DYNAMICS OF LATTICE STRAIN FIELD NEAR PHASE TRANSITION

近相变晶格应变场动力学

• 批准号: 09440133
• 负责人: KAKURAI Kazuhisa
• 金额: $ 6.4万
• 依托单位: THE UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440133/
• 关键词: NEUTRON SCATTERING; SPIN ECHO SPECTROSCOPY; PHASE TRANSITION; 中性子錯乱

The aim of this project is the development of the thermal neutron spin echo spectroscopy for the detailed study of lattice dynamics near phase transition.1. For this purpose the newly developed thermal neutron spin echo option on ISSP-PONTA spectrometer has been improved.(1) Spin echo test experiment using neutron wave length λ=1.609Å has been performed. The use of this wave length pushes the lower limit of the dynamical time range down to 7 picosec, thus covering the dynamical range of 7 to 155 picosec by using both 1.609Å and 2.35Å wave length neutrons.(2) Spin echo experiment at large Q=2.9ÅィイD1-1ィエD1 has been successfully performed.(3) Pairs of gradient coils have been designed constructed and tested. These coils create additional neutron spin precession field integral component depending on the neutron flight paths within the divergence of the neutron beam and allow to match the slope of the spin echo line to the slope of the excitation dispersion to be studied (spin echo focussin … More g).2. Spin echo experiment at finite energy transfer and especially the use of above mentioned gradient coils demand the introduction of spin echo simulation program to plan and analyse the experiments.(1) Spin echo simulation program has been developed and is being tested.(2) The phonon line width measurement in SrTiO3 has been analysed using the simulation program.3. Few quasielastic thermal neutron spin echo experiments have been performed.(1) Slow spin dynamics in 2-D, triangular lattice system CuFeィイD20.95ィエD2AlィイD20.05ィエD2OィイD22ィエD2 has been studied, showing the static nature of the moment at low T in the time scale of 140 picosec.(2) Larmor spin precession phase shift near the magnetic satellite peak of Ho in transmission geometry has been observed for the first time.(3) Slow dynamics in Polybutadiene towards its glass transition at large Q=2.9ÅィイD1-1ィエD1 has been studied for the first time. The T-dependence of the dynamics at this large Q is found to be different than that of small Q sofar studied.4. Possible candidates to study the lattice distortions near phase transition with spin echo spectroscopy have been studied, especially the spin and lattice dynamics in the spin-Peierls system CuGeOィイD23ィエD2 and the charge ordering system NaVィイD22ィエD2OィイD25ィエD2 have been studied. Less

本项目的目的是发展热中子自旋回波谱，用于详细研究相变附近的晶格动力学1。为此，对ISSP-Ponta谱仪上新研制的热中子自旋回波选项进行了改进。(1)进行了中子波波长λ=1.609Å的自旋回波实验。该波长的使用将动力学时间范围的下限推低到7皮秒，从而覆盖了1.609Å和2.35Å波长中子的7-155皮秒的动力学范围。(2)成功地进行了大Q=2.9ÅィイD_1-1ィエD_1的自旋回波实验。(3)设计了多对梯度线圈并进行了测试。这些线圈根据中子束发散范围内的中子飞行路径创建额外的中子自旋进动场积分分量，并允许将自旋回波线的斜率与要研究的激发色散的斜率相匹配(…中的自旋回波焦点更多g)2.有限能量转移下的自旋回波实验，特别是上述梯度线圈的使用，需要引入自旋回波模拟程序来规划和分析实验。(1)自旋回波模拟程序已经开发完成并正在测试中。(2)利用模拟程序对钛酸锶声子线宽的测量进行了分析。(1)研究了二维三角形晶格系统CuFeィイD20.95ィエD2AlィイD20.05ィエD2OィイD22ィエD2的慢自旋动力学，表明在140pSec的时间尺度内，低T处的磁矩是静态的。(2)在透射层中首次观察到Ho的磁卫星峰附近的拉莫尔自旋进动相移。(3)首次研究了聚丁二烯在大Q=2.9ÅィイD~(-1)ィエD~(1)时向玻璃化转变的慢自旋动力学。发现在大Q下动力学的T依赖关系不同于目前所研究的小Q下的T依赖。研究了用自旋回波谱研究相变附近晶格畸变的可能方法，特别是研究了CuGeOィイD23ィエD2自旋-Peierls系统和电荷有序系统NAVィイD22ィエD2OィイD25ィエD2的自旋和晶格动力学。较少

项目成果

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Yoshihama T. 等人：“NaV_2O_5 中的自旋动力学 - 非弹性中子散射 -”J。

Nishi M. et al.: "New aspects of the b^*-LA phonon of CuGeO_3"J. Phys. Chem. Solods. 60. 1109-1112 (1999)

Nishi M. 等人：“CuGeO_3 的 b^*-LA 声子的新方面”J。

Nishi, M. et al.: "New aspects of the b^*-LA phonon of Cube O_3"J. Phys. Chem. Solids. 60. 1109-1112 (1999)

Nishi, M. 等人：“立方体 O_3 的 b^*-LA 声子的新方面”J。

Zeyen PHE et al.: "Thermal neutron spin echo 3-axis spectrometon with MeV resolution" Neutron News. 8. 7-10 (1997)

Zeyen PHE 等人：“具有 MeV 分辨率的热中子自旋回波 3 轴谱仪”中子新闻。

K. kakurai and Y. Morii: "Neutron Scattering Activities at JRR-3M"Neutron News. 9. 15-22 (1998)

K. kakurai 和 Y. Morii：“JRR-3M 的中子散射活动”中子新闻。