Electrical Conductivity and Electronic Absorption Spectra of CaTiO3Doped with Ga2O3

Abstract

The temperature dependence of the electrical conductivity of pure CaTiO₃ and that containing Ga₂O₃ dopant with different concentration was investigated between 291 and 773°C. The conductivity in this temperature range varied widely with the percentage change in the concentration of dopant. In the lower temperature range, no variation of conductivity was observed. This was interpreted as impurity controlled conduction. In the higher temperature range, all doped investigated samples, as wen as pure CaTiO₃ exhibited nearly the same shape and the same value of activation energy. This behaviour was attributed to ionization energy present and/or change from cubic to orthorhombic modification. The optical absorption spectra indicate two absorption maxima (ΔE₁ and ΔE₂). The values of  ΔE₁ depend on the lattice defects present; ΔE₂ represents the gap width of CaTiO₃. It was observed that change of  Δe₂ due to additives is very slight; these changes may be attributed to the variation in the volume of unit cell of the doped samples.