prevent generation of aCO 3 . The obtained precipitate is calcined at 1200 ° C. for 2 hours to obtain a powder having an average particle size of about 0.6 μm.
【００２３】（放電プラズマ焼結）放電プラズマ焼結機
としては、住友石炭鉱業（株）製放電プラズマ焼結機Ｓ
ＰＳ−２０４０を用いた。また治具はグラファイト製で
直径２ｃｍの円筒形のものを用いた。この治具に、加水
分解法により調製したチタン酸バリウム粉末約３ｇを均
一に入れ、４００ｋｇｆ／ｃｍ2の圧力を印加した。さ
らに試料周辺を１１００℃に加熱し、４０００Ａの直流
電流を印加した。この状態を３分間保持した後、印加電
流を止め、試料近傍を室温にまで冷却した。(Discharge Plasma Sintering) As a discharge plasma sintering machine, a discharge plasma sintering machine S manufactured by Sumitomo Coal Mining Co., Ltd.
PS-2040 was used. A jig made of graphite and having a cylindrical shape with a diameter of 2 cm was used. About 3 g of barium titanate powder prepared by the hydrolysis method was uniformly charged into this jig, and a pressure of 400 kgf / cm 2 was applied. Further, the periphery of the sample was heated to 1100 ° C., and a DC current of 4000 A was applied. After maintaining this state for 3 minutes, the applied current was stopped, and the vicinity of the sample was cooled to room temperature.
【００２４】この状態で取り出した焼結体は、図２に示
したＸ線回折から明らかな通り、治具のグラファイトが
含まれており、電気伝導性を有する。グラファイトの含
有は図３のＥＤＸからも明らかである。この焼結体を１
２００℃で２時間熱処理すると、図２および図３に示さ
れている通り、ＢａＴｉＯ3のみとなった。すなわち、
この２段プロセスによりＢａＴｉＯ3焼結体を得ること
ができた。The sintered body taken out in this state contains graphite as a jig and has electrical conductivity, as is apparent from the X-ray diffraction shown in FIG. The graphite content is also evident from the EDX of FIG. This sintered body is
After heat treatment at 200 ° C. for 2 hours, only BaTiO 3 was obtained as shown in FIGS. That is,
A BaTiO 3 sintered body was obtained by this two-step process.
【００２５】この熱処理後の焼結体中の粒径の大きさ
は、図４のＳＥＭ写真に示されている通り約０．６μｍ
で、原料粉末の粒径を保ったまま焼結が進行している。
得られた焼結体の密度は５．８３ｇ／ｃｍ3で、これは
理論密度（６．０１２ｇ／ｃｍ3）の９７％であり、非
常に高密度の焼結体である。The size of the grain in the sintered body after the heat treatment is about 0.6 μm as shown in the SEM photograph of FIG.
Thus, sintering is progressing while maintaining the particle size of the raw material powder.
The density of the obtained sintered body is 5.83 g / cm 3 , which is 97% of the theoretical density (6.012 g / cm 3 ), and is a very high density sintered body.
【００２６】本焼結体の測定誘電率は図５に示す通り
で、室温で約３５００、転移点近傍（１２０℃）で約６
２００と、同じ原料粉末を用いた通常の外熱式焼結法に
よる値（室温で約１７００、転移点近傍で約２８００、
竹内友成ら，Ｊ．Ｃｅｒａｍ．Ｓｏｃ．Ｊａｐａｎ，１
０２（１９９４）１１７７）に比べ非常に高いものであ
る。これは粒径・ドメインサイズを保持したまま高密度
に焼結させたために得られたものと考えられる。The measured dielectric constant of the sintered body is about 3500 at room temperature, and about 6 near the transition point (120 ° C.) as shown in FIG.
200 and a value obtained by a normal external heat sintering method using the same raw material powder (about 1700 at room temperature, about 2800 near the transition point,
Takenari Tomonari et al. Ceram. Soc. Japan, 1
02 (1994) 1177). It is considered that this was obtained because sintering was performed at high density while maintaining the grain size and domain size.
【００２７】（その他）本方法は他のペロブスカイト型
構造、パイロクロア型構造、イルメナイト型構造、岩塩
型構造、スピネル型構造、フルオロライト型構造を有す
る様々な金属酸化物、およびそれらの複合体（コンポジ
ット）にも適用可能であり、従来の外熱式焼結法による
ものに比べ高誘電率・高導電率・高磁化率の焼結体を得
ることができる。(Others) The present method is applicable to various metal oxides having other perovskite-type structures, pyrochlore-type structures, ilmenite-type structures, rock salt-type structures, spinel-type structures, fluorolite-type structures, and composites thereof. ), And a sintered body having a high dielectric constant, a high conductivity, and a high magnetic susceptibility can be obtained as compared with a conventional external heat sintering method.
