Preparation and luminescence properties of SiO₂@LaBO₃:Eu³⁺ nanoparticles

Spherical SiO₂ particles having a LaBO₃:Eu³⁺ shell have been prepared by coating of silica nanoparticles (size around 130–150 nm) with a LaBO₃:Eu³⁺ sol–gel precursor and subsequent calcination. The SiO₂@LaBO₃:Eu³⁺ nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, and transmission electron microscopy. The XRD and FTIR results revealed that the LaBO₃:Eu³⁺ layer on SiO₂ nanoparticles formed an H-LaBO₃ crystal phase when calcination at a temperature up to 700 °C. Both excitation and emission properties were characterized. The strong excitation lines at 393 and 465 nm of SiO₂@LaBO₃:Eu³⁺ indicated that the core–shell phosphor matched well with the output wavelength of near-UV (350–400 nm) or blue LED (450 nm) chips in phosphor-converted W-LEDs. The emission spectra of the ⁵D₀ → ⁷F _J (J = 0, 1, 2, 3, and 4) transitions at blue/near-UV light showed strong emission lines around 615 nm which were attributed to the induced electric dipole transition of ⁵D₀ → ⁷F₂. The coating cycles affected the luminescence of SiO₂@LaBO₃:Eu³⁺ nanoparticles and their CIE chromaticity coordinate shifted from orange-red to the deep red zone with the increase in the coating cycles (up to 3). The luminescence lifetime of the Eu³⁺ ions in SiO₂@LaBO₃:Eu³⁺ was 2.32 ms. Such a luminescent material may be useful for display and light applications.