Frequency and temperature dependence dielectric behavior of barium zirconate titanate nanocrystalline powder obtained by mechanochemical synthesis

Nanocrystalline barium zirconium titanate ceramic has been synthesized by high-energy ball milling. This nano-ceramic is characterized by X-ray diffraction, scanning electron microscopy, dielectric study and impedance spectroscopy. The X-ray diffraction pattern shows single phase ceramic of tertragonal symmetry with space group P4 mm. Temperature and frequency dependent dielectric study of the sample shows a normal ferroelectric phase transition behavior. Impedance spectroscopy analyses reveal a non-Debye type relaxation phenomenon. A significant shift in impedance loss peaks toward higher frequency side indicates conduction in material and favoring the long range motion of mobile charge carriers. Grain and grain boundary conduction is observed from complex impedance spectrum by the appearance of two semicircular arcs in the Nyquist plot. The frequency dependent ac conductivity at different temperatures indicates that the conduction process is thermally activated. The variation of dc conductivity exhibited a negative temperature coefficient of resistance behavior.