Improving the near-infrared luminescence of Ca3MgSnGe3O12:Cr3+ using cation modulation and energy transfer for night-vision and nondestructive testing

A series of Ca3Mg1-x Sr x SnGe3O12:0.05Cr3+ (x = 0.005-0.3) phosphors were synthesized in this study; varying the Cr3+-ion crystal-field strength through Sr2+-concentration variation resulted in a luminescence-center redshift. Nd3+-ion co-doping resulted in a broad-spectrum emissive material with a 468 nm excitation wavelength, expanded full width at half maximum (FWHM) (195 nm), Cr-Nd energy transfer, and an ultra-high temperature stability (99.59% at 423 K). Combining Ca3Mg0.7Sr0.3SnGe3O12:0.05Cr3+, 0.05Nd3+ with blue LED chips resulted in near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) for night-vision and nondestructive testing applications. This study reports what we believe is a novel method for designing NIR light-emitting materials with excellent luminescence properties that could guide future research on NIR phosphors with widespread applicability.