Study of the annealing temperature effect on the structural and luminescent properties of SrWO4:Eu phosphors prepared by a non-hydrolytic sol–gel process

In this paper, we investigate the influence of temperature on the structural and luminescent properties of Eu3+-doped strontium tungstate oxide (SrWO4) prepared by the non-hydrolytic sol–gel route. X-ray diffraction (XRD) analyses showed that the SrWO4:Eu scheelite type structure was formed in a unique phase at 900 and 1000 °C over 2 h. Raman spectra indicated only one type of [WO4] tetrahedron. The optical properties were investigated by ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) measurements at room and liquid N2 temperatures. PL study showed 5D0 → 7F2 electric dipole transition is dominant when Eu3+ occupies a non-centrosymmetric environment. The (FEG-SEM) images indicated that an increase in the annealing temperature contributed to the coalescence process which promoted the growth of aggregated particles of a polydisperse nature. A qualitative analysis of the powders obtained by dispersive X-ray detector (EDS) indicated that the samples are composed of Sr, W and O while Eu3+ ion was not observed due to it low concentration.

► Non-hydrolytic sol–gel route showed efficient in the preparation of SrWO4:Eu phosphors. ► Raman spectra indicated only one kind of [WO4] tetrahedron. ► The values of the Eu3+5D0 → 7F2/5D0 → 7F1 transitions show that Eu3+ are in a non-centrosymmetric site. ► The emission quantum efficiencies (η) and lifetimes (τ) the Eu3+ were higher at lower temperatures. ► The average crystallite sizes of SrWO4:Eu nanopowder were estimated as 45 nm.