O. Glenn Ramer

Synthesis of water soluble precursors for ferroelectric materials

Abstract Solution deposition processes for the production of thin multi-element metal oxide films continue with great interest and varied success. Solution deposition via either sol-gel or MOD (Metal Organic Decomposition) methods are of interest due to the ability to produce a wide variety of compositional products at low capital investment cost. The sol-gel method generally uses hydrolytically sensitive metal alkoxides as the starting materials. Manipulation of the reagents and different hydrolysis rates for multi-element mixtures are issues. The MOD method utilizes large organic acid metal salts as the starting materials. In general, MOD solutions are more hydrolytically stable than the sol-gel solutions. MOD process challenges include large quantities of carbon to be decomposed during the firing, variable chemistry in synthesis of the starting materials (especially when the starting materials for the MOD precursors are metal alkoxides), and long reaction times for the synthesis. For both the current state of the art sol-gel and MOD precursors, toxic and volatile solvents are employed as the vehicle. This paper will review the chemistry related issues to production of consistent high quality metal oxide films via the MOD process. The solid solution BaxSr(1-x)TiO3 will be used as an example. A new technique to quickly obtain controlled carbon content MOD precursor solutions from available starting materials is described. Several new water stable and water soluble BST precursors are described. Details of the electrical properties of capacitors made from the new water based precursors are shown.