Low-temperature thermometry based on upconversion emission of Ho/Yb-codoped Ba0.77Ca0.23TiO3 ceramics

Ho/Yb-codoped Ba0.77Ca0.23TiO3 ferroelectric ceramics were prepared by a solid-state reaction method. Under the excitation of 980 nm, all the samples exhibited strong green, red and near-infrared upconversion emissions. Upconversion emission intensities of the Ho/Yb-codoped Ba0.77Ca0.23TiO3 ferroelectric ceramics can be enhanced with moderate Yb addition. Additionally, optical temperature sensing properties based on the upconversion emissions of the Ba0.77Ca0.23Ti0.975Ho0.005Yb0.03O3 ferroelectric ceramics were also investigated. The result demonstrated that the optical temperature sensor can be operated in the temperature range of 93-300 K with a maximum sensitivity of about 0.0053 K−1 at 93 K. Compared with other rare-earth doped materials, it is much easier and cheaper to synthesize Ho/Yb-codoped Ba0.77Ca0.23TiO3 ferroelectric ceramics.