AVS 53rd International Symposium
    Thin Film Tuesday Sessions
       Session TF-TuP

Paper TF-TuP27
Zirconia in Sputter Deposited Oxide Nanolaminate Films: Interfacial Structures, Size Effects, and Metastable Phases

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Thin Film Poster Session
Presenter: C.R. Aita, University of Wisconsin-Milwaukee
Authors: C.R. Aita, University of Wisconsin-Milwaukee
R.S. Sorbello, University of Wisconsin-Milwaukee
Correspondent: Click to Email
The interfacial structure of ZrO@sub 2@ with its oxide partner in ZrO@sub 2@-Al@sub 2@O@sub 3@, ZrO@sub 2@-Y@sub 2@O@sub 3@, and ZrO@sub 2@-TiO@sub 2@ nanolaminate films is investigated here. The films were grown on unheated substrates by sequential reactive sputter deposition from metal targets in O@sub 2@-bearing discharges. This set of nanolaminates provides a model of interfaces formed under three different conditions for chemical cation mixing and physical atomic registry (heteroepitaxy or pseudomorphism). Bulk ZrO@sub 2@ and Al@sub 2@O@sub 3@ are insoluble. Neither interfacial cation mixing or atomic registry occurs. Al@sub 2@O@sub 3@ serves as ZrO@sub 2@ growth termination and restart layers in a nanolaminate, leading to tetragonal ZrO@sub 2@ formation in thin ZrO@sub 2@ layers via surface energy considerations. Bulk ZrO@sub 2@ and Y@sub 2@O@sub 3@ are mutually soluble and have a common fluorite-type cubic lattice. Both cation mixing and heteroepitaxy leads to needle-like mixed cation nanocrystals. TheZrO@sub 2@-TiO@sub 2@ system is more complex. Bulk (Zr,Ti)-oxide phases have an orthorhombic lattice, different from any ambient pressure phase of bulk ZrO@sub 2@ or TiO@sub 2@. Although there is a driving force for cation mixing, there is no obvious path to achieve it via formation of a crystalline substitutional solid solution with a lattice structure that is common to the end-members. However, we identify the following path: tetragonal rutile-type (P42/mnm) - orthorhombic columbite-type (Pbcn) - monoclinic baddelyite-type (P21/c) for structure evolution, unusual because it involves the formation of high pressure phases, stabilized here by the Gibbs-Thomson effect. When applied to Zr@sub x@,Ti@sub (1-x)@O@sub 2@ with increasing x where 0