Kaiguo Chen, Bo Chen, Yinan Cui, Yuying Yu, Jidong Yu, Huayun Geng, Dongdong Kang, Jianhua Wu, Yao Shen, Jiayu Dai
Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extreme conditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50 is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physical properties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change are successfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relatively insensitive to the strain rate γ̇ when γ̇ ranges from 7.5 × 108 to 2 × 109/s, which are values reachable in QIC experiments, with a magnitude of the order of 10−2kB/atom per GPa. However, when γ̇ is extremely high (>2×109/s), a notable increase in entropy production rate with γ̇ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated that entropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase in configurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamental relation between microstructure evolution and plastic dissipation.
{"title":"On the thermodynamics of plasticity during quasi-isentropic compression of metallic glass","authors":"Kaiguo Chen, Bo Chen, Yinan Cui, Yuying Yu, Jidong Yu, Huayun Geng, Dongdong Kang, Jianhua Wu, Yao Shen, Jiayu Dai","doi":"10.1063/5.0176138","DOIUrl":"https://doi.org/10.1063/5.0176138","url":null,"abstract":"Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extreme conditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50 is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physical properties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change are successfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relatively insensitive to the strain rate γ̇ when γ̇ ranges from 7.5 × 108 to 2 × 109/s, which are values reachable in QIC experiments, with a magnitude of the order of 10−2kB/atom per GPa. However, when γ̇ is extremely high (>2×109/s), a notable increase in entropy production rate with γ̇ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated that entropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase in configurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamental relation between microstructure evolution and plastic dissipation.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"93 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139773517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Cone-inserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on the point-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peak compression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metal microwire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamic simulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, areal densities of the targets were evaluated.
我们介绍了短脉冲激光产生的硬 X 射线在间接驱动双壳目标诊断中的应用。在升级版 SG-II 激光设备上，通过间接驱动方法对锥形插入式双壳目标进行了内爆。然后，基于点投影硬 X 射线射线照相技术，获得了双壳靶的时间分辨射线照相，包括其近峰值压缩的射线照相。背光源是由高强度短脉冲激光与金属微线靶相互作用产生的。使用金微线获得了目标接近峰值压缩的图像。此外，还进行了辐射流体力学模拟，得到的目标演变与实验结果非常吻合。利用射线图像，对目标的面积密度进行了评估。
{"title":"Diagnosis of indirectly driven double shell targets with point-projection hard x-ray radiography","authors":"Chao Tian, Minghai Yu, Lianqiang Shan, Fengjuan Wu, Bi Bi, Qiangqiang Zhang, Yuchi Wu, Tiankui Zhang, Feng Zhang, Dongxiao Liu, Weiwu Wang, Zongqiang Yuan, Siqian Yang, Lei Yang, Zhigang Deng, Jian Teng, Weimin Zhou, Zongqing Zhao, Yuqiu Gu, Baohan Zhang","doi":"10.1063/5.0045112","DOIUrl":"https://doi.org/10.1063/5.0045112","url":null,"abstract":"We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Cone-inserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on the point-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peak compression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metal microwire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamic simulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, areal densities of the targets were evaluated.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"11 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tao Chen, Qianrui Liu, Yu Liu, Liang Sun, Mohan Chen
In traditional finite-temperature Kohn–Sham density functional theory (KSDFT), the partial occupation of a large number of high-energy KS eigenstates restricts the use of first-principles molecular dynamics methods at extremely high temperatures. However, stochastic density functional theory (SDFT) can overcome this limitation. Recently, SDFT and the related mixed stochastic–deterministic density functional theory, based on a plane-wave basis set, have been implemented in the first-principles electronic structure software ABACUS [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]. In this study, we combine SDFT with the Born–Oppenheimer molecular dynamics method to investigate systems with temperatures ranging from a few tens of eV to 1000 eV. Importantly, we train machine-learning-based interatomic models using the SDFT data and employ these deep potential models to simulate large-scale systems with long trajectories. Subsequently, we compute and analyze the structural properties, dynamic properties, and transport coefficients of warm dense matter.
