A Comparative Study of SiO₂:Tb³⁺@Gd₂O₃:Eu³⁺ and Its Inverted Tb³⁺-Eu³⁺ Core-Shell Phosphors

How to effectively improve energy transfer efficiency and luminous intensity inspired us to synthesize a series of SiO₂:x%Tb³⁺@Gd₂O₃:y%Eu³⁺ samples, study their luminescence properties and interfacial energy transfer (IET), and compare with SiO₂:x%Eu³⁺@Gd₂O₃:y%Tb³⁺. The results show that SiO₂:x%Tb³⁺@Gd₂O₃:y%Eu³⁺ can exhibit adjustable multicolor luminescence from red to green at different concentrations of Eu³⁺ and Tb³⁺ or under different excitation wavelengths, and there exists efficient IET from Tb³⁺ to Eu³⁺ in SiO₂:x%Tb³⁺@Gd₂O₃:y%Eu³⁺ and SiO₂:x%Eu³⁺@Gd₂O₃:y%Tb³⁺, which improves the energy transfer efficiency and luminous intensity. In addition, the luminescence properties are different between SiO₂:3%Tb³⁺@Gd₂O₃:3%Eu³⁺ and SiO₂:3%Eu³⁺@Gd₂O₃:3%Tb³⁺, and the energy transfer efficiency of Tb³⁺ → Eu³⁺ in SiO₂:3%Tb³⁺@Gd₂O₃:3%Eu³⁺ is obviously higher than that in SiO₂:3%Eu³⁺@Gd₂O₃:3%Tb³⁺. The present study not only developed a kind of multicolor luminescent phosphor but also offered an important new strategy for improving the energy transfer efficiency and luminescent intensity.