Electrical and Piezoelectric Studies of (Na_1-xK_x)_1/2Bi_1/2TiO₃

Abstract

Lead-free ceramic samples of [(Na_1-xK_x)_1/2Bi_1/2Ti O₃] (NKBT) (x = 0.1, 0.15, 0.2, 0.3, 0.45) were prepared by double sintering method and the impedance measurements were carried out in the frequency range of 100 Hz–1 MHz. The Cole–Cole plot show depressed semicircular arcs with spur-like behavior indicate that the temperature dependent dielectric relaxation phenomenon associated with grain boundary conductivity. The temperature variation of grain and grain boundary resistance is found to be linear and obeys Arrhenius law. AC–activation energies, evaluated from the variation of ac-conductivity with inverse temperature plots, were found to decrease with decreasing frequencies and obey the Universal power law. The ferroelectric hysteresis measurements were carried out on poled sample at room temperature and the sample with x = 0.15 composition exhibited the highest P_r value (= 19.2μC/Cm²). The d₃₃ measurements indicate that the sample with x = 0.2 composition has shown the maximum d₃₃ = 85pC/N, when compared with other compositions.

Keywords:

• Ferroelectric
• impedance
• conductivity
• piezoelectric coefficient

Acknowledgment

We acknowledge the helpful discussions of Prof. S.V. Suryanarayana. One of the authors (PVB) acknowledge Principal & management, CVR College of Engg, for encouragement and support.