Impedance spectroscopy analysis of the diffuse phase transition in lead-free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic elaborated by sol-gel method

We investigate the lead free ferroelectric perovskite ceramic, (Ba0.85Ca0.15)(Zr0.1Ti0.9)O-3 (BCZT), prepared by sol-gel method. The as-synthesized precursor powder is calcined at 1000 degrees C for 4 h in order to obtain single-phase perovskite structure. X-ray diffraction (XRD) analysis at room temperature shows the formation of single-phase compound with a tetragonal structure refined in P4mm space group. The dielectric measurements in a frequency range of [100 Hz-1 MHz] and in a temperature range [35-400 degrees C] in the ceramic sintered at 1350 degrees C for 2 h, reveal a high maximum dielectric constant similar to 5200 (100 Hz) at 107 degrees C, which is associated with ferroelectric paraelectric phase transition. The sol-gel method has displayed a very important advantages comparing to the conventional solid-state method. Special emphasis was done to characterize diffuse phase transition (DPT) that occurs close to similar to 107 degrees C. We have shown that the real part of the permittivity close to DPT is well described by Santos-Eiras phenomenological model. Impedance spectroscopy analysis over the frequency range of 100 Hz to 1 MHz illustrated mainly bulk contribution up to 300 degrees C while grain and grain-boundary effects were present above 300 degrees C using the impedance spectroscopy technique. (C) 2018 Elsevier Ltd. All rights reserved.