JP2854350B2 - Method for producing conductive metal oxide - Google Patents
Method for producing conductive metal oxideInfo
- Publication number
- JP2854350B2 JP2854350B2 JP1306126A JP30612689A JP2854350B2 JP 2854350 B2 JP2854350 B2 JP 2854350B2 JP 1306126 A JP1306126 A JP 1306126A JP 30612689 A JP30612689 A JP 30612689A JP 2854350 B2 JP2854350 B2 JP 2854350B2
- Authority
- JP
- Japan
- Prior art keywords
- metal oxide
- present
- conductive metal
- resistance
- vanadium
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G37/00—Compounds of chromium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G31/00—Compounds of vanadium
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、３価のバナジウム酸化物のバナジウムの一
部をクロム、アルミニウムあるいは希土類元素で置換し
た組成を有し、常温付近で温度上昇に伴ない抵抗が増大
する金属半導体転移を示す導電性金属酸化物を製造する
方法に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention has a composition in which a part of vanadium of a trivalent vanadium oxide is substituted with chromium, aluminum, or a rare earth element, and the temperature rises around normal temperature. The present invention relates to a method for producing a conductive metal oxide exhibiting a metal-semiconductor transition in which the resistance increases.
（従来の技術とその問題点） 酸化バナジウムには、V2O3、VO、V2O5等が存在する
が、この中でV2O3は、160K付近で絶縁体金属転移を、室
温付近で金属半導体転移を示す。特にこの室温付近の金
属半導体転移は、V2O3中に添加元素としてCr、Alあるい
は希土類元素を用いることにより明瞭に現われる。この
転移を利用してこの導電性金属酸化物を大電流用の限流
素子として用いる試みが今までになされて来た。(And its Problems Prior Art) The vanadium oxide, V 2 O 3, VO, V 2 is O 5 or the like are present, V 2 O 3 in this, the insulator-metal transition at around 160K, room temperature A metal-semiconductor transition is shown in the vicinity. In particular, the metal-semiconductor transition around room temperature clearly appears when Cr, Al, or a rare earth element is used as an additional element in V 2 O 3 . Attempts have been made to use this conductive metal oxide as a current-limiting element for large currents by utilizing this transition.
前述の酸化物は（MXV1-X）2O3（Ｍは前記Cr等の添加
元素）で表現され、第１図に示すように、単結晶を材料
とすれば、常温付近における温度上昇に伴なう抵抗変化
率が数百倍の材料が得られる一方、従来の焼結方による
焼結体の場合は百倍程度が限度であり、単結晶を材料と
した限流素子を製造することが望まれる。なお第１図の
単結晶に関するデータは、Kuwamotoらによる測定データ
である。（Physical Review B22 P2626（1980））。The above-mentioned oxide is represented by (M X V 1-X ) 2 O 3 (M is the above-mentioned additive element such as Cr). As shown in FIG. A material with a resistance change rate of several hundred times as high can be obtained, whereas a sintered body by the conventional sintering method has a limit of about one hundred times, and manufactures a current limiting element using a single crystal as a material. It is desired. The data relating to the single crystal in FIG. 1 is measured data by Kuwamoto et al. (Physical Review B22 P2626 (1980)).
しかし、前記クロム等で一部置換したバナジウム酸化
物の単結晶としては、せいぜい直径4mm程度のサイズの
小さいものしか得ることができないため、比較的大型の
限流素子を得る場合は、やむをえず焼結体の形で限流素
子材料を得ているのが現状である。すなわち、従来は、
まずV2O3とCr2O3を所定の比で湿式混合し、乾燥した
後、粉砕し、成形して焼結するという工程により焼結体
を得ていた。また、このような製造工程において、前記
百倍程度の抵抗変化率を得るため、焼結温度を1500℃以
上に上げなければならなかった。しかし、焼結温度が高
くなると、バナジウムの蒸発という問題があるので、あ
まり焼結温度を上げることもできず、従って、抵抗変化
率を上げることが困難であった。However, as a single crystal of vanadium oxide partially substituted with chromium or the like, at most only a small crystal having a diameter of about 4 mm can be obtained. At present, current limiting element materials are obtained in the form of a unity. That is, conventionally,
First, V 2 O 3 and Cr 2 O 3 were wet-mixed at a predetermined ratio, dried, pulverized, molded and sintered to obtain a sintered body. In such a manufacturing process, the sintering temperature had to be raised to 1500 ° C. or higher in order to obtain the resistance change rate of about 100 times. However, when the sintering temperature is increased, there is a problem that vanadium evaporates. Therefore, the sintering temperature cannot be increased so much, and it is difficult to increase the resistance change rate.
