Symmetry Models in Solid State Chemistry

Abstract

One aspect of solid state chemistry which has flourished in recent years is the ability of chemists to synthesize new and exciting materials. Unfortunately, the synthesis of most advanced materials has been directed toward applications; as a result, solid state chemistry has become a collection of unrelated topics. Furthermore, chemistry departments have been slow in accepting the solid state as a part of chemistry. Part of the problem is that chemists are obsessed with molecules. Even the models of crystal structures which have been used for almost 75 years are an outgrowth of molecular models (i.e. ball-and-stick models). Our laboratory, has devoted many years to the systematic preparation and characterization of fundamental inorganic systems and we have concluded that the structural behavior of non-molecular solids may be explained better through symmetry models. Our models employ two aspects of symmetry: (1) fundamental structures are represented by tilings and/or packings and (2) dynamic behaviors involving structural changes are governed by laws of symmetry. Results which support these conclusions are presented in this paper.