Abstract
SbNbO
4
ferroelectric thin films were formed by using d.c. magnetron sputtering. The orthorhombic SbNbO
4
ferroelectric phase was formed at about 600°C under relatively low pressure of about 1.2mTorr. The optical reflection (R) and transmission (T) spectra in the wavelength range 190-800 nm of the films deposited on sapphire substrates were measured and hence the absorption coefficient (α) was estimated. The allowed indirect transitions were found to be responsible for interband transitions of SbNbO
4
films. The absorption coefficient α was calculated as a function of γ-dose and as a function of heat treatment at 500°C and 700°C. The values of optical energy gap E
g
and optical moment E
p
for the electronic interband transition of irradiated and annealed SbNbO
4
films were deduced. A number of bands show a continuous shift in position and an increase in intensity with increasing γ-dose and annealing temperature.