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Full-Text Articles in Physics
Response Of The Mode Grüneisen Parameters With Anisotropic Compression: A Pressure And Temperature Dependent Raman Study Of Β-Sn, Jasmine K. Hinton, Christian Childs, Dean Smith, Paul B. Ellison, Keith V. Lawler, Ashkan Salamat
Response Of The Mode Grüneisen Parameters With Anisotropic Compression: A Pressure And Temperature Dependent Raman Study Of Β-Sn, Jasmine K. Hinton, Christian Childs, Dean Smith, Paul B. Ellison, Keith V. Lawler, Ashkan Salamat
Physics & Astronomy Faculty Research
The lattice dynamic response of body-centered tetragonal β−Sn (I41/amd) under high pressure and -temperature conditions is determined using experimental optical vibration modes. Raman scattering is used to map the phase stability region of β−Sn to perform mode Grüneisen analysis, and we demonstrate the necessity of an optical intensity calibration for Raman thermometry. The Grüneisen tensor is evaluated along a set of isotherms to address shortcomings of single-mode Grüneisen parameters with respect to anisotropic deformations of this tetragonal structured soft metal. The changes observed here in the Grüneisen tensor as a function of temperature are related to anharmonicity and denote potential …
Xenon Iron Oxides Predicted As Potential Xe Hosts In Earth’S Lower Mantle, Feng Peng, Xianqi Song, Chang Liu, Quan Li, Maosheng Miao, Changfeng Chen, Yanming Ma
Xenon Iron Oxides Predicted As Potential Xe Hosts In Earth’S Lower Mantle, Feng Peng, Xianqi Song, Chang Liu, Quan Li, Maosheng Miao, Changfeng Chen, Yanming Ma
Physics & Astronomy Faculty Research
An enduring geological mystery concerns the missing xenon problem, referring to the abnormally low concentration of xenon compared to other noble gases in Earth’s atmosphere. Identifying mantle minerals that can capture and stabilize xenon has been a great challenge in materials physics and xenon chemistry. Here, using an advanced crystal structure search algorithm in conjunction with first-principles calculations we find reactions of xenon with recently discovered iron peroxide FeO2, forming robust xenon-iron oxides Xe2FeO2 and XeFe3O6 with significant Xe-O bonding in a wide range of pressure-temperature conditions corresponding to vast regions in Earth’s lower mantle. Calculated mass density and sound …
Toughening A Superstrong Carbon Crystal: Sequential Bond-Breaking Mechanisms, Hui Liang, Hefei Li, Quan Li, Changfeng Chen
Toughening A Superstrong Carbon Crystal: Sequential Bond-Breaking Mechanisms, Hui Liang, Hefei Li, Quan Li, Changfeng Chen
Physics & Astronomy Faculty Research
A complex orthorhombic carbon allotrope in Pbam symmetry with 32 atoms in its unit cell, thus termed Pbam-32 carbon, was recently predicted [C. Y. He et al., Phys. Rev. Lett. 121, 175701 (2018)]. Its crystal structure comprises alternating fivefold, sixfold, and sevenfold carbon rings and exhibits reduced bonding anisotropy compared to diamond, raising the prospects of finding a superstrong material with distinct and favorable mechanical properties. Here we report findings from first-principles calculations that reveal peculiar stress-strain relations in Pbam-32 carbon. The obtained stress responses under various tensile and shear strains display outstanding characteristics contrasting those of traditional superhard materials …
Pressure-Stabilized Divalent Ozonide Cao3 And Its Impact On Earth’S Oxygen Cycles, Yanchao Wang, Meiling Xu, Liuxiang Yang, Bingmin Yan, Qin Qin, Xuecheng Shao, Yunwei Zhang, Dajian Huang, Xiaohuan Lin, Jian Lv, Dongzhou Zhang, Huiyang Gou, Ho-Kwang Mao, Changfeng Chen, Yanming Ma
Pressure-Stabilized Divalent Ozonide Cao3 And Its Impact On Earth’S Oxygen Cycles, Yanchao Wang, Meiling Xu, Liuxiang Yang, Bingmin Yan, Qin Qin, Xuecheng Shao, Yunwei Zhang, Dajian Huang, Xiaohuan Lin, Jian Lv, Dongzhou Zhang, Huiyang Gou, Ho-Kwang Mao, Changfeng Chen, Yanming Ma
Physics & Astronomy Faculty Research
High pressure can drastically alter chemical bonding and produce exotic compounds that defy conventional wisdom. Especially significant are compounds pertaining to oxygen cycles inside Earth, which hold key to understanding major geological events that impact the environment essential to life on Earth. Here we report the discovery of pressure-stabilized divalent ozonide CaO3 crystal that exhibits intriguing bonding and oxidation states with profound geological implications. Our computational study identifies a crystalline phase of CaO3 by reaction of CaO and O2 at high pressure and high temperature conditions; ensuing experiments synthesize this rare compound under compression in a diamond anvil cell with …
On-Chip Terahertz Modulation And Emission With Integrated Graphene Junctions, Joshua O. Island, Peter Kissin, Jacob Schalch, Xiaomeng Cui, Sheikh Rubaiat Ui Haque, Alex Potts, Takashi Taniguchi, Kanji Watanabe, Richard D. Averitt, Andrea F. Young
On-Chip Terahertz Modulation And Emission With Integrated Graphene Junctions, Joshua O. Island, Peter Kissin, Jacob Schalch, Xiaomeng Cui, Sheikh Rubaiat Ui Haque, Alex Potts, Takashi Taniguchi, Kanji Watanabe, Richard D. Averitt, Andrea F. Young
Physics & Astronomy Faculty Research
