부산대학교 도서관

Background: Y2O3:Gd phosphor nanostructures were prepared homogeneously by the combustion synthesis method at 500 °C using water and urea as the solvent and fuel, respectively. The synthesized phosphors were calcined at 800 °C and 1000 °C to improve the crystallinity and remove the organic phases. The crystal structures were characterized by an X-ray diffractometer and the morphology of the synthesized nanostructures were studied using a field emission scanning electron microscope, a transmission electron microscope, a scanning transmission electron microscopy and an energy-filtered transmission electron microscopy. The crystallite size of the phosphor materials was obtained in the range of 60 nm and changed remarkably with dopant concentration and calcination process. The maximum intensity of emission can be achieved when the dopant concentration is 7%. Further gadolinium doping resulted in the decrease of luminescence properties due to concentration quenching. Methods: Combustion synthesis method was utilized to produce the phosphor powder with the composition of Y2-2xGd2xO3. In a typical synthesis of Y2O3:1%Gd3+ phosphor nanostructure, 5 g of yttrium nitrate and 0.055 g of gadolinium nitrate were dissolved in de-ionized water and stirred for 15 minutes at room temperature in an alumina crucible. Then 2 g urea was added to the mixture as a fuel while vigorous stirring. The precursor solution was transferred into a box furnace and heated at 500 °C for five minutes. The evaporation process started and a quick spontaneous combustion process resulted in producing a foamy and low dense powder. The produced powders were calcined at 800 °C and 1000 °C for 1 h in a box furnace in order to remove the organic materials and improve the crystallinity. Results: Y2O3:Gd phosphor nanostructures were synthesized to present the enhanced emission intensity with gadolinium doping concentration adjustment of 7%. Further doping increase resulted in the decrease of luminescence properties due to concentration quenching. Conclusion: The nanoparticles of Y2O3:xGd3+ (x=1-12%) phosphors were synthesized by a simple combustion method. The crystallite size of synthesized powders was obtained in the approximate range of 50 nm to 90 nm. It was seen that due to similar characters of Y3+ and Gd3+ ions and Y2O3 and Gd2O3, even after doping of relatively high amounts of the dopants, all the XRD spectrum are well matched with the Y2O3 (JCPDS No. 83-0927) structure. In addition, it was found that the dopant concentration affects the crystallite size and photoluminescence properties. This study results show that Y2O3 nanostructures doped with 7%Gd3+ ions have the highest emission intensity and the increase of dopant decreases the photoluminescence properties due to quenching phenomenon.