Relaxorlike dielectric properties and history-dependent effects in the lead-free K0.5Na0.5NbO3–SrTiO3 ceramic system

Abstract

Typical relaxorlike dielectric properties, such as broad dispersive dielectric maximum, Vogel–Fulcher temperature dependence of the characteristic relaxation frequency, and paraelectric-to-glass crossover in the temperature dependence of the dielectric nonlinearity, have been detected in the derived lead-free K0.5Na0.5NbO3–SrTiO3 ceramic system. Relatively large values of the dielectric constant, being almost independent of the frequency in the range of 100Hz–1MHz, suggest possible applications based on this environmentally friendly system. Furthermore, the history-dependent effects, such as aging of the dielectric constant and fatigue of the polarization switching, are much weaker than in some widely used lead-based relaxors.