甘氨酸对固相法合成钛酸钡粉体的影响

Effect of glycine on solid-state synthesis of barium titanate powder

以BaCO_(3)和TiO_(2)为原料、甘氨酸为添加剂,采用固相法合成钛酸钡(BT)粉体。研究了不同合成温度和甘氨酸添加量对BT粉体性能的影响,利用XRD、BET、SEM、DSC、TG等手段对合成的BT粉体进行表征。结果表明,添加甘氨酸可以促进BaCO_(3)在650℃附近分解,使BT粉体的合成温度降低50℃,在900℃就能得到纯相BT,在1000℃可以得到四方率(c/a)>1.010的BT粉体,但添加过量的甘氨酸使粉体粒径急剧增大反而会降低其性能;添加15%的甘氨酸在1000℃保温2 h可以得到c/a=1.0103、平均粒径为520 nm、k=9.00的BT粉体,其性能整体优于平均粒径为600 nm的商业BT粉。将二者在1280℃烧结2 h得到的陶瓷进行介电性能对比发现,商业粉室温和居里点介电常数略大于添加15%甘氨酸的合成粉,但室温下正交-四方的相变峰使介电损耗急剧增大。

Barium titanate(BT)powders were synthesized by solid-state reaction using BaCO_(3) and TiO_(2) as raw materials and glycine as additive.The effects of different synthesis temperatures and glycine addition on the properties of BT powder were studied.The synthesized BT powders were characterized by XRD,BET,SEM,DSC and TG.The results showed that the addition of glycine could promote the decomposition of BaCO_(3) near 650℃ and reduce the synthesis temperature of BT powder by 50℃.After adding glycine,pure phase BT could be obtained at 900℃,and BT powder with c/a>1.010 could be obtained at 1000℃.However,the addition of excessive glycine made the particle size increase sharply,which would deteriorate the performance of BT powder.The BT powder with c/a=1.0103,average particle size of 520 nm and k=9.00 could be obtained by adding 15%glycine at 1000℃ for 2 h,and its performance was better than that of commercial BT powder with 600 nm.BT ceramics were obtained by sintering commercial powder and synthetic powder with 15% glycine at 1280℃,respectively.Comparing the dielectric properties of the two ceramics,it was found that the dielectric constants of the former at room temperature and Curie point were slightly larger than those of the latter,but the dielectric loss was increased obviously due to the orthorhombic-tetragonal phase transition peak at room temperature.