One-dimensional CaWO4 and CaWO4:Tb3+nanowires and nanotubes: electrospinning preparation and luminescent properties

Abstract

One-dimensional CaWO₄ and CaWO₄:Tb³⁺ nanowires and nanotubes have been prepared by a combination method of sol-gel process and electrospinning. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra, as well as kinetic decays were used to characterize the resulting samples. The results of XRD, FT-IR, TG-DTA indicate that the CaWO₄ and CaWO₄:Tb³⁺ samples begin to crystallize at 500 °C with the scheelite structure. Under ultraviolet excitation and low-voltage electron beams excitation, the CaWO₄ samples exhibit a blue emission band with a maximum at 416 nm originating from the WO₄²⁻groups, while the CaWO₄:Tb³⁺ samples show the characteristic emission of Tb³⁺ corresponding to ⁵D₄–⁷F_6,5,4,3 transitions due to an efficient energy transfer from WO₄²⁻ to Tb³⁺. The energy transfer process was further studied by the time-resolved emission spectra as well as kinetic decay curves of Tb³⁺ upon excitation into the WO₄²⁻groups. Furthermore, the PL emission colour of CaWO₄: x mol %Tb³⁺ can be tuned from blue to green by changing the concentrations (x) of the Tb³⁺ ion, making the materials have potential applications as fluorescent lamps and field emission displays (FEDs).