Preparation, luminescence and electrons selected energy level transition of Dy3+ in Ba7Hf(PO4)6 through temperature control

A novel single-phase Eulytite-type orthophosphate Ba7Hf(PO4)6:Dy3+ was prepared via sintering method. X-ray powder diffraction analysis confirmed the obtained samples were good single phase and no impure phase was found. The optical properties of Ba7Hf(PO4)6:Dy3+ phosphors were characterized and the influence on the luminescent properties with various Dy3+ contents was studied clearly. Moreover, the photoluminescence spectra, decay times as well as the temperature quenching spectra of Ba7Hf(PO4)6:Dy3+ phosphors were studied minutely. The experiment results illustrated the prepared Ba7Hf(PO4)6:Dy3+ phosphor showed two photoluminescence bands centered at 485 nm and 578 nm which were attributed to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ when pumped by UV. Meanwhile, an abnormal phenomenon was found that when the temperature increased, the emission intensity of Ba7Hf(PO4)6:Dy3+ at 485 nm and 578 nm gradually decreased but the emission spectra at 451 nm assigned to 4I15/2 → 6H15/2 increased sharply with increasing temperature. Hence, temperature dependent 4I15/2 → 6H15/2 transition was analyzed in detail by X-ray powder diffraction, emission spectra and decay curves at different temperature, which was rarely discussed before. We found that the electrons preferentially select energy level transition of Dy3+ in Ba7Hf(PO4)6 through temperature control. All the results showed that Ba7Hf(PO4)6:Dy3+ is a high-performance single-component phosphor.