Modulating optical and electrical properties of chemically synthesized ZnMn2O4 nanoparticles through crystallinity: Integrating theoretical and experimental insights

Theoretical and experimental analyses of zinc manganite (ZnMn2O4) nanoparticles were carefully conducted for in-depth exploration of their electronic and optical properties. Nanosized particles, approximately 11-15 nm in size, were synthesized using a post-sintering assisted co-precipitation method. Theoretical calculations using Rietveld refinement were conducted to accurately predict crystal parameters and simulate XRD patterns consistent with experimental XRD observations. UV-visible absorption spectra and Tauc plot analysis indicated a bandgap ranging from 0.65 to 0.79 eV, while photoluminescence spectra revealed the most intense peak at 466 nm, possibly arising from exciton recombination processes or defect-related emissions. Density function theory (DFT) calculations were employed to compute the band structure and density of states of ZnMn2O4, resulting in a calculated bandgap of 0.73 eV, which aligned closely with the experimental findings. Moreover, DFT calculation identified atomic-level transitions responsible for absorption peaks in the material. Comprehensive evaluations of the mechanical and optical properties, integrating theoretical insights with experimental data, provided a holistic understanding of the intricate electronic and optical characteristics of ZnMn2O4. Furthermore, frequency and temperature-dependent dielectric properties demonstrated the MWS-type polarization effect. Besides, the activation energy of 0.582-0.553 eV, calculated using the Arrhenius plot, was good in accordance with our dielectric analysis, solidifying the potential of this nanomaterial for advanced optoelectronic applications.