铅欠缺对PZN基陶瓷相组成和介电性能的影响

The Effect of Lead Deficiency on Phase Structure and Dielectric Properties of PZN-based Relaxor Ceramics

研究了初始粉体中的氧化铅欠缺对PZN基预烧粉体和无铅气氛烧结的陶瓷的相组成和介电性能的影响。研究发现:任何微量的铅欠缺都会使预烧粉体和陶瓷中产生焦绿石相,而且随着氧化铅欠缺量的增加预烧粉体和陶瓷中的钙钛矿相含量逐渐地下降。随着铅欠缺量的增加,PZN基陶瓷的介电常数大幅度地增加,但是铅欠缺对介电损耗影响很小。介电常数的增加主要是由于"有效有序微区"尺寸的增大和晶界间过量氧化铅层的消除。

The three series of PZN-based ceramics 0.75PZN-0.15BT-0.10PT?0.85PZN-0.10BT-0.05PT and 0.80PZN-0.20BT are prepared by the columbite method, and the effect of PbO deficiency in starting raw powders on the phase structure of calcined powders and ceramics sintered with Lead free atmosphere is investigated. At the same time, the effect of PbO deficiency on the dielectric properties is also studied. The results demonstrate that even minor content of PbO deficiency would result in pyrochlore phase in the calcined powders and sintered ceramics. With the increase of deficient PbO content, the perovskite phase content in both calcined powders and ceramics will decrease gradually. The dielectric constant of the three series of PZN-based ceramics is greatly increased with the increment of PbO deficiency, and their peak relative dielectric constant reaches the maximum value with 1% mole PbO deficiency. However, PbO deficiency hardly affected the dielectric loss of the PZN-based ceramics. The increase of dielectric constant results from the enlargement of the size of effective ordered micro-regions and the elimination of PbO film among crystal borders. 