Surface Relaxation and Size Effects in Perovskite Type Ferroelectrics

钙钛矿型铁电体的表面弛豫和尺寸效应

• 批准号: 12650011
• 负责人: ISHIKAWA Kenji
• 金额: $ 1.92万
• 依托单位: Yokkaichi University (2001-2002)Shizuoka University (2000)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650011/
• 关键词: ferroelectrics; size effect; nano-crystal; phase transition temperature; surface relaxation; BaTiO_3; PbTiO_3; SrTiO_3

The purpose of this research is to investigate the origin of the size effect on the ferroelectric phase transition in perovskite type oxides such as barium titanate (BT), lead titanate (PT), strontium titanate (ST) and mixed crystals of BT and ST.The samples of several to several hundred nanometer in diameter were prepared through an alkoxide route. The average size and surface relaxation were examined by X-ray diffraction measurements. The results show that the lattice parameter of the nanoparticle becomes large compared to that of bulk crystal.Detailed analysis of the XRD patterns shows that crystal lattice on the surface expands towards the outside by 0.035 nm in PT, 0.015 nm in BT and 0.001 nm in ST. Mixed crystals show intermediate character.Computer simulation was performed for BT clusters of 25 to 100 atoms using ab initio ultra soft pseudopotentials. The electron distribution calculated shows the atomic binding changes from covalent to an ionic one.We conclude that the size effect originates from the unavoidable change in the bond nature near the surface of the nanoparticle.

本研究的目的是探讨钙钛矿型氧化物如钛酸钡（BT）、钛酸铅（PT）、钛酸锶（ST）以及BT和ST的混晶中铁电相变的尺寸效应的起源。通过X射线衍射测量检查的平均尺寸和表面松弛。结果表明，纳米粒子的晶格常数比体相晶体的晶格常数变大，XRD分析表明，纳米粒子表面的晶格向外扩展了0.035 nm，BT团簇为0.015nm，ST团簇为0.001nm，混合晶体为中间晶体，用ab第一性超软赝势计算的电子分布表明，纳米粒子表面的原子键合由共价键变为离子键，说明纳米粒子的尺寸效应是由于纳米粒子表面的键合性质发生了不可避免的变化。

项目成果

Desheng Fu: "Dielectric and Piezoelectric Properties of Pb(Zr_<0.53>Ti_<0.47>)O_3-Pb(Mg_<1/3>Nb_<2/3>)O_3 Multi-layer Thin Films"Ferroelectrics. Vol.270. 185-190 (2002)

付德胜：“Pb(Zr_<0.53>Ti_<0.47>)O_3-Pb(Mg_<1/3>Nb_<2/3>)O_3多层薄膜的介电和压电性能”铁电体。

Desheng Fu, Hisao Suzuki and Kenji Ishikawa: "Size-induced phase transition in PbTiO_3 nanocrystals: Raman scattering study"Phys. Rev. B. Vol. 62, No. 5. 3125-3129 (2000)

付德胜、铃木久男、石川健二：“PbTiO_3纳米晶体中尺寸诱导的相变：拉曼散射研究”Phys.

Shin Tsunekawa, Kenji Ishikawa, Zhi-Qiang Li, Yoshiyuki Kawazoe and Kasuya Atsuo: "Origin of anomalous lattice expansion in oxide nanoparticles"Phys. Rev. Letters. Vol. 85, No. 16. 3440-3443 (2000)

Shin Tsunekawa、Kenji Ishikawa、Zhi-Qiang Li、Yoshiyuki Kawazoe 和 Kasuya Atsuo：“氧化物纳米粒子中异常晶格膨胀的起源”Phys。

D.S.Fu: "Long-Time Piezoelectric Relaxation in Lead Zirconate Titanate Thin Film"Jpn. J. Appl. Phys.. 41. L580-L580 (2002)

D.S.Fu：“锆钛酸铅薄膜中的长时间压电弛豫”Jpn。

H.Suzuki: "Microstructure control of porous mullite ceramic by gel-casting"Key Engineering Materials. 206-21. 2021-2024 (2002)

H.Suzuki：“凝胶注模法控制多孔莫来石陶瓷的微观结构”关键工程材料。