A first-principles study on the structural, electronic, magnetic and optical properties of lithium zinc ferrite Li1−xZn2xFe5−xO8

Abstract

Lithium–zinc (Li–Zn) ferrites are of great importance in numerous applications, but no detailed theoretical study has yet been reported. In this work, we investigated the structural, electronic, magnetic and optical properties of Li–Zn ferrites Li_1−xZn_2xFe_5−xO₈ (LZFO, x = 0, 0.25, 0.5, 0.75, and 1) by using first-principles calculations. We determined the optimized crystalline structures and spin configurations for all the treated compositions among various spin configurations by calculating the formation energy and drawing a convex hull plot. Using the DFT+U approach, we calculated the lattice constants, total magnetization and band gaps for spin up and down states of the compounds, found variation tendencies as a function of Zn content x, and compared with the available experimental values. Moreover, our calculations revealed that with the increase of Zn content, the static dielectric constant and its maximum value gradually decreased from 5.89 and 10.27 to 5.34 and 8.06, the light absorption coefficient, reflectivity and refractive index were reduced in the photon energy range of 0 to 8 eV, and the intensity and position of the electron energy loss peak were systematically lowered from 16.8 to 4.7 and red-shifted from 21.2 to 18.3 eV. Highlighting their potential application in optical devices, our work contributes to the development of improved ferrite materials with a theoretical guide for material design.