摘要
对于采用加直流电场水热法制备的ＢａＴｉＯ＿３粉体体系，测定了反应过程中外加直流电场电流和反应后溶液中残余ＯＨ￣－量。水热反应初期，电流随着反应温度的升高而增大。反应继续进行，电流达到极大值，然后急剧减小。反应温度越高，反应时间越长，反应后溶液里残余的ＯＨ￣－量越少。结合粉体物相和晶粒形貌的表征，对水热条件下ＢａＴｉＯ＿３晶粒的形成机理进行了探讨。在反应初期，随着温度的升高，前驱物逐渐溶解，体系中导电离子数不断增多，因此电流不断增大。溶液中ＯＨ￣－与从前驱物ＴｉＯ＿２粒子溶解进入溶液的钛氧基团结合形成羟基化的生长基元，它们与Ｂａ￣２＋一起在晶核生长界面上叠合、脱水、结晶，从而使ＢａＴＯ＿３晶粒长大。ＢａＴｉＯ＿３晶粒生成反应消耗体系中导电离子数，由于无其他新导电离子来源，所以电流达到极大值后又迅速减小。
Variation of DC electric current of the electro-hydrothermal system during synthesis of barium titanate powder and quantity of OH￣-remaining in solution after reactions(parameter ρ)were measured. Electric current increases with reaction temperature at initial stage, and reaches the maximum, then rapidly decreases during reaction. The higher the reaction temperature, the longer the reaction time, and the smaller the quantity of OH￣- remaining in the solution after reactions. Based on the characteristics of the phase and morphology of the synthesized powder,the formation mechanism of barium titanate powder under hydrothermal conditions is discussed. In the initial reaction period, precursors used gradually dissolve with the increase of reaction temperature, which causes the quantity of ions in solutions to increase, so electric current increases. The growth units are formed by combination of OH￣-anions and titanium-oxygen groups which are dissolved with TiO_2 particles used as one of precursors in the solution.The barium titanate crystallites grow by precipitation, dehydration and crystallization of growth units with Ba￣(2+) cations on the interface of the nucleus. Electric current reaches maximum and rapidly decreases because. the ions in system are consumed during formation of barium titanate crystallites and there is no other source of ions in the system.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1996年第1期45-52,共8页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金
关键词
钛酸钡
水热法
晶粒
陶瓷粉体
s: barium titanate powder, hydrothermal method, formation mechanism
