Crystal structures bonds and reliance in MX (M = La, Ce...Yb and Sc, Ti...Zn; X = S, Se, Te)

Abstract

Large variations of the molecular volume of the monochalcogenides of rare earths are attributed to cation-cation bond which involves one deep valence electron. Similar results are found with monochalgenides of 3d metals. The phase transformation Ceγ ⇄ Ceα is interpreted in a similar way bearing in mind the existence of compounds such as XeF4. This work introduces the notion of reliance which enlightens the notion of valence and is closely related, to the notion of intermediate and fluctuating valences.