熔盐法制备片状CaBi_4Ti_4O_(15)晶粒的研究

以TiO_2、CaCO_3和Bi_2O_3为原料,加入NaCl和KCl(物质的量比为1:1)为熔盐,采用熔盐法制备Ca-Bi_4 Ti_4 O_(15)片状晶体.研究了熔盐含量、合成温度以及保温时间对制备CaBi_4 Ti_4 O_(15)片状晶体的影响,并对其反应机理进行了初步的探讨.结果表明,当熔盐质量分数为30%时开始生成CaBi_4 Ti_4 O_(15),当熔盐质量分数增加到40%左右时可获得较纯的CaBi_4 Ti_4 O_(15)相.熔盐含量对钛酸铋钙晶体的形貌有一定的影响,随着熔盐含量的增加,CaBi_4 Ti_4 O_(15)片状晶体逐渐长大,各向异性程度增大.合成温度的升高和保温时间的延长有利于CaBi_4 Ti_4 O_(15)片状形貌的形成.制备完整片状形貌的CaBi_4 Ti_4 O_(15)晶体的最佳熔盐含量为40%,合成温度为1150℃,保温时间为4h.

Preparation of Plate-like CaBi_4Ti_4O_(15) Microcrystal by Molten Salt Method

The prepare plate-like CaBi_4 Ti_4 Oi_5 microcrystal is prepared with TiO_2, CaCO_3 and Bi_2 O_3 as raw materials, NaCl and KC1 (molar ratio 1 : 1) as the molten salt by molten salt method. The effects of salt-to-raw materials ratio, synthesis temperature and soaking time on preparation of plate-like CaBi_4 Ti_4 O_(15) crystals are investigated, and the mechanism of reaction is approached preliminary. The results show that CaBi_4 Ti_4 O_(15) crystals are synthesized initially when salt-to-raw materials ratio is 30%, relatively pure CaBi_4 TI_4 O_(15) crystals are obtained when the content of molten salt increases to 40%. The shape of CaBi_4 Ti_4 O_(15) is affected by the content of molten salt, with the increasing of molten salt content, the plate-like CaBi_4 Ti_4 O_(15) crystals gradually increases, anisotropy becomes obviously. The increase of synthesis temperature and the extension of soaking time are also beneficial for the formation of plate-like Ca-Bi_4 Ti_4 O_(15) powder. The best synthesis parameters for integrated plate-like CaBi_4 Ti_4 O_(15) powder are as following: the molten salt content is 40%, the synthesis temperature is 1150(C) and the soaking time is 4h.