【００２８】実施例２ （ＮａＺｒ2（ＰＯ4）3微粒子の合成）焼結に用いるＮ
ａＺｒ2（ＰＯ4）3（以下ＮＺＰと略す）微粒子の合成
は、原料、条件などの点で特に限定されるものではない
が、通常以下の様にして合成することができる。まず、
Ｎａ2ＣＯ3、ＺｒＯ（ＮＯ3）2・２Ｈ2Ｏ、及びＮＨ4Ｈ
2ＰＯ4の各水溶液をＮＺＰの組成になるように混合して
共沈反応を行い、沈澱を得る。これを８０℃で一夜間乾
燥し、５００℃で１時間仮焼を行い、ＮＨ4 +、Ｃ
Ｏ3 2-、ＮＯ3 -の除去を行う。更にこれを充分粉砕混合
し、８００℃で２時間焼成することによりＮＺＰ粉末を
得ることができる。 Example 2 (Synthesis of NaZr 2 (PO 4 ) 3 Fine Particles) N used for sintering
The synthesis of aZr 2 (PO 4 ) 3 (hereinafter abbreviated as NZP) fine particles is not particularly limited in terms of raw materials, conditions and the like, but can be generally synthesized as follows. First,
Na 2 CO 3 , ZrO (NO 3 ) 2 .2H 2 O, and NH 4 H
Each aqueous solution of 2 PO 4 is mixed so as to have a composition of NZP, and a coprecipitation reaction is performed to obtain a precipitate. This was dried at 80 ° C. overnight, calcined at 500 ° C. for 1 hour, and NH 4 + , C
O 3 2- and NO 3 - are removed. Further, this is sufficiently pulverized and mixed, and calcined at 800 ° C. for 2 hours to obtain an NZP powder.
【００２９】（放電プラズマ焼結）放電プラズマ焼結機
としては、住友石炭鉱業（株）製放電プラズマ焼結機Ｓ
ＰＳ−２０４０を用いた。また治具はグラファイト製で
直径２ｃｍの円筒形のものを用いた。この治具に、共沈
法により調製したＮＺＰ粉末約３ｇを均一に入れ、８０
０ｋｇｆ／ｃｍ2の圧力を印加した。さらに試料周辺を
１０００℃に加熱し、４０００Ａの直流電流を印加し
た。この状態を５分間保持した後、印加電流を止め、試
料近傍を室温にまで冷却した。(Discharge Plasma Sintering) As a discharge plasma sintering machine, a discharge plasma sintering machine S manufactured by Sumitomo Coal Mining Co., Ltd.
PS-2040 was used. A jig made of graphite and having a cylindrical shape with a diameter of 2 cm was used. About 3 g of NZP powder prepared by the coprecipitation method is uniformly put into this jig, and
A pressure of 0 kgf / cm 2 was applied. Further, the periphery of the sample was heated to 1000 ° C., and a DC current of 4000 A was applied. After maintaining this state for 5 minutes, the applied current was stopped, and the vicinity of the sample was cooled to room temperature.
【００３０】この状態で取り出した焼結体は、側面は黒
色をしているものの、上下の面は白色のままであった。
側面の黒色は治具からのグラファイトと考えられ、これ
はダイヤモンドカッターで取り除いた。図６に示したＸ
線回折から明らかな通り、焼結体は主として出発原料で
あるＮＺＰから成り、焼結過程の高温反応で生成したＺ
ｒＰ2Ｏ7が不純物として若干含まれていた。得られた焼
結体の密度は１．９９ｇ／ｃｍ3で、これは理論密度
（３．１９ｇ／ｃｍ3）の６２％であり、同じ原料粉末
を用いた通常の外熱式焼結法による値（３９％）よりも
非常に高密度のものであった。The sintered body taken out in this state had black sides, but the upper and lower faces remained white.
The black side was considered graphite from the jig and was removed with a diamond cutter. X shown in FIG.
As is clear from X-ray diffraction, the sintered body is mainly composed of NZP, which is a starting material, and is formed by a high-temperature reaction in the sintering process.
rP 2 O 7 was slightly contained as an impurity. The density of the obtained sintered body is 1.99 g / cm 3 , which is 62% of the theoretical density (3.19 g / cm 3 ), and is obtained by a normal external thermal sintering method using the same raw material powder. The density was much higher than the value (39%).
【００３１】本焼結体の導電率は図７に示す通りで、３
００℃で１．１×１０-6Ｓ／ｃｍと、同じ原料粉末を用
いた通常の外熱式焼結法による値（３．７×１０-7Ｓ／
ｃｍ）に比べ約３倍程度高いものである。これは高密度
に焼結させたために得られたものと考えられる。The conductivity of the sintered body is as shown in FIG.
