原料预处理对BaTiO3压电陶瓷的物性影响

Raw-material Pre-milling on Physical Property of BaTiO_3 Piezoelectric Ceramics

BaCO_3微粉原料通常由尺寸较大的棒状颗粒所组成,这些棒状颗粒在一次球磨过程中由于不容易粉碎,从而对经预烧、二次球磨所得到的BaTiO_3陶瓷微粉的化学组分的均匀性和颗粒度产生影响,进而影响后序烧结制备的BaTiO_3陶瓷的微观组织结构和压电性能。本研究重点探讨了以BaCO_3和Ti O_2为原料、通过固相反应途径制备BaTiO_3陶瓷时,实施原料预处理对所制备的BaTiO_3压电陶瓷物性的影响。研究发现,配料前对BaCO_3原料实施球磨预处理可明显地降低棒状颗粒的尺寸,从而可获得颗粒度细化的BaTiO_3陶瓷微粉,进而制备致密度更高和晶粒尺寸更小而压电性能更高的BaTiO_3陶瓷材料。研究中对BaCO_3微粉进行不同时间的球磨预处理,然后制备钛酸钡陶瓷,考察了其压电性能、介电性质、铁电性能和微观结构等物理性质。利用同样的BaCO_3微粉原料,未经球磨预处理所制备的BaTiO_3陶瓷的压电系数d33最高值为410 p C/N,而实施合适的球磨预处理制备的BaTiO_3陶瓷的压电系数d33最高值可达470 p C/N。

BaCO3 powder usually consists of large rod-shaped particles, which can not be easily broken up into fine ones when ball-milled together with TiO2 powder. This may lead to chemical compositional non-uniformity and large particle sizes of the subsequently synthesized BaTiO3 powder through the calcination and the secondary ball-milling procedure, and may eventually affect the microstructure and the piezoelectric properties of resultant BaTiO3 ceramics. Effects of the pre-milling treatment of BaCO3 powder on physical properties of the resultant BaTiO3 ceramics prepared by conventional solid-state reaction were investigated. The results show that an additional ball-milling treatment of BaCO3 powder before being mixed with TiO2 powder can remarkably reduce the size of the rod-like particles, which is an effective way to get good-quality BaTiO3 fine powder. In such a way, a series of small-grained dense BaTiO3 ceramics are fabricated with sig- nificantly high piezoelectric coefficient d33. The BaTiO3 ceramics were prepared with the BaCO3 powders ball-miUed for different time before mixing with raw TiO2 powder. Physical properties of the resultant ceramics, including piezoelectric properties, dielectric properties, ferroelectric properties, and microstructure were investigated. A much enhanced d33 value of 470 pC/N was achieved for the BaTiO3 ceramics prepared with the BaCO3 powders ball-milled for 8 h, in comparison to the maximum value of 410 pC/N for those BaTiO3 ceramics prepared with un-ball-milled BaCO3 powders.