Tuning in optical, magnetic and Curie temperature behaviour of nickel ferrite by substitution of monovalent K+1 ion of Ni0·8K0·2Fe2O4 nanomaterials for multifunctional applications

Abstract

The synthesis of nickel potasium ferrite (Ni0·8K0·2Fe2O4) nanoparticles with the doping of Monovalent K1+ ions has been synthesized by sol-gel auto combustion method. Differential Thermal Analysis (DTA) was performed to analyze the phase formation of the prepared sample. The crystal phase formation has been confirmed by employing the XRD (X-ray diffraction) technique. The crystallite size and Strain were calculated by using the W–H (Williamson-Hall) plot. The crystallite of nanoparticles of K1+ doped nickel ferrite is ~30 nm. The FTIR spectra were recorded in the range of 560–590 cm−1 to analyze the changes in nickel ferrite due to K1+ ion manipulation. The optical property was studied in the field of 200 nm–1000 nm using UV visible spectrometer, and the results show that band gap was improved as in the case for nickel ferrite and the observed value was 2.20 eV, which was furthered decreased to 1.91 eV. The strong photoluminescence was observed in the visible range, and substitutions of monovalent potassium ion are improving its luminescence property. Its intensity peaks get shifted towards orange range 610 nm (2.03 eV). This shows that the monovalent ion may creates defects, leading to porosity and oxygen vacancy in the nanomaterial. The porous structure was confirmed by scanning electron microscope. The magnetic hysteresis loop has been recorded by employing the VSM (Vibrating Sample Magnetometer). The saturation magnetization and Curie temperature were found to increase with the substitution of monovalent potassium. Thus prepared material is soft magnetic nature, possess strong luminescence in the visible range, and high Curie temperature (798 K). Hence the present materials may be used as functional nanomaterials for various technological applications.