Large piezoelectric effect of (Ba, Ca)TiO3–xBa(Sn, Ti)O3 lead-free ceramics. Issue 4 (March 2016) - Zhu, Li-Feng
Abstract: (Ba0.9 Ca0.1 )TiO3 – x Ba(Sn0.2 Ti0.8 )O3 ceramics (abbreviated as BCT- x BST) were obtained and the relationships among phase structure, energy barrier and piezoelectric properties were studied. Their phase structures are tetragonal ( T )–orthorhombic ( O ) coexistence at 0.20 ≤ x ≤ 0.40, rhombohedral ( R )– O – T multiphase coexistence at x = 0.45 and R phase or R -cubic ( C ) two-phase coexistence at 0.50 ≤ x ≤ 0.60, respectively. The energy barrier of polarization rotations and extension for R–O and O–T two-phase coexistence as well as R–O – T multiphase one was analyzed by the conservation law of energy and Landau–Devonshire theory. Because of extremely low energy barrier for polarization rotation and extension, high piezoelectric coefficients d 33 = 630 pC/N, k p = 0.52 and the lower E C = 0.81 kV/cm were achieved at x = 0.45 which has R–O–T multiphase coexistence. These results confirm that the low energy barrier for polarization rotation and extension at R – O – T multiphase coexistence composition is beneficial to enhance the d 33 value. The high piezoelectric property also indicates that BCT– x BST ceramics are a promising candidate for lead-free piezoelectric ceramics.