Effects of monovalent cation doping on the structure and photoluminescence of GdAlO<SUB align="right">3:Eu<SUP align="right">3+</SUP> phosphor

Abstract

Monovalent cations such as Li (1 mol%) co-doped in GdAlO3:Eu3+ phosphors were synthesised by solution combustion technique using oxalyl dihydrazide (ODH: C2H6N4O2) as a fuel. X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) techniques have been employed to characterise the synthesised nanoparticles. All the compounds crystallised are in the pure orthorhombic phase with no impurity peak. SEM showed the porous, agglomerated and irregular shaped crystallites. The crystallite size was calculated by the Debye Scherrer's method and was found to be in the range 40-45 nm. Photoluminescence (PL) measurements were carried out for GdAlO3:Eu3+ and GdAlO3:Eu3+, Li+ phosphors. The characteristic emission peaks of Eu3+ ions were recorded at 590 and 597, 615 and 627, 650 and 695 nm corresponding to 5D0 → 7FJ (J = 1, 2, 3, 4) transitions respectively. The PL intensity of GdAlO3:Eu3+ phosphor was improved evidently by co-doping with Li+ ions whose radius is less than that of Gd3+. The effect of co-dopant on enhanced luminescence was mainly regarded as the result of a suitable local distortion of crystal field surrounding the Eu3+ activator. These results will play an important role in seeking some more effective co-dopants. The CIE colour coordinates values of these phosphors are determined using CIE 1931 standard. These phosphors can act as a potential candidate in white LEDs and solid state lighting applications.