Yb3+/Er3+ co-doped Lu2TeO6 nanophosphors: Hydrothermal synthesis, upconversion luminescence and highly sensitive temperature sensing performance

Abstract Upconversion (UC) nanophosphors of Lu 2 TeO 6 :Yb 3+ /Er 3+ as temperature sensing material have been successfully synthesized via hydrothermal method followed by a subsequent heat treatment process. The phase and micrographs of the as-prepared phosphors were characterized by XRD, SEM, and TEM. Results indicate that the phosphors of hexagonal Lu 2 TeO 6 :Yb 3+ /Er 3+ , formed after heat-treatment at 800 °C for 5 h, consist of rice-like nanoparticles with size mostly distributed less than 200 nm in length. Under the 980-nm NIR excitation, the tellurite nanophosphors exhibit strong green and red UC emissions. The optimum Yb 3+ and Er 3+ concentrations for UC luminescence are determined to be 10% and 1%, respectively. The possible energy transfer mechanism implicated in the nanophosphors is discussed based on the pump power dependence of UC emissions. Furthermore, temperature sensing ability of Lu 2 TeO 6 :Yb 3+ /Er 3+ (10/1) is investigated by employing the temperature dependent fluorescence intensity ratio (FIR) of two emission bands ( 2 H 11/2 / 4 S 3/2  →  4 I 15/2 ) of Er 3+ ion. The maximum sensitivity achieved in this developed material is as high as 0.0103 K −1  at 623 K. This work provides a new qualified UC nanomaterial for application in optical remote temperature sensing.