Determination of the Void Volume in Silicon Single Crystals for Use in the Precision Measurement of Avogadro's Constant

该项目由美国国家科学基金会和欧盟委员会在材料科学领域的合作活动NSF支持。千克是现存的唯一仍由特定文物定义的基本单位：标准千克，保存在巴黎的国际度量局。需要一个更基本的标准，如果更准确地知道阿沃加德罗的数字，就可以定义这个标准。在过去的十年里，一个国际财团一直在努力通过测量高度完美的硅晶体的物理性质来更准确地确定阿伏加德罗数。然而，这些研究揭示了由于小空洞的存在，名义上同等质量的浮区硅的密度出现了令人惊讶的偶然变化。该项目旨在开发一种通过高精度测量硅中溶解的铜来准确确定这些空洞的体积的方法。该项目是与欧洲委员会参考材料研究所、国家标准与技术研究所和德国联邦技术研究所合作实施的。

This project is supported by NSF as a Cooperative Activity in Materials Sciences between the National Science Foundation and the European Commission. The kilogram is the only remaining fundamental unit that is still defined by a specific artifact: the standard kilogram, kept at the International Bureau of Weights and Measures in Paris. A more fundamental standard is needed and could be defined if Avogadro's number were known more accurately. An international consortium has been working for the last decade to determine Avogadro's number more accurately by measuring the physical properties of highly perfect silicon crystals. These studies, however, revealed a surprising occasional variation in the density of nominally equal quality float-zone silicon caused by the presence of small voids. This project aims to develop a method for determining the volume of these voids accurately through high-precision measurements of copper dissolved in silicon. The project is being carried out in collaboration with the Institute for Reference Materials of the European Commission, the National Institute of Standards and Technology, and the German Physikalisch-Technische Bundesanstalt.