Ca18.75Li10.5[Al39N55]:Eu2+—Supertetrahedron Phosphor for Solid-State Lighting

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• 作者：Peter Wagatha ; Philipp Pust ; Volker Weiler ; Angela S. Wochnik ; Peter J. Schmidt ; Christina Scheu ; Wolfgang Schnick
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：February 23, 2016
• 年：2016
• 卷：28
• 期：4
• 页码：1220-1226
• 全文大小：425K
• ISSN：1520-5002

文摘

Highly efficient red-emitting luminescent materials deliver the foundation for next-generation illumination-grade white light-emitting diodes (LEDs). Recent studies demonstrate that the hardly explored class of nitridoaluminates comprises intriguing phosphor materials, e.g., Sr[LiAl<sub>3sub>N<sub>4sub>]:Eu<sup>2+sup> or Ca[LiAl<sub>3sub>N<sub>4sub>]:Eu<sup>2+sup>. Here, we describe the novel material Ca<sub>18.75sub>Li<sub>10.5sub>[Al<sub>39sub>N<sub>55sub>]:Eu<sup>2+sup> with highly efficient narrow-band red emission (λ<sub>emsub> ≈ 647 nm, full width at half-maximum, fwhm ≈ 1280 cm<sup>–1sup>). This compound features a rather uncommon crystal structure, comprising sphalerite-like T<sub>5sub> supertetrahedra that are composed of tetrahedral AlN<sub>4sub> units that are interconnected by additional AlN<sub>4sub> moieties. The network charge is compensated by Ca<sup>2+sup> and Li<sup>+sup> ions located between the supertetrahedra. The crystal structure was solved and refined from single-crystal and powder X-ray diffraction data in the cubic space group Fd3̅m (No. 227) with a = 22.415(3) Å and Z = 8. To verify the presence of Li, transmission electron microscopy (TEM) investigations including electron energy-loss spectroscopy (EELS) were performed. Based on the intriguing luminescence properties, we proclaim high potential for application in high-power phosphor-converted white LEDs.