Dielectric properties of tungsten oxide thin film prepared by spray pyrolysis

Polycrystalline tungsten oxide thin films were prepared using spray pyrolys is technique. The film thickness was calculated from the interference maxim a and minima. The effect of temperature (300 to 440 K) and frequency (50 Hz to 100 kHz) on the dielectric constant and loss factor tan delta of these films was studied and the results were discussed suggesting that space char ge polarization is predominant. The maximum of the peaks for M" and Z" whic h occured at the same frequency is associated with a bulk-dispersed phase. The impedance Z" against the logarithm of frequency shifts towards the high er frequency side and the activation energy associated with such process is 0.301 eV. The calculated values of the activation energy (Delta H) and the entropy (Delta S) for dipole rotation are 25.2 kJ/mol and 92.3 J/mol K.