上述のように、従来の焼結体の場合には、単結晶に比
較して、抵抗変化率が小さい理由は次のように考えられ
る。室温程度における金属半導体転移は水における水と
氷の転移と同様な一次転移であり、これは必ず体積変化
を伴ない、ヒステリシスを伴なうものである。従って、
抵抗の変化もバルク全体が同時に起こるのではなく、部
分的に起こるため、見かけ上抵抗変化も小さくなるので
ある。従って、抵抗変化率を大きくするには、焼結体の
各部がなるべく均一な特性すなわち均一な組成であるこ
とが望ましいと考えられる。As described above, the reason why the resistance change rate of the conventional sintered body is smaller than that of the single crystal is considered as follows. The metal-semiconductor transition at about room temperature is a first-order transition similar to the transition between water and ice in water, which necessarily involves a change in volume and is accompanied by hysteresis. Therefore,
Since the change in resistance does not occur simultaneously with the entire bulk but occurs partially, the change in resistance is apparently small. Therefore, in order to increase the rate of change in resistance, it is considered desirable that each part of the sintered body has as uniform characteristics as possible, that is, a uniform composition.
焼結体等を作成する際に組成の均一性を得る手法とし
て、例えばシュウ酸塩のPHを調節して沈殿を生じさせる
共沈法や、金属イオンを含む溶液を瞬時に蒸発させて金
属粉末を得るスプレーパイロリシス法があるが、充分な
結果が得られていない。Examples of techniques for obtaining uniformity of composition when producing sintered bodies, such as co-precipitation method in which the pH of oxalate is adjusted to cause precipitation, or metal powder by instantaneously evaporating a solution containing metal ions There is a spray pyrolysis method for obtaining, but sufficient results have not been obtained.
（発明が解決すべき課題） このように、従来技術によれば、単結晶では大型の限
流素子を得ることが困難であり、一方従来の焼結法によ
れば、大きな抵抗変化率が得られないのが現状であり、
これらに代わる方法も見い出されていない。(Problems to be Solved by the Invention) As described above, according to the conventional technology, it is difficult to obtain a large current limiting element with a single crystal, while a large resistance change rate is obtained according to the conventional sintering method. It is not possible at present,
No alternative has been found.
本発明は、このような問題点を解決し、室温付近にお
ける抵抗変化率が大きく、かつ充分なサイズの（M
XV1-X）2O3（Ｍは前記添加元素）なる導電性金属酸化物
が得られる製造方法を提供することを目的とする。The present invention solves such a problem, and has a large resistance change rate near room temperature and a sufficient size (M
It is an object of the present invention to provide a production method capable of obtaining a conductive metal oxide which is X V 1-X ) 2 O 3 (M is the above-mentioned additional element).
（課題を解決するための手段） 上記の目的を達成するため、本発明による導電性金属
酸化物の製造方法は、バナジウムのアルコキシドとクロ
ム等の添加元素のアルコレートとの混合物を加水分解し
て（MXV1-X）2O5を得、該（MXV1-X）2O5を還元して（MX
V1-X）2O3を得、これを焼結することを特徴とする。(Means for Solving the Problems) In order to achieve the above object, a method for producing a conductive metal oxide according to the present invention comprises hydrolyzing a mixture of an alkoxide of vanadium and an alcoholate of an additional element such as chromium. (M X V 1-X) to give the 2 O 5, the (M X V 1-X) 2 O 5 by reducing (M X
V 1-X ) 2 O 3 is obtained and sintered.
