Atom-level analysis of structures of lattice defects in materials

一些新发现的和最近合成的材料不仅用X射线或电子衍射法，而且用电子显微镜进行了检验。高T_c超导材料Y-Ba-Cu-氧化物：用高分辨电子显微镜观察其微观结构，指出双晶层结构对超导质量也是重要的。确定了合成70%以上的107K级超导材料时，氧化球中不含铅的条件。材料中的铋浓度出乎意料地高。形状记忆合金，钛镍：扩散散射中的三个特征已经得到证实。弥散极大值位于n/7、2n/7、3n/7(n为整数)附近和等效位置。在h01倒易面上观察到了环型扩散散射，并发现其分布在低温下发生了反向变化。当电子束平行于&lt；111&gt；-direction.[(GaAS)_4/(AlAs)_4]_&lt；150&gt；-Superlattice：入射时，所有的弥散散射都消失在电子衍射图中。超晶格的周期在整个样品中并不相同，在原子层的8~9倍之间波动。B19有序合金：在相变温度以下，发现了感兴趣的磁畴结构。微构造解释为各种类型的倾角的存在。Laves相合金：通过扩展CSL模型的概念，分析了层结构的边界结构。Ce-金属间化合物：在低温下研究了各种含Ce的金属间化合物。发现了电阻率和热电功率与温度的反常关系。还发现了热膨胀系数和晶格相变的异常。

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.