1.1 × 10 −6 S / cm at 00 ° C., which is a value (3.7 × 10 −7 S / cm) obtained by a normal external heat sintering method using the same raw material powder.
cm) about three times higher. This is considered to have been obtained due to sintering at high density.
【００３２】[0032]
【発明の効果】このように本発明を用いることにより、
粒成長を起こさずに短時間で高密度の酸化物焼結体を安
定に作製し、高誘電率・高導電率・高磁化率を有する焼
結体が得られる。As described above, by using the present invention,
A high-density oxide sintered body can be stably produced in a short time without causing grain growth, and a sintered body having a high dielectric constant, a high electrical conductivity, and a high magnetic susceptibility can be obtained.
【図１】 放電プラズマ焼結装置の概略構成を示す図。FIG. 1 is a diagram showing a schematic configuration of a spark plasma sintering apparatus.
【図２】 放電プラズマ焼結法により得られたＢａＴｉ
Ｏ3焼結体の熱処理前および熱処理後のＸ線回折パター
ンを示す図。FIG. 2 BaTi obtained by spark plasma sintering
Shows the X-ray diffraction pattern before and after heat heat treatment O 3 sintered body.
【図３】 放電プラズマ焼結法により得られたＢａＴｉ
Ｏ3焼結体の熱処理前および熱処理後のＥＤＸを示す
図。FIG. 3 BaTi obtained by spark plasma sintering
Shows the EDX before and after heat heat treatment O 3 sintered body.
【図４】 放電プラズマ焼結法により得られたＢａＴｉ
Ｏ3焼結体の熱処理後の破断面（粒子構造）のＳＥＭ写
真。FIG. 4 BaTi obtained by spark plasma sintering
SEM photograph of fracture surface (particle structure) after heat treatment of O 3 sintered body.
【図５】 放電プラズマ焼結法（ＳＰＳ）及び通常法に
より得られたＢａＴｉＯ3焼結体の誘電率の温度依存性
を示すグラフ。FIG. 5 is a graph showing the temperature dependence of the dielectric constant of a BaTiO 3 sintered body obtained by a spark plasma sintering method (SPS) and a normal method.
【図６】 ＮａＺｒ2（ＰＯ4）3原料粉末及び放電プラ
ズマ焼結法により得られた焼結体（ＳＰＳ）のＸ線回折
パターンを示す図。FIG. 6 is a diagram showing an X-ray diffraction pattern of a NaZr 2 (PO 4 ) 3 raw material powder and a sintered body (SPS) obtained by a spark plasma sintering method.
【図７】 通常焼結法及び放電プラズマ焼結法（ＳＰ
Ｓ）により得られたＮａＺｒ2（ＰＯ4）3焼結体の導電
率の温度依存性を示すグラフ。FIG. 7: Normal sintering method and spark plasma sintering method (SP
5 is a graph showing the temperature dependence of the conductivity of the NaZr 2 (PO 4 ) 3 sintered body obtained by S).
───────────────────────────────────────────────────── フロントページの続き (72)発明者 野村 勝裕 大阪府池田市緑丘１丁目８番31号 工業 技術院大阪工業技術研究所内 (72)発明者 中村 治 大阪府池田市緑丘１丁目８番31号 工業 技術院大阪工業技術研究所内 (72)発明者 蔭山 博之 大阪府池田市緑丘１丁目８番31号 工業 技術院大阪工業技術研究所内 (72)発明者 鴇田 正雄 東京都港区西新橋３丁目20番４号 住友 石炭鉱業株式会社技術本部・研究開発部 内 (72)発明者 川原 正和 東京都港区西新橋３丁目20番４号 住友 石炭鉱業株式会社技術本部・研究開発部 内 (72)発明者 金澤 修男 東京都港区西新橋３丁目20番４号 住友 石炭鉱業株式会社技術本部・研究開発部 内 審査官 山田 勇毅 (56)参考文献 特開 平８−208341（ＪＰ，Ａ) 特開 平３−93670（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C04B 35/64 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuhiro Nomura 1-81-31 Midorioka, Ikeda-shi, Osaka Inside the Institute of Industrial Science and Technology (72) Inventor Osamu Nakamura 1-81-31 Midorioka, Ikeda-shi, Osaka No. 72, Osaka Institute of Industrial Technology, Institute of Industrial Science (72) Inventor Hiroyuki Kageyama 8-31, Midorigaoka, Ikeda-shi, Osaka Prefecture, Japan Inside (72) Inventor Masao Tokita 3-chome, Nishishinbashi, Minato-ku, Tokyo No. 20-4 Sumitomo Coal Mining Co., Ltd. Technology Headquarters R & D Department (72) Inventor Masakazu Kawahara 3-20-4 Nishishinbashi, Minato-ku, Tokyo Sumitomo Coal Mining Co., Ltd. Technology Headquarters R & D Department (72) Inventor Norio Kanazawa 3-20-4 Nishi-Shimbashi, Minato-ku, Tokyo Sumitomo Coal Mining Co., Ltd.Technology Headquarters R & D Department Inspector Yuki Yamada (56) Reference Document JP-flat 8-208341 (JP, A) JP flat 3-93670 (JP, A) (58 ) investigated the field (Int.Cl. 7, DB name) C04B 35/64
Claims (7)
れた焼結体を熱処理する酸化物微粒子の焼結方法。1. A method for sintering oxide fine particles, wherein the oxide fine particles are subjected to discharge plasma sintering and the obtained sintered body is heat-treated.
