SYNTHESIS OF LUMINESCENT sral2o4:Eu2+,Dy3+ NANOMATERIALS FOR EMERGENCY DISPLAYS

Abstract

SrAl2O4:Eu2+,Dy3+ are phosphors with unique tuneable properties. This work comprises of several aspects of strontium-aluminate phosphor doped with rare earth metal ions (SrAl2O4:Eu2+,Dy3+). In particular the optical and structural properties of the long afterglow SrAl2O4:Eu2+,Dy3+ phosphors prepared by urea-nitrate solution-combustion method were investigated. The solution-combustion method is more efficient because phosphors with high efficiency were obtained at low temperature in a very short period of time (5 min). The effects of varying concentration of host matrix composition (Sr:Al), co-dopant and growth temperature on the structural and optical properties of the SrAl2O4:Eu2+,Dy3+ phosphors were studied. Temperature is a critical variable in thermodynamics that has a substantial impact on the shape, size, and surface properties of the produced nanoparticles. A study was carried out to investigate the influence of this factor on the optical and structural characteristics of SrAl2O4:Eu2+, Dy3+. The results of the X-ray diffraction (XRD) analysis reveal that the 2mol % favored the formation of monoclinic phase. The X-ray diffraction patterns for all the SrAl2O4:Eu2+,Dy3+ NPs exhibited a highly crystalline and monoclinic structure of SrAl2O4:Eu2+,Dy3+ with no impurity phases. The values of the crystallite sizes range from 35 to 42 nm and 32.23 to 29.7 nm for the NPs prepared at different furnace temperatures and varied concentrations respectively. A similar trend was observed also for other growth on varying concentration of host matrix composition (Sr:Al). The research on the impact of Dy3+ concentration revealed that the average lattice constants 'a' were determined to be a = 0.84470 nm, indicating a decreasing tendency with higher degrees of Dy3+ doping and Al/Sr ratios. The results closely match the bulk SrAl2O4:Eu2+, Dy3+ lattice constants provided in the standard JCPDS data file No.34-0379. The ultraviolet and visible analysis (UV-Vis) displayed well-resolved absorption maxima which were red shifted upon increase in growth temperature and varying concentration of host matrix composition (Sr:Al) concentration. There was an inverse relation between the bandgap and the reaction parameters under study (reaction time, growth temperature and varying concentration of host matrix composition (Sr:Al). The band gap energies of the SrAl2O4:Eu2+, Dy3+ nanoparticles were adjusted within the range of approximately 5.62 to 5.4 eV by increasing the temperature of the furnace. The band gaps of SrAl2O4:Eu2+, Dy3+ exhibited a range of 6.5 to 5.5 eV as the concentration of Dy3+ during growth increased. The sample of SrAl2O4:Eu2+, Dy3+ NPs, synthesized with a doping of 0.4 mol% Dy3+, grown in a growth medium with a ratio of 2 Al/Sr, and prepared at 700 ºC, exhibited optimal crystallinity, minimal lattice stress, and favorable optical characteristic