（作用） 本発明の方法において、（MXV1-X）2O5を得る工程は
ゾルゲル法の一種であり、これにより添加元素をバナジ
ウム酸化物中に均一に添加できる。より詳しくは、V2O5
はゲル状をなすとき、層状構造をなすため、添加元素が
その層間に位置することが考えられる。その結果とし
て、Cr等の添加元素とV2O5が原子オーダーで規則的に存
在し、かつ混合されていると推定される。さらに本発明
によれば、加水分解後に従来法に比べて粒子の微細化が
できる。(Action) In the method of the present invention, the step of obtaining (M X V 1-X ) 2 O 5 is a kind of the sol-gel method, whereby the additive element can be uniformly added to the vanadium oxide. More specifically, V 2 O 5
When a layer is formed into a gel, the layer has a layered structure, and thus it is conceivable that the additional element is located between the layers. As a result, it is estimated that the additive element such as Cr and V 2 O 5 are regularly present in the atomic order and are mixed. Further, according to the present invention, it is possible to reduce the size of particles after hydrolysis as compared with the conventional method.
従って、本発明により得られる導電性金属酸化物は、
焼結体でありながら単結晶と同様の大きな抵抗変化率を
示し、焼結温度も低くなる。Therefore, the conductive metal oxide obtained by the present invention is:
Although it is a sintered body, it exhibits a large resistance change rate similar to that of a single crystal, and the sintering temperature is lowered.
（実施例） 室温で液体であるバナジルエトキシド｛VO（OC2H5）
３｝とクロムエトキシエチレート｛Cr（OC2H4OEt）３｝
をバナジウムとクロムが所定の比となるように含ませた
濃度１モル/kgのトルエン溶液を室温でエタノール溶液
に混合し、その後ロータリーエバポレーターを用いてト
ルエンを蒸発させて溶媒はエタノールのみとした。この
溶液を撹拌しながら純水を滴下し、加水分解を行なっ
た。この加水分解によりCrを含むV2O5・3H2Oが沈澱とし
て生成する。(Example) vanadyl ethoxide is liquid at room temperature {VO (OC 2 H 5)
3 ｝ and chromium ethoxyethylate ｛Cr (OC 2 H 4 OEt) 3 ｝
Was mixed with an ethanol solution at room temperature at a concentration of 1 mol / kg containing vanadium and chromium in a predetermined ratio, and then the toluene was evaporated using a rotary evaporator to use only ethanol as a solvent. While stirring this solution, pure water was added dropwise to carry out hydrolysis. V 2 O 5 · 3H 2 O containing Cr by this hydrolysis is produced as a precipitate.
なお、この化合物は、リバージュらの報告（Material
Reseach Bulltin Vol.16 p669（1981））によると層状
化合物をなしているが、このことは本発明者もＸ線回折
により確認した。また、前記沈澱物において、添加元素
のクロムの正確な位置の判断はできないが、この種の化
合物が（MXV1-X）2O5のブロンズ構造をとりやすいこと
から、バナジウムと酸素が形成する層間にクロムが局在
した構造をとっていると考えられる。This compound was reported by Rivage et al. (Material
According to Reseach Bulltin Vol.16 p669 (1981)), it forms a layered compound, which was also confirmed by the present inventors by X-ray diffraction. In addition, it is not possible to determine the exact position of the additional element chromium in the precipitate, but vanadium and oxygen are separated because this kind of compound tends to have a bronze structure of (M X V 1-X ) 2 O 5. It is considered that chromium was localized between the layers to be formed.
次に前記沈澱のみを取り出すため、200℃で脱水後、H
2雰囲気でかつ600℃の温度で３時間還元し、（Cr
XV1-X）2O3を生成させ（この実施例の場合、Ｘ＝0.00
5）とした、ボールミルで乾式粉砕し、２次粒子径とし
て、0.5μｍ〜1.0μｍの粉体を得た。Next, to remove only the precipitate, dehydrate at 200 ° C.
