La改性BaTiO_3陶瓷的结构与电性能  

Effects of La on structure and electr ical characteristics of BaTiO_3 ceramics

作　　者：郝素娥[1] 孙亮[1] 李晓丹[1] 韦永德[1] 

机构地区：[1]哈尔滨工业大学应用化学系,哈尔滨150001

出　　处：《功能材料与器件学报》2004年第4期407-412,共6页Journal of Functional Materials and Devices

基　　金：黑龙江省重点攻关项目(GB02A301)

摘　　要：采用气相扩渗和液相掺杂两种方法制备了La改性的BaTiO3陶瓷,并对其组成、结构、形貌以及电性能的变化进行了研究。La的液相掺杂可使纯BaTiO3陶瓷的电阻率从4.0×1012Ω·m下降为3.0×106Ω·m;而La的气相扩渗使其电阻率下降更为明显,变为8.2×104Ω·m。La掺杂BaTiO3陶瓷的晶粒电阻随温度的变化,呈现出明显的NTC效应,而晶界电阻则呈现PTC效应。La扩渗BaTiO3陶瓷的晶粒电阻随温度的变化,呈现出明显的PTC效应;晶界电阻随着温度的升高急剧连续降低,样品总电阻的PTC效应已不存在。XRD分析表明,La掺杂的BaTiO3陶瓷并没有形成新相,而扩渗的La元素已经与陶瓷组元发生了复杂反应,生成了La2C2O2、Ba5La4Ti8O27一些新的化合物,从而导致了导电性的显著变化。SEM分析表明,La扩渗的BaTiO3陶瓷,因形成新相,从而使形核数量增多,形成了均匀、细小、弥散的形貌特征。The modified BaTiO 3 ceramics were prepared by two method s:liquid doping and gas penetra -tion,and the effects of La doping and La penetration on structure and electric characteristics of BaTiO 3 ceramics were studied.The BaTiO 3 ceramic doped with La 3+ was prepared by Sol -Gel method.The resistivity of BaTiO 3 ceramic doped with La 3+ decreases obviously,and when La 3+ content is 0.003mol,the resistivity becomes the smallest,which changes from 4.0×10 12 Ω·m to 3.0×10 6 Ω·m.The BaTiO 3 ceramic penetrated with La 3+ was prepared by gas penetration meth od under different tempera -tures.The resistivity of BaTiO 3 ceramics penetrated with La 3+ decreases obviously too,and when th e La 3+ content in the solvent is 0.02,the penetration temperature is 920℃and th e penetration time is4h,the resistivity decreases to the smallest,value which is 8.2×10 4 Ω·m.The grain resistance of BaTiO 3 ceramic doped with La 3+ exhibits NTC effect,but the grain boundary resistance shows PTC effect,and the grain boundary resistance is larger than the grain resistance,so the PTC effect originates from the grain boundary.But the grain resistance of BaTiO 3 ceramic penetrated with La 3+ exhibits an obvious PTC effect with the change of tempera ture,the grain boundary resistance decreases rapidly with increase of temperature,and the change rule o f the total resistance is similar to t hat of the grain boundary,the PTC effect disappears.Through XRD a nalyses,it show that the crystal typ e of BaTiO 3 ceramic doped with La 3+ is tetragonal,there is no new peaks a ppear.However,it is found that in th e XRD pattern of BaTiO 3 ceramic penetrated with La 3+ ,there are characteristic peaks of BaTiO 3 ,La 2 C 2 O 2 and Ba 5 La 4 Ti 8 O 27 .It shows that the La enter into the Ba TiO 3 ceramics during gas penetration and the complex reactions

关 键 词：气相扩渗 液相掺杂 钛酸钡陶瓷 电性能 稀土 

分 类 号：TQ174.756[化学工程—陶瓷工业]