The indium chalcogenides include all compounds of indium with the chalcogen elements, oxygen, sulfur, selenium and tellurium.
This group of compounds has attracted a lot of research attention because they include semiconductors, photovoltaics and phase-change materials.
Some compounds that were reported and have found their way into text books have not been substantiated by later researchers.
None of the indium chalcogenides can be described simply as ionic in nature, they all involve a degree of covalent bonding.
Compounds almost invariably have multiple polymorphs, that is they can crystallise in slightly different forms depending on either the method of production, or the substrate upon which they are deposited.