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.

这项研究的目的是研究钙钛矿类型氧化物（例如钛盐盐（BT）（BT），钛酸铅（PT），钛酸盐（ST）和BT和ST的混合晶体，尺寸效应对铁电相型氧化物中的铁相变的起源。通过烷氧化途径制备了直径几到几百个纳米的样品。通过X射线衍射测量值检查了平均大小和表面弛豫。结果表明，与散装晶体相比，纳米颗粒的晶格参数变大。对XRD模式进行了详细分析表明，表面上的晶体晶格在pt中朝外0.035 nm扩展，在BT中，BT和0.001 nm IN 0.015 nm和0.001 nm英石。混合晶体显示了中间字符：使用Ab Itible Ultra Soft Pseudoptients对25至100个原子进行BT簇进行了模拟。计算出的电子分布显示了从共价到离子的原子结合变化。我们得出的结论是，尺寸效应源于纳米颗粒表面附近键的不可避免的变化。

项目成果

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。

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.

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。

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。

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。