Preparation and analysis of single-phase Pb(Mn1/2Nb1/2)O3

Single-phase polycrystalline ceramic sample of Pb(Mn1/2Nb1/2)O3 has been prepared through a standard solid-state reaction method. A preliminary structural analysis indicates tetragonal crystal structure. The surface morphology examined through scanning electron microscope (SEM) confirmed single-phase polycrystalline texture of the material in close agreement with the X-ray diffraction (XRD) observation. Electrical properties of the material, investigated using complex impedance spectroscopy (CIS) technique have revealed the presence of both the bulk (grain) and grain-boundary contribution to the overall electrical response. It has been modeled, according to the bricklayer model, as a cascading of parallel combination of the resistive and capacitive elements. Impedance spectrum clearly provides evidence of temperature dependent electrical relaxation in the material occurring at a unique frequency for each temperature. The bulk resistance (Rb) and grain-boundary resistance (Rgb) show strong temperature dependence and conductivity (σdc) variation obeys Arrhenius behaviour. The conductivity spectrum has been observed to follow the Jonscher's universal power law feature: σ(ω) = σdc + Aωn.