Luminescence dynamics and concentration quenching in Gd2−xEuxO3 nanophosphor

Abstract Gd 2−x Eu x O 3 nanophosphor with enhanced luminescence has been synthesized by solution combustion method in diethylene glycol medium. The effect of Eu 3+ content on the structure, morphology and luminescence dynamics has been investigated. The observed red shift in charge transfer band of the nanophosphor with increase in Eu 3+ content is attributed to the increase in covalency and Eu–O bond length. Excess europium content leads to reduction in intensity of photoemission as a result of concentration quenching. Transient characteristics exhibit single exponential behaviour and the fitted life time values get shortened with increase of Eu 3+ content, due to increase in non-radiative transition rate. The observed quenching of luminescence in the phosphor is found to be in agreement with the energy transfer theory proposed by Dexter and Schulman and found that dipole–dipole interaction between Eu 3+ ions is the key mechanism responsible for quenching. Critical energy transfer distance between Eu 3+ ions in Gd 2−x Eu x O 3 is determined to be 1.148 nm. Judd–Ofelt intensity parameters and the radiative parameters of the phosphors were evaluated from the emission spectrum to analyse the crystal field environment and the degree of covalency between the rare-earth ion and the surrounding ligands. The value of Ω 2 intensity parameter confirmed the hypersensitive nature of the 5 D 0 – 7 F 2 transition with larger asymmetry around Eu 3+ ions.