Effect of R2O3 (R=Y, La) on the microstructure, optical, and photoluminescent properties of MgAl2O4:Cr3+ transparent ceramics

MgAl 2 O 4 :Cr 3+ transparent ceramics were prepared by a hot-pressed sintering process with Y 2 O 3 and La 2 O 3 as sintering aids, and the effects on the microstructure, densification, optical transmission, and photoluminescent properties were investigated. The sintering aids of Y 2 O 3 and La 2 O 3 enhanced the relative density, reaching 99.33% with 2.4 wt% Y 2 O 3 and 99.24% with 0.8 wt% La 2 O 3 . La 2 O 3 also inhibited abnormal grain growth and obtained ceramics with uniform grain size. In addition, the optical transmission was also improved with Y 2 O 3 and La 2 O 3 as sintering aids. The transmission of the ceramic with 2.4 wt% Y 2 O 3 exceeded 78% in the region of 700–6000 nm and reached 83% at 1450 nm. Moreover, Y 2 O 3 and La 2 O 3 both contributed to improving the quantum yield of the ceramics, especially for Y 2 O 3 , and the quantum yield was about 0.354, which was approximately two times higher than that without R 2 O 3 . In summary, La 2 O 3 was helpful for improving sintering process, inhibiting grain growth, and homogenizing the grain size, while Y 2 O 3 was significant for enhancing the optical and photoluminescent properties.