La掺杂对0.75PMN-0.25PT压电陶瓷结构及其性能的影响

Effects of La-doping on the Structure and Electrical Properties of 0.75PMN-0.25PT Piezoelectric Ceramics

采用铌铁矿预产物合成法制备La掺杂Pb(1-x)Lax(Mg1/3Nb2/3)0.75Ti0.25O3(0.75PMN-0.25PT-xLa,x=0、0.01、0.015、0.02)铁电陶瓷,并研究了不同含量La掺杂对PMN—PT的微观结构及其性能的影响。结果表明,所有陶瓷样品均为纯钙钛矿结构,没有其他任何杂相,而且随La含量的增加,材料相结构逐渐由三方相向四方相转变。当La掺杂量为0.015时,0.75PMN-0.25PT-xLa陶瓷出现三方和四方相共存现象,即出现了准同型相界(MPB),使得0.75PMN-0.25PT-xLa陶瓷的电学性能得到了较大的提高,压电常数d33～360 pC/N,介电常数εr～6000。La掺杂量达到0.02时,材料的相结构已全部转化为四方相,提高了晶体的对称性,为制备La掺杂0.75PMN-0.25PT电光透明陶瓷提供了依据。

Pb（1-x） La x（Mg1/3Nb2/3） 0.75Ti0.25 O3（0.75PMN-0.25PT-xLa,x = 0,0.01,0.015,0.02） ferroelectric ceramics were prepared by the columbite precursor method,and research the effects of different content of La doped on Microstructures and properties of PMN-PT.The results showed that pure perovskite phase is obtained for all the specimens and no other phase is detected;La-doping induced a perovskite structure transition from tetragonal phase to rhombohedra phase.A morphotropic phase boundary（MPB） between tetragonal and rhombohedra phases appears at x = 0.015,which could greatly improve the electrical properties of the ceramics（piezoelectric constant d 33 ～ 360 pC/N,dielectric constant ε r ～ 6000）.La doping amount reaches 0.02,the composites basically have all been converted to tetragonal phase,greatly improving the symmetry of the crystal and the materials electro-optic properties,for preparation of La-doped 0.75PMN-0.25PT transparent electro-optic ceramics provided a basis.