Down- and up-conversion luminescence processes in olivine-type ceramic phosphors Li2AGeO4:Er3+(A = Zn, Mg)

Luminescence properties of olivine-type germanate phosphors with general formula Li2AGeO4:0.5Er3+ (A = Zn, Mg) have been studied. Olivine-type materials prepared via conventional solid-state reaction method were examined for down-and up-conversion luminescence processes. In the down-conversion process after 381 nm excitation, two strong green emission bands due to 2H11/2/4S3/2 -> 4I15/2 transitions of Er3+ were registered, with a change in the intensity ratio depending on the ceramic matrix. Weak red emission bands related to 4F9/2 -> 4I15/ 2 transition were also recorded. In contrast, luminescence bands behaved completely differently for the up -conversion process after infrared excitation at lambda exc = 980 nm. Red emission bands were much more significant than green emission bands. These effects are stronger for Li2MgGeO4:0.5Er3+ than Li2ZnGeO4:0.5Er3+. In the red and green spectral range, slope values for both matrices Li2AGeO4:0.5Er3+ (A = Zn, Mg) confirmed two -photon process.

Automated summary

The luminescence properties of olivine-type germanate phosphors have been studied, showing different behaviors in down-conversion and up-conversion processes. The red emission bands are more significant in the up-conversion process.