Large Electromechanical Coupling Factors in Perovskite Binary Material System

Abstract

Similarities of large electromechanical coupling factors ( k s ) in perovskite binary material systems were studied. Five large- k s material systems, PZT 53/47, PZNT 91/9, PMNT 67/33, PSTT 55/45 and PSNT 57/43, were compared. These five large-ks material systems were found to show four similarities: rhombohedral and tetragonal morphotropic phase boundary (MPB), large polarization ( P r >25 µ C/cm 2 ), proper B1 ionic size (70–72 pm) and large B2 ion (64 pm) in Pb(B1, B2)O 3 relaxors and proper B-site average ionic sizes of MPB composition (64.7–66.8 pm). For example, in this study, the maximum coupling factors ( k p =72 %, k 31 =45 %, and k 33 =77 %) were obtained in Pb[(Sc 1/2 Nb 1/2 ) 0.57 Ti 0.43 ]O 3 +0.005Nb 2 O 5 (PSNTN 57/43) piezoelectric ceramic materials.