Characterization of Luminescent and Thermal Properties of Long Afterglow SrAlxOy:Eu~(2+),Dy~(3+) Phosphor Synthesized by Combustion Method

摘要

Europium and dysprosium codoped strontium aluminate green phosphor was synthesized by combustion method using urea as reducer and fuel. The morphology, particle size, and structure of the products were characterized by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy, while the characteristic luminescence properties were investigated using excitation and emission spectra. Polymer-phosphor composites were made and thermally characterized by means of differential scanning calorimetry and thermogravimetric analysis. Phosphor nanocrystallites with high brightness were obtained without significantly changing the structure of the aluminate host. The average crystallite sizes, calculated from the Scherrer equation ranged between 34 ± 7 and 43 ± 7 nm. Emissions arising from transitions between the 5d and 4f orbital gaps of Eu~(2+) are manifested in the broadband excitation and emission spectra with major peaks at 360 and 515 nm, respectively. The decay curves and half-life times show a clear trend in the influence of the phosphor in the improvement of the initial brightness and the afterglow times, which are ascribed to the presence of shallow and deep traps. Thermal results indicate that the phosphor nanoparticles acted as nucleating agents and improved the overall crystallinity in the LDPE/phosphor system.