Chemical and Mechanical Pressure-Induced Photoluminescence Tuning via Structural Evolution and Hydrostatic Pressure

A chemical and mechanical pressure-induced photoluminescence tuning method was developed through the structural evolution and hydrostatic pressure involving phase transition. A series of Ga_1.98–xAl_xO₃:0.02Cr³⁺ phosphors were synthesized. Structural evolution reveals a crystal phase change with the incorporation of Al ions. The luminescent analysis shows the broad-to-sharp emission process with a high internal quantum efficiency value (>90%). The high-pressure study reveals the emission from the exchange-coupled Cr³⁺ pairs and the phase transition under high pressure. Electron paramagnetic resonance indicates the distortion in the microstructures of the emission center. Finally, an ultra-broadband phosphor-converted light-emitting diode is achieved by utilizing the mixture of Ga_1.18Al_0.8O₃:0.02Cr³⁺ and Ga_1.18Sc_0.8O₃:0.02Cr³⁺ phosphors with a bandwidth of 209 nm and an output power of 119 mW. This study provides insights into the effect of chemical and mechanical pressure on the Cr³⁺-doped materials and the development of high-quality near-infrared luminescent materials.