Achieving spectrally tunable and thermally stable near-infrared emission in Fe3+-activated spinel phosphors via cation site modulation strategy

Abstract

Environment-friendly Fe3+ ions as near-infrared (NIR) activators have recently evoked considerable interest in intelligent NIR light source field, but designing wavelength-tunable and thermally stable Fe3+-doped NIR luminescence material remains a daunting challenge. Here, by selecting spinel compound as the host, a series of Mg1-yAl2+yO4:Fe3+ NIR phosphors featuring tunable wavelengths and high thermal stability are developed utilizing a cation site modulation strategy. Through Mg2+/Al3+ chemical substitution to modify the local crystal environment and the site occupation of Fe3+, the emission peak can be adjusted from 730 to 770 nm along with a greatly enhanced emission intensity. The emission redshift and intensity increased mechanism of as-prepared phosphors are unraveled by structural analyses. The emission intensity of Mg0.87Al2.13O4:Fe3+ at 423 K can maintain 85.13% of the initial intensity at room temperature. The synergistic effect of weak electron-phonon coupling effect, high structural rigidity, and large bandgap renders the excellent anti-quenching properties of developed phosphors. Additionally, the as-prepared phosphors demonstrated great potential in non-destructive detection and quantitative analysis of Cu2+ contents. This work provides a new design principle toward the optical properties optimization of Fe3+-activated NIR materials for multiple photonic applications.