Influence of oxygen deficiency on optical and dielectric properties of La0.75Ba0.10Sr0.15FeO2.875-δ compounds

Abstract

Using the conventional sol-gel process, the series of non-stoichiometric oxygen lanthanum ferrites with the formula 𝐿𝑎0.75𝐵𝑎0.10𝑆𝑟0.15𝐹𝑒𝑂2.875 ― 𝛿(δ=0.00, 0.125 and 0.25) were prepared. X-ray diffraction analysis confirmed the formation of the orthorhombic structure with Pnma space group. In the present work, we confirm the potential of 𝐿𝑎0.75𝐵𝑎0.10𝑆𝑟0.15𝐹𝑒 𝑂2.875 ― 𝛿(δ=0.00, 0.125 and 0.25) as an efficient dielectric material. All samples show high absorbance in the visible region with wavelength above 300 nm. The optical band gaps are found to increase from 3.25 to 4.1 with increasing oxygen vacancy concentration. The dielectric constant, dielectric loss and loss factor were carried out as a function of oxygen vacancy concentration and frequency (102 -106 Hz) at room temperature. The variation of dielectric constant with frequency indicates dispersive behavior and giant dielectric response (more than 104 ) at low frequencies for compounds deficient in oxygen. Such value of makes 𝜀′ these samples an interesting material to be used in applications namely the reduction of electronic components size. To summarize, incorporating vacancy oxygen enhances the dielectric properties. Thus, the interesting dielectric constant and weak loss strengthen the use for potential applications.