Methods of forming a material include exposing a substrate to a first germanium-containing compound and a second, different germanium-containing compound; exposing the substrate to a first antimony-containing compound and a second, different antimony-containing compound; and exposing the substrate to a first tellurium-containing compound and a second, different tellurium-containing compound. Methods of forming chalcogenide materials include exposing a substrate to a first precursor comprising a reactive precursor of a first metal and a co-reactive precursor of the first metal, the reactive precursor and the co-reactive precursor each having at least one ligand coordinated to an atom of the first metal, wherein the at least one ligand of the co-reactive precursor is different from the at least one ligand of the reactive precursor. The substrate is also exposed to a reactive antimony precursor and a co-reactive antimony precursor and to a reactive tellurium precursor and a co-reactive tellurium precursor.