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

Abstract

To develop continuous broadband emission near-infrared (NIR) phosphors compatible with blue LED chips, numerous Cr3+-Yb3+ co-doped phosphors have been synthesized. However, the emission spectra of Cr3+ vary significantly across different matrix materials, while Yb3+ maintains a relatively stable emission spectrum. This variation leads to notable luminescence depressions between 850 and 900 nm in many Cr3+-Yb3+ co-doped phosphors. To address this emission spectrum gap, we utilized Cr3+ as a sensitizer and introduced Nd3+ as the luminescence center within the La3Sc2Ga3O12 matrix material, establishing a Cr3+-Nd3+ energy transfer channel. Under 480 nm excitation, we tuned emission peaks at 800 nm (Cr3+) and 881 nm (Nd3+). The stable NIR emission of Nd3+ effectively compensates for the missing spectrum in Cr3+-Yb3+ co-doping. The Cr3+-Nd3+ energy transfer process was thoroughly analyzed using diffuse reflection spectrum, excitation spectrum, and fluorescence decay curves. The LSGO:0.125Cr3+, 0.03Nd3+ 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.