材料期刊网

通过设计组分制备出综合性能优异的铁电陶瓷（1-x）PZT-x（0.2PFN-0.2PZN-0.6PNN）（x取0.1、0.2、0.3、0.4和0.5）,确定其准同型相界,并研究了铁电畴结构与材料宏观性能的关系。XRD结果表明,随着A（B′B″）O3型弛豫铁电成分含量的增加材料由四方相向三方相转变;透射电镜结果显示,样品的铁电畴由较大的鲱鱼骨状畴逐渐变为弥散的畴结构形态,畴结构的变化对材料的性能产生很大影响。介电温谱表明,随x增大居里温度逐渐降低,x≥0.3时材料表现出弛豫铁电体的性质,x=0.3时室温介电常数达到最大值3050。x=0.2时材料表现出优良的介电、压电和铁电性能,压电系数取最大值485pC/N,剩余极化强度达最大值37μC/cm2,居里温度对应的介电常数达最大值22000。综上所述,该体系材料的准同型相界位于0.2～0.3。

A series of ferroelectric ceramics with variable compositions of（1-x）PZT-x（0.2PFN-0.2PZN-0.6PNN）（x=0.1,0.2,0.3,0.4 and 0.5） were prepared by the precursor method.The proveskite structure and ferroelectric domains were studied by X-ray diffraction（XRD） and transmission electron microscopy（TEM）,respectively.The morphotropic phase boundary was determined and the relations among electric property,composition and microstructure were briefly discussed.It was found from XRD data that with an increase of x value the crystal structures transformed from tetragonal to rhombohedral phase.The transformations from herringbone-like domain patterns with parallel stripes to small relaxor ferroelectric domains,observed by TEM,significantly influenced the electric properties.The Curie temperature decreased apparently with the increase of x values according to the temperature-dependent relative permittivity measurements.The typical feature of relaxor ferroelectrics was observed at x≥0.3 with the maximum dielectric constants of 3050 at x=0.3.At x=0.2 the ceramics exhibited excellent dielectric,piezoelectric and ferroelectric properties： the maximal piezoelectric coefficient reached 485pC/N with the maximal remnant polarization being 37μC/cm2.The maximal relative dielectric constant of 22000 was achieved at Curie temperature.The morphotropic phase boundary was determined to be 0.2x0.3 based on the experiment.