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

Upconversion (UC) nanophosphors of Lu2TeO6:Yb3+/Er3+ 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 Lu2TeO6:Yb3+/Er3+, 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 Yb3+ and Er3+ 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 Lu2TeO6:Yb3+/Er3+ (10/1) is investigated by employing the temperature dependent fluorescence intensity ratio (FIR) of two emission bands (2H11/2/4S3/2 → 4I15/2) of Er3+ 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.