Low frequency internal friction study on the ferroelectric perovskite Na0.5Bi0.5TiO3

Lead-free piezoelectric ceramic Na0.5Bi0.5TiO3 was investigated by the internal friction method. The internal friction of the Na0.5Bi0.5TiO3 ceramic at low frequency (0.5 ∼ 4Hz) was measured in the temperature range from room temperature to 900 K. Three prominent internal friction peaks were observed. The P1 peak is composed of three internal friction peaks. The lower temperature peaks (P1L1 and (P1L2) may be caused by the stress-induced motion of domain walls pinned by the oxygen vacancies and the oxygen ion diffusion in Na0.5Bi0.5TiO3 sample, respectively. The higher temperature peak (P1H) may be related with the phase transition between the ferroelectric and anti-ferroelectric phase. The broader P2 peak shows that the phase transition between rhombohedral and tetragonal phase is a gradually changing process. The asymmetry of the P3 peak includes the two subpeaks (P3L and P3H peak). The two subpeaks are caused by the light Na ions diffusion by vacancies in NBT sample and the phase transition between the...