Synthesis, characterisation and spectroscopic properties of GdOF:Eu3+ phosphors and their Judd-Ofelt analysis

A series of Eu3+-doped gadolinium oxyfluoride (GdOF) phosphors (1-9 mol%) were successfully prepared by a low temperature solid state method. The phosphors were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), UV-Visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy. Rietveld refinement of PXRD data confirmed that all the compounds were crystallised in the rhombohedral structure. The photoluminescence properties were investigated under 254 nm excitation wavelengths. On substitution of Eu3+ ion to Gd3+-site in GdOF, the photoluminescence spectra exhibit D-5(0)-> F-7(0) (579 nm), D-5(0)-> F-7(1) (593 nm), D-5(0)-> F-7(2) (612, 620 nm), D-5(0)-> F-7(3) (651 nm) and D-5(0)-> F-7(4) (705 nm) transitions. Judd-Ofelt theory was applied to evaluate the intensity parameters (Omega(2), Omega(4)) of Eu3+-doped GdOF phosphors. The transition probabilities (A(T)), radiative lifetime (tau(rad)), and branching ratio (beta) were investigated by using the intensity parameters. CIE colour coordinates confirmed that the Eu3+-doped GdOF phosphors exhibit red luminescence. The obtained results revealed that the present phosphors can be a potential candidate for red component in white LEDs applications