Up-conversion luminescence, temperature sensing properties and laser-induced heating effect of Er/Yb co-doped YNbO phosphors under 1550 nm excitation.

YNbO phosphors with various Er and Yb concentrations were synthesized via a traditional high-temperature solid-state reaction method. Their crystal structure was investigated by means of X-ray diffraction (XRD) and Rietveld refinements, and it was confirmed that the obtained samples exist in monoclinic phase. The Er and Yb concentration-dependent up-conversion (UC) luminescence was studied under 1550 nm excitation. By inspecting the dependence of UC intensity on the laser working current, it was found that four-photon and three-photon population processes were co-existent for generating the green UC emissions in the samples with higher Yb concentrations. In addition, it was observed that the temperature sensing properties of YNbO: Er/Yb phosphors were sensitive to both Er and Yb doping concentrations. Furthermore, based on the obtained temperature response of the UC luminescence phosphors, 1550 nm laser-irradiation-induced thermal effect was studied, and it was discovered that the sample temperature was very sensitive to the doping concentrations of Er and Yb and the excitation power.