A first-principles investigation of interfacial properties and electronic structure of SiO2/Al interface

The structural, adhesive and electronic properties of a SiO2/Al interface are investigated via first-principles calculations. The SiO2/Al interface is constructed based on SiO2 (0001) and Al (1 1 1) planes, which are respectively the close-packed planes of SiO2 and Al with a lattice mismatch of less than 1% between them. Our calculations indicate that among three differently terminated SiO2 (0001) surfaces, the SiO2 (0001) surface terminated with two oxygen atoms is the most stable one with the smallest surface energy of 1.36 J/m(2). Among three differently stacked O-terminated SiO2 (0001)/Al (1 1 1) interfaces (hollow, top and bridge), the hollow-site SiO2/Al interface has not only the smallest interfacial energy of 1.345 J/m(2) but also the largest work of adhesion of 2.51 J/m(2), and hence is the most stable one. Electronic structure investigations show that polar covalent bonding exists in the SiO2/Al interface, which can mainly be attributed to the interaction between electrons from s and p orbitals of the interfacial O atoms and those from p orbitals of the interfacial Al atoms. Coulomb's law calculations reveal that the interfacial Al-O bonding is weaker than the Si-O bonding in the bulk SiO2. Through the present investigation, an enhanced understanding of the interfacial bonding is obtained and several data are given which are very useful for the optimum design and multi-scale simulations of oxidized-SiC reinforced aluminum matrix composites.