Influence of Ni Doping on the Optical Properties of BiFeO3 Multiferroic

The Ni doped BiFeO3 (BFO) samples with composition BiFe1-xNixO3 (0 <= x <= 0.07) were prepared through sol gel method. In order to investigate the influence of Ni on optical properties of BFO, we have evaluated the various optical parameters. The UV-visible diffuse reflectance spectra exhibit the strong absorption in the visible region. The Kubelka-Munk (K-M) function is used to evaluate the Urbach energy (EU). The value of EU is found to decrease for the doped samples. The refractive index has been determined from the reflectance data and found to increase with the increase in wavelength of incident photons and Ni concentration in BFO. Its values remain constant in the wavelength range from 250-450 nm for all the samples. Further, skin depth, extinction coefficient, steepness parameter and optical conductivity have been evaluated. The values of skin depth (delta) was found to decrease with increase in the energy of incident radiation for all the samples. However, the optical conductivity decreases as wavelength of the incident radiation increases.