采用两种不同的添加方式,研究了Ba^2+部分取代Pb^2+所获得的PZN基铁电陶瓷的结构和介电性能。一种是BaCO3、PbO和ZnNb2O6进行预合成,然后烧结制备PZN基陶瓷;另一种是ZnNb2O6先分别与BaCO3、PbO进行预合成,然后再将两种预合成产物进一步烧结制备PZN基陶瓷。实验结果表明:随Ba^2+取代量的增加,不同添加方式制备的陶瓷其钙钛矿相的稳定性增强;介电性能先上升然后又下降,相变温度n移向低温。比较Ba^2+的两种不同添加方式,前者制备的陶瓷具有相对较低的Tm值和较小的晶粒尺寸,添加8mol%的Ba^2+即可获得100%的钙钛矿结构;而后者为获得100%的钙钛矿结构则需要25mol%Ba^2+。
The dielectric properties and microstructure of Pb1-x Bax ( Zn1/3 Nb2/3 ) O3 ferroelectric ceramics were investigated. Two different ways of substituting Ba^2+ for Pb^2+ were adopted to obtain perovskite single phase structures. One way is wet mixing BaCO3, PbO and ZnNb2O6. First the mixtures were calcined at 880℃ for 8h, then the calcined powders were ball milled and dried, finally the samples were pressed and sintered. The other way is that wet mixing ZnNb2O6 + BaCO3 and ZnNb2O6 + PbO, respectively. The mixtures were calcined respectively at 880℃ for 4h, the two calcined powders were mixed in different ratios then ball milled and dried, the samples were pressed and sintered. The results show that for the ceramics prepared by two different adding ways the stabilization of perovskite phase of PZN - based ceramics increases and dielectric properties increase firstly and then decrease with increasing Ba^2+ while Curie temperature of different compositions shifts to the low temperature. By comparing two adding ways, it's found that the temperature of the maximum of the dielectric constant (Tm) is lower and the grain size of ceramics are smaller for the former. More than 8mol% Ba^2+ was needed to stabilize the 100% perovskite phase for the former while more than 25mol% Ba^2+ was needed to obtain 100% pemvskite structure for the latter.