Narrow-Band Deep-Blue Emission and Superior Thermal Stability of Fluoroaluminate Phosphor Based on Tungsten Bronze-Type Mineral Structure

Screening novel narrow-band phosphors inspired by natural mineral structures is urgently demanded for improving the performance of phosphor-converted light-emitting diodes. In this work, a novel narrow-band deep-blue-emitting tungsten bronze-type KCaAl(2)F(9):Eu(2+) phosphor with superior thermal stability is successfully synthesized. Structural analysis shows that the representative KCaAl(2)F(9):0.013Eu(2+) phosphor crystallizes in an orthorhombic space group C222(1) with a rigid network. The rigid [AlF(6)](3−) octahedrons are linked together by sharing corners to build endless [AlF(6)](3−)(∞) chains, further stacking with each other in a highly cross–linked way to establish the rigid network of the KCaAl(2)F(9) host. Benefiting from the rigid microenvironment, the developed phosphor not only shows a narrow-band deep-blue emission with a full width at half maximum of 45 nm and a high color purity of 92%, but it also exhibits the superior thermal stability with an emission loss of only 10% at 423 K, demonstrating its application potential in bridging the deep-blue spectral cavity toward sunlight-like full-spectrum lighting. In addition, the concentration/temperature quenching behaviors of KCaAl(2)F(9):Eu(2+) phosphor are systematically investigated. By revealing the specific structure–property relationship of tungsten bronze-type KCaAl(2)F(9):Eu(2+) phosphor, the present study provides a significant guide for identifying the novel narrow-band deep-blue-emitting component applicable to full-spectrum warm white light-emitting diode devices.