Anti-thermal quenching phosphors based on the new phosphate host Ca3.6In3.6(PO4)6

Abstract

To enhance the working quality of WLEDs, considerable efforts have been made to upgrade the thermal quenching resistance of existing phosphors or design new anti-thermal quenching (ATQ) phosphors. Developing a new phosphate matrix material with special structural features has great importance for the fabrication of ATQ phosphors. By phase relationship and composition analysis, we have prepared a novel compound Ca_3.6In_3.6(PO₄)₆ (CIP). Coupling ab initio and Rietveld refinement techniques, the novel structure of CIP with partly vacant cationic positions was solved. Taking this unique compound as the host and using the inequivalent substitution of Dy³⁺ for Ca²⁺, a series of C_1−xIP:Dy³⁺ rice-white emitting phosphors were successfully developed. When the temperature was raised to 423 K, the emission intensity of C_1−xIP:xDy³⁺ (x = 0.01, 0.03, and 0.05) increased to 103.8%, 108.2%, and 104.5% of the original intensity at 298 K, respectively. Except for the strong bonding network and inherent cationic vacancy in the lattice, the ATQ property of the C_1−xIP:Dy³⁺ phosphors is mainly attributed to the generation of interstitial oxygen from the substitution of unequal ions, which releases electrons with the thermal stimulus, causing anomalous emission. Finally, we have explored the quantum efficiency of C_1−xIP:0.03Dy³⁺ phosphor and the working performance of PC-WLED prepared with C_1−xIP:0.03Dy³⁺ phosphor and 365 nm chip. The research work sheds light on the relationship between lattice defects and thermal stability, and meanwhile offers a new strategy for the development of ATQ phosphors.