Abstract: The present invention provides a vapour deposition process for the preparation of a phosphate compound, wherein the process comprises providing each component element of the phosphate compound as a vapour, and co-depositing the component element vapours on a common substrate, wherein the component elements react on the substrate to form the phosphate compound.

Abstract: The present invention provides a vapour deposition process for the preparation of a chemical compound, wherein the process comprises providing each component element of the chemical compound as a vapour, and co-depositing the component element vapours on a common substrate, wherein: the vapour of at least one component element is provided using a cracking source; the vapour of at least one other component element is provided using a plasma source; and at least one further component element vapour is provided; wherein the component elements react on the substrate to form the chemical compound.