Preparation and characterization of perovskite Cu doped LaFeO₃semiconductor ceramics

Abstract

Orthorhombic structured polycrystalline Cu doped LaFeO3 perovskite ceramics were prepared by sol-gel route and characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopic (FT-IR) techniques. The complex dielectric properties for these ceramic samples investigated as function of temperature, in the range 80K – 300K, and frequency, in the range 20 Hz -1MHz. These samples exhibiting colossal dielectric constant value of 104 near room temperature at low frequencies. The response is similar to that observed for relaxor ferroelectrics. Impedance spectroscopy (IS) data analysis indicates the ceramics to be electrically heterogeneous semiconductors consisting of semiconducting grains with dielectric constant below 100. We conclude, therefore that grain boundary effects is the primary source for the high effective dielectric constant in Cu doped LaFeO3 ceramics.