JP2003277987A - Electrolytic synthetic method of ceramic thin film - Google Patents
Electrolytic synthetic method of ceramic thin filmInfo
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- JP2003277987A JP2003277987A JP2002083338A JP2002083338A JP2003277987A JP 2003277987 A JP2003277987 A JP 2003277987A JP 2002083338 A JP2002083338 A JP 2002083338A JP 2002083338 A JP2002083338 A JP 2002083338A JP 2003277987 A JP2003277987 A JP 2003277987A
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- thin film
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- aqueous solution
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えば、センサ
ー、ディスプレイ、太陽電池、蛍光体、光触媒など種々
の用途における電気、電子、光学デバイスの作製に有用
なセラミックス薄膜の電解合成法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrolytically synthesizing a ceramic thin film useful for producing electric, electronic and optical devices in various applications such as sensors, displays, solar cells, phosphors and photocatalysts.
【０００２】[0002]
【従来の技術】様々な電気、電子、光学デバイスに用い
られる機能性セラミックスは薄膜の形態で用いられるこ
とが多く、組成、構造、膜厚さなどを容易に制御できる
薄膜作成法が必要となる。温和な環境での薄膜作製手法
であり、膜厚さの調節やパターニングも容易な溶液から
の電解合成は、低環境負荷で低コストな手法となる。電
解合成法は、金属薄膜などの導電性材料については表面
処理（いわゆる「電解めっき」）には工業的に幅広く用
いられており、高密度電子デバイスの微細配線パターン
作製についても実用化されつつある。しかし、電気伝導
性の限られるセラミックス材料については、薄膜の電解
合成は通常困難となる。2. Description of the Related Art Functional ceramics used in various electric, electronic and optical devices are often used in the form of a thin film, and a thin film forming method capable of easily controlling the composition, structure, film thickness and the like is required. . It is a method of forming a thin film in a mild environment, and electrolytic synthesis from a solution that allows easy adjustment of the film thickness and patterning is a method with low environmental load and low cost. The electrolytic synthesis method is industrially widely used for surface treatment (so-called “electrolytic plating”) of conductive materials such as metal thin films, and is also being put to practical use for the production of fine wiring patterns for high density electronic devices. . However, for ceramic materials with limited electrical conductivity, electrolytic synthesis of thin films is usually difficult.
【０００３】[0003]
【発明が解決しようとする課題】導電性に乏しいセラミ
ックス薄膜の電解合成手法としては、金属硝酸塩の酸性
水溶液（あるいは他の金属塩に硝酸塩を添加）中でのカ
ソード電解によって硝酸イオンを還元し、電極基板近傍
でのｐH上昇によって金属水酸化物の薄膜析出を誘起
し、これを熱処理して金属酸化物薄膜を得る手法がTiO2
(C. Natarajan andG. Nogami, J. Electrochemical. S
oc.,143, 5 (1996).), ZrO2 (L. Gal-Or, I. Silberman
n and R. Chaim, J. Electrochem. Soc., 138, 1939 (1
991).), CeO 2 (Y. Zhou, R.J. Phillips and J.A. Swit
zer, J. Am. Ceram. Soc., 78, 981(1995).), YBa2Cu3O
7-x , Bi2Sr2CaCu2Oy (H. Minoura, K. Naruto, H. Tak
ano,E. Haseo, T. Sugiura, Y. Ueno and T. Endo, Che
m. Lett., 397 (1991).) などについて知られている
が、析出する水酸化物薄膜が電気的に絶縁性のため、特
に析出物が構造的に密で基板を一様に覆ってしまう場合
には極薄い膜厚さで薄膜成長が停止してしまう。定電流
電解によって強制的に薄膜を成長させることも出来る
が、この場合導電パスが確保されることが必要となっ
て、ポーラスな形態の膜となったり、膜中に溶媒成分が
多量に含まれることが原因で、熱処理段階において著し
い体積収縮が起こり、膜にクラックを生じたりしやす
い。TiO2については、三塩化チタンの酸性水溶液中での
Ti(III) 種のTi(IV)への酸化を利用したアノード析出
(L. Kavan, B. O'Regan and M. Gratzel,J. Electroana
l. Chem., 346, 291 (1993).) も知られているが、この
場合も得られる析出物は絶縁性の水酸化チタンで、前述
のカソード析出手法と同様の問題点を有している。上記
以外に、結晶化したセラミックス微粒子の懸濁液中で2
電極間に高い電圧を印加して、電気泳動によって薄膜を
形成させる手法（特開平１１−３１０８９８「結晶性酸
化チタン膜の形成方法」、A. Stanley, B. Verity and
D. Matthews, Sol. Energy Mater. Sol. Cells, 52, 14
1 (1998). ）なども知られている。数マイクロメートル
程度の厚い膜が得られるものの、微粒子を出発原料とす
るために得られる薄膜はポーラスな形態となり、コンパ
クトな構造の膜を得るには不向きである。[Problems to be solved by the invention] Ceramics having poor conductivity
The method of electrolytic synthesis of thin film is the acidity of metal nitrate.
