Selective reaction and chemical anisotropy in epitaxial bismuth layer-structured ferroelectric thin films
- Department of Innovative and Engineered Materials, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)
- Department of Innovative and Engineered Materials, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan) and PRESTO, Japan Science and Technology Corporation (JST), 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)
Bismuth layer-structured ferroelectric thin films consisting of a stacking of pseudoperovskite and bismuth oxide blocks along the c-axis were epitaxially grown on single-crystal substrates by metalorganic chemical vapor deposition (MOCVD), and a selective reaction of the bismuth oxide layer with HCl was demonstrated. Epitaxial films with contrasting crystal orientations were used for the acid treatment in order to probe chemical anisotropy. For a/b-axis-oriented SrBi{sub 2}Ta{sub 2}O{sub 9}, Bi{sub 4}Ti{sub 3}O{sub 12}, and SrBi{sub 4}Ti{sub 4}O{sub 15} films with sequential stacking of the two vertical blocks, notable structural selectivity of the reaction was observed only for SrBi{sub 2}Ta{sub 2}O{sub 9}. For this film, the pseudoperovskite block remained and the bismuth oxide block was removed, while both blocks of Bi{sub 4}Ti{sub 3}O{sub 12} and SrBi{sub 4}Ti{sub 4}O{sub 15} dissolved into the acid. In addition to the bismuth, the other cations in the pseudoperovskite blocks, strontium and titanium, also decreased for Bi{sub 4}Ti{sub 3}O{sub 12} and SrBi{sub 4}Ti{sub 4}O{sub 15}. The selective reaction observed for a/b-axis-oriented SrBi{sub 2}Ta{sub 2}O{sub 9}, however, was not observed for c-axis-oriented SrBi{sub 2}Ta{sub 2}O{sub 9} films in which the pseudoperovskite and bismuth oxide blocks were stacked horizontally. The results clearly show that SrBi{sub 2}Ta{sub 2}O{sub 9} has sub-nano-order structural selectivity and chemical anisotropy in the unit cell in the reaction with HCl.
- OSTI ID:
- 20721667
- Journal Information:
- Journal of Solid State Chemistry, Vol. 178, Issue 1; Other Information: DOI: 10.1016/j.jssc.2004.10.019; PII: S0022-4596(04)00553-5; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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