Synthesis and characterization of monodisperse spherical core-shell structured SiO2@Y3Al5O12:Ce3+/Tb3+ phosphors for field emission displays

Nanocrystalline Y₃Al₅O₁₂: Ce³⁺/Tb³⁺ (average crystalline size 30 nm) phosphor layers were coated on non-aggregated, monodisperse and spherical SiO₂ particles by the sol-gel method, resulting in the formation of core-shell structured SiO₂@Y₃Al₅O₁₂:Ce³⁺/Tb³⁺ particles. X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, photoluminescence, cathodoluminescence spectra, as well as lifetimes were utilized to characterize the core-shell structured SiO₂@Y₃Al₅O₁₂:Ce³⁺/Tb³⁺ phosphor particles. The obtained core-shell structured phosphors consist of well-dispersed submicron spherical particles with a narrow size distribution. The thickness of the Y₃Al₅O₁₂:Ce³⁺/Tb³⁺ shells on the SiO₂ cores (average size about 500 nm, crystalline size about 30 nm) could be easily tailored by varying the number of deposition cycles (100 nm for four deposition cycles). Under the excitation of ultraviolet and low-voltage electron beams (1–3 kV), the core-shell SiO₂@Y₃Al₅O₁₂:Ce³⁺/Tb³⁺ particles show strong yellow-green and green emission corresponding to the 5d–4f emission of Ce³⁺ and ⁵D₄–⁷F _J (J = 6, 5, 4, 3) emission of Tb³⁺, respectively. These phosphors may have potential application in field emission displays.