Atom-level analysis of structures of lattice defects in materials

对一些新发现和新合成的材料，不仅用x射线或电子衍射法，而且用电子显微镜进行了研究。高tc超导材料Y-Ba-Cu-Oxide：高分辨率电子显微镜对其微观结构的观察表明，双片层结构对超导性的质量也很重要。Bi-Ca-Sr-Cu-Oxide：确定了在氧化物球团中不含铅的情况下合成70%以上107k级超导材料的条件。材料中的铋浓度出乎意料地高。形状记忆合金，Ti-Ni：已经证实了扩散散射的三个特征。弥散极大值位于n/7、2n/7、3n/7 （n为整数）及其等价位置附近。在h01倒平面上观察到环状扩散散射，在低温下分布发生了反向变化。当电子束平行于<111>-方向入射时，电子衍射图中的漫射散射全部消失。[(GaAS)_4/(AlAs)_4]_<150>-超晶格：在整个样品中，超晶格的周期并不相同，在原子层的8 ~ 9倍之间波动。b19有序合金：在相变温度以下，发现了一个有趣的畴结构。微观结构的解释是各种类型的偏斜的存在。通过对csl模型概念的扩展，分析了层状结构的边界结构。铈金属间化合物：在低温下研究了各种含铈的金属间化合物。发现了电阻率和热电功率的反常温度依赖性。在热膨胀系数和晶格变换方面也发现了异常。

Some materials newly found as well as recently synthesized were examined by not only the X-ray or electron diffraction methods but also the electron microscopy.High-Tc superconducting materials, Y-Ba-Cu-Oxide: Observations of the microstructures by high-resolution electron microscopy have pointed that the twin-lamellar structures are also important for the quality of the supercon-ductivity. Bi-Ca-Sr-Cu-Oxide: The conditions under which more than 70% of the 107K-class superconducting materials are synthesized without Pb in the pellets of the oxise are determined. The Bi-concentration in the materials is unexpectedly high.Shape memory alloy, Ti-Ni: Three features in the diffuse scattering have been confirmed. Diffuse maxima locate near n/7, 2n/7, 3n/7 (n an integer) and equivalent positions. A ring-type diffuse scattering is observed in the h01 reciprocal plane and the distribution is found to be reversively changed at low temperatures. All the diffuse scattering disappear in the electron diffraction pattern when the electron beam is incident parallel to the <111>-direction.[(GaAS)_4/(AlAs)_4]_<150>-Superlattice: The period of the superlattice is not the same throughout the specimen, and fluctuates between eight and nine times of the atomic layer. B19-ordered alloy: Below the phase transition temperature, an interesing domain structure has been discovered. The micro-structures are interpreted by the existence of various types of disclinations. Laves phase alloys: Boundary structure of layer structures are analyzed by proposing an extention of the concept of the CSL-model.Ce-intermetallic compounds: Various intermetallic compounds containing Ce, have been investigated at low temperatures. Anomalous temperature dependences of the electric resistivities as well as the thermo-electric power have been discovered. Anomaly in the thermal expansion coeffeicients and latticc transformations have also been detected.