Effect of Pressure on Atomic Transport in Covalent Network Materials

这项研究的目的是了解高压对扩散和晶体生长的影响。凝聚态物质中原子的输运速率通常通过施加压力而降低，这是由于点缺陷或自由体积的浓度降低所致。目前的研究是关于一类被称为共价网络材料的材料，这种材料在压力下表现出更强的原子迁移率。研究的重点是探讨导致这一行为的机制。所研究的材料包括无定形半导体、硫化物、硅酸盐熔体和玻璃。测量原子输运的压力依赖关系提供了不能通过测量依赖温度的输运来确定的直接信息。实验技术包括高压熔融和相变、X射线衍射、离子束溅射、卢瑟福背散射、二次离子质谱学和电子显微镜。

The objective of this investigation is to understand the effects of high pressure on diffusion and crystal growth. The rates of atomic transport in condensed matter are typically reduced by the application of pressure, due to a reduction in the concentration of point defects or free volume. The present research is on a class of materials known as covalent network materials which exhibits enhanced atomic mobility under pressure. The emphasis of the research is to investigate the mechanisms responsible for this behavior. Materials studied include amorphous semiconductors, chalcogenides, and silicate melts and glasses. Measurement of the pressure-dependence of atomic transport provides direct information that cannot be determined by measurement of temperature-dependent transport. Experimental techniques include high pressure melting and phase transformation, x-ray diffraction, ion beam sputtering, Rutherford backscattering, secondary ion mass spectroscopy, and electron microscopy.