Achieving spectrally tunable properties in Ca9ZnLi(PO4)7 by utilizing energy transfer between Eu2 + and Dy3+ ions

Abstract

In the field of luminescent materials, introducing co-doping ions is a common approach for spectral modulation. In this work, a series of Ca₉ZnLi(PO₄)₇: xEu²⁺, yDy³⁺ phosphors were synthesized by traditional high-temperature solid-phase synthesis. This material represents a derivative structure of β-Ca₃(PO₄)₂-type phosphors. Inspired by the spectral overlap between Eu²⁺ and Dy³⁺ excitation bands, Dy³⁺ ions were introduced into the Ca₉ZnLi(PO₄)₇: 0.02Eu²⁺ host matrix. Through energy transfer between Eu²⁺ and Dy³⁺ ions, achieved spectral modulation from blue-white to warm-white emission, ultimately realizing the preparation of single-phase white-emitting phosphor Ca₉ZnLi(PO₄)₇: 0.02Eu²⁺, 0.08Dy³⁺. Through systematic characterization of the phosphor's morphology and photoluminescence properties, the luminescence intensity, temperature dependence, and fluorescence lifetime of the samples were investigated. These studies not only confirmed the feasibility of energy transfer but also elucidated its underlying mechanism. A comparative analysis was conducted to highlight the performance differences between Eu²⁺ singly-doped samples and Eu²⁺/Dy³⁺ co-doped systems. Furthermore, to explore the practical applications of the Ca₉ZnLi(PO₄)₇: xEu²⁺, yDy³⁺ phosphor series, white light-emitting diode was fabricated during this work using the as-synthesized single-phase phosphor under an operating current of 0.35 A. The resulting devices exhibited excellent color rendering properties Ra = 82.3) and an appropriate correlated color temperature (4430 K). Finally, in this article, the demonstration of the sample phosphor in anti-counterfeiting ink applications confirms its multifunctional potential.