Up-conversion Luminescence and Temperature Sensing Properties of CaBi4Ti4O15:Tm3+, Yb3+ Ceramics

Tm3+/Yb3+ co-doped CaBi4Ti4O15 (CBT) bismuth layer structured ferroelectric ceramics were synthesized by a solid state reaction method and their microstructural and up-conversion (UC) luminescence properties were studied. Under 980-nm laser excitation, a strong blue light (475 nm) and a weaker red (650 nm) UC emission band were obtained, in which a three-photon UC mechanism is dominant, contributing to the transitions of 1G4 → 3H6, and 1G4 → 3F4. The optimal UC emission intensity was observed in the CBT: 0.005Tm3+/0.04Yb3+ samples. The transition 1G4 → (3H6, 3F4) of Tm3+ indicated a temperature-dependent behavior in the 163–503 K range. The maximum sensitivity was found to be 0.016 K−1 at 503 K based on the blue and red emissions. This indicates that CBT: 0.005Tm3+/0.04Yb3+ ferroelectric ceramics have great potential for applications in optical temperature sensors.