Abstract

Near-infrared (NIR) phosphor tetragonal K3GaF6:Cr3+ with the space group of I41/a is synthesized through the coprecipitation method, which shows a broadband emission from 600 to 950 nm due to the 4T2→4A2 transition at ambient condition. The luminescent properties and phase transition of K3GaF6:Cr3+ are investigated under different temperatures and pressures using luminescence spectra and Raman spectra. K3Ga0.95F6:0.05Cr3+ undergoes two phase transitions at 170 °C and 230 °C respectively, but Cr3+ exhibits similar broad emission in three different structures. Different from a sequence of phase transitions upon heating, no phase transition is observed up to 22 GPa. However, pressure-induced crossover of the 4T2 and 2E states presents at 9.3 GPa, resulting in dominant narrow-band emissions from the 2E→4A2 transition at higher pressure. These results suggest that pressure can regulate the luminescence properties of K3GaF6:Cr3+ phosphor effectively. This work will deepen the understanding of Cr3+-doped fluoride, which is helpful to expand the application of NIR luminescent materials under extreme conditions.