STATISTICAL MECHANICS ANALYSIS OF THE ORDERING OF SI AND AL ATOMS IN ALBITE BY THE CLUSTER VARIATION METHOD

Abstract

The temperature dependence of the distribution of Al and Si in tetrahedral positions in the feldspar lattice has been studied experimentally for a rather long time. Recent publications present a theoretical analysis of the problem based on a quasichemical approximation. The present paper proposes a more rigorous approach in which the cluster variation method is used to obtain the best self-consistent approximation of the combinatorial multipliers that define the entropy of the crystals. The theoretical analysis allows for local effective-charge balance.