Dielectric Properties and Conductivity of Iron Oxide-Barium Titanate Composites

Abstract

Sintered composites of iron oxide plus barium titanate in form of core-shell structures are investigated by impedance spectroscopy. The measurements were performed in the frequency and temperature ranges 20 Hz to 1 MHz and 150 K to 510 K, respectively. The composites exhibit strong low-frequency dispersion of electrical modulus and dielectric permittivity which is caused by different mechanisms of electron transfer at low and high temperatures. A hopping transport process with activation energy of 0.22 eV for exchange between Fe²⁺ and Fe³⁺ was tentatively assigned to reign below room temperature. It gradually changes to a conducting mechanism with activation energy of 0.45 eV above 345 K.

Keywords:

• Composite
• Fe₃O₄-BaTiO₃
• dielectric permittivity
• electrical modulus