Chapter 10 Crystalline Chain Compounds

This chapter discusses crystalline chain compounds and the systems that consist of more or less weakly interacting chains. The crystalline systems consist of more than one type of atoms. Therefore, the properties of these materials are markedly influenced by the fact that the systems are true three-dimensional ones, which is a clear difference from many of the systems. For those systems, the three-dimensional structure provides a frame for stabilizing chains whose intrinsic properties are largely determined by the intrachain interactions and, only to a smaller extent, by the interactions between the individual chains and their surroundings. CaNiN demonstrates this aspect. Theoretical studies can be used to decompose the interactions into those by charge transfers between the NiN chains and the Ca counterions and those from interactions among the NiN chains. Although these interactions are non-negligible, it is clear that the electronic properties are primarily due to the individual (and charged) NiN chains.