Glycothermal synthesis of ZnGa₂O₄:Mn²⁺ nanophosphor and change in its photoluminescence intensity by heat-treatment

Zn Ga2 O4: Mn2+ nanophosphors were synthesized from zinc acetate dihydrate, gallium acetylacetonate, and manganese(II) acetate tetrahydrate in 1,4-butanediol by glycothermal method at 300°C for 2 h. Their average particle diameter was 12.1±2.5 nm. We investigated the influence of temperatures of postheat-treatment in Ar on the luminescent and structural properties. The photoluminescence (PL) intensity slightly decreased after heating below 900°C. The PL intensity increased between 900 and 1200°C, reached at the maximum at 1200°C and decreased over 1200°C. The decrease of the PL intensity by heating below 900°C occurred by the removal of adsorbed organic species. The X-ray diffraction profile indicated the decomposition of Zn Ga2 O4 to Ga2 O3 and ZnO by heating over 1200°C, resulting in the decrease of the PL intensity. The change in the integrated intensity of electron paramagnetic resonance due to paramagnetic Mn2+ with the temperature of heat-treatment in Ar was similar to that of the PL intensity. This suggests that the PL intensity is correlated to the incorporated Mn2+ amount.