Ab initio two-sites occupancy and broadband near-infrared emission of Cr3+ in Li2MgZrO4

Abstract

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) light sources have great potential in non-destructive detection, promoting plant growth and night vision applications, while the discovery of a broad-band NIR phosphor remains a challenge. In this study, Li₂MgZrO₄:Cr³⁺ (LMZ:Cr³⁺) phosphors, which emit an ultra-broad band near-infrared light ranging from 650 to 1300 nm with an excellent full width at half maximum (FWHM = 187 nm), have been synthesized via a high-temperature solid-state reaction method. Rietveld refinement was performed to obtain information on the structure and sites, and the geometric arrangement of Mg and Zr atoms and the sites of Cr³⁺ occupancy were also determined by first-principles calculations. The site-occupancy and the relationship between luminescent centers and emission spectra of Cr³⁺ were investigated through the strength of crystal field and photo-luminescent emission and excitation spectra, lifetimes at about 4 K. Furthermore, the NIR pc-LED was also fabricated and has great potential as a non-visible light source.