Vol. 7, Issue 1 (2018)

Author(s):
Sheetal, SP Khatkar, VB Taxak and Sonika Singh

Abstract:
Nanocrystalline La_1-xDy_xSrAl₃O₇ phosphor has been successfully synthesized via low temperature urea assisted solution combustion route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infra-red spectroscopy were used to characterize structural properties of Dy³⁺ doped LaSrAl₃O₇ nanophosphor. The results of XRD patterns indicate that all samples crystallized completely in tetragonal phase at sintering temperature 550 ^oC. The functional melilite AlO₄^5- groups in LaSrAl₃O₇ host were identified using FT-IR spectrum. SEM and TEM analysis revealed tetragonal shaped particles with an average size in the range 65-75 nm. Optical properties were investigated by measuring excitation and emission spectra with decay curves of La_1-xDy_xSrAl₃O₇ nanophosphors. Emission spectrum exhibits characteristic blue (479 nm) and yellow emission (574 nm) corresponding to ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 transitions of Dy³⁺ ions, respectively under excitation at 352 nm. Luminescence concentration quenching could be observed when the doping concentration of Dy³⁺ ions was more than 10 mol%. The CIE color coordinates (x = 0.332, y = 0.354) located in the white light region, makes this nanophosphor as potential candidate in new lighting devices.