Depolarization temperature shift of Li0.08Na0.92NbO3 lead-free piezoelectric ceramics by high-ellectric-field poling

The increase in depolarization temperature induced by the poling of (LixNa1-x)NbO3 ceramics having an Li concentration of x = 0.08 (LNN8) was studied. Initially, the Curie temperature TC was measured to be approximately 300 degrees C, and it increased after the application of poling at the high elctric fields; this increase in Curie temperature depended on the poling conditions emplyed. When poling was performed at 120C at an electric field of 5 kV/mm for 5 min. there was no change in TC and the depolarization temperature was slightly lower then TC . however, both these temperatures increased up on poling at a higher electric field. The X-ray diffraction patterns obtained suggested that the domain volumes of the ceramics were altered by poling at a high electric field and that this structural change caused a change in depolarization temperature.