In aqueous solution (or adding nitrate to other metal salts)
Nitrate ion is reduced by sword electrolysis, near the electrode substrate
Induction of metal hydroxide thin film deposition by increasing pH at room temperature
The method of heat-treating this and obtaining a metal oxide thin film is TiO 2.2
(C. Natarajan and G. Nogami, J. Electrochemical. S
oc., 143, 5 (1996).), ZrO2 (L. Gal-Or, I. Silberman
n and R. Chaim, J. Electrochem. Soc., 138, 1939 (1
991).), CeO 2(Y. Zhou, R.J.Phillips and J.A. Swit
zer, J. Am. Ceram. Soc., 78, 981 (1995).), YBa2Cu3O
7-x, Bi2Sr2CaCu2Oy(H. Minoura, K. Naruto, H. Tak
ano, E. Haseo, T. Sugiura, Y. Ueno and T. Endo, Che
m. Lett., 397 (1991).) and others
However, since the precipitated hydroxide thin film is electrically insulating,
When the precipitates are structurally dense and cover the substrate uniformly
However, the thin film growth stops at an extremely thin film thickness. Constant current
It is possible to forcibly grow a thin film by electrolysis
However, in this case, it is necessary to secure a conductive path.
As a result, a porous film is formed or solvent components are contained in the film.
Due to the large amount contained,
Volume shrinkage occurs easily and the film is likely to crack.
Yes. TiO2For titanium trichloride in an acidic aqueous solution
Anodic deposition utilizing oxidation of Ti (III) species to Ti (IV)
(L. Kavan, B. O'Regan and M. Gratzel, J. Electroana
l. Chem., 346, 291 (1993).) is also known.
In the case where the obtained precipitate is insulative titanium hydroxide,
It has the same problems as the cathode deposition method of. the above
In addition, 2 in the suspension of crystallized ceramics particles
Apply a high voltage between the electrodes and electrophorese the thin film.
Method for forming (Japanese Patent Application Laid-Open No. 11-310898 “Crystalline acid
Method for forming titanium oxide film, "A. Stanley, B. Verity and
D. Matthews, Sol. Energy Mater. Sol. Cells, 52, 14
1 (1998).) Is also known. A few micrometers
Although a thick film can be obtained, fine particles are used as the starting material.
The resulting thin film has a porous morphology
It is not suitable for obtaining a film having a perfect structure.
【０００４】[0004]
【課題を解決するための手段】本発明は、金属種として
チタン、バナジウム、ニオブまたはタンタルを含む化合
物の安定な塩基性水溶液に、少なくとも部分的にこの水
溶液に溶解し、電気化学的に酸化されプロトンを放出す
る性質を持つ有機分子を混合した液を浴とし、この浴か
らのアノード電解によって導電性基板上に金属酸化物と
有機分子の複合膜を形成し、得られた複合膜の熱処理に
よって膜中の有機分子を除去することを特徴とするセラ
ミック薄膜の電解合成法を提供することによってコンパ
クトな構造のセラミックス薄膜を得る課題を解決する。The present invention is directed to a stable basic aqueous solution of a compound containing titanium, vanadium, niobium or tantalum as a metal species which is at least partially dissolved in this aqueous solution and electrochemically oxidized. A liquid mixed with organic molecules that release protons is used as a bath, and a composite film of metal oxide and organic molecules is formed on a conductive substrate by anodic electrolysis from this bath. To solve the problem of obtaining a ceramic thin film having a compact structure by providing an electrolytic synthesis method of a ceramic thin film, which is characterized by removing organic molecules in the film.
【０００５】[0005]
【実施態様】本発明は、特開２００１−３２２８１５
「チタン含有水溶液の製造方法」に記載された手法と日
本セラミックス協会第13回秋季シンポジウム講演予稿集
(2000年10月11日発行)177ページに記載された手法によ
って調製したTi, V, Nb, Ta などの塩基性水溶液に、電
気化学的に容易に酸化されプロトンを放出する性質を持
つハイドロキノンなどの有機分子を混合した浴からのア
ノード電解によって、金属塩と有機分子の複合膜が得ら
れ、これが導電性を有する事を利用し、本来導電性を有
さない材料について高速な薄膜電解合成に成功したもの
である。得られた複合膜は熱処理によって膜中の有機分
子が除去され、金属酸化物薄膜となる。従来知られるセ
ラミックス薄膜の電解合成手法によっては、析出物が絶
縁性であるため、特に膜が構造的に緻密で導電性基板の
露出が無い場合には、極めて薄い膜しか得られないが、
本手法では膜中に導入される有機分子の導電性を利用す
ることで、緻密な構造を有した平滑な膜について比較的
厚い膜厚領域までの容易な膜厚制御が可能となる。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is disclosed in Japanese Patent Laid-Open No. 2001-322815.
