La调节Pb(Zr,Sn,Ti)O_3反铁电陶瓷的相变与电学性质

Phase transformation and electrical properties of La-modified Pb(Zr,Sn,Ti)O_3 antiferroelectric ceramics

利用X射线衍射、弱场介电温度谱、强场极化强度研究了不同La含量 (Pb1 -xLa2x 3) (Zr0 6 Sn0 3Ti0 1 )O3(0 0 0≤x≤ 0 12 ) (PLZSnT)陶瓷的相变与电学特性 .实验发现 ,随La含量增大 ,室温下材料由铁电三方相 (x =0 0 0 )转变为反铁电四方相 (0 0 3≤x≤ 0 0 9)和立方相 (x=0 12 ) .介电测试表明 ,La含量增大 ,反铁电→顺电相变温度降低 ,峰值介电常量减小 .在x =0 0 6的PLZSnT三元相图中 ,反铁电四方相区扩大到Ti含量约为 18at% ,该系统反铁电陶瓷具有“窄、斜”型双电滞回线和“三电滞回线” ;在高Zr、高Sn区 ,反铁电→顺电相变呈现弥散相变和介电频率色散特征 ,即反铁电极化弛豫现象 .从ABO3钙钛矿结构的容忍因子 (t)和反铁电相的结构特征出发 ,讨论了La对Pb(Zr,Sn ,Ti)O3相变与电学性质的影响机理 .

Phase transformation and electrical properties of lanthanum modified lead zircono stanno titanate (Pb 1 x La 2 x /3 )(Zr 0 6 Sn 0 3 Ti 0 1 )O 3(0 00≤ x ≤0 12, PLZSnT)ceramics with a composition near antiferroelectric/ferroelectric(AFE/FE) phase boundary were investigated by dielectric spectroscopy, Sawyer Tower polarization technique, and X ray diffraction. It was found that, as lanthanum content increases, the ferroelectric rhombohedral phase( x =0 00, FE R) transforms to antiferroelectric tetragonal (0 03≤ x ≤0 09), and cubic phase( x =0 12, PE). In the phase diagram of the PLZSnT system with x =0 06, AFE t region has been extended to 18 at%Ti. A diffused AFE→PE phase transition with dielectric frequency dispersion, is observed in PLZSnT specimens with high Zr and high Sn contents, which is proved to be an antiferroelectric relaxor. A kind of \!slant, narrow\' double hysterisis loops, and a peculiar \!triple hysteresis loops\' were observed in the specimens with a composition near AFE/FE phases boundary due to the coexistence of FE and AFE phases. Effects of lanthanum modification on the phase transformation and electrical properties of Pb(Zr,Sn,Ti)O 3 AFE ceramics were discussed based upon the tolerance factor and lattice structure of AFE phase.