La3Sc2Ga3O12:Cr3+, Nd3+ near-infrared phosphor for nondestructive detection and luminescence thermometry

To develop continuous broadband emission near-infrared (NIR) phosphors compatible with blue LED chips, numerous Cr 3+ -Yb 3+ co-doped phosphors have been synthesized. However, the emission spectra of Cr 3+ vary significantly across different matrix materials, while Yb 3+ maintains a relatively stable emission spectrum. This variation leads to notable luminescence depressions between 850 and 900 nm in many Cr 3+ -Yb 3+ co-doped phosphors. To address this emission spectrum gap, we utilized Cr 3+ as a sensitizer and introduced Nd 3+ as the luminescence center within the La 3 Sc 2 Ga 3 O 12 matrix material, establishing a Cr 3+ -Nd 3+ energy transfer channel. Under 480 nm excitation, we tuned emission peaks at 800 nm (Cr 3+ ) and 881 nm (Nd 3+ ). The stable NIR emission of Nd 3+ effectively compensates for the missing spectrum in Cr 3+ -Yb 3+ co-doping. The Cr 3+ -Nd 3+ energy transfer process was thoroughly analyzed using diffuse reflection spectrum, excitation spectrum, and fluorescence decay curves. The LSGO:0.125Cr 3+ , 0.03Nd 3+ compound with the best optical performance was packaged with a 480 nm LED chip to create a NIR light source. At a working current of 10 mA, it achieved a photoelectric conversion efficiency of 9.45 %, demonstrating its potential for applications in non-destructive detection and luminescence thermometry. This work presents a novel strategy for tuning NIR spectral distribution and developing continuous broadband NIR phosphors.