Abstract
ZnGaOx nanoparticles with varied ratios of Zn2+ to Ga3+ were synthesized by a polyacrylamide gel route. The phase purity and structure are confirmed by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectrometer (XPS). High crystal quality and elemental distribution are determined by transmission electron microscopy (TEM) measurements. The band gaps of the samples ranging from 3.22 to 4.47 eV are estimated by ultraviolet–visible (UV–Vis) diffuse refectance spectroscopy (DRS). Under the excitation of 325 nm laser light, ZnGaOx nanoparticles with the Zn2+/Ga3+ molar ratios of 0.8:2 and 0.7:2 show two emission peaks at 415 and 510 nm. A marked emission band at 695 nm is observed from the samples with Zn2+/Ga3+ molar ratios of 0.6:2, 0.5:2 and 0.4:2. The luminescence mechanism is discussed based on the experimental results. The luminescence color of as-synthesized samples gradually shifts from blue-green to green-yellow region with decreasing Zn2+/Ga3+ ratio. Interestingly, the sample with Zn2+/Ga3+ ratio of 0.7:2 has the CIE chromaticity coordinates of (x = 0.26, y = 0.33) close to the coordinates (x = 0.33, y = 0.33) of pure white light. Together, ZnGaOx phosphors with different emission colors without doping with rare earths have considerable potential applications in tunable light emitting diodes (LEDs) and color display.
Published Version
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