Synthesis and photoluminescence properties of Eu3+-activated LiCa3ZnV3O12 white-emitting phosphors

Abstract

Single-component white-emitting phosphors are highly promising for applications in phosphor-converted white light-emitting diodes. In this paper, novel single-phase LiCa_3(1−x)ZnV₃O₁₂:Eu³⁺ (x = 0–0.05) phosphors with tunable white emissions were prepared by a conventional solid-state reaction. The LiCa₃ZnV₃O₁₂ (x = 0) phosphor showed an efficient self-activated bluish-green emission due to the V⁵⁺–O²⁻ charge transfer transition of the [VO₄]³⁻ groups, and possessed an intense broad excitation spectrum in the 250–400 nm wavelength range. Together with the [VO₄]³⁻ emission, the red emission of Eu³⁺ ions was also observed in LiCa_3(1−x)ZnV₃O₁₂:Eu³⁺ phosphors. The energy transfer from the [VO₄]³⁻ groups to the Eu³⁺ ions was studied. Importantly, the emission colors of LiCa_3(1−x)ZnV₃O₁₂:Eu³⁺ phosphors varied from greenish-blue to whitish and then to red with increasing Eu³⁺ content and the white-light emission was realized in the single-phase phosphor of LiCa₃ZnV₃O₁₂:0.003Eu³⁺ by combining the [VO₄]³⁻-emission and the Eu³⁺-emission. The energy-transfer efficiency from [VO₄]³⁻ groups to Eu³⁺ ions in the LiCa₃ZnV₃O₁₂:0.003Eu³⁺ sample was determined to be about 52% and the internal quantum efficiency of the LiCa₃ZnV₃O₁₂:0.003Eu³⁺ phosphor was found to be about 41.5%. In addition, the CIE chromaticity coordinates of LiCa₃ZnV₃O₁₂:0.003Eu³⁺ were (x = 0.3374, y = 0.3596), and the correlated color temperature was estimated to be about 5311 K.