Special quasirandom structures of alon

The crystal structure of Al23O27N5, which is an ideal stoichiometry of aluminum oxynitride (or alon), is a defect spinel in which a vacancy is present in the unit cell. Despite the lattice positions being fixed, the location of the vacancy and the positions of the five nitrogen atoms are not unique, presenting a challenge to the prediction of the crystal structure. This problem is analogous to random alloys, for which a technique has been developed to identify small scale simulation cells called special quasirandom structures (SQS). We present SQS for alon, and discuss the unique features of these structures for this material. We also modified the SQS methodology to identify the first cubic crystal structure for alon with the above stoichiometry. Published by Elsevier B.V.