Selective reaction and chemical anisotropy in epitaxial bismuth layer-structured ferroelectric thin films

Journal Article · Sat Jan 15 04:00:00 EST 2005 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2004.10.019· OSTI ID:20721667

Watanabe, Takayuki ^[1]; Funakubo, Hiroshi ^[2]

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1. 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)
2. 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, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANISOTROPY
BISMUTH
BISMUTH OXIDES
CHEMICAL VAPOR DEPOSITION
EPITAXY
FERROELECTRIC MATERIALS
LAYERS
MONOCRYSTALS
THIN FILMS