We propose a microscopic method for modeling atomic ordering effects in multi-component solid solutions, which is based on minimizing the number of unfavorable interatomic bonds in the system. Atomic ordering effects are studied in the solid solutions Si{ 6-x}AlxOxN{ 8-x} (beta-SiAlONs) and hypothetical Si{ 6-x}BexO{ 2x}N{ 8-2x} in the beta-Si3N4-Be-O system. It is established that in beta-SiAlONs, Al,O atoms form separate quasi-one-dimensional ``channels''. On the contrary, in Si{ 6-x}BexO{ 2x}N{ 8-2x}, Be and O atoms constitute a whole cluster. This means that homogeneous solid solutions cannot be formed in the beta-Si3N4-Be-O system under equilibrium conditions.
Categories: cond-mat.mtrl-sci
