Investigation of the optical properties of MgGa2O4:Eu3+ phosphors synthesised by solid-state reaction method

Abstract

Red-emitting MgGa₂O₄:Eu³⁺ phosphors were synthesised via an improved solid-state reaction method. The formation of a monophasic structure was confirmed at calcination temperatures exceeding 1200°C, exhibiting a cubic spinel crystal structure. FESEM analysis revealed that the synthesised particles possessed sizes ranging from 500 nm to 1 µm. Photoluminescence excitation (PLE) spectra showed a broad excitation band in the 270-500 nm region, with prominent excitation peaks at 272, 394, and 465 nm. In particular, the excitation peak located at approximately 394 nm can be attributed to the ⁷F₀→⁵L₆ electronic transition of Eu³⁺ ions. Upon excitation at 394 nm, the MgGa₂O₄:Eu³⁺ phosphors exhibited intense orange-red emission in the 570-700 nm region, with the strongest red emission peaks at 613 and 616 nm. The highest photoluminescence (PL) intensity was observed for the sample calcined at 1300°C. These results demonstrate the considerable potential of MgGa₂O₄:3%Eu³⁺ red-emitting phosphors for applications in white light-emitting diodes (WLEDs).