Synthesis and characterization of ZnxMg1 − xGa2O4:Co2+ fabricated by low-temperature burning method

A series of ZnxMg1 − xGa2O4:Co2+ spinels (x = 0, 0.25, 0.5, 0.75, and 1.0) was successfully produced through low-temperature burning method by using Mg(NO3)2·4H2O, Zn(NO3)2·6H2O, Ga(NO3)3·6H2O, CO(NH2)2, NH4NO3, and Co(NO3)2·6H2O as raw materials. The product was characterized by X-ray diffraction, transmission electron microscopy, and photoluminescence spectroscopy. The product was not merely a simple mixture of MgGa2O4 and ZnGa2O4; rather, it formed a solid solution. The lattice constant of ZnxMg1 − xGa2O4:Co2+ (0 ≤ x ≤ 1.0) crystals has a good linear relationship with the doping density, x. The synthesized products have high crystallinities with neat arrays. Based on an analysis of the form and position of the emission spectrum, the strong emission peak around the visible region (670 nm) can be attributed to the energy level transition [4T1(4P) → 4A2(4F)] of Co2+ in the tetrahedron. The weak emission peak in the near-infrared region can be attributed to the energy level transition [4T1(4P) → 4T2(4F)] of Co2+ in the tetrahedron.