The manipulation of the microstructure of functional metal oxides using aerosol assisted chemical vapour deposition

• Main Author: Kaye, Karl
• Other Authors: Hyett, Geoffrey
• Published: University of Southampton 2016
• Subjects: 541
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690317

The presence of organic ionic additives during aerosol assisted chemical vapour deposition of zinc oxide has a profound influence on the microstructure of the resulting films. Growth of crystallites can be controlled to grow a range of shapes, including irregular shaped clusters, individual hexagonal plates and stacks of plates growing perpendicular to the substrate. During testing of organic additives in the deposition of zinc oxide via aerosol assisted chemical vapour deposition, urea was found to result in the formation of zinc carbodiimide. By adjusting the parameters it was determined that a temperature of 450 °C and a molar ratio of 3:1 of urea:zinc acetate are ideal conditions to form uniform films of zinc carbodiimide. This is the first example of the formation of a thin film of zinc carbodiimide. By using a mixed solution of zinc acetate and titanium (IV) isopropoxide, it is possible to deposit mixed phase films of zinc oxide, titanium dioxide and various zinc titanate phases. Stepwise treatment of these films with dilute acid and hydrogen results in the leeching of the zinc phases. The resulting films are composed of porous titanium dioxide which exhibits greater photocatalytic activity than dense films of titanium dioxide. By using a solution of tetrakis (diethylamido) titanium in hexane or toluene, it is possible to deposit a thin film of titanium nitride onto float glass in a single step at temperatures as low as 350 °C. Introduction of ethyl acetate results in the formation of thin films comprised of phases of both titanium nitride and titanium dioxide.