Lattice Vibration and Heat Transport in Dielectric Solids

介电固体中的晶格振动和热传输

• 批准号: 9115981
• 负责人: Robert Pohl
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-01-15 至 1997-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9115981&HistoricalAwards=false
• 关键词: Lattice; Vibration; Heat; Transport; Dielectric

9115981 Pohl Disorder in thin metallic and dielectric films on polished crystalline silicon substrates is investigated by measuring heat flow in the substrate. Below several degrees K, the phonons will not be scattered in the substrate; thus any scattering observed will be induced by the disorder in the films. A second study focuses on the effect of dimensionality on the observation of mechanical relaxation phenomena. Thin metallic and diekectric films will be deposited on silicon paddle oscillators. The technique has been refined so that it is sufficiently sensitive to detect amorphous films less than 1nm thick. One of the questions to be answered is whether the relaxation which is characteristic of all amorphous solids can also be observed in extremely thin films, or only in extended, three dimensional bodies. % % % Thin films of metals or electrical insulators play an increasingly important role in modern technology, e.g. as components in integrated circuits in the semiconductor industry. The current study focuses on characterizing such films by measuring their thermal and elastic properties. A specific example are microcrystalline films of fullerines (buckyballs). In addition to exploring their disorder, the potential of such films for storing gases like helium or hydrogen will be investigated. Preliminary measurements have sshown an extremely high solubility for helium. If a similar solubility could be achieved for hydrogen, this could have considerable practical applications for energy storage. ***

小行星9115981 通过测量衬底中的热流来研究抛光晶体硅衬底上金属和介质薄膜中的无序。 低于几度K，声子将不会在衬底中散射;因此观察到的任何散射都将由薄膜中的无序引起。 第二项研究的重点是观察力学松弛现象的维度的影响。 薄金属和介电薄膜将沉积在硅桨振荡器上。 该技术已被改进，使其足够灵敏，以检测厚度小于1 nm的非晶薄膜。 需要回答的问题之一是，所有无定形固体特有的弛豫现象是否也能在极薄的薄膜中观察到，还是只能在延伸的三维物体中观察到。 金属或电绝缘体薄膜在现代技术中发挥着越来越重要的作用，例如作为半导体工业中集成电路的组件。 目前的研究重点是通过测量它们的热性能和弹性性能来表征这种薄膜。 一个具体的例子是富勒烯（巴基球）的微晶膜。 除了探索它们的无序性外，还将研究这种薄膜用于储存氦或氢等气体的潜力。 初步测量表明氦具有极高的溶解度。 如果氢可以达到类似的溶解度，这可能在能量储存方面有相当大的实际应用。 ***