陶瓷材料的電化學沉積可以利用電泳沉積法或電解沉積法達成。其中電泳沉積是膠體製程在鍍膜技術方面的一種應用，其原理是在一外加電壓下，驅動懸浮溶液中帶電荷之粒子往與本身所帶電荷相反之電極移動，並沉積於基板上。電解沉積是在電極上發生陰極反應產生膠體粒子沉積。在適當條件下可結合電泳沉積及電解沉積，進行電化學共沉積。
　　本研究利用均勻分散且懸浮於溶劑中的奈米二氧化鈦粒子，在一外加電壓驅動下，於陰極基板上形成一均勻之鍍層。藉由溶劑之選擇、改變外加電壓、濃度、基板、以及沉積方式，探討鍍層之微結構變化，及添加電解質對於沉積機制的影響，最後嘗試利用電泳製程製備感測材料。
　　研究結果顯示：沉積鍍層厚度及表面形態可利用改變電泳製程參數而獲得控制。適當添加電解質，利用其在溶劑中易解離得到正離子，在電泳懸浮液之外加大電壓作用下，於陰極基板上發生電化學反應，進而探討電解質添加量對於沉積機制的改變，發現電解質濃度低於10-4M時，可獲得單純二氧化鈦電泳沉積；適當的電解質添加量，濃度約為10-3M，可於陰極基板上發生電化學共沉積；當濃度高於10-2M之高電解質濃度時，則電化學陰極沉積氧化鋅成為主要的沉積機制。
　　此外，奈米二氧化鈦粒子因其粒子尺寸小、比表面積大，可以應用於表面效應需求較高之氣體感測器上。因此本研究首次利用電泳沉積法在絕緣基板上製備無裂縫之TiO2薄膜，並應用於感測性質之研究。研究結果發現，在室溫中二氧化鈦薄膜對400ppm酒精氣體之感測性質最大靈敏度約為6。

　　Electrodeposition of ceramic materials can be achieved by electrophoretic (EPD) and electrolytic (ELD) deposition, depending on the experimental conditions. EPD was achieved via forced motion of charged particles under an applied voltage towards an electrode with opposite charge, and then the particles coagulate to form a deposit. ELD proceeds via deposition of colloid particles formed as a result of cathodic reactions.
　　In this work, positively charged TiO2 nanoparticles were dispersed in selected solvents and then electrophoretically deposited to form uniform deposits on cathodic electrode under an applied voltage. This research focuses on the effect of electrophoretic parameters, such as solvents, applied voltages, concentrations of particles, substrate property, and the method of deposition, on the deposit characteristics and the related deposition kinetics. Additionally, the influence of electrolyte additive on the deposition mechanism is also considered in this work. Finally, some work on the feasibility of fabricating TiO2 gas sensor using the EPD process is also performed.
　　The results show that the thickness and morphology of the deposited layers can be well controlled by proper selection of deposition parameters. Addition of electrolyte can lead to the formation of cations and then ELD could be achieved on cathode electrode under EPD voltage. The concentration of the electrolyte influences the deposition mechanisms, where pure TiO2 films are obtained by EPD at low concentration of the electrolyte of about 10-4M; however, the deposition mechanism becomes the cathodic ELD of ZnO films when the concentration was increased to above 10-2M. For the concentrations in between the extremes, composite coatings on the cathode are obtained from electrochemical codeposition.
　　Furthermore, TiO2 nanoparticles, exhibiting small particle size and large surface area, are suitable to be applied as gas sensor for which a significant surface effect is required. A crack-free TiO2 thin film deposited on insulating SiO2 substrate is obtained by EPD at a high voltage to dielectrically breakdown the SiO2 layer. It is found that the fabrication of oxide gas sensor by EPD is feasible, but the device’s performance as an ethanol sensor needs to be optimized. In this work the maximum sensitivity of about 6 for the TiO2 sensor to 400ppm ethanol at room temperature is observed.

[1] A. Fujishima, and K. Honda, “Electrochemical photolysis of water at a semiconductor electrode,” Nature, 238 (1972) 37-38.

[2] P. Sarkar, and P. S. Nicholson, “Electrophoretic deposition (EPD): mechanisms, kinetics, and application to ceramics,” J. Am. Ceram. Soc. 79 (1996) 1987-2002.

[3] K. Kamada, K. Maehara, M. Mukai, S. Ida, and Y. Matsumoto, “Fabrication of metal oxide-diamond composite films by electrophoretic deposition and anodic dissolution,” J. Mater. Res. 18 (2003) 2826-2831.

