Influence of electric fields on the depolarization temperature of Mn-doped (1-x)Bi1/2Na1/2TiO3-xBaTiO3

The transition between induced long-range order and relaxor-like behavior upon heating is investigated in lead-free (1-x)Bi1/2Na1/2(Ti0.995Mn0.005)O-3-xBa(Ti0.995Mn0.005)O-3 piezoceramics with x = 0.03, 0.06, and 0.09 (BNT-100xBT:Mn). Temperature-dependent permittivity epsilon'(T) and thermally stimulated depolarization currents (TSDC) of poled samples were measured under identical heating conditions to clarify the depolarization mechanism. In both methods, the influence of electric bias fields on the transition temperature was investigated. Fields applied in the poling direction shift the transition to higher temperatures, with corresponding results in epsilon'(T) and TSDC measurements. While the response of transition temperature to external fields displays a similar trend in all investigated compositions, the shape of TSDC is clearly connected with the composition and, hence, the crystal symmetry of the sample. Furthermore, the comparison of epsilon'(T) and TSDC data reveals a systematic shift between transition temperatures obtained with the two different methods. (C) 2012 American Institute of Physics. [doi:10.1063/1.3674275]