Green and red photoluminescence from ZnAl2O4:Mn phosphors prepared by sol–gel method

Luminescence investigations of Mn-activated ZnAl2O4 phosphors prepared by using sol–gel method were described. The phosphor was characterized by X-ray diffraction (XRD) and electronic paramagnetic resonance (EPR). The EPR spectra of the samples suggested that Mn ions possessed homogeneous distribution in ZnAl2O4 phosphors. Photoluminescence studies of the prepared phosphors showed green and red emissions. The red emission became weaker, and vanished at last with sintering temperature increasing from 600 to 900 °C in reducing atmosphere, while the intensity of green emission peak increased. Furthermore, when the phosphor was sintered at 900 °C in air, the intensity of red and green emissions decreased, but the value of intensity ratio increased. It suggested that the green emission resulted from Mn2+ and the red emission resulted from Mn4+.