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Thermal expansion

About: Thermal expansion is a research topic. Over the lifetime, 21040 publications have been published within this topic receiving 349407 citations. The topic is also known as: heat expansion.


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Journal ArticleDOI
TL;DR: In this article, the authors developed an understanding of the beneficial surface modifications by plasma and a model based on short range low temperature diffusion through bonding experiments combined with results from spectroscopic ellipsometry, depth resolving Auger electron spectroscopy, and transmission electron microscopy measurements.
Abstract: Reducing the temperature needed for high strength bonding which was and is driven by the need to reduce effects of coefficient of thermal expansion mismatch, reduce thermal budgets, and increase throughput has led to the development of plasma treatment procedures capable of bonding Si wafers below 300 °C with a bond strength equivalent to Si bulk. Despite being widely used, the physical and chemical mechanisms enabling low temperature wafer bonding have remained poorly understood. We developed an understanding of the beneficial surface modifications by plasma and a model based on short range low temperature diffusion through bonding experiments combined with results from spectroscopic ellipsometry, depth resolving Auger electron spectroscopy, and transmission electron microscopy measurements. We also present experimental results showing that even at room temperature reasonable bond strength can be achieved. We conclude that the gap closing mechanism is therefore a process which balances the lowering of the total energy by minimizing the sum of the free surface energy (maximizing the contact area between the surfaces) and strain energy in the oxide at the bond interface.

121 citations

Journal ArticleDOI
Shunichi Numata1, Shuuichi Oohara1, Koji Fujisaki1, Junichi Imaizumi1, Noriyuki Kinjo1 
TL;DR: In this article, the thermal expansion behavior of various aromatic polymides was investigated and it was shown that their low thermal expansion coefficient related to the linearity in their polymer molecular skeltons.
Abstract: The thermal expansion behavior for various aromatic polymides was investigated. Usally polymers, including polyimides, have high thermal expansion coefficients (3–6 × 10−5 K−1), compared with metals and ceramics. However, there are some polyimides which have very low thermal expansion coefficients below 1 × 10−5 K−1. This property was observed for the polymides obtained from pyromellitic dianhydride or 3,3′ 4,4′-biphenyltetracarboxylic dianhydride and aromatic diamines which were constituted of only benzene rings fused at para positions. It was proposed that their low thermal expansion coefficient related to the linearity in their polymer molecular skeltons.

121 citations

Journal ArticleDOI
V. L. Moruzzi1
TL;DR: In this paper, total energy band calculations that show the coexistence of a high-spin and low-spin state in fcc transition metals and alloys are presented, and the energy difference between the two states is shown to be a function of the electron concentration and to vanish at 8.6.
Abstract: Total-energy band calculations that show the coexistence of a high-spin and low-spin state in fcc transition metals and alloys are presented. The energy difference between the two states is shown to be a function of the electron concentration and to vanish at 8.6. At larger electron concentrations the low-temperature state is the high-spin state, and the thermal expansion is shown to pause at a system-dependent characteristic temperature. At lower electron concentrations the low-temperature state is the low-spin state, and enhanced thermal expansion is expected. An analysis that leads to a qualitative understanding of the thermal properties of Invar and that implies a connection with martensitic transformations and spin glasses in related alloys is presented. For Invar a magnetic collapse from the high-spin to the low-spin state at a pressure of 55 kbar is predicted.

121 citations

Journal ArticleDOI
TL;DR: In this paper, the results of neutron powder diffraction experiments with the D2B instrument at Institut Laue Langevin on Al 2 (WO 4 ) 3 and Y 2 (wO 4 ), over the temperature range 20 to 800°C were presented.

121 citations

Journal ArticleDOI
TL;DR: In this article, the effect of cracks initially present in a rock was studied by measuring the full tensor of the coefficient of thermal expansion on two rocks with anisotropic crack distributions.

120 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023603
20221,249
2021683
2020742
2019759
2018767