Phase Diagram and Properties of High T_C/T_(R-T) Pb(In_(1/2)Nb(1/2)) O_3-Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 Ferroelectric Ceramics

摘要

A ternary ferroelectric ceramic system, (1-x-y)Pb(In_(1/2)Nb_(1/2) O_3-xPb(Zn_(1/3)Nb_(2/3)O_3-yPbTiO_3 (PIN-PZN-PT, x = 0.21, 0.27, 0.36, 0.42), was prepared using a two-step precursor method. The phase structure, dielectric, piezoelectric, and ferroelectric properties of the ternary ceramics were systematically investigated. A morphotropic phase boundary (MPB) was identified by X-ray diffraction. The optimum piezoelectric and electromechanical properties were achieved for a composition close to MPB (0.5PIN-0.21PZN-0.29PT), where the piezoelectric coefficient d_(33), planar electromechanical coupling factor k_p, and remnant polarization P_r are 660 pC/N,72%, and 45 μC/ cm~2, respectively. The Curie temperature T_c and rhombohedral to tetragonal phase transition temperature 7_(r-T) were also derived by temperature dependence of dielectric measurements. The strongly "bended" MPB in the PIN-PT system was found to be "flattened" after addition of PZN in the PIN-PT-PZN system. The results demonstrate a possibility of growing ferroelectric single crystals with high electromechanical properties and expanded range of application temperature.