Yu-Chung Chen

Nanostructured red-emitting MgGa 2 O 4 :Eu 3+ phosphors

Nano-grained phosphors of Eu 3+ -doped MgGa 2 O 4 crystallites were prepared by sol-gel technique. The characterization and optical properties of luminescent MgGa 2 O 4 :Eu 3+ powders have been investigated. The dried sol-gel powders were calcined in air at different temperature from 600 to 1000 °C for 5 h. The x-ray diffraction profiles showed that the MgGa 2 O 4 :Eu 3+ powders began to crystallize around 600 °C and formed stable MgGa 2 O 4 phase in the temperature range of 600–900 °C. The transmission electron microscopy morphology observations revealed that the fired powders exhibit small grain size less than 20 nm. In the PL studies, under ultraviolet (394 nm) excitation, the calcined powders emitted bright red luminescence (615 nm, 5D 0 →7F 2 ), and the powders fired at 900 °C were found to have the maximum photoluminescence intensity. The quenching concentration of Eu 3+ in MgGa 2 O 4 crystallites was also indicated to be about 5∼6 mol%.