Structural and luminescent properties of red-emitting Eu3+-doped ternary rare earth antimonates R3SbO7 (R = La, Gd, Y)

Abstract

The red-emitting Eu³⁺-doped rare earth antimonates R₃SbO₇ (R = La, Gd, Y) were prepared by high-temperature solid-state reaction. The crystal-phase formations were verified by X-ray powder diffraction (XRD) and structural refinements. The luminescence properties such as photoluminescence (PL) excitation and emission spectra, fluorescence decay curves, absolute luminescence quantum efficiency (QE), CIE color coordinates and the dependence of luminescence intensity on doping level were investigated. The luminescence QE, CIE color coordinates, and the spectrum characteristics of Eu³⁺ ions have a strong dependence on both R (La, Gd, Y) cations and Eu³⁺ doping levels. The ⁵D₀ → ⁷F₄ emission peak at 710 nm was the dominant transition in Eu³⁺-doped La₃SbO₇, while ⁵D₀ → ⁷F₀ at 580 nm was the strongest transition in Eu³⁺-doped Y₃SbO₇. The luminescence properties were discussed on the basis of the crystal structure. Different Eu³⁺ luminescence centers, such as isolated centers, pair broadening, and cluster centers, were discussed based on the dependence of the lifetime values on Eu³⁺ concentration. The luminescence QE of La₃SbO₇:0.4Eu³⁺ can reach 63.8% under excitation of UV light at room temperature; thus, it can have potential application as a red-emitting phosphor for solid-state lighting.