Optimising luminescence and functionality of Ca(WO4): Er3 + /Yb3+ phosphors via dual modulation with Li+ and Mg2+ ion doping for non-contact optical thermometry and anti-counterfeiting applications

Abstract

The communal impact of Li+ and Mg2+ ions on the photoluminescent characteristics, optical thermometry attributes, and anti-counterfeiting potential of CaWO4: Er3+/Yb3+ phosphors. Infusing rare-earth ions Er3+/Yb3+ into calcium tungstate, CaWO4, exhibits considerable promise for optoelectronic applications. Nevertheless, the augmentation of alkali and alkaline earth metal ions represents a strategic avenue to elevate the performance and versatility of these phosphors. A series of CaWO4:Er3+/Yb3+ co-doped phosphors, incorporating Li+ and Mg2+ ions, was successfully synthesized via a high-temperature solid-state reaction method. Structural and morphological evaluations were studied with XRD & FE-SEM, and elemental analysis through energy-dispersive X-ray spectroscopy (EDS). Photoluminescence spectroscopy was employed to scrutinize the luminescent attributes of the phosphors. Our findings underscore a profound influence of Li+ and Mg2+ ions on the luminescence properties of CaWO4: Er3+/Yb3+ phosphors. We recorded excellent temperature-dependent upconversion, indicating the potential of these phosphors for optical thermometry applications. Additionally, the optimized phosphor sample demonstrated efficacy in latent fingerprint detection and security ink applications. These revelations offer crucial insights into conceptualizing and fabricating innovative luminescent materials, with implications spanning a broad spectrum of optical temperature sensing and security-oriented endeavors.