Structural Stability And Depolarization Of Manganese-Doped (Bi0.5na0.5)(1-X)Baxtio3 Relaxor Ferroelectrics

This work reveals that 0.5 mol. % manganese (Mn) doping in (Bi0.5Na0.5)(1-x)BaxTiO3 (x = 0 and 0.075) solid solutions can increase structural thermal stability, depolarization temperature (T-d), piezoelectric coefficient (d(33)), and electromechanical coupling factor (k(t)). High-resolution X-ray diffraction and transmission electron microscopy reveal coexistence of rhombohedral (R) R3c and tetragonal (T) P4bm phases in (Bi0.5Na0.5)(0.925)Ba0.075TiO3 (BN7.5BT) and 0.5 mol. % Mn-doped BN7.5BT (BN7.5BT-0.5Mn). (Bi0.5Na0.5)TiO3 (BNT) and BN7.5BT show an R - R + T phase transition, which does not occur in 0.5 mol. % Mn-doped BNT (BNT-0.5Mn) and BN7.5BT-0.5Mn. Dielectric permittivity (epsilon') follows the Curie-Weiss equation, epsilon' = C/(T - T-o), above the Burns temperature (T-B), below which polar nanoregions begin to develop. The direct piezoelectric coefficient (d(33)) and electromechanical coupling factor (k(t)) of BN7.5BT-0.5Mn reach 190 pC/N and 47%. (C) 2014 AIP Publishing LLC.