Monodispersed Sr2GdF7:Yb3+, Er3+ nanocrystals: Hydrothermal synthesis and optical temperature sensing behavior

Abstract Uniform and monodispersed upconversion nanoparticles Sr2GdF7 codoped with Yb3+ and Er3+ were successfully synthesized by a facile hydrothermal method. The crystal structure and morphology of as-prepared nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and selected area electron diffraction. A possible upconversion mechanism implicated in the nanoparticles is discussed based on the dependence of upconversion emissions on pump power. Furthermore, the temperature sensing ability of Sr2GdF7 nanoparticles codoped with Yb3+ and Er3+ ions is investigated by employing temperature dependence of fluorescence intensity ratios for two green upconversion emission bands (2H11/2/4S3/2 → 4I15/2) in the temperature range of 300–660 K. The maximum sensitivity achieved in this developed material is approximately 1.67% K−1 at 300 K. This work provides a new qualified upconversion nanomaterial for application in optical thermometry.