溶胶-水热法制备BaTiO3基PTC超细粉体

采用乙酸钡和钛酸四丁酯为原料,用溶胶沉淀与水热相结合的方法制备钛酸钡基正温度系数(PTC)纳米粉体.通过改变KOH强碱溶液用量调节水热反应的pH值,用X射线衍射分析了不同pH值条件下钛酸钡粉体晶相,确定了钛酸钡晶核稳定存在的条件.采用化学沉淀和溶液滴定方法研究了反应前驱物中Ba(AC)2和Ti(OC4H9)4的摩尔比对生成粉体化学计量比的影响.将Ba(AC)2Ti(OC4H9)4按照摩尔比为1配置的前驱物置于饱和氢氧化钡溶液构成的富钡环境下进行水热反应,获得了符合化学计量比、晶粒尺寸30nm左右的立方相钛酸钡纳米粉.在钛酸钡纯粉制备基础之上,将施主元素Y及受主元素Mn在前驱物制备过程中引入,瓷体实现了半导化,并获得了PTC效应.

Synthesis of PTC nanocrystals by coprecipitation/hydrothermal reaction

PTC(positive temperature coefficients) fine powders based on the adulteration of barium titanate(BaTiO3) was synthesized using Barium acetate and Tetra-n-butyl titanate as starting materials through the coprecipitation and the hydrothermal reaction.KOH was used to adjust the pH value of the hydrothermal solution.To make sure when the BaTiO3 nucleus were stable,the structure of BaTiO3 powders under different pH was analyzed through X ray diffraction.The mole ratio of Start materials has been changed and the effect on synthesis of BaTiO3 powders was studied by chemical analysis methods.The stoichiometric BaTiO3 powders were obtained by hydrothermal reaction from the stoichiometric precursor(mole ratio=1.0) in the saturated Ba(OH)2 solution.The BaTiO3 powders were cubic and the sizes of crystallites were around 30 nm.Based on the preparation of pure BaTiO3 powders,the elements of Y and Mn were added to the precursor to syntheses the PTC fine powders,and they could make the ceramics semiconducted and have PTC effect.