Synthesis and characterization of BaxMgyAl2O4: Eu,Dy nanophosphors prepared using solution-combustion method

Abstract

Europium-doped barium magnesium aluminate (BaxMgyAl2O4:Eu) phosphors were obtained at low temperature using the solution-combustion of corresponding metal nitrate-urea solution mixtures. The particle sizes, morphology, structural and luminescent properties of the as-synthesized phosphors were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL). It was found that the change in Ba:Mg molar ratios showed great influence not only on the particle size and morphology, but also on their PL spectra and crystalline structure. The structure of BaxMgyAl2O4 nanophosphors changes from a monoclinic structure for Ba 26 mole% to orthorhombic for Mg 26 mole% and a small change in peak position at high angles due to differences in size between Ba and Mg ions. The peak of the emission band occurs at longer wavelength (around 615nm) with increase in Mg concentration but display a broad band emission at 498 nm for lower Mg concentration. The blue-green emission is probably due to the influence of 5d electron states of Eu 2+ in the crystal field because of atomic size variation causing crystal defects while the red emission is due to f-f transitions. This finding clearly demonstrate the possibility of fine tuning the colour emission and solid solubility limit in BaxMgyAl204:Eu phosphors through the simple and a cheap process.