Magnetic and optical properties of La-doped BiFeO3 films prepared by sol–gel route

Abstract

La-doped BiFeO3 films were prepared on quartz substrates by sol–gel method. X-ray diffraction results showed that La doping can refrain from the forming of the impurity phase in the films. Magnetic measurement at room temperature indicated that the magnetization of the samples have been enhanced by the addition of La dopants. The optical constants and optical band gaps of the films were extracted from the transmittance spectra at the same time. At the wavelength of 650 nm, the refractive indices and extinction coefficients of the films decrease and increase with increasing La content, respectively. The optical band gaps of the samples decrease from 2.52 to 2.42 eV, and the electro-optical parameters E0/S0 of the samples increase from 9.40 × 10−14 to 2.71 × 10−13 eV m2 with the addition of La dopants. The optical electronegativity parameters ∆χ* decrease gradually from 0.68 to 0.65 with increasing the La composition, indicating La doping slightly affecting BFO ionic in nature.