La2(MoO4)3:Eu3+phosphors with a uniform twinned hemisphere morphology have been successfully synthesized by a sodium citrate (Na3Cit) mediated hydrothermal approach. The crystal structure has been determined by X-ray powder diffraction (XRD) and the microstructures were characterized by scanning electron microscopy (SEM). The controlled experiments indicate the reaction temperature and reaction time are responsible for shape determination of the La2(MoO4)3:Eu3+ products. The possible formation mechanism for these particles is presented by increasing the reaction time. The emission spectra of the samples at different reaction times exhibited intense emission bands at different wavelengths. Under UV light excitation, La2(MoO4)3:Eu3+ emits bright red luminescence. This property shows that these materials have potential applications in lighting and display fields.

Well-dispersed SrCO3:Tb3+ hollow microspheres have been synthesized in the water-ethanol-ethylene glycol solvent system using oleic acid (OA) as an additive without further annealing treatment. X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FT–IR), and field emission scanning electron microscopy (FE-SEM), as well as photoluminescence spectroscopy (PL) were used to characterize the resulting samples. The dosage of OA and the reaction time play key roles in the formation of the final samples. The possible formation mechanism for SrCO3:Tb3+ hollow microsphere is proposed. The SrCO3:Tb3+ phosphors show strong photoluminescence with green emission 5D4–7F5 (544 nm) as the most prominent group under ultraviolet excitation, which have potential applications in field emission displays. The present synthesis process may be extended to fabricate other inorganic materials with special morphologies and functions.Graphical abstract

Non-aggregated spherical polystyrene (PS) particles were coated with GdPO4:Tb3+/Ce3+ phosphor layers by a conventional hydrothermal synthesis using poly(vinylpyrrolidone) (PVP) as an additive without further annealing treatment. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), as well as luminescence decay experiments were used to characterise the resulting core-shell structured PS@GdPO4:Tb3+/Ce3+ samples. The results of XRD indicated that the PS particles were successfully coated with the GdPO4:Tb3+/Ce3+ phosphor layers, which could be further verified by the images of FESEM. Under ultraviolet excitation, the PS@GdPO4:Tb3+/Ce3+ phosphors show Tb3+ characteristic emission, i.e. 5D4-7FJ (J = {6, 5, 4, 3}) emission lines with green emission 5D4-7F5 (543 nm) as the most prominent group. The core-shell phosphors so obtained have potential applications in field emission display (FED) and plasma display panels (PDP).

Nanocrystalline SrCO3:Tb3+ phosphor layers were coated on monodisperse and spherical polystyrene particles by a typical hydrothermal synthesis without further annealing treatment, resulting in the formation of core-shell-structured polystyrene@SrCO3:Tb3+ particles. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, as well as lifetimes were employed to characterize the resulting composite particles. Under ultraviolet excitation, the polystyrene@SrCO3:Tb3+ phosphors show the characteristic 5D4–7FJ (J = 6, 5, 4, 3) emission lines with green emission 5D4–7F5 (544 nm) as the most prominent group. The obtained core-shell phosphors are potentially applied in fluorescent lamps.