Low-temperature microwave synthesis and luminescence properties of far-red emission ZnGa2O4:Cr3+ phosphor for plant cultivation

Abstract In this work, microwave (MW) sintering method is employed to synthesize far-red (FR) emission ZnGa2O4:Cr3+ phosphor at a lower sintering temperature (900 °C), comparing with the conventional high temperature solid-state sintering (SS) method. Micrometer-size phosphor particles with smooth morphology are obtained due to the MW-induced small temperature gradient between the constituent particles upon the local dielectric volumetric heating. The MW sintering ZnGa2O4:Cr3+ phosphor exhibited excitable properties at the wavelengths of 260 nm, 410 nm and 550 nm, and the intensity of photoluminescence excitation (PLE) at 260 nm showed a dramatic enhancement, which is 2–3 times higher than that of SS sintering sample due to MW “non-thermal effect” in reducing the defect amount in the ZnGa2O4 host latices. These results together with decay time, thermal quenching and color coordinate evaluations showed that synthesis of FR emission ZnGa2O4:Cr3+ by MW-sintering method has advantages of high efficiency, energy saving and least environmental threats.