Temperature dependence of unipolar fatigue behavior of lead-free alkali niobate ceramics

抄録

The unipolar fatigue behavior of undoped Li_0.06Na_0.52K_0.42NbO₃ (LNKN6-a) and the same compound with additives (LNKN6-b) were observed. Unipolar cycling was performed between room temperature and 150°C under a high unipolar electric field of 4 kV/mm. LNKN6-a fatigued under crack formation throughout the examined temperature range. The switchable polarization 2P_r of LNKN6-a decreased for 20% (=2 µC/cm²) at 150°C. In contrast, mechanical degradation was not observed in LNKN6-b. The switchable polarization 2P_r of LNKN6-b decreased for 15% (=3.2 µC/cm²) at 150°C. It should be noted that at 50°C, fatigue-free behavior was observed for LNKN6-b over at least 10⁶ cycles. The influence of phase transition on this fatigue-free behavior was discussed.