Superstructure of Mullite-type KAl9O14

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• 作者：Biljana Lazic ; Hannes Kr眉ger ; Reinhard Kaindl ; Lukas Perfler ; Aleksandar Kremenovi膰 ; Vladica Cvetkovi膰 ; Ray L. Withers
• 刊名：Chemistry of Materials
• 出版年：2013
• 出版时间：February 12, 2013
• 年：2013
• 卷：25
• 期：3
• 页码：496-502
• 全文大小：545K
• 年卷期：v.25,no.3(February 12, 2013)
• ISSN：1520-5002

文摘

Large whiskers of a new KAl₉O₁₄ polymorph with mullite-type structure were synthesized. The chemical composition of the crystals was confirmed by energy-dispersive X-ray spectroscopy, and the structure was determined using single-crystal X-ray diffraction. Nanosized twin domains and one-dimensional diffuse scattering were observed utilizing transmission electron microscopy. The compound crystallizes in space group P2₁/n (a = 8.1880(8), b = 7.6760(7), c = 8.7944(9) 脜, 尾 = 110.570(8)掳, V = 517.50(9) 脜³, Z = 2). Crystals of KAl₉O₁₄ exhibit a mullite-type structure with linear edge-sharing AlO₆ octahedral chains connected with groups of two AlO₄ tetrahedra and one AlO₅ trigonal bipyramid. Additionally, disproportionation of KAl₉O₁₄ into K 尾-alumina and corundum was observed using in situ high-temperature optical microscopy and Raman spectroscopy.

Keywords:

whiskers; mullite-type; superstructure; diffuse scattering; stacking faults