Phase transitions, piezoelectric and pyroelectric properties of KTa_1−xNb_xO₃ ceramics (x = 0.3 and 0.4)

Abstract

The successive phase transitions of KTa_1−xNb_xO₃ (x = 0.3 and 0.4) (KTN) ceramics have been investigated by various techniques including DTA, dielectric, piezoelectric and pyroelectric measurements from 100 to 450 K. In this temperature range, all the phase transactions have been detected by pyroelectric measurements. All the phase transitions in KTa_0.6Nb_0.4O₃ were detected by piezoelectric measurements as a function of temprature. The d₃₁ piezoelectric coefficient presents around T_c a maximum value (of 20·10⁻¹²C/N). The DTA, dielectric and pyroelectric measurements allow to deduce that the ferroelectric-paraelectric phase transition is probably of first order for KTa_0.6Nb_0.4O₃

Key Words:

• Ceramic
• pyroelectric
• piezoelectric