The effect of doping by methyl red and methyl blue on the absorption spectra and the optical energy gap of poly (methyl methacrylat) PMMA film have been studied. The optical transmission (T%) in the wavelength range 190-900 nm for films deposited by using solvent casting method were measured. The Absorptance data reveals that the doping affected the absorption edge as a red and blue shift in its values. The films show indirect allowed interband transitions that influenced by the doping. Optical constants; refractive index, extinction coefficient and real and imaginary part of dielectric constant were calculated and correlated with doping.

Effective field approach with two sub- latticemodel  have been used  in mixed ferroelectric systems . The non-linear relationship observed experimentally between the Curie temperature and the composition rate is attributed to the coupling between the two sub- lattices. The theoretical expression is fitted with experimental data of (TGS/DTGS).