掺杂 Al_2O_3对 Ba_2Ti_9O_(20)相形成的影响

本文研究了在BaO-TiO_2-SnO_2固相反应系统中掺杂 Al_2O_3对 Ba_2Ti_9O_(20)相形成的影响。实验结果表明,即使掺杂少量的 Al_2O_3,在反应过程中 Ba_2Ti_9O_(20)相也变得更容易形成。微观结构分析结果表明,Ba_2Ti_9O_(20)晶体结晶时,由于具有层状结构特征,往往会出现结构层间应力;这种应力会严重制约Ba_2Ti_9O_(20)晶体的形核和长大。掺杂少量 Al_2O_3后,能形成与 Ba_2Ti_9O_(20)晶体共生的 BaAl_2Ti_6O_(16)晶体;这种共生机制抑制了应力的发展。Al_2O_3改善了 Ba_2Ti_9O_(20)结晶的动力学条件,促进了 Ba_2Ti_9O_(20)相的形成。

EFFECT OF Al_2O_3 ON THE FORMATION OF Ba_2Ti_9O_(20)

An investigation was made of the effect of Al_2O_3 compound on the formation ofBa_2Ti_9O_(20)phase in the solid state reactions.The formation of Ba_2Ti_9O_(20)crystal,which is diffi-cult in the BaO-TiO_2 binary system because of stress arising along the crystal-sturcture layerscaused by the structural factor,can be eased by the addition of a little Al_2O_3 into the binary re-action system.When Al_2O_3 participates in the reaction,BaAl_2Ti_6O_(16)crystal is formed and ex-ists in the way of inter-growth with the crystallizing Ba_2Ti_9O_(20)crystal.The intergrowthremarkebly decreases the stress arising along the crystal-structured layers of the crystallizingBa_2Ti_9O_(20)and reduces the height of potential energy barrier of its crystallization,resulting in itseasy formation in the reactions.