Ratiometric thermometry is among the emerging applications in phosphor materials. Particularly, the technique of ultrafine-space thermometry has garnered significant attention in bio-imaging. Near-infrared (NIR) light, with its high tissue permeability, serves not only as an excitation source for up-conversion photoluminescence (UCPL) but also induces down-shifting photoluminescence (DSPL) at longer wavelengths. These luminescence mechanisms offer promising avenues for bio-available thermometry. In this study, we focused on highly bio-adaptable yttria-stabilized zirconia (YSZ), Zr

Er3+/Tm3+ co-doped Zr0.85Y0.15O1.925:Yb3+ phosphors: Dual-mode ratiometric thermometry based on near infrared up-conversion/down-shifting photoluminescence