The efficient modulation and control of ultrafast signals on-chip is of central importance in terahertz (THz) communications and a promis- ing route toward sub-diffraction limit THz spectroscopy. Two-dimensional (2D) materials may provide a platform for these endeavors. We explore this potential, integrating high-quality graphene p–n junctions within two types of planar transmission line circuits to modulate and emit picosecond pulses. In a coplanar strip line geometry, we demonstrate the electrical modulation of THz signal transmission by 95%. In a Goubau waveguide geometry, we achieve complete gate-tunable control over THz emission from a photoexcited graphene junction. These studies inform the development …
Vibration Overtone Hyperpolarizability Measured For H2, Rachel M. Ellis, David P. Shelton
Vibration Overtone Hyperpolarizability Measured For H2, Rachel M. Ellis, David P. Shelton
Physics & Astronomy Faculty Research
The second hyperpolarizability (γ) of the H2 molecule was measured by gas-phase electric field induced second harmonic generation at the frequencies of the one-photon resonance for the 3–0 Q(J) overtone transitions (v, J = 0, J → 3, J for J = 0, 1, 2, and 3). The magnitude of the resonant contribution to γ was measured with 2% accuracy using the previously determined non-resonant γ for calibration. Pressure broadening and frequency shift for the transitions were also measured. A theoretical expression for the resonant vibrational γ contribution in terms of transition polarizabilities is compared to the observations. The measured …
Superconductivity In Compression-Shear Deformed Diamond, Chang Liu, Xianqi Song, Quan Li, Yanming Ma, Changfeng Chen
Superconductivity In Compression-Shear Deformed Diamond, Chang Liu, Xianqi Song, Quan Li, Yanming Ma, Changfeng Chen
Physics & Astronomy Faculty Research
Diamond is a prototypical ultrawide band gap semiconductor, but turns into a superconductor with a critical temperature Tc≈4 K near 3% boron doping [E. A. Ekimov et al., Nature (London) 428, 542 (2004)]. Here we unveil a surprising new route to superconductivity in undoped diamond by compression-shear deformation that induces increasing metallization and lattice softening with rising strain, producing phonon mediated Tc up to 2.4–12.4 K for a wide range of Coulomb pseudopotential μ∗=0.15–0.05. This finding raises intriguing prospects of generating robust superconductivity in strained diamond crystal, showcasing a distinct and hitherto little explored approach to driving materials into superconducting …
The Breakup Of A Helium Cluster After Removing Attractive Interaction Among A Significant Number Of Atoms In The Cluster, Tao Pang
Physics & Astronomy Faculty Research
The breakup of a quantum liquid droplet is examined through a 4He cluster by removing the attractive tail in the interaction between some of the atoms in the system with the diffusion quantum Monte Carlo simulation. The ground-state energy, kinetic energy, cluster size, and density profile of the cluster are evaluated against the percentage of the atoms without the attractive tail. The condition for the cluster to lose its ability to form a quantum liquid droplet at zero temperature is found and analyzed. The cluster is no longer able to form a quantum liquid droplet when about two-thirds of pairs …
High Dielectric Ternary Oxides From Crystal Structure Prediction And High-Throughput Screening, Jingyu Qu, David Zagaceta, Weiwei Zhang, Qiang Zhu
High Dielectric Ternary Oxides From Crystal Structure Prediction And High-Throughput Screening, Jingyu Qu, David Zagaceta, Weiwei Zhang, Qiang Zhu
Physics & Astronomy Faculty Research
The development of new high dielectric materials is essential for advancement in modern electronics. Oxides are generally regarded as the most promising class of high dielectric materials for industrial applications as they possess both high dielectric constants and large band gaps. Most previous researches on high dielectrics were limited to already known materials. In this study, we conducted an extensive search for high dielectrics over a set of ternary oxides by combining crystal structure prediction and density functional perturbation theory calculations. From this search, we adopted multiple stage screening to identify 441 new low-energy high dielectric materials. Among these materials, …
Buckling Of Blue Phosphorus Nanotubes Under Axial Compression: Insights From Molecular Dynamics Simulations, Shiping Jiang, Huiling Wu, Liangzhi Kou, Chun Tang, Chengyuan Wang, Changfeng Chen
Buckling Of Blue Phosphorus Nanotubes Under Axial Compression: Insights From Molecular Dynamics Simulations, Shiping Jiang, Huiling Wu, Liangzhi Kou, Chun Tang, Chengyuan Wang, Changfeng Chen
Physics & Astronomy Faculty Research
We report on mechanical properties of blue phosphorus nanotubes (BluePNTs) from systematic molecular dynamics simulations, adopting a Stillinger-Weber potential with parameters determined by fitting to energetic and structural data from first-principles calculations. Our results corroborate the previously reported bending poison effect and size-dependent buckling behaviors. Under axial compression, current simulations predict a shell-to-column buckling mode transition for BluePNTs with increasing aspect ratios; further compression of BluePNTs with large aspect ratios results in a column-to-shell buckling mode transition. Associated critical buckling strains can be described by the continuum mechanics theory. We also simulated buckling behavior of black phosphorus nanotubes (BlackPNTs) and …