Some remarks on substitution effects in sodalites

Some recent examples of substitution effects in the three partial structures of selected sodalites are presented. Framework-cation, and cage-cation substitution effects are discussed for the series |(EuxCa2–x)4(OH)8|[(Al2+xSi1–x)4O24]-SOD, cage-anion substitutions for |Ca8[(WO4)x(MoO4)1–x]2|[Al12O24]-SOD. While in a first approximation decomposition into partial structures seems reasonable, it is shown that, however, effects arising from substitutions in one partial structure are not limited to it. This is due to the fact that three main interactions have to be considered, namely, cage-cation – framework, cage-anion – framework, and cage-cation – cage-anion interactions. These can be co-operative or competitive and may lead to structural frustrations.