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

MgAl 2 O 4 : Cr 3+ transparent ceramics were synthesized by hot pressing (HP) technique, LiF and Y 2 O 3 as sinter aids. The effect of Cr 3+ on the densification, structure, and luminescence of MgAl 2 O 4 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 Cr 3+ content, meanwhile, more Al 3+ sites were occupied by Cr 3+ ions, and the Y 3+ 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% Cr 3+ 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 Cr 3+ ions were observed. The quantum yield of the R-line was improved with the increase of x and reached 35.8% at Cr 3+ content of 0.37%. Additionally, with the increase of Cr 3+ content, the Dq/B value increased from 3.19 to 3.31. • The transmittance of MgAl 1.9988 O 4 :0.12%Cr 3+ was above 67% in the range of 700–6000 nm, and the highest was 74% at 1440 nm. • The QY value of MgAl 1.9963 O 4 :0.37%Cr 3+ transparent ceramic was about 35.8%, and its decay time was about 7.97 ms. • As the increase of x , more Al 3+ sites were occupied by Cr 3+ and Y 3+ gathered at the grain boundary.