Host matrix impact on Er3+ upconversion emission and its temperature dependence

Abstract

By synthesizing Y_(1.9−2x)Yb_0.1Er_2xO₃, Y_(0.95−x)Yb_0.05Er_xVO₄ and Y_(0.95−x)Yb_0.05Er_xPO₄ phosphors, with phonon frequency maxima at 560, 826 and 1050 cm⁻¹, respectively, we present the impact of phonon energy and crystal structure of the host matrix on upconversion and temperature sensing behavior. The spectral upconversion characteristics of all three phosphors reveal noticeable differences. The temperature sensing studies reveal that the phosphors have maximum sensitivity at ∼490 K, which is found to be highest (0.0105 K⁻¹) in Y_0.947Yb_0.05Er_0.003VO₄ followed by Y_1.894Yb_0.1Er_0.006O₃ and Y_0.947Yb_0.05Er_0.003PO₄ phosphors. We found that the temperature sensitivity basically depends on the intensity ratio of two thermally coupled emission bands, ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2, of Er³⁺. Further, the intensity ratio depends on phonon energy of the host lattice, crystal structure, surface quenching centers and the temperature dependence of non-radiative decay rate.