title: Ab initio study of the effect of Si on the phase stability and electronic structure of γ- and α-Al2O3.
abstract: Using density functional theory, the effect of Si on the stability and electronic structure of γ- and α-Al2O3 has been investigated. The concentration range from 0 to 5 at.% is probed and the additive is positioned at different substitutional sites in the γ-phase. The calculations for (Al,Si)2O3 predict a trend towards spontaneous decomposition into α-/γ-Al2O3 and SiO2. Therefore, the formation of the metastable γ-(Al,Si)2O3 phase can only be expected during non-equilibrium processing where the decomposition is kinetically hindered. The Si-induced changes in stability of this metastable solid solution may be understood based on the electronic structure. As the Si concentration is increased, stiff silicon-oxygen bonds are formed giving rise to the observed stabilization of the γ-phase.
authors: Materials Chemistry, RWTH Aachen University, Aachen, Germany. nahif@mch.rwth-aachen.de
authors: F
authors: F
authors: Nahif
authors: D
authors: D
authors: Music
authors: S
authors: S
authors: Mráz
authors: M
authors: M
authors: to Baben
authors: J M
authors: JM
authors: Schneider