Contribution of in-situ experiment in a high resolution/analytical electron microscope to materials science.

研制了一种适用于电子显微镜原位实验的新型样品加热架。这个支架允许以近原子分辨率观察在高达177 3K的温度下发生的现象。此外，它还允许从纳米级区域进行元素分析。利用这一强大的新工具解决了材料科学中尚未解决的各种问题，具体如下：1)观察了Al(金属)和氧化铝(陶瓷)的固液反应(熔融、凝固和液相烧结)熔化和凝固过程，并分析了固液界面的原子结构。在Al中，熔化在晶体表面开始。Al中的固液界面是原子粗糙的，而氧化铝中的固液界面是平的。2)固-固反应(晶界和界面)，观察到铜-镓金属间化合物中的晶界发生强烈的振动。振动与电子显微镜的温度和加速电压有关。结果表明，振动是由点缺陷引起的。在近原子分辨率下观察到了Au与Si表面的反应。当Au熔化在硅表面后，硅表面变得清洁，即使它最初被自然氧化物覆盖。3)固气反应(氧化和还原)当二氧化硅被还原时，硅/二氧化硅界面发生强烈的振动。

A new specimen-heating holder for use of in-situ experiments in an electron microscope was developed. This holder allows observation at near-atomic resolution of phenomena which occur at temperatures as high as 177 3K.Also, it allows elemental analysis from nanometer scale area. Various unsolved problems in materials science have been attacked using this powerful new tool as is descibed in the following :1) Solid-Liquid Reactions (Melting, Solidification and Liquid-Phase Sintering)Melting and solidification processes of Al (metals) and alumina (ceramics) were observed and the atomic structure of the solid-liquid interfaces were analyzed. In Al melting initiates at the crystal surface. The solid-liquid interface in Al is atomically rough, while that in alumina is flat. Reactions between solid Fe and molten Zn were also observed for the first time by TEM.2) Solid-Solid Reactions (Grain Boundaries and Interfaces)It was observed that a grain boundary in Cu-Ga intermetallics vibrates strongly. The vibration depends on temperature and accelerating voltage of the electron microscope. It is suggested that the vibration is induced by point defects. Reaction between Au and Si surface was observed at near-atomic resolution. Surface of Si becomes clean after Au melts on the surface of Si, even it was initially covered with a native oxide. As a result, surface reconstruction took place.3) Solid-Gas Reactions (Oxidation and Reduction)When silica is reduced the Si/silica interface vibrates strongly.