Structural stability and depolarization of manganese-doped (Bi 0.5 Na 0.5 ) 1-x Ba x TiO 3 relaxor ferroelectrics

Abstract

This work reveals that 0.5 mol. % manganese (Mn) doping in (Bi0.5Na0.5)1−xBaxTiO3 (x = 0 and 0.075) solid solutions can increase structural thermal stability, depolarization temperature (Td), piezoelectric coefficient (d33), and electromechanical coupling factor (kt). High-resolution X-ray diffraction and transmission electron microscopy reveal coexistence of rhombohedral (R) R3c and tetragonal (T) P4bm phases in (Bi0.5Na0.5)0.925Ba0.075TiO3 (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 (ε′) follows the Curie-Weiss equation, ε′ = C/(T − To), above the Burns temperature (TB), below which polar nanoregions begin to develop. The direct piezoelectric coefficient (d33) and electromechanical coupling factor (kt) of BN7.5BT-0.5Mn reach 190 pC/N and 47%.

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Citation

S.-F. Wang, C.-S. Tu, T.-L. Chang, P.-Y. Chen, C.-S. Chen, V.H. Schmidt, and J. Anthoniappen, “Structural stability and depolarization of manganese-doped (Bi 0.5 Na 0.5 ) 1-x Ba x TiO 3 relaxor ferroelectrics, Journal of Applied Physics 116, 154101 (2014). doi: 10.1063/1.4898322.
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