Ferroelectric-relaxor crossover effects on the nonlinear dielectric properties and switching character in BaZrxTi1-xO3 ceramics

The B-site doping into the BaTiO3 lattice has effect in changing the ferroelectric-paraelectric phase transition and the other structural phase transitions temperatures, but also to induce a gradual disruption of the cooperative dipolar long-range order formed by the off-centre displacement of Ti4+ ions in their TiO6 octahedra. This leads to a broadening of the transition in the Curie range, thus producing a diffuse phase transition. As a result, by the formation of B-site homovalent solid solutions via Zr4+ [1], incorporation in the BT perovskite lattice, one can obtain a composition-induced ferroelectric-relaxor crossover. In the present paper, the specific features related to the ferroelectric-relaxor crossover in BaZrxTi1- xO3 ceramics when increasing x and in particular the high-field properties, e.g. tunability and P(E) loops are reported. BaZrxTi1-xO3 ceramics with x=0.05, 0.10, 0.15, 0.20 and 0.40 and high densities (above 95%) have been prepared by solid state reaction. A complex dielectric non-linear behavior was found, with multiple polarisation components with various weights which are responsible for the dielectric and ferroelectric properties. Such behavior is discussed in terms of the existence of mixture of phases at room temperature for particular compositions (x=0.05, 0.10 and 0.15) and by considering the ferroelectric-relaxor crossover as result of the increasing Zr addition.