Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/9390
標題: 電化學法鍍著鈦酸鋇膜
Electrochemical Deposition of BaTiO3 Films
作者: 洪雀雅
HUNG CHUEN, YA
關鍵字: electrochemical;電化學;barium titanate;鈦酸鋇
出版社: 材料工程學研究所
摘要: 
摘 要
本研究是以電化學法在鈦基材陽極上,於高鹼性鍍液中利用陽極氧化方式鍍著鈦酸鋇膜。電解液分別是0.5與0.35 M Ba(CH3COO)2+2 M NaOH,此鍍液pH值都大於13.5,鍍著溫度則控制在55℃。
首先以0.35 M Ba(CH3COO)2+2 M NaOH鍍液以電流掃瞄程控模式由0增加到100 mA,並由掃瞄時電解電壓明顯變化區域,由此得知鍍膜生成的電流值的範圍在5-40 mA之間,再選用定電流的程控模式在固定電量於432庫侖,分別以定電流5, 10, 20, 30, 40 mA條件進行鈦酸鋇膜鍍著。在定電流10 mA條件鍍著下,由XRD分析得知已有二氧化鈦(rutile相)生成,而在定電流20, 30, 40 mA條件則已經鍍著出單一立方相的鈦酸鋇膜。另以0.5 M Ba(CH3COO)2+2 M NaOH鍍液以定電流30 mA改變不同鍍著時間條件鍍著,由XRD結果得知,鍍著時間經過0.5小時,此時主要生成物是二氧化鈦,但隨鍍著時間增加至1小時就有鈦酸鋇的生成,由上述可以得知二氧化鈦為鈦酸鋇生成之前趨物。
截至目前本實驗鈦酸鋇膜鍍著最佳條件是在0.35 M與0.5 MBa(CH3COO)2+2 M NaOH鍍液以定電流30 mA鍍著4小時,此時鈦酸鋇的厚度可高達20 mm,這樣的厚度是以電化學法鍍著鈦酸鋇所未見的。再由0.5 M Ba(CH3COO)2+2 M NaOH鍍液定電流30 mA,改變不同鍍著時間0.5、1、2、4 小時進行鍍著,電解電壓變化-鍍著時間的關係以及XRD分析與SEM微結構分析結果,可知在電壓值低於60 V時主要是生成二氧化鈦(rutile相),在電解電壓超過60 V到電解電壓明顯振盪區前,因二氧化鈦膜在介電崩潰作用下產生溶解而與鍍液中Ba2+形成鈦酸鋇,成核成長為晶粒小於0.3 mm小顆粒鈦酸鋇,這部分是屬於溶解與再結晶的機制。
可由電解電壓圖中得知,當到達電解電壓明顯振盪區時,此時由微結構的觀察得知鈦酸鋇已聚集成長為不規則形狀分佈的大顆粒,且晶粒可大至10 mm以上,這是屬於陽極火花放電成長機制所造成,由此可知本研究鍍著鈦酸鋇膜涵蓋了兩個成長機制。

Abstract
The aim of this research is to fabricate BaTiO3 films by the electrochemical method in the electrolytes, 0.35M/0.5 M Ba(CH3COO)2 and 2M NaOH. The pH value was greater than 13.5 and the deposition temperature was controlled at 55C.
We firstly applied the scanning current mode varying from 0 to 100 mA to deposite BaTiO3 films in the electrolyte of 0.35M Ba(CH3COO)2 and 2M NaOH to find the suitable deposition conditions. Secondly, we. used a fixed electric content, 432 C to prepare the films. XRD results show that the crystal structures of the films are TiO2 (rutile phase) at 10 mA and BaTiO3 (cubic phase) at 20, 30 and 40 mA.
We varied the deposited time from 0.5 to 4 hr at constant current of 30 mA in the electrolyte of 0.5 M Ba(CH3COO)2 and 2M NaOH. TiO2 (rutile phase) existed at 0.5 hr and BaTiO3 (cubic phase) appeared above 1 hr. We believed that TiO2 appeared before the formation of BaTiO3. The optimized condition for depositing BaTiO3 films follows: anodic current at 30 mA and deposited time at 4 hr, where, the thickness of BaTiO3 films reached about 20 mm.
The growth of BaTiO3 films possessing small grain size which was formed at low voltage range could be due to the dissolution-recrystallization mechanism.
The large grained BaTiO3 films formed at high current (voltage) could attribute to size anodic spark deposition.
URI: http://hdl.handle.net/11455/9390
Appears in Collections:材料科學與工程學系

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