Elucidating Structure–Composition–Property Relationships of the β-SiAlON:Eu2+ Phosphor

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• 作者：Zhenbin Wang ; Weike Ye ; Iek-Heng Chu ; Shyue Ping Ong
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：December 13, 2016
• 年：2016
• 卷：28
• 期：23
• 页码：8622-8630
• 全文大小：542K
• ISSN：1520-5002

文摘

In this work, we performed a systematic investigation of structure–composition–property relationships in Eu<sup>2+sup>-activated β-SiAlON, one of the most promising narrow-band green phosphors for high-power light-emitting diodes and liquid crystal display backlighting with wide color gamut. Using first-principles calculations, we identified and confirmed various chemical rules for Si–Al, O–N, and Eu activator ordering within the β-SiAlON structure. Through the construction of energetically favorable models based on these chemical rules, we studied the effect of oxygen content and Eu<sup>2+sup> activator concentrations on the local EuN<sub>9sub> activator environment, and its impact on important photoluminescence properties such as emission peak position (using the band gap as a proxy), bandwidth, and thermal quenching resistance. Increasing oxygen content is shown to lead to an increase in Eu–N bond lengths and distortion of the EuN<sub>9sub> coordination polyhedron, modifying the crystal field environment of the Eu<sup>2+sup> activator, and resulting in red-shifting and broadening of the emission. We also show that the calculated excited band structure of β-SiAlON exhibits a large gap between the 5d levels and the conduction band of the host, indicating a large barrier toward thermal ionization (>0.5 eV) and, hence, excellent thermal quenching stability. Based on these insights, we discuss potential strategies for further composition optimization of β-SiAlON.