Effect of Fe₃O₄ addition on dielectric properties of LaFeO₃ nano-crystalline materials synthesized by sol-gel method

Dielectric properties of nano-crystalline material LaFeO₃.xFe₃O₄ with x = 0, 0.1, 0.2, 0.3, and 0.4 at.% have been studied by impedance spectroscopy method. LaFeO₃ was synthesized by sol-gel method resulting nano-particle. Then, it was mixed with Fe₃O₄ powder. The mixture powder was pressed to form pellet and then sintered at 1300°C for 1 h to form nano-crystalline of LaFeO₃.xFe₃O₄. X-ray diffraction characterization at room temperature for all samples show two phases i.e. perovskite LaFeO₃ (orthorhombic) as a main phase and Fe₃O₄ (cubic) as second phase. It is found that the crystallite size of main phase increases with addition of Fe₃O₄ until 0.3 at.%. The electrical properties as a function of temperature (300-500 K) and frequency (100 Hz - 1 MHz) are presented in Nyquist and Bode plots. It is observed that from equivalent circuit and their parameters, dielectrical properties are contributed by grain and grain boundary. The dielectric constant, ε′ were calculated by parallel plate method and their values reach up to 10⁷ exhibiting typical colossal dielectric constant (CDC) material like behavior. (paper)