Temperature- and pressure-dependent luminescence properties of K3AlF6: Cr3+ phosphor

Abstract

Temperature and pressure are two effective methods to tune the structure and luminescence properties of phosphors. In this study, tetragonal K3AlF6: Cr3+ phosphors were synthesized through the solid-state method. Its structure stability and luminescence property were in situ studied under temperature and pressure using differential scanning calorimetry (DSC), Raman, and photoluminescence spectra. At ambient conditions, one broadband emission presented in the 1.3–1.9 eV range due to the 4T2→4A2 transition. Three phase transitions presented with increasing temperature to 400 °C, but no much change was observed for its luminescence property. In contrast, its structure was stable during compression, and no phase transition was observed up to 26.1 GPa. Furthermore, the crystal field around Cr3+ was enhanced under pressure, leading to its luminescence changing from broad 4T2→4A2 emission to narrow 2E→4A2 emission above 4.2 GPa. It was suggested that pressure was more effective for K3AlF6:5%Cr3+ phosphor. This result provides one effective method to modulate the luminescence property of Cr3+.