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

详细信息	查看全文 | 推荐本文 |

• 作者：Watanabe ; Takayuki ; Funakubo ; Hiroshi
• 关键词：Intercalation ; Proton ; Epitaxial film ; Layer structure ; Bismuth layer-structured ferroelectrics
• 刊名：Journal of Solid State Chemistry
• 出版年：2005
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：January, 2005
• 卷：178
• 期：1
• 页码：64-71
• 文件大小：2.09 M

摘要

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 SrBi₂Ta₂O₉, Bi₄Ti₃O₁₂, and SrBi₄Ti₄O₁₅ films with sequential stacking of the two vertical blocks, notable structural selectivity of the reaction was observed only for SrBi₂Ta₂O₉. For this film, the pseudoperovskite block remained and the bismuth oxide block was removed, while both blocks of Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅ dissolved into the acid. In addition to the bismuth, the other cations in the pseudoperovskite blocks, strontium and titanium, also decreased for Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅. The selective reaction observed for a/b-axis-oriented SrBi₂Ta₂O₉, however, was not observed for c-axis-oriented SrBi₂Ta₂O₉ films in which the pseudoperovskite and bismuth oxide blocks were stacked horizontally. The results clearly show that SrBi₂Ta₂O₉ has sub-nano-order structural selectivity and chemical anisotropy in the unit cell in the reaction with HCl.