Reduced in 2 atmospheres at a temperature of 600 ° C for 3 hours, (Cr
X V 1-X ) 2 O 3 is generated (in this example, X = 0.00
The powder was dry-ground with a ball mill as described in 5) to obtain a powder having a secondary particle diameter of 0.5 μm to 1.0 μm.
この粉体を原料とし、有機バインダーを混合後、成形
し、1400℃〜1450℃で５時間、H2雰囲気中で焼成し、直
径20mmのディスクタイプの焼結体を得た。焼成したサン
プルについては、直流４端子法で抵抗を測定した。その
結果を第１図に示す。This powder was used as a raw material, mixed with an organic binder, molded, and fired at 1400 ° C. to 1450 ° C. for 5 hours in an H 2 atmosphere to obtain a disk-type sintered body having a diameter of 20 mm. The resistance of the fired sample was measured by a DC four-terminal method. The result is shown in FIG.
第１図から分るように、本発明の方法による場合、抵
抗変化率は単結晶の場合に比較しても遜色がなく、ほぼ
同様の抵抗変化率が得られ、従来の焼結法による焼結体
に比較し、抵抗変化率がはるかに大となった。また、焼
結温度も従来の1500℃以上に比較い、1400℃〜1450℃程
度と低くしてもよい。この理由は、２次粒子径はほぼ従
来と同じであるが、１次粒子径が小さくなったためであ
る。As can be seen from FIG. 1, in the case of the method of the present invention, the rate of change in resistance is not inferior to that in the case of a single crystal, and almost the same rate of change in resistance is obtained. The rate of change in resistance was much larger than that of the union. Also, the sintering temperature may be as low as about 1400 ° C. to 1450 ° C. as compared with the conventional 1500 ° C. or higher. The reason for this is that the secondary particle diameter is almost the same as the conventional one, but the primary particle diameter has become smaller.
また、単結晶はせいぜい直径が4mm程度のものしか作
成できないのが現状であるが、本発明による場合には、
20mm以上のものを容易に作成することができる。Also, at present, it is possible to produce a single crystal having a diameter of only about 4 mm at most, but according to the present invention,
Items with a size of 20 mm or more can be easily created.
以上本発明を実施例により説明したが、本発明は、バ
ナジウムの原料として、前記以外に、バナジルブトキシ
ド、バナジルプロポキシド、バタジルメトキシド等の他
のアルコキシドを用いることができ、また、クロムの原
料として、クロムエトキシプロピレート、クロムエトキ
シブチレート、クロムエトキシメチレート等の他のアル
キレートを用いることができる。Although the present invention has been described above by way of examples, the present invention can use, as a raw material of vanadium, other alkoxides such as vanadyl butoxide, vanadyl propoxide, and batadyl methoxide in addition to the above. As a raw material, other alkylates such as chromium ethoxy propylate, chromium ethoxy butyrate, and chromium ethoxy methylate can be used.
また、クロムの代わりに、アルミニウムや希土類元素
を用いても、表１に示すように、同様の結果を得ること
ができる。Also, similar results can be obtained as shown in Table 1 by using aluminum or a rare earth element instead of chromium.
また、本発明における添加物の添加量の好適範囲は金
属酸化物を（MXV1-X）2O3で表現した場合、Ｘ＝0.001〜
0.5である。0.001以下であると添加による抵抗変化率向
上効果が現われず、0.5を超えても抵抗変化率が劣化す
る。 In addition, a preferable range of the additive amount of the additive in the present invention is as follows: when the metal oxide is represented by (M X V 1 -X ) 2 O 3 , X = 0.001 to
0.5. If it is 0.001 or less, the effect of improving the resistance change rate by addition does not appear, and if it exceeds 0.5, the resistance change rate deteriorates.
