Ferroelectric properties and dynamic scaling of < 100 > oriented (K0.5Na0.5)NbO3 single crystals

Abstract

In this letter, we report the dielectric and ferroelectric (FE) characteristics of potassium sodium niobate (K0.5Na0.5NbO3) single crystals grown by flux method. Orientation analysis of as-grown cubical-shaped crystals was conducted by electron backscattered diffraction technique revealing the < 100 > crystallographic orientation of two opposing major faces. Annealed crystals were found to exhibit FE orthorhombic to FE tetragonal transition temperature of 200 degrees C and Curie temperature of 407 degrees C. Poled < 100 > oriented crystals had longitudinal piezoelectric constant of 148 pC/N. Dielectric measurement as a function of temperature was conducted to determine the second order parameter in Gibbs free energy expansion. Dynamic hysteresis analysis on these crystals showed the power law relations to be of the form < A > proportional to f(0.47Eo-0.85)E(o)(1.45f0.14) and < A > proportional to f(0.04)E(o) below and above the coercive field. (C) 2011 American Institute of Physics. [doi:10.1063/1.3600058]