Prepare high efficiency Mn2+-doped Zn2SiO4 green phosphors in air using nano-particles

In this study, nano-scale precursors of ZnO, SiO2, and MnO2 powders were used to prepare mixtures with the compositions of 2ZnO+SiO2+X mol% MnO2 (X=MnO2/2ZnO, abbreviated as Zn2SiO4-X-MnO2), where 2≤X≤5. The mixed Zn2SiO4-X-MnO2 mixtures were calcined from 900 to 1300 °C in air in order to synthesize Zn2SiO4:Mn2+ green phosphors. The X-ray diffraction patterns of Zn2SiO4-X-MnO2 particles indicated that ZnO was present in the 900 °C-calcined Zn2SiO4-X-MnO2 phosphors, but not in particles calcined at temperatures of 1000 °C and higher. However, the unapparent secondary phase of ZnMnO3 was found in the 1200 and 1300 °C-calcined Zn2SiO4-5-MnO2 compositions. The luminescent characteristics of Zn2SiO4-X-Mn2+ phosphors were compared with that of a commercial product (Nichia Corp., Japan). The photoluminescence (PL) intensity of 1200 °C-calcined Zn2SiO4-4-MnO2 phosphors was higher and the decay times of all synthesized Zn2SiO4-X-MnO2 phosphors were longer than those of the commercial product.