Morphotropic phase diagram and dielectric and ferroelectric properties of (1-x)Ba(Zn_1/3Nb_2/3)O₃-xPbTiO₃ solid solution

A new solid solution of (1-x) Ba (Zn13 Nb23) O3 -x PbTiO3 [(1-x) BZN-xPT] has been synthesized in the form of ceramics by solid state reactions and characterized by means of x-ray diffraction, dielectric spectroscopy, and ferroelectric measurements. A partial solid state phase diagram of the binary system is established. It exhibits a morphotropic phase boundary region in the composition range between x=0.58 and 0.61. The dielectric permittivity of BZN has been greatly enhanced by the substitution of PT. The ceramics with compositions x=0.5-0.58 show typical relaxor ferroelectric behavior with the diffuse maximum of high permittivity shifting to higher temperature with increasing frequencies. With further increase of the PT content, the permittivity peaks become frequency-independent, indicating a normal ferroelectric phase transition, the temperature of which (TC) increases with x. Thus a composition-induced transformation from a simple dielectric to relaxor and to ferroelectric phase has been realized in this solid solution system.