Super-Multi-Elements Doped Bita7o19:Er3+/Yb3+ with Excellent Upconversion Luminescence

Abstract

Fourteen kinds of elements were successfully doped on BiTa7O19 (BTO):Er3+/Yb3+ upconversion luminescence phosphors (UCLPs) by solid phase sintering method. Super-multi-elements doping decreases the phonon vibration and central symmetry of oxygen coordination of luminescence center, and increases structural disorder. Under the excitation of 980 nm laser, the integral intensity of green upconversion luminescence (UCL) reached 2.37 times of β-NaYF4:Er3+/Yb3+. In situ varied-temperature XRD was employed to test the microstructure of super-multi-elements doped sample with temperature. The results show that the cell volume expands first and then shrinks with the increase of temperature. It is proved that the change of the distance between Er3+ and Yb3+ with temperature leads to the change of n value in the multi-photon process. The highest relative temperature sensitivity is 0.00726 K-1 at 303 K based on the luminescence intensity branch ratio (LIR) of thermally coupled energy levels. Ultra-multi-elements doped BTO:Er3+/Yb3+ has high pure green UCL intensity, which is expected to replace fluoride in some high temperature or acid-base environments, and can be applied in luminescence displays, solar cells or temperature sensing.

Keywords: Upconversion, BiTa7O19, Super-multi-elements, Rare-earth, Phosphors