Atomic ordering effects and bond indices in quaternary systems Si-(Be,Al)-O-N

TL;DR

This paper introduces a microscopic method for modeling atomic ordering in multi-component solid solutions, revealing distinct atomic arrangements in different systems and implications for their formation.

Contribution

A new microscopic approach for analyzing atomic ordering effects in multi-component solid solutions, applied to beta-SiAlONs and Si-B-O-N systems.

Findings

Al and O form quasi-one-dimensional channels in beta-SiAlONs

Be and O form clusters in Si-B-O-N systems

Homogeneous solutions are unlikely in the Si-B-O-N system under equilibrium

Abstract

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.