Pr,Mn改性BaTiO_3陶瓷的制备及其PTC特性  

Preparation of Pr, Mn Modified BaTiO_3 Ceramics and Their PTC Effect

作　　者：郝素娥[1] 黄金祥[1] 张巨生[1] 

机构地区：[1]哈尔滨工业大学,黑龙江哈尔滨150001

出　　处：《稀有金属材料与工程》2008年第A04期821-824,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金资助项目(20571020)

摘　　要：采用溶胶凝胶法制备了Pr,Mn掺杂的BaTiO3陶瓷,并对其进行了Pr,Mn气相扩渗。研究结果表明,Mn掺杂能提高BaTiO3陶瓷的室温电阻率至1015Ω·m,但再经Pr扩渗后降至107Ω·m,经Pr-Mn共渗后降至2.01Ω·m。Pr掺杂能降低BaTiO3陶瓷的室温电阻率至105Ω·m,再经Mn扩渗后,室温电阻率变化不大,但经Pr-Mn共渗后室温电阻率显著降低,达到2.04Ω·m。Pr气相扩渗能显著降低电阻率,而Mn的加入有利于改善PTC特性。经Pr扩渗的Mn掺杂BaTiO3陶瓷在350℃后有明显的NTC效应,升阻比高达106;经Mn扩渗的Pr掺杂BaTiO3陶瓷在370℃附近出现突降点,电阻率降至0.1Ω·m,升阻比约为105。XRD分析表明,Pr,Mn掺杂或扩渗都没有改变BaTiO3陶瓷的物相结构。XPS分析表明,在气相扩渗过程中,C和Pr元素都进入了陶瓷体,并主要分布于晶界或者陶瓷的气孔中,导致了改性BaTiO3陶瓷电阻率的明显下降和NTC效应的产生。气相扩渗对掺杂后的陶瓷有减小结合能的活化作用,而对纯BaTiO3陶瓷有增强稳定性的作用。Different kinds of BaTiO3 ceramics doped by Pr or Mn were prepared by sol-gel method, and then the ceramics were penetrated by Pr and Mn in gaseous state. The results show that the resistivities of Mn-doped BaTiO3 ceramics are increased to 1015 Ω·m, but they are decreased to 10^7 Ω·m after Pr penetration and decreased to 2.01 Ω·m after Pr-Mn co-penetration. The resistivities of the Pr-doped BaTiO3 ceramics are decreased to 105 Ω·m, and they do not change after Mn penetration, but they are decreased to 2.04 Ω·m after Pr-Mn co-penetration. It is indicated that Pr penetration could decrease the resistivities of BaTiO3 ceramics evidently, but Mn addition could improve PTC effect. The Mn-doped BaTiO3 ceramics after Pr penetration give a distinct NTC effect above 350 ℃, the changing extent of resistivities is high to 10^6. There is a mutation point at 370 ℃ of Pr-doped BaTiO3 ceramics after Mn penetration, the resistivity is decreased to 0.1Ω·m, and the changing extent of resistivities is about 105. The XRD results show that the perovskite structure of modified BaTiO3 ceramics after Pr, Mn doping and penetration do not change obviously. The XPS results show that C and Pr element have been penetrated into BaTiO3 ceramics and are distributed at grain boundary or spiracles, which lead to the obviously lower resistivities and NTC effect of modified BaTiO3 ceramics. The gaseous penetration could decrease the binding energy of doped BaTiO3 ceramics, but could increase the binding energy of pure BaTiO3 ceramics and improve their stability.

关 键 词：钛酸钡 稀土 气相扩渗 PTC效应 

分 类 号：TQ174.1[化学工程—陶瓷工业]