れた焼結体を熱処理して酸化物焼結体を作製する高密度
焼結体の製造方法。2. A method for producing a high-density sintered body in which oxide fine particles are subjected to discharge plasma sintering, and the obtained sintered body is heat-treated to produce an oxide sintered body.
いて粒成長を起こさせずに焼結させ、得られた焼結体を
熱処理して酸化物焼結体を作製する高密度焼結体の製造
方法。3. A high-density sintering method in which oxide fine particles are sintered using a discharge plasma sintering machine without causing grain growth, and the obtained sintered body is heat-treated to produce an oxide sintered body. How to make the body.
造、パイロクロア型構造、イルメナイト型構造、岩塩型
構造、スピネル型構造又はフルオロライト型構造を有す
る請求項２又は３に記載の高密度焼結体の製造方法。4. The high-density sintering according to claim 2, wherein the oxide sintered body has a perovskite structure, a pyrochlore structure, an ilmenite structure, a rock salt structure, a spinel structure or a fluorolite structure. How to make the body.
結し、得られた焼結体を熱処理して酸化物／酸化物複合
体の焼結体を作製する高密度焼結体の製造方法。5. Production of a high-density sintered body in which two or more oxide fine particles are subjected to discharge plasma sintering, and the obtained sintered body is heat-treated to produce a sintered body of an oxide / oxide composite. Method.
焼結機を用いて粒成長を起こさせずに焼結させ、得られ
た焼結体を熱処理して酸化物／酸化物複合体の焼結体を
作製する高密度焼結体の製造方法。6. An oxide / oxide composite of an oxide / oxide composite obtained by sintering two or more kinds of oxide fine particles without causing grain growth using a discharge plasma sintering machine. A method for producing a high-density sintered body for producing a sintered body.
の焼結体が、高誘電率、高導電率、高磁化率を有する請
求項２〜６のいずれかに記載の高密度焼結体の製造方
法。7. The high-density oxide according to claim 2, wherein the oxide sintered body or the oxide / oxide composite sintered body has a high dielectric constant, a high electrical conductivity, and a high magnetic susceptibility. A method for manufacturing a sintered body.
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| JP4530114B2 (en) * | 2000-09-14 | 2010-08-25 | 独立行政法人産業技術総合研究所 | Method for producing lead-containing perovskite complex oxide sintered body |
| JP4334894B2 (en) | 2003-03-20 | 2009-09-30 | 日産自動車株式会社 | Method for producing solid electrolyte |
| JP5071919B2 (en) * | 2005-11-17 | 2012-11-14 | 独立行政法人産業技術総合研究所 | High density acetylene black and method for producing the same |
| FR2900148B1 (en) * | 2006-04-19 | 2008-07-11 | Centre Nat Rech Scient | CERAMICS BASED ON LANTHAN DOPED BARIUM TITANATE, NOVEL PREPARATION METHOD AND USES. |
| JP5019323B2 (en) * | 2007-03-20 | 2012-09-05 | 独立行政法人物質・材料研究機構 | Ceria sintered body doped with rare earth element and manufacturing method thereof |
| ES2362533B1 (en) * | 2009-12-21 | 2012-05-17 | Consejo Superior De Investigaciones Cientificas (Csic) | COMPOSITE MATERIAL WITH THERMAL EXPANSION COEFFICIENT CONTROLLED WITH OXIDIC MICAS CERAMICS AND THEIR OBTAINING PROCEDURE. |
| JP5477715B2 (en) * | 2010-03-31 | 2014-04-23 | 独立行政法人物質・材料研究機構 | Highly transparent alumina ceramic and method for producing the same |
| EP3254729B1 (en) | 2015-05-04 | 2019-09-04 | Neuboron Medtech Ltd. | Beam shaping body for neutron capture therapy |
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