Simulation of Al/Fe disorder in Ca2Fe Al2−O5
2002; Elsevier BV; Volume: 63; Issue: 4 Linguagem: Inglês
10.1016/s0022-3697(01)00212-8
ISSN1879-2553
AutoresMatthew O. Zacate, Robin W. Grimes,
Tópico(s)Advanced Condensed Matter Physics
ResumoA method is described which is capable of simulating disorder across a range of composition. It is used to study the disorder of iron and aluminium on the octahedral and tetrahedral cation sites in the Brownmillerite phase Ca2FexAl2−xO5. The arrangements with the lowest lattice energies are those that maximize the number of Fe3+ on octahedral sites throughout the composition range. An exchange of one Fe3+ with one Al3+, which results in a decrease in the number of iron ions on octahedral sites, increases the lattice energy by an amount that is dependent on x but is independent of the number of exchanges. The exchange of trivalent cations also results in an expansion in the b lattice direction, accompanied by a decrease in the a and c directions across the full range of composition.
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