Proceedings of the 13th Autumn Symposium of the Ceramic Society of Japan and the method described in "Production method of titanium-containing aqueous solution"
(Issued October 11, 2000) Hydroquinone, which has the property of electrochemically easily being oxidized and releasing a proton, in a basic aqueous solution of Ti, V, Nb, Ta, etc. prepared by the method described on page 177 Anodic electrolysis from the mixed organic molecule bath gives a composite film of metal salt and organic molecule, which is used for high-speed thin-film electrolytic synthesis of non-conductive materials. It was successful. The obtained composite film is subjected to heat treatment to remove organic molecules in the film, and becomes a metal oxide thin film. According to a conventionally known electrolytic synthesis method of a ceramic thin film, since the precipitate is insulative, only an extremely thin film can be obtained, especially when the film is structurally dense and the conductive substrate is not exposed.
In this method, by utilizing the conductivity of the organic molecules introduced into the film, it becomes possible to easily control the film thickness up to a relatively thick film thickness region for a smooth film having a dense structure.
【０００６】Ti(IV), Nb(V), Ta(V)などの金属イオンは
水酸化物イオンとの親和性が極めて高く、水溶液中で容
易にハイドロゲルを生成するため、安定な水溶液を得る
ことが困難である。フッ化物イオン、塩化物イオン、硫
酸イオンなどの特定の酸を含む強酸性水溶液や、ペルオ
キソ錯体や特定の有機酸配位子を含む錯体を形成するこ
とで水溶液となることが知られている。これらの溶液の
ｐH を上昇させると溶存種の加水分解が起こり、水酸化
物のゲルを与える。従来知られるセラミックス薄膜の電
解合成法はこの原理を利用したものであるが、析出物が
絶縁性のために問題を生じることは上記の通りである。Metal ions such as Ti (IV), Nb (V) and Ta (V) have a very high affinity with hydroxide ions and easily form hydrogels in aqueous solution, so stable aqueous solution is used. Hard to get. It is known that an aqueous solution is formed by forming a strongly acidic aqueous solution containing a specific acid such as a fluoride ion, a chloride ion or a sulfate ion, or a complex containing a peroxo complex or a specific organic acid ligand. Raising the pH of these solutions causes hydrolysis of the dissolved species, giving a hydroxide gel. Conventionally known methods for electrolytically synthesizing ceramic thin films utilize this principle, but as described above, the precipitates cause a problem due to their insulating properties.
【０００７】一方、本発明者らは金属アルコキシドと特
定のアルキルアンモニウム水酸化物の混合によって安定
な塩基性水溶液を得る手法を近年発明した（特開2001−
322815「チタン含有水溶液の製造方法」、日本セラミッ
クス協会第13回秋季シンポジウム講演予稿集(2000年10
月11日発行)177ページ）。溶存種の厳密な構造は現在ま
でに明らかとされていないが、この溶液はｐH を低下さ
せることで金属水酸化物の沈殿を生じるという、上述の
酸性水溶液とは逆の性質を持つ。よってアノード電解に
よって電極近傍のｐHを低下させることで水酸化物の薄
膜を析出させることが可能となるが、この場合析出物が
絶縁性であるゆえに生じる問題は解決されない。これに
対し、発明者らは特定の芳香族有機分子(主に有機色素)
を共存させた亜鉛塩の水溶液からのカソード電解によっ
て、酸化亜鉛と有機分子の複合膜を形成する手法（T. Y
oshida, K. Miyamoto, N. Hibi, T. Sugiura, H. Minou
ra, T. Oekermann, G. Schneider and D. Woehrle, Che
m. Lett ., 599-600 (1998)., T. Yoshida and H. Mino
ura,“Electrochemical Self-Assembly of Dye-Modifie
d Zinc Oxide Thin Films", Adv. Mater., 12, 1219-12
22 (2000).）をこれまでに見出している。特定の有機分
子はこの過程で電気化学的に還元され、亜鉛イオンと安
定な錯体を形成することが分かり（T. Yoshida, K. Ter
ada, D. Schlettwein, T. Oekermann, T. Sugiura and
H. Minoura, “Electrochemical Self-Assembly of Nan
o-Porous ZnO/EosinY Thin Films and its Sensitized
Photoelectrochemical Performance", Adv. Mater., 1
2, 1214-1217 (2000). ）、薄膜の成長を促進する作用
があることが分かった。On the other hand, the present inventors have recently invented a method for obtaining a stable basic aqueous solution by mixing a metal alkoxide and a specific alkylammonium hydroxide (JP 2001-
322815 Proceedings of the 13th Autumn Symposium of the Ceramic Society of Japan, “Method for producing aqueous solution containing titanium” (2000 October
Issued May 11) 177 pages). Although the exact structure of the dissolved species has not been clarified to date, this solution has a property opposite to that of the above-described acidic aqueous solution that the pH is lowered to cause precipitation of metal hydroxide. Therefore, it becomes possible to deposit a thin film of hydroxide by lowering the pH in the vicinity of the electrode by anodic electrolysis, but in this case the problem that occurs because the deposit is insulating cannot be solved. On the other hand, the inventors have found that certain aromatic organic molecules (mainly organic dyes)
A method for forming a composite film of zinc oxide and organic molecules by cathodic electrolysis from an aqueous solution of zinc salt coexisting with (T. Y.
