Refractive Index and Dispersive Energy of NiSO4 Doped Poly (Ethylene Oxide) Films

Refractive index and dispersive energy of NiSO4 doped with Poly (ethylene oxide) (PEO) films have been studied. The films are characterized by using X-ray diffractometry (XRD) at room temperature. The peak observed at 2 = 19.16 o for pure PEO and shifted to 19.43 o for doped films. The XRD results indicate the reducing crystallinity and increasing amorphous nature with NiSO4. The optical absorption and transmittance studies were made in the wavelength range 200-800 nm. The optical transmittance decreases with increasing of NiSO4 doping concentration; it can be explained in terms of a reduction in cross linking. Reflectance is calculated by using absorbance and transmittance data and hence the refractive index has been calculated. The refractive index shows increasing trend with dopant concentration and it can be explained in terms of real and imaginary part. The real part of the refractive index gives the dispersion and the imaginary part of the refractive index, k, gives the absorption of the electromagnetic wave. The dispersion of the refractive index is discussed in terms of the single oscillator model proposed by Wemple and DiDomenico. By using this model, i.e., by plotting (n 2 −1) −1 against E 2 and fitting a straight line, oscillator parameters, Eo—the single oscillator energy and Ed—the dispersion energy, were directly determined. The Eo is the energy of the effective dispersion oscillator is found to be 6.33 eV, 6.23 eV and 5.99 eV for PA05, PA10 and PA15, respectively. The Ed, which measures the average strength of inter band optical transitions is found to be 1.52 eV, 0.48 eV, and 0.16 eV for PA05, PA10 and PA15, respectively. The optical conductivity is found in the range of 2 Scm -1 . The real part of dielectric constant is in the range of 4 and imaginary part of dielectric constant is in the range of 6.0 × 10 -5 for PEO and increases for doped polymer films.