Cation distribution in magnetoplumbite and β′′-alumina structures

• Published in: Materials letters 1990-07, Vol.9 (11), p.474-479
• Main Authors: Xie, Like, Cormack, A.N.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Exact sciences and technology; Impurities: concentration, distribution, and gradients; Physics; Structure of solids and liquids; crystallography
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/0167-577X(90)90121-2

Atomistic computer simulation techniques have been used to investigate the structural features influencing relative cation enrichments in magnetoplumbite structure based on A1 2O 3 and β′′-alumina. The simulation results indicate that, like in spinel structure, Mg 2+, Co 2+, Mn 2+, Zn 2+, and Fe 2+ ions strongly prefer a tetrahedral coordinated environment in both magnetoplumbite and β′′-alumina structures. Due to its large octahedral site preference energy, Cr 3+ ion is enriched in octahedral sites. Therefore, in general, the normal site preferences of cations for tetrahedral or octahedral sites are paralleled in magnetoplumbite and β′′-alumina structures, but in the case of Ni 2+, the crystal structure has an effect on its distribution. There is a mixed Ni 2+ ion distribution among both tetrahedral and octahedral sites, with the tetrahedral site being more energetically favorable in both structures. More detailed site preferences of Ni 2+ ions in the presence of Zn 2+ in magnetoplumbite structure are also reported in this study.