Characterizing modulated structures with first-principles calculations: a unified superspace scheme of ordering in mullite

作     者：Klar, Paul Benjamin Etxebarria, Inigo Madariaga, Gotzon 

作者机构：Univ Basque Country UPV EHU Fac Ciencia & Tecnol Dept Fis Mat Condensada Apartado 644 E-48080 Bilbao Spain Univ Basque Country UPV EHU Fac Ciencia & Tecnol Dept Fis Aplicada 2 Apartado 644 E-48080 Bilbao Spain 

出 版 物：《ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES》 (Acta crystallogr., A Found. Adv.)

年 卷 期：2019年第75卷第2期

页      面：260-272页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0702[理学-物理学] 

基　　金：Spanish government (Ministerio de Economia y Competitividad) FEDER funds [MAT2015-66441-P] Basque government [IT-779-13] Basque government 

主　　题：density functional theory (DFT) superspace modulation functions Al/Si ordering silicates mullite 

摘      要：The benefit of computational methods applying density functional theory for the description and understanding of modulated crystal structures is investigated. A method is presented which allows one to establish, improve and test superspace models including displacive and occupational modulation functions from firstprinciples calculations on commensurate structures. The total energies of different configurations allow one to distinguish stable and less stable structure models. The study is based on a series of geometrically optimized superstructures of mullite (A(l4+2x)Si(2-2x)O(10-x)) derived from the superspace group Pham(alpha 01/2)0ss. Despite the disordered and structurally complex nature of mullite, the calculations on ordered superstructures are very useful for determining the ideal Al/Si ordering in mullite, extracting atomic modulation functions as well as understanding the SiO2-Al2O3 phase diagram. The results are compared with experimentally established models which confirm the validity and utility of the presented method.