Ca2+和Mn2+共掺杂Ba1-xSrxTiO3固溶体的制备及其电学性能 研究

利用溶胶-凝胶法制备了Ca2 和Mn2 共掺杂Ba1-xSrxTiO3 (BST)固溶体．采用TG-DTA热分析、XRD衍射和TEM透射电镜对其进行了表征,并研究了热处理温度和外加直流偏压对其电学性能的影响．XRD显示,Ca2 和Mn2 共掺杂没有改变BST的结构．TEM照片揭示了热处理温度对其形貌的影响．阻温特性曲线显示,在低频时它显示正温度系数效应(PTC),在其它频率则显示负温度系数效应(NTC)．电阻与电压关系显示,低频时它呈现电阻特性,而高频时则显示容抗特性．这些结果说明,掺杂能调节BST材料的电学性能;这些现象可以用晶界电阻效应,Heywang模型和离子极化理论来解释．

Preparation and Electrical Properties of (Ca, Mn)-codoped Ba1-xSrxTiO3 Solid Solution

(Ca, Mn)-codoped Ba1-xSrxTiO3 (BST) solid solution, i.e. Ba0.4Sr0.5Ca0.08Mn0.02TiO3, was successfully synthesized via sol-gel process. The product was characterized by TG-DTA thermal analyses, XRD, TEM. The effects of both curing temperature and applied voltage on the resistance, etc. were investigated. It showed that the structure of BST was unable to be changed even though it was codoped by Ca2 and Mn2 . TEM photographs demonstrated the influence of curing temperature on the morphologies of the tested samples. The dependence of resistance on the curing temperature illustrated that (Ca, Mn)-codoped BST was capable of exhibiting the positive temperature coefficient (PTC) effect at low frequency; nevertheless, it might display the negative temperature coefficient (NTC) effect at other frequencies. The relationships between the resistance and applied voltage revealed that the resistance property of (Ca, Mn)-codoped BST appeared at low frequencies, but its property of capacitive reactance might present at high frequency. These findings mean that the electrical property of BST can be adjusted by codoping method. These phenomena can be explained by the grain boundary resistance effect, Heywang model and ion polarization theory.