We report on successful preparation of Er3+doped transparent alumina (0.1–0.17 at.%) exhibiting visible light photoluminescence using wet shaping method and hot isostatic pressing. The effects of dopantamount, type of doping powder and powder pre-treatment on final microstructure, real in-line transmittance and photoluminescence characteristics were studied.The real in-line transmittance ranged between 28 and 56%, depending on processing parameters. The transparency decreased with increased amount of dopant. The decrease is dependent on the type ofdoping powder and its pre-treatment. The photoluminescence spectra measured in both visible and NIR region showed typical emissionbands due to the presence of Er3+ions. The decay profiles of the 4S3/24I15/2 transition were fitted with a 2-exponential function, with faster component in the range of 360–700 ns and slower component around 1.6-2.4 us. The intensity of emissions and lifetime of the 4S3/2 level decrease significantly with increasingconcentration of Er3+ions

This manuscript presents a comprehensive exploration of the band gap structure of (CoCrFeNiMn)₃O₄ powders through a series of experimental investigations. The combined use of optical techniques and X-ray photoelectron spectroscopy in this study leads to a comprehensive characterization of the band gap structure in (CoCrFeNiMn)₃O₄ powders. The findings contribute to the understanding of this material’s electronic properties and pave the way for potential applications in electronic and optical devices.