Effect of Cr3+ on the microstructure and photoluminescence of MgAl2O4 transparent ceramic

MgAl2O4: Cr3+ transparent ceramics were synthesized by hot pressing (HP) technique, LiF and Y2O3 as sinter aids. The effect of Cr3+ on the densification, structure, and luminescence of MgAl2O4 transparent ceramic was studied. The phase structure, micromorphology, and photoluminescence were analyzed by using an x-ray diffractometer, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, excitation, emission spectra, quantum yield, and decay curves. The results showed that the relative density of the ceramic increased from 99% to 99.45% with the increase of Cr3+ content, meanwhile, more Al3+ sites were occupied by Cr3+ ions, and the Y3+ ion in the sinter aids gathered at the grain boundary, which caused the decrease of the optical transmittance. The relative density of the ceramic with 0.12 mol% Cr3+ is 99.17%, and its optical transmittance was above 67% in the range of 700-6000 nm, and the highest was 74% at 1440 nm. The characteristic R-line centered at 686 nm, and the N-line centered at 700 nm of Cr3+ ions were observed. The quantum yield of the R-line was improved with the increase of x and reached 35.8% at Cr3+ content of 0.37%. Additionally, with the increase of Cr3+ content, the Dq/B value increased from 3.19 to 3.31.

Automated summary

Transparent MgAl2O4: Cr3+ ceramics were synthesized using the hot pressing technique with LiF and Y2O3 as sinter aids. The study found that the relative density of the ceramic increased with the increase of Cr3+ content, Al3+ sites were occupied by Cr3+ ions, and Y3+ ions gathered at the grain boundary, leading to a decrease in optical transmittance.