Phase diagram and phase transitions in the relaxor ferroelectric Pb(Fe2/3W1/3)O-3-PbTiO3 system

摘要

A complete solid solution between relaxor ferroelectric Pb(Fe2/3W1/3)O-3 (PFW) and ferroelectric PbTiO3 (PT), (1-x)PFW-xPT, was synthesized by a B-site precursor method and characterized by X-ray diffraction, differential scanning calorimetry, and dielectric measurements. A phase diagram between PFW and PT has been established. The diffuse phase transition temperature (T-max approximate to 180 K) of PFW was found to continuously increase with the increasing amount of Ti4+ ions on the B-site. At the same time, the relaxor ferroelectric behavior of PFW is gradually transformed toward a normal ferroelectric state, as evidenced by sharp and nondispersive peaks of dielectric permittivity around T-C for x greater than or equal to 0.25. At room temperature, a transition from a cubic to a tetragonal phase takes place with x increased up to 0.25. A morphotropic phase boundary is located within the composition interval 0.25 less than or equal to x less than or equal to 0.35, which separates a pseudocubic (rhombohedral) phase from a tetragonal phase. (C) 2002 Elsevier Science. [References: 27]