oshida, K. Miyamoto, N. Hibi, T. Sugiura, H. Minou
ra, T. Oekermann, G. Schneider and D. Woehrle, Che
m. Lett., 599-600 (1998)., T. Yoshida and H. Mino
ura, “Electrochemical Self-Assembly of Dye-Modifie
d Zinc Oxide Thin Films ", Adv. Mater., 12, 1219-12
22 (2000).) Has been found so far. It was found that certain organic molecules are electrochemically reduced during this process and form stable complexes with zinc ions (T. Yoshida, K. Ter.
ada, D. Schlettwein, T. Oekermann, T. Sugiura and
H. Minoura, “Electrochemical Self-Assembly of Nan
o-Porous ZnO / EosinY Thin Films and its Sensitized
Photoelectrochemical Performance ", Adv. Mater., 1
2, 1214-1217 (2000).), Which has the effect of promoting the growth of thin films.
【０００８】そこで上記の金属塩の塩基性水溶液に、電
気化学的に容易に酸化されてプロトンを放出する性質の
あるハイドロキノンなどの有機分子を添加し、アノード
電解を行なったところ、金属成分とキノン種の複合膜が
得られることが明らかとなった。膜中に導入されたキノ
ン成分が導電性を有するために、析出する薄膜が極めて
平滑で密な構造を有するにも関わらず、数マイクロメー
トル程度の厚さの膜を短時間に形成できることが分かっ
た。薄膜を熱処理することで有機成分は除去され、結晶
性の金属酸化物薄膜とすることが出来る。この段階で膜
体積は半分程度に減少するが、これに伴うクラック生成
は見られなかった。本発明は従来知られる手法とは全く
異なる原理に基づくものであり、特に導電性の限られた
セラミックス薄膜を容易に電解合成できるという特徴を
持つ。Therefore, when an organic molecule such as hydroquinone, which has a property of being easily oxidized electrochemically to release a proton, is added to the basic aqueous solution of the above metal salt, and anodic electrolysis is performed, the metal component and the quinone are obtained. It was revealed that a composite membrane of the species was obtained. Since the quinone component introduced into the film has conductivity, it was found that a film with a thickness of several micrometers can be formed in a short time, even though the thin film to be deposited has an extremely smooth and dense structure. It was By heat-treating the thin film, organic components are removed, and a crystalline metal oxide thin film can be obtained. At this stage, the film volume was reduced to about half, but no crack formation was observed with it. The present invention is based on a principle completely different from the conventionally known method, and is characterized in that a ceramic thin film having a limited conductivity can be easily electrolytically synthesized.
【０００９】[0009]
【実施例】TiO2薄膜の作製について例を示すが、V, Nb,
Ta の水溶液を原料に用いることで同様にV2O5, Nb2O5,
Ta2O5の薄膜を得ることが出来る。なお、Tiと同族のZr
については水溶液が調製出来ない事が分かっており、Zr
O2薄膜を同手法で作製することは困難と思われる。[Example] An example of the preparation of a TiO 2 thin film will be described. V, Nb,
By using an aqueous solution of Ta as a raw material, V 2 O 5 , Nb 2 O 5 ,
A thin film of Ta 2 O 5 can be obtained. In addition, Zr of the same family as Ti
It is known that an aqueous solution cannot be prepared for
It seems difficult to produce O 2 thin films by the same method.
【００１０】〈電解浴の調製〉チタン水溶液は特開2001
−322815「チタン含有水溶液の製造方法」と日本セラミ
ックス協会第13回秋季シンポジウム講演予稿集(2000年1
0月11日発行)177ページに記載された原料、条件、手法
によって種々調製可能だが、ここではチタンテトライソ
プロポキシド・Ti(OPri )4と水酸化テトラメチルアンモ
ニウム・(CH3)4NOH]をモル比２：１に混合し、チタン濃
度を0.05 Mとした溶液を用いた。上記溶液にヒドロキシ
ベンゼン類（p-ヒドロキノン、レソルシノール、カテコ
ール、1,2,4-ベンゼントリオール、ピロガロールなど）
を添加する。ここではp-ヒドロキノンを0.1Mの濃度で上
記チタン溶液に添加した。<Preparation of Electrolytic Bath> An aqueous titanium solution is disclosed in Japanese Patent Application Laid-Open No. 2001.