（発明の効果） 本発明によれば、V2O3のバナジウムの一部をCr、Alあ
るいは希釈土類元素によって置換した金属酸化物を得る
ため、原料として、バナジルアルコキシド、添加物のア
ルコレートを用い、これらの溶液を加水分解してV2O5の
一部を添加元素で均一に置換した微細な粉末を得、これ
を還元してV2O3の一部を添加元素で置換した微細な原料
粉末を得、焼結することにより、目的酸化物を得る方法
であるから、焼結体であるにも拘らず、単結晶と同様な
大きな抵抗変化率を有し、しかも単結晶としては得られ
ない大きなサイズの材料を得ることができ、室温付近で
抵抗が変化する大型の限流素子の用途に使用するに好適
なものを提供することが可能となる。また、本発明によ
れば、従来の焼結法より低い温度で焼結しても良好な特
性のものが得られるから、焼結時におけるバナジウムの
蒸発の問題が緩和され、目的とする組成の酸化物を容易
に得ることができる。(Effects of the Invention) According to the present invention, in order to obtain a metal oxide in which a part of vanadium of V 2 O 3 is substituted by Cr, Al or a diluted earth element, vanadyl alkoxide and an alcoholate additive are used as raw materials. These solutions were hydrolyzed to obtain a fine powder in which a part of V 2 O 5 was uniformly replaced with an additional element, and this was reduced and a part of V 2 O 3 was replaced with an additional element. This is a method of obtaining the target oxide by obtaining and sintering a fine raw material powder, so that it has a large resistance change rate similar to that of a single crystal despite being a sintered body, and as a single crystal Therefore, it is possible to obtain a material having a large size that cannot be obtained, and to provide a material suitable for use in a large current limiting element whose resistance changes near room temperature. In addition, according to the present invention, since good characteristics can be obtained even when sintering at a lower temperature than the conventional sintering method, the problem of evaporation of vanadium during sintering is reduced, and the desired composition An oxide can be easily obtained.
第１図は本発明法、従来の焼結法により得られた金属酸
化物と、単結晶の金属酸化物の温度に対する抵抗変化を
比較して示す図である。FIG. 1 is a diagram showing a comparison of the change in resistance with respect to temperature between a metal oxide obtained by the method of the present invention and a conventional sintering method and a single crystal metal oxide.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) C01G 31/00 H01B 1/08 H01C 7/02 C01G 37/00──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) C01G 31/00 H01B 1/08 H01C 7/02 C01G 37/00
Claims (1)
類元素で、Ｘ＝0.001〜0.5）なる導電性金属酸化物を製
造する方法であって、バナジウムのアルコキシドと前記
元素Ｍのアルコレートとの混合物を加水分解することに
より（MXV1-X）2O5を得、該（MXV1-X）2O5を還元して
（MXV1-X）2O3を得、これを焼結することを特徴とする
導電性金属酸化物の製造方法。1. A method for producing a conductive metal oxide comprising (M X V 1-X ) 2 O 3 (where M is Cr, Al, a rare earth element and X = 0.001 to 0.5), comprising the steps of: a mixture of alcoholate of the alkoxide element M to obtain a (M X V 1-X) 2 O 5 by hydrolysis, by reducing the (M X V 1-X) 2 O 5 (M X V 1-X ) A method for producing a conductive metal oxide, comprising obtaining and sintering 2 O 3 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1306126A JP2854350B2 (en) | 1989-11-25 | 1989-11-25 | Method for producing conductive metal oxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1306126A JP2854350B2 (en) | 1989-11-25 | 1989-11-25 | Method for producing conductive metal oxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03170336A JPH03170336A (en) | 1991-07-23 |
| JP2854350B2 true JP2854350B2 (en) | 1999-02-03 |
Family
ID=17953366
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1306126A Expired - Lifetime JP2854350B2 (en) | 1989-11-25 | 1989-11-25 | Method for producing conductive metal oxide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2854350B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2741612A1 (en) * | 1995-11-29 | 1997-05-30 | Cernix | New aluminovanadates containing nitrogen and hydrogen and their preparation |
| CN117904673A (en) * | 2024-03-19 | 2024-04-19 | 四川大学 | Electrocatalyst and preparation and application thereof |
-
1989
- 1989-11-25 JP JP1306126A patent/JP2854350B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03170336A (en) | 1991-07-23 |
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