Electron-densitiy distributions in transition-metal compounds-Observation by short wave-length SR.

过渡金属化合物中的电子密度分布 - 通过短波长 SR 观察。

• 批准号: 02044051
• 负责人: MARUMO Fumiyuki
• 金额: $ 2.24万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02044051/
• 关键词: Electron-Density Distribution; Transition Metal Compounds; Short Wavelength; Synchrotron Radiation; Extinction Correction; Perovskite-type Compounds; 単結晶構造解析; 積分強度; X線回折; 放射光; ペロブスカイト型構造; 温度因子; 超伝導

This project has been undertaken as an international joint program between Japanese and Australian crystallographers for the purpose of solving various experimental problems posed on an attempt to develop the X-ray diffraction technique to an promising analytical method for precise electron-distribution analysis in crystals. The primary concern was on establishment of a technique to remove the secondary extinction effects on the integrated intensities of X-rays diffracted from crystals by making use of short wavelength synchrotron radiations (SR). The obtained results can be summarized as follows :Integrated intensities of a spherically-shaped FeTiO_3 crystal with diameter of 145mum have been collected on a horizontal-type four circle diffractomator at the beam line 14A in the Photon Factory of the National Laboratory for High Energy Physics, Japan. Synchrotron radiations, emitted from the vertical wiggler and monochromatized to 0.34965(5) and 0.41996(14)* using an Si double-crystal mo … More nochromator, were employed for the data collection. Similar measurements were also carried out on the same crystal using AgKalpha (0.56087, *) and MoKalpha (0.71073*) radiations. The effect of secondary extinction on the diffraction data has been examined using these data sets taken with the four different wavelengths. It was revealed that the difference between the observed structure factors before and after the extinction correction was less than 4% at maximum in the 0.35* SR data, indicating that the extinction correction might be practically negligible for the data collected with X-rays of wavelength shorter than 0.3*. In the overall accuracy, however, the 0.35, * SR data were worse those taken with Mo Kalpha radiation because of the instability of the incident SR beam and enlarged errors in counting statistics of the diffracted beams due to the low fraction of the incident beam. The instability is supposed to be mainly caused by a steep drop of intensity against shortening of the wavelength in the case of SR emitted from the vertical wiggler in the wavelength region shorter than around 0.5*. In conclusion, it was suggested to use smaller crystals in combination with a strong and stable SR having a wavelength between 0.5 and 0.9* in place of a SR with a short wavelength such as 0.35* in order to avoid secondary extinction effects. Successful results have been obtained on crystals of K_2SiF_6 and KZnF_3 with dimensions of about 30mum in diameter, utilizing 0.7* SR. In addition, precise analyses of SR data from small crystals of KCuF_3, SrTiO_3, BaTiO_3 and La_<1.88>Sr_<0.12>CuO_4, which were obtained in almost extinction-free conditions, are now in progress and expected to give fruitful. results with respect to their electron-density distributions. Less

该项目是日本和澳大利亚晶体学家之间的国际联合项目，目的是解决各种实验问题，试图将X射线衍射技术发展为一种有前途的分析方法，用于精确分析晶体中的电子分布。主要关注的是建立一种技术，以消除二次消光效应的积分强度的X射线衍射晶体利用短波长同步辐射（SR）。在日本高能物理研究所光子工厂的水平型四圆衍射仪上，在14A光束线上，对直径为145 μ m的球形FeTiO_3晶体的积分强度进行了测量。用Si双晶单晶单色化器单色化到0.34965（5）和0.41996（14）* 的垂直扭摆器的同步辐射 ...更多信息 nochromonium用于数据收集。还使用AgK α（0.56087，*）和MoK α（0.71073*）辐射对同一晶体进行了类似的测量。二次消光对衍射数据的影响已被检查使用这些数据集与四个不同的波长。结果表明，在0.35* SR数据中，消光校正前后观测到的结构因子之间的差异最大小于4%，这表明对于波长小于0.3* 的X射线收集的数据，消光校正实际上可以忽略不计。然而，在总体准确度方面，0.35，* SR数据比Mo Ka辐射获得的数据更差，因为入射SR光束的不稳定性以及由于入射光束的低分数而导致的衍射光束计数统计误差扩大。不稳定性被认为主要是由强度急剧下降对缩短的波长的情况下，从垂直摆动器在波长区域短于约0.5* 发射的SR。总之，建议使用较小的晶体与具有0.5和0.9* 之间的波长的强且稳定的SR组合来代替具有诸如0.35* 的短波长的SR，以避免二次消光效应。在直径约30 μ m的K_2SiF_6和KZnF_3晶体上，利用0.7* SR已获得成功的结果。此外，在几乎无沉淀条件下获得的KCuF_3、SrTiO_3、BaTiO_3和La_ Sr_ CuO_4小晶体的SR数据的精确分析<1.88><0.12>正在进行中，并可望取得丰硕的成果。结果相对于其电子密度分布。少

项目成果

T.Ito,F.Marumo,T.Maslen,Y.Satw and K.Tanaka: "Accurate Diffraction Seudies of Perovskite Structures at Two Wevelength" Photon Factory Activity Report. 8. 282 (1990)

T.Ito、F.Marumo、T.Maslen、Y.Satw 和 K.Tanaka：“两个波长处钙钛矿结构的精确衍射研究”光子工厂活动报告。

M. Ohgaki, F. Marumo and K. Tanaka: "Integrated Intensities Collected with short Wavelength Xrays and Extinction Effects" Report of the Research Laboratory of Engineering Materials. (1992)

M. Ohgaki、F. Marumo 和 K. Tanaka：“用短波长 X 射线收集的积分强度和消光效应”工程材料研究实验室的报告。

T. Ito, F. Marumo, T. Maslen, Y. Satow and K. Tanaka: "Accurate Diffraction Studies of Perovskite Structures at Two Wavelength" Photon Factory Activity Report. 8. 282 (1990)

T. Ito、F. Marumo、T. Maslen、Y. Satow 和 K. Tanaka：“两个波长下钙钛矿结构的精确衍射研究”光子工厂活动报告。

N.Spadaccini,E.N.Maslen: "The Electron Density Distribution in KZnF_3 From Xーray Diffraction Data Collected at 0.5 and 0.7A" Acta Crystallographica.

N.Spadaccini、E.N.Maslen：“根据 0.5 和 0.7A 收集的 X 射线衍射数据得出 KZnF_3 中的电子密度分布”《晶体学报》。

M.Ohgaki,F.Marumo and K.Tanaka: "Integrated Intensities Collected with Short Wavelength X-Rays and Extinction Effects" Report of the Research Laboratory of Engineering Materials. (1992)

M.Ohgaki、F.Marumo 和 K.Tanaka：“用短波长 X 射线收集的积分强度和消光效应”工程材料研究实验室的报告。