−322815 “Method of producing aqueous solution containing titanium” and Proceedings of the 13th Autumn Symposium of the Ceramic Society of Japan (2000 1
It can be prepared in various ways according to the raw materials, conditions, and methods described on page 177.Here, titanium tetraisopropoxide.Ti (OPr i ) 4 and tetramethylammonium hydroxide (CH 3 ) 4 NOH are used. ] Was mixed at a molar ratio of 2: 1 and a solution having a titanium concentration of 0.05 M was used. Hydroxybenzenes (p-hydroquinone, resorcinol, catechol, 1,2,4-benzenetriol, pyrogallol etc.) in the above solution
Is added. Here, p-hydroquinone was added to the titanium solution at a concentration of 0.1M.
【００１１】〈電解セルの構成〉導電性基板としてここ
ではITOガラス(10 Ω/sq.) を用いたが、導電性であれ
ば他の基板材料でも良い。対極には白金板を用い、飽和
カロメル参照電極と共に一室型のガラスセルにセットし
た。セルの形状、材質は問わない。ここに上記溶液を基
板が浸るだけの適当量導入し、Arガスをバブリングして
脱気した。脱気するのは空気中の酸素で原料のヒドロキ
ノンが酸化されるのを抑制するためである。<Structure of Electrolytic Cell> Although ITO glass (10 Ω / sq.) Is used as the conductive substrate here, other conductive substrate materials may be used. A platinum plate was used as the counter electrode, and it was set in a one-chamber glass cell together with a saturated calomel reference electrode. The shape and material of the cell do not matter. An appropriate amount of the above solution was introduced into the substrate so that the substrate was dipped, and Ar gas was bubbled to degas. The purpose of degassing is to prevent the raw material hydroquinone from being oxidized by oxygen in the air.
【００１２】〈電解条件〉浴温度は室温(20℃)とした
が、温度調節はセルをウォーターバスに浸すことで可能
であり、温度が高いほど薄膜成長速度は高速化できる。
電解は基板の電位を制御する定電位電解でも電流密度を
制御する定電流電解でも構わないが、ここではアノード
電流密度1mA/cm2 、電解時間0-1800秒（電解電気量＝0-
1800mC/cm2）の定電流電解を行い、電解中の基板と参照
電極の電位差（基板電位）の経時変化（クロノポテンシ
オグラム）を記録した。<Electrolysis conditions> The bath temperature was room temperature (20 ° C.), but the temperature can be adjusted by immersing the cell in a water bath. The higher the temperature, the faster the thin film growth rate.
The electrolysis may be constant potential electrolysis for controlling the electric potential of the substrate or constant current electrolysis for controlling the current density, but here, the anode current density is 1 mA / cm 2 , the electrolysis time is 0-1800 seconds (electrolytic amount of electricity = 0-
A constant current electrolysis of 1800 mC / cm 2 ) was performed, and the change with time (chronopotentiogram) of the potential difference (substrate potential) between the substrate and the reference electrode during electrolysis was recorded.
【００１３】〈薄膜の熱処理〉得られた薄膜は、マッフ
ル炉を用いて空気下、450℃、30分間熱処理した。<Heat Treatment of Thin Film> The obtained thin film was heat-treated at 450 ° C. for 30 minutes in air using a muffle furnace.
【００１４】〈作製した薄膜の同定と膜厚測定、表面形
態観察〉熱処理前後の薄膜について、X線回折測定装置
により結晶状態を調べた。膜厚さは触針式表面粗さ計に
より測定した。得られた薄膜及び熱処理前の薄膜を濃ア
ンモニア水に溶解した溶液のUV-VIS吸収スペクトルを測
定した。薄膜表面形態は電子顕微鏡及び原子間力顕微鏡
により観察した。<Identification of the prepared thin film, film thickness measurement, and surface morphology observation> The crystalline state of the thin film before and after the heat treatment was examined by an X-ray diffraction measuring device. The film thickness was measured by a stylus type surface roughness meter. UV-VIS absorption spectra of the obtained thin film and a solution of the thin film before heat treatment dissolved in concentrated aqueous ammonia were measured. The surface morphology of the thin film was observed by an electron microscope and an atomic force microscope.
