晶粒可控钛酸钡致密陶瓷的制备及表征

Preparation and characterization of grain-controlled dense barium titanate ceramics

采用超重力反应沉淀法制备的纳米钛酸钡粉体和常规陶瓷工艺,通过控制烧结温度在1200～1300℃,分别制备了晶粒尺寸0.45～2.2μm的致密陶瓷.实验结果表明超重力反应沉淀法制备的粉体具有良好的烧结和介电性能.烧结温度为1200℃时,相对密度即可达到95%,晶粒尺寸为0.45μm,随烧结温度的升高,晶粒逐渐长大,未出现晶粒的异常长大现象,到1300℃相对密度和晶粒尺寸分别达到97.7%和2.2μm.钛酸钡陶瓷介电性能有明显的粒度效应,晶粒在1.2μm左右时,室温介电常数达到最大(4143).由于晶粒内部立方相成分的出现,包含更细晶粒的陶瓷(d=0.45μm)呈现低的介电常数.

Barium titanate (BaTiO3) powder was prepared by high-gravity reactive precipitation (HGRP) process. BaTiO3 ceramics with average grain size from 0.45 μ m to 2.2 μ m were obtained by the conventional ceramic technology and as-prepared powder. The sintering temperature was adjusted in the range of 1200-1300°C. The experimental results showed that as-prepared BaTiO3 powder had good sintering and electrical properties. Sintered ceramic can reach the relative density of >95% when sintered at 1200°C; The exaggerated grain growth did not appear when increased the sintering temperature, and the grain size and relative density increased and reached 2.2 μm and 97.7% at 1300°C, respectively. The grain size effect on the dielectric constant of the sintered ceramics was also studied. The dielectric constant had a maximum (4143) at 1.2 μm grain size. Lower dielectric constant of fine-grains ceramic (d=0.45 μm) was attributed to the incomplete development of the tetragonal structure from cubic structure.