Effect of Eu3+ on optical and energy bandgap of SrY2O4 nanophosphors for FED applications

摘要

The red colour emitting Eu3+ (0.01, 0.03, 0.05, 0.07, 0.09 and 0.11 at mol) doped SrY2O4 nanophosphors were prepared via a novel solution combustion synthesis route by taking glycine as a fuel. The prepared nanophosphors further annealed at 1300 degrees C for three hour. The structural, morphological and spectroscopic properties of nanophosphors are characterized by means of XRD, FESEM, HR-TEM, PL, Ultra Violet-Visible DRS and FTIR spectroscopy. The XRD studies for all Eu3+ doped samples support crystallinity to the orthorhombic CaFe2O4 structure with Pnam space group and cell parameters, a=10.07 angstrom, b=11.91 angstrom, c=3.41 angstrom. Using Debye Scherrer formula, the particles size were estimated to be 92 nm, which agrees with HR-TEM studies. Nearly spherical and agglomeration of the particles were detected from the FE-SEM micrographs. A powerful red colour release was noticed with a powerful peak at 613 nm because of D-5(0) -> F-7(2) transition at an excitation wavelength of 254 nm and it has been confirmed by CIE chromaticity graph. FTIR, UV-vis DRS indicate that the Sr2+ replacement by Eu3+ ions makes prompt structural defects in SrY2O4 lattice. Direct energy bandgap of nanophosphors estimated by the help of Kubelka-Munk's approximation thru UV-vis DRS, energy bandgap of the red nanophosphors is lesser (similar to 4.974 eV) compared to un-doped SrY2O4 (similar to 5.043 eV), corroborating that ions of Eu3+ shoot ups SrY2O4 structural deficiencies. These analyses reveal that SrY2O4:Eu3+ nanophosphors would be used as the red colour emitting nanophosphors for the improvement of W-LEDs and field emission displays (FED).