Avoiding Binary Compounds as Reaction Intermediates in Solid State Reactions

Preparing new ternary compounds via traditional high temperature synthesis techniques is essentially limited to ternary compounds that are thermodynamically more stable than any mixture of binary compounds because binary compounds typically form as reaction intermediates. By using a precursor having elemental layers thinner than a critical thickness, it is possible to decrease diffusion times such that the layers interdiffuse before nucleation of binary compounds occurs at reacting interfaces. To nucleate the ternary compounds CuInSe2 and CuCr2Se4 directly from amorphous reaction intermediates, however, it is shown to be necessary to use the order of the elemental layers to control of the order of mixing of the elemental layers. Controlling layer thickness and layer sequence is a general strategy for avoiding binary compounds as reaction intermediates, providing a general approach to preparing kinetically stable ternary compounds.