Opposite temperature luminescent behaviours of Tb3+ and Pr3+ co-doped BaMoO4 glass ceramics for temperature sensing

Abstract

Tb3+/Pr3+ co-doped transparent glass ceramics (GC) containing BaMoO4 nano-crystalline phase were synthesized and characterized by differential scanning calorimetry, X-ray diffraction, transmittance spectra, and high-resolution transmission electron microscope. The excitation spectra of the sample for the characteristic emission of Tb3+ and Pr3+ ions show a strong broad bands in between 250–300 nm, which are attributed to Pr3+/Tb3+−Mo6+ charge transfer transitions. Under 266 nm excitation, the luminescent intensities of Tb3+: 5D4 → 7F5 (543 nm) and Pr3+: 3P1 → 3H5 (527 nm) show opposite temperature dependences, as the former decreases due to thermo-quenching while the latter increases due to thermo-coupling of 3P0 and 3P1 emissive levels of Pr3+. This leads to a strong temperature dependent luminescent intensity ratio, which is adopted for temperature sensing. Improved relative temperature sensitivity is achieved by making use this novel opposite temperature dependences of two dopants in a single GC sample. The scheme is subject to further optimization in choosing composition and dopants, and promising for application as optical-fiber temperature sensors.