Upconversion luminescence, and temperature sensing properties of 12CaO·7AlO single crystal sensitized with lanthanide ions Er(III) and Yb(III).

12CaO·7AlO (C12A7) single crystal had extraordinary application in optical field, owing to its special structure. Here, Yb and Er co-doped C12A7 single crystal (Er/Yb/C12A7) were prepared by Czochralski method. XRD patterns of C12A7 single crystal performed a single diffraction peak, indicating that pure single structure was achieved. With over-stoichiometric ratio, infrared absorption spectrum had two peaks between 600 cm and 850 cm, which belonged to the frame structure of C12A7 single crystal. The band gap of Er/Yb/C12A7 single crystal was 4.25 eV, which reduced the temperature quenching of Ln ions. Raman scattering spectra showed that the highest phonon energy of C12A7 single crystal was about 880 cm, which was beneficial for upconversion emission. The temperature sensitivity coefficient of Er/Yb/C12A7 polycrystal and single-crystal were 1124.81 and 1122.69 range from 373 K to 573 K, respectively. Compared with polycrystal, sensitivity coefficient of Er/Yb/C12A7 single crystal increased. Moreover, absolute sensitivity (S) of single crystal of Er/Yb/C12A7 increased with the increasing of temperature, suggesting single crystal was suitable for detecting high temperature.