Calculation of the anisotropic coefficients of thermal expansion: A first-principles approach

Pike, Nicholas A.; Løvvik, Ole Martin

doi:10.1016/j.commatsci.2019.05.045

Cited by 23 publications

(13 citation statements)

References 74 publications

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“…Figure 8 shows variation in Von Misses stress and ADS after performing thermalcompression cyclic tests. These results are harmonious with those in works [39,40] about thermal expansion. By calculating thermal stresses ℎ using the known following equation:…”

Section: Figuresupporting

confidence: 89%

Study of the Contact Thermal Compression Behavior of Copper using Scanning Contact Potentiometry Method and Finite Element Analysis

Ghazal¹,

Alkhdour

Husein³

et al. 2021

Walailak J Sci & Tech

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The issue of tracking residual stresses initiation in welding copper under various affected conditions is essential in increasing safety through improving the welding quality in particular, in the nuclear industry. This study investigated the behavior of welded copper numerically and experimentally under contact-heating compression test with constant clamping force. The scanning contact potentiometry (SCP) method was used to track the initiation and development of residual stresses within the weld zone. Furthermore, the finite element analysis (FEA) method was used to simulate and study the effect of thermal variations, with a constant compressive force, on mechanical factors that contribute to residual stresses formation within the weld zone. Additionally, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to get further information about the topography and composition of the specimen's surface. SCP results show that residual stress initiated from within the volume after 200 °C, and with further oxidation, its formation began on the surface after 250 °C. Using the relationship between maximum values of linearized von Mises stresses and maximum values of ADS at high SLS = 4.523, it was found that residual stresses generation began after 150 °C within the weld zone, and thermal stresses linearly increase with temperature due to further thermal expansion, which is associated with variation in linearized von Mises stresses and ADS maximum values. Comparison between potentiograms after 300 °C and FEA results have shown that the distribution of von Mises stress, normal stress, and total deformation are matching those in the distribution of ADS and are localized within the weld zone. HIGHLIGHTS The behavior of welded copper under compression at medium-low temperature range Residual stresses detection at an early stage localized within weldment zone Residual stresses increase with increased oxidation at copper surface Matched the SCP Experimental and FEA simulation results GRAPHICAL ABSTRACT

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Section: Figuresupporting

confidence: 89%

Study of the Contact Thermal Compression Behavior of Copper using Scanning Contact Potentiometry Method and Finite Element Analysis

Ghazal¹,

Alkhdour

Husein³

et al. 2021

Walailak J Sci & Tech

View full text Add to dashboard Cite

show abstract

“…In each case, we constructed ground-state geometries through complete geometry optimization. The Birch−Murnaghan equation-of-state calculation 59 was performed on crystalline Cu x Si y (various space groups). We carried out periodic QM calculations based on density functional theory (DFT).…”

Section: Methodsmentioning

confidence: 99%

Development of the ReaxFF Reactive Force Field for Cu/Si Systems with Application to Copper Cluster Formation during Cu Diffusion Inside Silicon

et al. 2021

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Transition-metal impurities such as nickel, copper, and iron in solid-state materials like silicon have a significant impact on the electrical performance of integrated circuits and solar cells. To study the impact of copper impurities inside bulk silicon on the electrical properties of the material, one needs to understand the configurational space of copper atoms incorporated inside the silicon lattice. In this work, we developed a ReaxFF reactive force field and used it to perform molecular dynamics simulations on models with up to 762 atoms to study the various configurations of individual and crystalline clusters of copper atoms inside bulk silicon by examining copper’s diffusional behavior in silicon. The ReaxFF Cu/Si parameter set was developed by training against density functional theory (DFT) data, including the energy barrier for an individual Cu atom traveling inside a silicon lattice. We found that the diffusion of copper atoms is dependent on temperature. Moreover, we show that individual copper atoms start to form clusters inside bulk silicon at temperatures above 500 K. Our simulation results provide a comprehensive understanding of the effects of temperature and copper concentration on the formation of copper clusters inside a silicon lattice. Finally, the stress–strain relationship of Cu/Si compounds under uniaxial tensile loading has been obtained. Our results indicate a decrease in the elastic modulus with increasing Cu-impurity concentration. We observe spontaneous microcracking of the Si during the stress–strain tests as a consequence of the formation of a small Cu cluster adjacent to the Si surface.

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“…This discrepancy could also be explained by anharmonic contributions to the phonon free energy, which our perturbative methodology does not capture. A more refined and numerically accurate calculation of the anisotropic thermal expansion coefficients would rely on the full temperature-dependent phonon-perturbed potential, taking into account all anharmonic interactions, as implemented in the Temperature Dependent Effective Potential method (TDEP) method [89].…”

Section: Thermal Expansionmentioning

confidence: 99%

Temperature dependence of the topological phase transition of BiTeI from first principles

Brousseau-Couture,

Antonius,

Côté

2020

Preprint

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A topological phase transition from a trivial insulator to a Z2 topological insulator requires the bulk band gap to vanish. In the case of noncentrosymmetric materials, these phases are separated by a gapless Weyl semimetal phase. However, at finite temperature, the gap is affected by atomic motion, through electron-phonon interaction, and by thermal expansion of the lattice. As a consequence, the phase space of topologically nontrivial phases is affected by temperature. In this paper, the pressure and temperature dependence of the indirect band gap of BiTeI is investigated from first principles. We evaluate the contribution from both electron-phonon interaction and thermal expansion, and show that their combined effect drives the topological phase transition towards higher pressures with increasing temperature. Notably, we find that the sensitivity of both band extrema to pressure and topology for electron-phonon interaction differs significantly according to their leading orbital character. Our results indicate that the Weyl semimetal phase width is increased by temperature, having almost doubled by 100 K when compared to the static lattice results. Our findings thus provide a guideline for experimental detection of the nontrivial phases of BiTeI and illustrate how the phase space of the Weyl semimetal phase in noncentrosymmetric materials can be significantly affected by temperature.

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Calculation of the anisotropic coefficients of thermal expansion: A first-principles approach

Cited by 23 publications

References 74 publications

Study of the Contact Thermal Compression Behavior of Copper using Scanning Contact Potentiometry Method and Finite Element Analysis

Study of the Contact Thermal Compression Behavior of Copper using Scanning Contact Potentiometry Method and Finite Element Analysis

Development of the ReaxFF Reactive Force Field for Cu/Si Systems with Application to Copper Cluster Formation during Cu Diffusion Inside Silicon

Temperature dependence of the topological phase transition of BiTeI from first principles

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