【００１５】〈実施例において得られた結果〉図1 にハ
イドロキノンを添加しない浴と添加した浴での同条件の
電解において記録されたクロノポテンシオグラムを示
す。ハイドロキノンを加えない場合は、電解電流は主に
水の酸化
2H2O→ O2 + 4H+ + 4e- (Eo = +1.229 V vs. NHE) (1)
により、副生したプロトンによって金属成分が基板上に
析出するが、析出物が絶縁性のために基板の電位は急速
に貴方向にシフトする。すなわち、析出物の抵抗のため
に大きな過電圧が必要となる。また、(1) の反応によっ
て酸素ガスが副生するために析出物は基板に対する付着
性に乏しく、実質的に薄膜を得ることが困難であった。
一方p-ハイドロキノンを添加すると、p-ハイドロキノン
のp-ベンゾキノンへの酸化反応は
C6H4(OH)2 → C6H4O2 + 2H + + 2e - (Eo = +0.699 V vs. NHE) (2)
と熱力学的にはるかに容易であり、気体成分の発生も伴
わない。これにより電解に要する過電圧は著しく減少し
ており、薄膜の成長に伴う電位の変動も極めて小さい。
後に示すように析出物はキノン種を含む複合体であり、
これが導電性を有するために薄膜の連続的な成長が可能
になる。<Results Obtained in Examples> FIG. 1 shows chronopotentiograms recorded in electrolysis under the same conditions in a bath containing no hydroquinone and a bath containing no hydroquinone. If no addition of hydroquinone, the oxidation 2H 2 O → O 2 + 4H + + 4e of the electrolysis current is predominantly water - by (Eo = +1.229 V vs. NHE) (1), the metal component by-produced protons Although it deposits on the substrate, the potential of the substrate rapidly shifts to the noble direction due to the insulating property of the deposit. That is, a large overvoltage is required due to the resistance of the precipitate. Further, since the oxygen gas was by-produced by the reaction of (1), the deposit had poor adhesion to the substrate, and it was substantially difficult to obtain a thin film.
On the other hand the addition of p- hydroquinone, the oxidation reaction to p- hydroquinone p- benzoquinone C 6 H 4 (OH) 2 → C 6 H 4 O 2 + 2H + + 2e - (Eo = +0.699 V vs. NHE ) (2) It is much easier thermodynamically, and it does not generate gas components. As a result, the overvoltage required for electrolysis is remarkably reduced, and the fluctuation of the potential accompanying the growth of the thin film is extremely small.
As will be shown later, the precipitate is a complex containing quinone species,
Since it has conductivity, the thin film can be continuously grown.
【００１６】ハイドロキノンを添加した浴から得られる
薄膜は淡黄色で、熱処理によって無色透明な膜となる。
図2には熱処理前後の膜について膜厚さと電解電気量の
関係をそれぞれ示した。膜厚さは電気量に対して直線的
に増加しており、電気化学反応によって膜が成長してい
ることが分かる。熱処理によって膜厚さがほぼ半分に減
少しているが、これは膜中の水分と有機成分が除去さ
れ、酸化チタンが結晶化することによるものである。The thin film obtained from the bath containing hydroquinone is pale yellow, and becomes a colorless and transparent film by heat treatment.
Fig. 2 shows the relationship between the film thickness and the amount of electrolytic electricity before and after the heat treatment. The film thickness increases linearly with the amount of electricity, and it can be seen that the film grows due to the electrochemical reaction. Although the film thickness is reduced to about half by the heat treatment, this is because the water and organic components in the film are removed and the titanium oxide is crystallized.
【００１７】熱処理前後の薄膜のX線回折パターンを図3
に示した。電析後に得られた熱処理前の膜(a)は、基板
の回折ピークしか示さず、アモルファスであるが、熱処
理後の膜(b)は、アナターゼ型酸化チタンに帰属される
回折ピークを示し、結晶化していることが分かる。The X-ray diffraction patterns of the thin film before and after heat treatment are shown in FIG.
It was shown to. The film before heat treatment (a) obtained after electrodeposition shows only the diffraction peak of the substrate and is amorphous, but the film after heat treatment (b) shows the diffraction peak attributed to anatase type titanium oxide, It can be seen that it is crystallized.
