A novel Eu3+ activated Ca3Zn3Te2O12 tellurate red phosphor for white LEDs with high color stability and color purity

Abstract

Research into red phosphors with a high color rendering index is particularly compelling, given the absence of a red component in the spectrum of commercial pc-WLEDs, which combine blue LED chips with yellow-emitting YAG:Ce³⁺ phosphors. Herein, we reported a novel Eu³⁺ activated Ca₃Zn₃Te₂O₁₂ red-emitting phosphor, synthesized using a conventional high-temperature solid-phase method. The phase and crystal structures were analyzed by powder X-ray diffraction and Rietveld refinement. The optimal excitation peak of the Ca₃Zn₃Te₂O₁₂:Eu³⁺ phosphor was located at 395 nm, matching those of conventional commercial near-ultraviolet chips. In addition, the Ca₃Zn₃Te₂O₁₂:9%Eu³⁺ phosphor exhibited good thermal stability, with an activation energy of 0.267 eV, and the CIE color coordinates hardly changed with temperature. Ultimatel, a high-quality white LED device was fabricated by combining Ca₃Zn₃Te₂O₁₂:9%Eu³⁺ red phosphor, a commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor, and(Ba,Sr)₂SiO₄:Eu²⁺ green phosphor with a 395 nm near-UV chip. Despite a substantial increase in the input current from 20 to 320 mA, the white-LED maintained a stable color rendering index of around 80, highlighting its consistent performance. These results indicated that Eu³⁺ activated Ca₃Zn₃Te₂O₁₂ phosphors are promising red emission candidates for white LEDs pumped by near ultraviolet chips.