Up-conversion luminescence, temperature sensing properties and laser-induced heating effect of Er(3+)/Yb(3+) co-doped YNbO(4) phosphors under 1550 nm excitation

YNbO(4) phosphors with various Er(3+) and Yb(3+) 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(3+) and Yb(3+) 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(3+) concentrations. In addition, it was observed that the temperature sensing properties of YNbO(4): Er(3+)/Yb(3+) phosphors were sensitive to both Er(3+) and Yb(3+) 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(3+) and Yb(3+) and the excitation power.