以新穎之低溫水熱–化學電池法於鈦薄膜與鈦塊材上製備鈦酸鋇膜之研究

Preparation of BaTiO3 Films on Ti/Si and Bulk- Ti by a Novel Low Temperature Hydrothermalgalvanic Couple Method

本研究主要是以新穎之水熱-化學電池法於低溫下（< 100℃）在鈦薄膜及鈦塊材上製備鈦酸鋇膜。其中鈦膜是以直流磁控濺鍍法鍍著於矽基材上，鈦塊材（純度99.7%）則須先經研磨拋光處理，再將二種試片置於2 M NaOH及0.5 M Ba（CH3COO）2溶液中進行反應。反應中以Ti/Si或鈦塊材當做工作電極，而白金則做為陰極，且不外加任何電壓。X光繞射分析（XRD）結果顯示鈦膜於溫度80℃反應5分鐘後即可生成立方相之鈦酸鋇，而鈦塊材上則需15分鐘以上才可發現立方相鈦酸鋇的生成，而在場發射掃描式電子顯微鏡（FE-SEM）觀察中，在溫度高於55℃反應2小時後，Ti/Si與鈦塊材表面都會生成似球狀顆粒的鈦酸鋇，在固定反應溫度與時間，Ti/Si上生成的鈦酸鋇顆粒較鈦塊材多，顯示使用低溫水熱-化學電池法於鈦膜製備鈦酸鋇膜的成長速率明顯比鈦塊材要快，研究中也探討鈦酸鋇可能的成長機制。

The objective of this study is to prepare of BaTiO3 films on Ti-coated silicon and bulk-Ti substrates by a novel hydrothermal-galvanic couple method at temperatures below 100 ℃. Ti films were deposited onto silicon wafers by d.c. sputtering. Bulk-Ti was mechanically ground and polished. In this hydrothermal-galvanic couple method, Ba(CH3COO)2 and NaOH alkaline solutions were employed as reaction solutions. Moreover, Ti/Si or bulk-Ti was used as the working electrode and Pt was utilized as the cathode, while no external voltage was applied. X-ray diffraction results show that cubic BaTiO3 films were successfully formed on Ti/Si and bulk-Ti for 2 h above 55 ℃ using the hydrothermal-galvanic couple method. BaTiO3 was formed at 80 ℃ for 5 min on Ti/Si while for 15 min on bulk-Ti. Field-emission scanning electron microscopy reveals a sphere-particulate morphology of BaTiO3 films above 55 ℃ for 2 h. The growth rate of BaTiO3 on Ti/Si is much faster than that on bulk-Ti by the new hydrothermal-galvanic couple method. The growth mechanism has been also discussed.