Dielectric and A.C Conductivity Behaviour of Flux Grown Nickel Titanate (NiTiO3) Crystal

The present paper deals with systematic study of dielectric characteristics and a. c conductivity of single crystal of NiTiO3 above room temperature. These crystals were prepared by high temperature flux technique. Dielectric constant, tangent loss and conductivity studied on these crystals strongly dependent on temperature and frequency of the applied a. c field, the variation depending on range of temperature and frequency. The appearance of pronounced peak at 773 degrees K in the curve of dielectric constant, loss tangent and conductivity versus temperature indicates ferroelectric phase transition. The increase of conductivity with increase of temperature suggests semiconductor behaviour of this material. The ln sigma(a.c) versus temperature plot indicates conduction mechanism to be hopping model. The temperature variation of conductivity confirms to Arrhenius law sigma = sigma(0)exp. [-E-a/RT], where E is activation energy per mole required for hopping process and sigma(0) is free space permittivity. The magnitude of activation energy is found to be greater than 0.2 eV per molecule for this crystal which suggest that conduction mechanism is due to hopping.