(1-x)(K0.5Na0.5)NbO3-xSrTiO3陶瓷的弛豫铁电性能

Relaxor ferroelectricity of (1-x)(K_(0.5)Na_(0.5))NbO_3xSrTiO_3 ceramics

通过对(1-x)(K0.5Na0.5)NbO3-xSrTiO3(0≤x≤0.15)陶瓷的相组成、晶体结构和介电性能的研究发现,该陶瓷为单一的钙钛矿结构相.当x含量较小(x<0.1)时为正交相结构,x≥0.1时转变为四方相结构.随着SrTiO3掺杂量的增加,样品的致密度增加,样品由正常铁电相逐渐向弥散铁电相转变,且相变温度明显下降,其相变峰的半高宽D和临界指数γ,随x的增加而增加.样品损耗ε″r(复介电常数虚部)随温度T的变化表明低温时弛豫极化损耗起主要作用,高温时漏导损耗起主要作用.同时介电常数实部ε′r随频率的变化显示(1-x)(K0.5Na0.5)NbO3-xSrTiO3弛豫为德拜弛豫.

SrTiO3 doped ceramics of （1-x）（K0.5Na0.5）NbO3-xSrTiO3 （0 ≤ x ≤ 0.15, （ 1 - x ） KNN-xST） were prepared using solid state reaction method and the phase components, crystal structure, and dielectric properties were investigated in this work. It is found that all samples （0≤ x ≤0.15） are single phases with a perovskite structure within the temperature range from 10 to 800 K. The （ 1 - x）KNN-xST compound has the orthorhombic structure when SrTiO3concentration is below 0.1, while it shows cubic structure when x ≥ 0.1. It changes from the normal ferroelectric phase to ferroelectric relaxors when increasing the SrTiO3 impurity below a certain temperature. The critical temperature of （1 - x）KNN-x ST decreases dramatically while the FWHM of D and the critical parameter γ increase with increasing SrTiO3 . The temperature spectrum of permittivity loss ε″, indicates that the loss duc to relaxor polarization plays the key role at low temperatures, however, the loss duc to current leakage is significant in the region of high temperatures.