[4] A. T. Kuhn (ed.), Industrial Electrochemical Processes; p. 128. Elsevier, Amsterdam, The Netherlands, 1971.

[5] A. Formeto, L. Montanaro, and M. V. Swain, “Micromechanical characterization of electrophoretic-deposited green films,” J. Am. Ceram. Soc., 82 (1999) 3251-3528 .

[6] T. Uchikoshi, K. Ozawa, B. D. Hatton, and Y. Sakka, “Dense, bubble-free, ceramic deposits from aqueous suspensions by electrophoretic deposition,” J. Mater. Res. 16 (2001) 321-324.

[7] O. O. Van der Biest, and L. J. Vandeperre, “Electrophoretic deposition of material,’’ Annu. Rev. Mater. Sci., 29 (1999) 327-352.

[8] J. A. Lewis, “Colloidal processing of ceramics,” J. Am. Ceram. Soc. 83, (2000) 2341-59.

[9] I. Zhitomirsky, “Cathodic electrodeposition of ceramic and organoceramic materials. Fundamental aspects,” Advances in colloid and interface science, 97 (2002) 279-317.

[10] J. A. Siracuse, J. B. Talbot, E. Sluzky, and K. R. Hesse, “The adhesive agent in cataphoretically coated phosphor screens,” J. Electrochem. Soc. 137 (1990) 346-348.

[11] B. E. Russ, and J. B. Talbot, “An analysis of the binder formation in electrophoretic deposition,” J. Electrochem. Soc. 145 (1998) 1253-1256.

[12] K.-H. Ahn, Y.-B. Park , and D.-W. Park , “Kinetic and mechanistic study on the chemical vapor deposition of titanium dioxide thin films by in situ FT-IR using TTIP,” Surface & Coatings Technology, 171 (2003) 198-204.

[13] N. Martin, A. M. E. Santo, R. Sanjines, and F. Levy, “Energy distribution of ions bombarding TiO2 thin films during sputter deposition,” Surface & Coatings Technology, 138 (2001) 77-83.
[14] Y. Zhu, L. Zhang, L. Wang, Y. Fu and L. Cao, “The preparation and chemical structure of TiO2 film photocatalysts supported on stainless steel substrates via the sol-gel method,” J. Mater. Chem, 11 (2001) 1864-1868.

[15] M. A. Fox, and M. T. Dulay, “Heterogeneous Photocatalysis,” Chem Rev., 93 (1993) 341-357.

[16] 高濂，鄭珊，張青紅，“奈米二氧化鈦光催化材料及應用”，化學工業出版社，p.35 (2002)。

[17] 黃相舜，“電漿化學氣相沉積二氧化鈦薄膜之特性研究”，國立成功大學材料科學及工程學系碩士論文，p.11-12 (2000)。

[18] Internet Website: “University of Colorado, Mineral Structure Data, http://ruby.colorado.Edu/~smyth/min/minerals.html ”

[19] S. M. Sze, “Semiconductor sensor,’’ John Wiley & Sons, New York, 1994, pp.383-410 (chap.8)

[20] C. Xu, J. Tamaki, N. Miura and N. Yamazoe, “Grain size effects on gas sensitivity of porous SnO2-Based elements,” Sensors and Actuators B, 3 (1991) 147-155.

[21] 馮輝明，“以溶膠凝膠法製備氧化鈦鎢氣體感測器薄膜”，國立成功大學材料科學及工程學系碩士論文，p.10 (2000)

[22] N. Yamazoe and N. Miura, “Some basic aspects of semiconductor gas sensors,” in S. Yamauchi (Ed.), Chemical Sensor Technology, 4 (1992) 19-42.

[23] H.-M. Lin, T.-Y. Hsu, C.-Y. Tung, and C.-M. Hsu, “Hydrogen sulfide detection by nanocrystal Pt doped TiO2-Based gas sensors,” Nanostructured Materials, 6 (1995) 1001-1004.

[24] H.-M. Lin, C.-H. Keng, and C.-Y. Tung, “Gas-sensing properties of nanocrystalline TiO2,” Nanostructured Materials, 9 (1997) 747-750.

[25] R. Schlesinger, and M. Bruns, “Quality control of gas sensor microarrys using Auger electron spectroscopy,” Thin Solid Films, 366 (2000) 265-271.

[26] S Roy, and S Basu, “Improved zinc oxide films for gas sensor applications,” Bulletin of Materials Science 25 (2002) 513-515.

[27] C.-Garzella, E. Comini, E. Tempesti, C. Frigeri, and G. Sberveglieri, “TiO2 thin films by a novel sol-gel processing for gas sensor applications,” Sensors and Actuators B, 68 (2000) 189-196.

