Structural, optical, and electrical properties of Mn0.9La0.1Fe2O4 nanocrystalline ferrites and its synthesis through sol-gel method

This work reports the formation of La-doped nano-crystalline manganese ferrite Mn0.9La0.1Fe2O4 through sol–gel route and examined using XRD and dielectric spectroscopy techniques. The single-phased cubic spinel structure of the ferrite is supported by X-ray diffraction (XRD). The mean crystallite dimension appraised from XRD data has been found to be 21 nm and 11 nm for un-doped and La3+ doped MnFe2O4, respectively, along with a significant rebate in the optical band gap. At room temperature, the frequency-dependent dielectric properties were studied in the frequency range (42 Hz − 5 MHz). The dielectric constant of both the samples narrowly lowers with enhancing frequency and, consequently, shows exemplary dielectric dispersion. The AC-conductivity of the un-doped samples enhances with increasing frequency while it decreases with doping. The dispersion in ac-conductivity (σac) and dielectric properties imply the ordinary dispersion of Maxwell-Wagner type due to the process of hopping of electrons between the Fe2+ and Fe3+ ions and interfacial polarization. The band gap of energy is evaluated with the help of the UV–visible spectra and found to be decreased when La3+ doped with MnFe2O4 ferrite.