Relaxor characteristics of Pb(Fe2/3W1/3)O3-BiFeO3 solid solution prepared by mechanosynthesis route

The polycrystalline nanosize (similar to 60 nm) of (1-x)Pb(Fe2/3W1/3)O-3-x(BiFeO3) solid solutions with a wide range of concentrations (0 <= x <= 0.20) were fabricated using a mechanical activation followed by a conventional solid-state reaction technique. The formation of single-phase material and better solubility of two phases [i.e., BiFeO3 (BFO) and Pb(Fe2/3W1/3)O-3 (PFW)] were confirmed using an x-ray diffraction technique. Studies of frequency and temperature dependences of dielectric parameters of solid solutions have provided unique relaxor characteristics of PFW on substitution of a critical composition (i.e., 10%) of BFO in it. The loss tangent (tan delta) peaks of PFW are frequency dependent above room temperature. The sharp tan delta peaks of PFW diffuse on increasing BFO content in PFW-BFO solid solution. This exhibits the induction of relaxation properties in the nonrelaxor PFW material. An ac conductivity (sigma(ac)) of solid solutions is very much dependent on the frequency and temperature. The nature of temperature dependent conductivity and values of activation energies suggest that space charge and oxygen ion vacancies play an important role in the conduction mechanism in the material. (c) 2006 American Institute of Physics.