【００１８】電析直後に得られる熱処理前の膜の吸収ス
ペクトル( 図4(a)) は350 nm付近に吸収極大を示し、こ
の吸収が可視域に広がっているために淡黄色であるが、
この吸収帯は熱処理によって( 図4(b))完全に消失し、
光学透明性に極めて優れた無色の膜となる。同時に360
nm付近から急激に立ち上がる紫外域の光吸収が現れる
が、これは熱処理によって生成した結晶性酸化チタンの
バンドギャップ遷移に基づく。熱処理前の膜は濃アンモ
ニア水に溶解する。この溶液のスペクトル( 図4(c)) は
320 nm付近に特徴的な吸収ピークを示す。p-ヒドロキノ
ン及びp-ベンゾキノンをアンモニア水に溶かした溶液(
図4(d),(e)) は同じ帯域に吸収ピークを示すことから、
電析された薄膜がキノン種を含んでいることが分かる。
チタン成分が電気化学的に反応活性なキノン種と複合化
するため、本来電気的に絶縁性のチタンハイドロゲルに
導電性が付与され、膜が厚くなっても薄膜の電気化学的
な成長が停止しなかったものと思われる。The absorption spectrum (FIG. 4 (a)) of the film before heat treatment obtained immediately after electrodeposition shows an absorption maximum at around 350 nm, and since this absorption is spread in the visible region, it is pale yellow,
This absorption band disappeared completely by heat treatment (Fig. 4 (b)),
It becomes a colorless film with excellent optical transparency. 360 at the same time
Light absorption in the ultraviolet region, which rises sharply from around nm, appears due to the band gap transition of crystalline titanium oxide produced by heat treatment. The film before heat treatment is dissolved in concentrated aqueous ammonia. The spectrum of this solution (Fig. 4 (c)) is
It shows a characteristic absorption peak near 320 nm. A solution of p-hydroquinone and p-benzoquinone in aqueous ammonia (
Since (d) and (e) in Fig. 4 show absorption peaks in the same band,
It can be seen that the electrodeposited thin film contains quinone species.
Since the titanium component is complexed with the electrochemically active quinone species, conductivity is imparted to the originally electrically insulating titanium hydrogel, and the electrochemical growth of the thin film stops even if the film becomes thicker. I think I didn't.
【００１９】熱処理前後の薄膜の表面電子顕微鏡写真に
よれば、熱処理前の薄膜は数ナノメートル程度の微細な
粒子が密に詰まった極めて均一且つ平滑な膜である。熱
処理後の膜においては10ナノメートル前後のサイズの隆
起部分が所々に見られるが、平滑さは一層増しているよ
うに見える。熱処理によって膜体積は半分程度に減少し
ているにもかかわらず、クラックの生成などは全く見ら
れず、薄膜の基板に対する付着性は極めて高い。According to surface electron micrographs of the thin film before and after the heat treatment, the thin film before the heat treatment is an extremely uniform and smooth film densely packed with fine particles of about several nanometers. In the film after heat treatment, ridges with a size of around 10 nm are found in some places, but the smoothness seems to be further increased. Although the volume of the film is reduced to about half by the heat treatment, no cracks are generated and the adhesion of the thin film to the substrate is extremely high.
【００２０】同じ膜を原子間力顕微鏡(AFM)によっても
観察した。断面プロファイルから、熱処理前の膜の凹凸
高さが3ナノメートル前後であるのに対し、熱処理後の
それは1.6ナノメートル程度に減少しており、平滑さが
向上していることが確認できる。観察した試料の膜厚さ
が熱処理前で1.3マイクロメートル、熱処理後で0.67マ
イクロメートルなので、いずれにしても極めて平滑度が
高く、緻密な構造であることが分かる。このように緻密
な構造の膜が得られるのは、これまでに知られているセ
ラミックス薄膜の電解合成法と本手法の大きな相違であ
る。The same film was also observed by atomic force microscopy (AFM). From the cross-sectional profile, it can be confirmed that the unevenness of the film before the heat treatment is about 3 nm, while that after the heat treatment is reduced to about 1.6 nm, and the smoothness is improved. Since the film thickness of the observed sample is 1.3 μm before the heat treatment and 0.67 μm after the heat treatment, it can be seen that the structure has extremely high smoothness and a dense structure in any case. The fact that a film having such a dense structure can be obtained is a major difference between the electrolytic synthesis method of ceramic thin films known so far and this method.
【００２１】以上のように、本発明は電気化学的反応活
性を有する有機分子との複合化によって、導電性に極め
て乏しいTiO2, V2O5, Nb2O5, Ta2O5などのセラミックス
薄膜の電解合成を実現する。1 マイクロメートルを超え
る膜厚さを容易に達成出来、得られる薄膜が緻密且つ平
滑で極めて高い光学透明性を有することも特徴である。As described above, the present invention makes it possible to form TiO 2 , V 2 O 5 , Nb 2 O 5 , Ta 2 O 5, etc., which have extremely poor conductivity, by forming a composite with an organic molecule having an electrochemical reaction activity. Realizes electrolytic synthesis of ceramics thin films. It is also characterized in that a film thickness exceeding 1 micrometer can be easily achieved, and the resulting thin film is dense and smooth and has extremely high optical transparency.
