Air-Annealing Impact on Spectroscopic Properties of the Nd³⁺ (1 mol %):YF₃ Phosphor

We report on the synthesis of Nd³⁺ (1 mol %):YF₃ phosphors obtained via co-precipitation from aqueous solutions. Annealing in air of the synthesized Nd³⁺ (1 mol %):YF samples resulted in the additional formation of an oxygen-vacancy complex (O_F–O_V complex). The luminescence intensity of the O_F–O_V complex increased by a factor of 12.5 relative to the non-annealed sample. The impact of oxygen-vacancy defects (O_F–O_V complex) on the luminescent properties of samples that doped with Nd³⁺ ions in temperature range from 80 to 320 K was studied. It was suggested that the thermal trapping of charge carriers by the defective O_F–O_V complex at low temperatures (≈80 K) leads to an increase in the intensity of defect luminescence compared with the luminescence of Nd³⁺ ions and vice versa. It was found that the energy transfer between the O_F–O_V complex and Nd³⁺ ions is unlikely.