Origin of blue emission of phosphors prepared by a solid-state reaction of Eu³⁺-doped LaCO₃OH with Al₂O₃ in a hydrogen atmosphere

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• 作者：Min-Ho Lee ; Woo-Sik Jung ; ^{wsjung@yu.ac.kr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Luminescence ; Blue emission ; Eu3+-doped LaCO3OH ; Eu3+-doped LaAlO3 ; Eu2+-doped lanthanum hexaaluminate
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：1424-1428
• 全文大小：716 K

文摘

The phosphor powders prepared by calcining mixtures (1:1, 1:2, and 1:3 mol ratios) of Eu³⁺-doped lanthanum(III) hydroxycarbonate (LaCO₃OH:Eu³⁺) and δ-alumina (δ-Al₂O₃) powders under a mixed gas flow of H₂ and N₂ exhibited orange (593 and 617 nm) and blue (441 nm) emission peaks, which were associated with Eu³⁺-doped lanthanum aluminate (LaAlO₃:Eu³⁺) and Eu²⁺-doped lanthanum hexaaluminate (La_0.827Al_11.9O_19.09:Eu²⁺) phosphors, respectively. The relative amount of the latter phosphor increased with increasing reaction temperature and relative amount of δ-Al₂O₃ in the mixture. The conclusion that the blue emission is not associated with LaAlO₃:Eu²⁺ but La_0.827Al_11.9O_19.09:Eu²⁺ was supported by the following experimental results: the reduction of LaAlO₃:Eu³⁺ did not give a blue emission; Eu²⁺ ions occupied more than one site in the host; the line shape and position of the blue emission band were close to those of the single La_0.827Al_11.9O_19.09:Eu²⁺ phase. No formation of LaAlO₃:Eu²⁺ might be due to the increase in the ionic radius caused by the reduction of Eu³⁺ to Eu²⁺.