【００２２】[0022]
【図１】薄膜電析過程のクロノポテンシオグラム
浴温20℃、電流密度1mA/cm2のアノード電解
(a) 0.05M 塩基性チタン水溶液の場合
(b) 0.05M 塩基性チタン水溶液にp-ヒドロキノンを0.1M
添加した場合[1] chronograph potentiometric grams bath temperature 20 ° C. of about thin conductive析過, when the anode electrolyte (a) 0.05M basic aqueous titanium current density 1mA / cm 2 (b) in 0.05M basic aqueous solution of titanium p- Hydroquinone 0.1M
When added
【図２】通過電気量と膜厚の関係 (a) 熱処理前 (b) 熱処理後[Fig. 2] Relationship between the amount of electricity passing through and the film thickness (a) Before heat treatment (b) After heat treatment
【図３】得られた薄膜のX線回折パターン
(a)塩基性チタン水溶液にヒドロキノンを添加した混合
溶液から、1mA/cm2,100秒間アノード電解して得られた
膜
(b) (a)の膜を空気下、450℃、30分間熱処理した膜FIG. 3 X-ray diffraction pattern of the obtained thin film (a) A film obtained by subjecting a mixed solution of basic titanium aqueous solution and hydroquinone to anodic electrolysis at 1 mA / cm 2 for 100 seconds (b) (a) The film was heat treated in air at 450 ° C for 30 minutes
【図４】図4 紫外可視吸収スペクトル (a)熱処理前の膜(図3(a)に相当) (b)熱処理後の膜(図3(b)に相当) (c)(a)の膜を濃アンモニア水に溶解した溶液 (d)p-ヒドロキノンを濃アンモニア水に溶解した溶液 (e)p-ベンゾキノンを濃アンモニア水に溶解した溶液[Figure 4] Figure 4 UV-visible absorption spectrum (a) Film before heat treatment (corresponding to Figure 3 (a)) (b) Film after heat treatment (corresponding to Fig. 3 (b)) (c) A solution prepared by dissolving the membrane of (a) in concentrated aqueous ammonia. (d) A solution of p-hydroquinone dissolved in concentrated aqueous ammonia (e) A solution of p-benzoquinone dissolved in concentrated aqueous ammonia
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉田 司 岐阜県岐阜市南鏡島４丁目29番地１ (72)発明者 箕浦 秀樹 岐阜県羽島郡笠松町下新町100 (72)発明者 高橋 康隆 岐阜県岐阜市安食字志良古26−159 (72)発明者 伴 隆幸 岐阜県岐阜市城田寺53−８ ハイツサカノ 202号 (72)発明者 澤谷 清一 岐阜県岐阜市折立841番地 安田学研会館 北棟110号 (72)発明者 大矢 智一 愛知県名古屋市北区金城４−９−２ ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Tsukasa Yoshida 4-29, Minamikajima, Gifu City, Gifu Prefecture (72) Inventor Hideki Minoura 100 Shimoshinmachi, Kasamatsu-cho, Hashima-gun, Gifu Prefecture (72) Inventor Yasutaka Takahashi Gifu City Gifu City (72) Inventor Takayuki Ban 53-8 Shirotaji, Gifu City, Gifu Prefecture Heights Sakano No. 202 (72) Inventor Seiichi Sawaya 841 Origata Gifu, Gifu Prefecture Yasuda Gakken Hall North Building 110 (72) Inventor Tomokazu Oya 4-9-2 Kinjo, Kita-ku, Nagoya-shi, Aichi
Claims (2)
またはタンタルを含む化合物の安定な塩基性水溶液に、
少なくとも部分的にこの水溶液に溶解し、電気化学的に
酸化されプロトンを放出する性質を持つ有機分子を混合
した液を浴とし、この浴からのアノード電解によって導
電性基板上に金属酸化物と有機分子の複合膜を形成し、
得られた複合膜の熱処理によって膜中の有機分子を除去
することを特徴とするセラミック薄膜の電解合成法。1. A stable basic aqueous solution of a compound containing titanium, vanadium, niobium or tantalum as a metal species,
A solution that is at least partially dissolved in this aqueous solution and is mixed with organic molecules that have the property of electrochemically being oxidized to release protons is used as a bath. Forming a complex membrane of molecules,
A method for electrolytically synthesizing a ceramic thin film, characterized in that organic molecules in the obtained composite film are removed by heat treatment.
ール、カテコール、ピロガロールまたは１，２，４−ベ
ンゼントリオールから選ばれる請求項１の方法。2. The method of claim 1 wherein the organic molecule is selected from hydroquinone, resorcinol, catechol, pyrogallol or 1,2,4-benzenetriol.
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| CN100429253C (en) * | 2003-12-26 | 2008-10-29 | 关西油漆株式会社 | Polymer and method for producing polymer |
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| CN100429253C (en) * | 2003-12-26 | 2008-10-29 | 关西油漆株式会社 | Polymer and method for producing polymer |
| US7649027B2 (en) | 2003-12-26 | 2010-01-19 | Kansai Paint Co., Ltd. | Polymer and process for producing polymer |
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