Origin of the Cr3+ concentration-dependent broadband near-infrared emission in Sc2Si2O7

In Sc 2- x Si 2 O 7 : x Cr 3+ , the NIR emission is strongly dependent on the Cr 3+ concentration, and the NIR emission centered at 840 nm and 1300 nm can be attributed to isolated Cr 3+ ions and Cr 3+ –Cr 3+ pairs, respectively.