Structural properties of liquid Al2O3 : A molecular dynamics study

• Molecular dynamics (MD) simulations of liquid aluminum oxide (Al2O3) were carried out on a system with up to 1800 particles, using a pairwise potential. All simulations were done in the microcanonical ensemble, for two densities, 3.0 and 3.175 g/cm(3), at temperatures of 2200, 2600, and 3000 K. A detailed analysis of the interatomic distances, given by the partial pair-distribution functions and the bond-angles distribution, reveals that in the liquid state there is st short range order dominated by a somewhat distorted (AlO4)(5-) tetrahedron, in agreement with recent experimental measurements. This conclusion is supported by the distribution of nearest-neighbor coordinations, where more than 60% of Al atoms have four O as nearest neighbors. This finding does not change over the explored temperature range. Because of the presence of twofold rings, the connectivity of (AlO4)(5-) units consists of corner, edge, and face sharing tetrahedra. Based in this structural information, i.e., bond lengths, coordination numbers, bond-angle distributions, and ring statistics, our MD simulation allows us to put forward a possible structure of liquid Al2O3.

Nyckelord

aluminum-oxide

system cao-mgo-al2o3-sio2

gamma-alumina

bulk moduli

simulation

transformation

polymorphs

pressure

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