[28] G. Sakai, N.-S. Baik, N. Miura, and N. Yamazoe, “Gas sening properties of tin oxide thin films fabricated from hydrothermally treated nanoparticles dependence of CO and H2 response on film thickness,” Sensors and Actuators B, 77 (2001) 116-121.

[29] I. R. Bickley, T. Gonzalez-Carreno, J. S. Lees, Leonardo Palmisano, and Richard J. D. Tilley, “A structural investigation of titanium dioxide photocatalysts,” J Solid State Chem, 92 (1991) 178-190.

[30] J. Zhang and B. I. Lee, “Electrophoretic deposition and characterization of micrometer-scale BaTiO3 based X7R dielectric thick films,” J. Am. Ceram. Soc. 83 (2002) 2417-2422.

[31] Z. Zhang, Y. Huang, and Z. Jiang, “Electrophoretic deposition forming of SiC-TZP composites in a nonaqueous sol media,” J. Am. Ceram. Soc., 77 (1994) 1946-1949.

[32] K. Kameyama, K. Tsukada, K. Yahikozawa and Y. Takasu, “The application of scanning auger microscopy to the surface characterization of RuO2-TiO2 coated titanium electrodes,” J. Electrochem. Soc. 140 (1993) 966-969.

[33] S. Pushpavanam and K. C. Narasimham, “Morphology of (Ru-Ti-Sn) mixed-oxide coatings,” J. Mater. Sci.29 (1994) 939-942.

[34] I. Zhitomirsky, A. Kohn, and L. Gal-Or, “Cathodic electrosynthesis of PZT films,’’ Mater. Lett. 25 (1995) 223-227.

[35] I. Zhitomirsky, and L. Gal-Or, “Ruthenium oxide deposits prepared by cathodic electrosynthesis,’’ Mater. Lett. 31 (1997) 155-159.

[36] I. Zhitomirsky, “Electrolytic TiO2-RuO2 deposits,’’ J. Mater. Sci. Lett. 34 (1999) 2441-2447.

[37] I. Zhitomisky, R. Chaim, L. Gal-Or, and H. Bestgen, “Electrochemical Al2O3-Cr2O3 alloy coatings on non-oxide ceramic substrates,” Journal of Materials Science, 32 (1997) 5205-5213.

[38] YC Wang, IC Leu, MH Hon, “Kinetics of electrophoretic deposition for nanocrystalline zinc oxide coatings,” J. Am. Ceram. Soc. 87 (2004) 84-88.

[39] Y. Hirata, A. Nishimoto, and Y. Ishihara, “Forming of alumina powder by electrophoretic deposition,” Nippon Seramikkus Kyokai Gakujutusu Ronbunshi, 99 (1991) 108-113.

[40] A. Sussman, and T. J. Ward, “Electrophoretic deposition of coatings from glass-isopropanol slurries,” RCA Rev., 42 (1985) 178-197.

[41] M. Shimbo, K. Tanzawa, M. Miyakawa, and T. Emoto, “Electrophoretic deposition of glass powder for passivation of high voltage transistors,” J. Electrochem. Soc. 132 (1985) 393-398.
[42] I. Zhitomirsky, “Electrophoretic deposition of chemically bonded ceramics in the system CaO-SiO2-P2O5,” J. Mater. Sci. letter 17 (1998) 2101-2104.
[43] H. Koelmans, “Suspension in non-aqueous media,” Philips Res. Rep., 10 (1955) 161.

[44] Y. Takayama, H. Negishi, S. Nakamura, N. Koura, Y. Idemotot, and F. Yamaguchi, “Zeta potential of various oxide particles and the charging mechanism,” J. Ceram. Soc. Jpn., 107 (1999) 119-122.

[45] I. Zhitomirsky and L. Gal-Or, “Electrophoretic deposition of hydroxyapatite,” J. Mater. Sci., Mater. Med., 8 (1997) 213-219.

[46] M. J. Shane, J. B. Talbot, B. G. Kinney, E. Sluzky, and K. R. Hesse, “Electrophoretic deposition of phosphors,” J. Colloid Interface Sci., 165 (1999) 334-340.

[47] P. Sarkar, X. Huang, and P. S. Nicholson, “Structural ceramic microlaminates by electrophoretic deposition,” J. Am. Ceram. Soc.,75 (1992) 2907-2909.

[48] F. Hossein-Babaei, and F. Taghibakhsh, “Electrophoretically deposited zinc oxide thick film gas sensor,” Electronic Letters, 36 (2000) 1815-1816.