在传统的有限温度 Kohn-Sham 密度泛函理论（KSDFT）中，大量高能 KS 特征态的部分占据限制了第一原理分子动力学方法在极高温下的使用。然而，随机密度泛函理论（SDFT）可以克服这一限制。最近，基于平面波基集的 SDFT 和相关的随机-确定混合密度泛函理论已在第一原理电子结构软件 ABACUS 中实现 [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]。在本研究中，我们将 SDFT 与 Born-Oppenheimer 分子动力学方法结合起来，研究温度范围从几十 eV 到 1000 eV 的系统。重要的是，我们利用 SDFT 数据训练基于机器学习的原子间模型，并利用这些深度势能模型模拟具有长轨迹的大规模系统。随后，我们计算并分析了温致密物质的结构特性、动态特性和传输系数。
{"title":"Combining stochastic density functional theory with deep potential molecular dynamics to study warm dense matter","authors":"Tao Chen, Qianrui Liu, Yu Liu, Liang Sun, Mohan Chen","doi":"10.1063/5.0163303","DOIUrl":"https://doi.org/10.1063/5.0163303","url":null,"abstract":"In traditional finite-temperature Kohn–Sham density functional theory (KSDFT), the partial occupation of a large number of high-energy KS eigenstates restricts the use of first-principles molecular dynamics methods at extremely high temperatures. However, stochastic density functional theory (SDFT) can overcome this limitation. Recently, SDFT and the related mixed stochastic–deterministic density functional theory, based on a plane-wave basis set, have been implemented in the first-principles electronic structure software ABACUS [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]. In this study, we combine SDFT with the Born–Oppenheimer molecular dynamics method to investigate systems with temperatures ranging from a few tens of eV to 1000 eV. Importantly, we train machine-learning-based interatomic models using the SDFT data and employ these deep potential models to simulate large-scale systems with long trajectories. Subsequently, we compute and analyze the structural properties, dynamic properties, and transport coefficients of warm dense matter.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"9 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139412091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianpeng Gao, Liang Sheng, Xinyi Wang, Yanhong Zhang, Liang Li, Baojun Duan, Mei Zhang, Yang Li, Dongwei Hei
Multiaxial neutron/x-ray imaging and three-dimensional (3D) reconstruction techniques play a crucial role in gaining valuable insights into the generation and evolution mechanisms of pulsed radiation sources. Owing to the short emission time (∼200 ns) and drastic changes of the pulsed radiation source, it is necessary to acquire projection data within a few nanoseconds in order to achieve clear computed tomography 3D imaging. As a consequence, projection data that can be used for computed tomography image reconstruction at a certain moment are often available for only a few angles. Traditional algorithms employed in the process of reconstructing 3D images with extremely incomplete data may introduce significant distortions and artifacts into the final image. In this paper, we propose an iterative image reconstruction method using cylindrical harmonic decomposition and a self-supervised denoising network algorithm based on the deep image prior method. We augment the prior information with a 2D total variation prior and a 3D deep image prior. Single-wire Z-pinch imaging experiments have been carried out at Qin-1 facility in five views and four frames, with a time resolution of 3 ns for each frame and a time interval of 40 ns between adjacent frames. Both numerical simulations and experiments verify that our proposed algorithm can achieve high-quality reconstruction results and obtain the 3D intensity distribution and evolution of extreme ultraviolet and soft x-ray emission from plasma.
{"title":"Five-view three-dimensional reconstruction for ultrafast dynamic imaging of pulsed radiation sources","authors":"Jianpeng Gao, Liang Sheng, Xinyi Wang, Yanhong Zhang, Liang Li, Baojun Duan, Mei Zhang, Yang Li, Dongwei Hei","doi":"10.1063/5.0177342","DOIUrl":"https://doi.org/10.1063/5.0177342","url":null,"abstract":"Multiaxial neutron/x-ray imaging and three-dimensional (3D) reconstruction techniques play a crucial role in gaining valuable insights into the generation and evolution mechanisms of pulsed radiation sources. Owing to the short emission time (∼200 ns) and drastic changes of the pulsed radiation source, it is necessary to acquire projection data within a few nanoseconds in order to achieve clear computed tomography 3D imaging. As a consequence, projection data that can be used for computed tomography image reconstruction at a certain moment are often available for only a few angles. Traditional algorithms employed in the process of reconstructing 3D images with extremely incomplete data may introduce significant distortions and artifacts into the final image. In this paper, we propose an iterative image reconstruction method using cylindrical harmonic decomposition and a self-supervised denoising network algorithm based on the deep image prior method. We augment the prior information with a 2D total variation prior and a 3D deep image prior. Single-wire Z-pinch imaging experiments have been carried out at Qin-1 facility in five views and four frames, with a time resolution of 3 ns for each frame and a time interval of 40 ns between adjacent frames. Both numerical simulations and experiments verify that our proposed algorithm can achieve high-quality reconstruction results and obtain the 3D intensity distribution and evolution of extreme ultraviolet and soft x-ray emission from plasma.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"128 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139084762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chaoxin Chen, Tao Gong, Zhichao Li, Liang Hao, Yonggang Liu, Xiangming Liu, Hang Zhao, Yaoyuan Liu, Kaiqiang Pan, Qi Li, Sanwei Li, Zhijun Li, Sai Jin, Feng Wang, Dong Yang
In an experiment performed on the Shenguang-III prototype laser facility, collective Thomson scattering (TS) is used to study the spatial growth of stimulated Brillouin scattering (SBS) in a gas-filled Hohlraum by detecting the SBS-driven ion acoustic wave. High-quality time-resolved SBS and TS spectra are obtained simultaneously in the experiment, and these are analyzed by a steady-state code based on the ray-tracing model. The analysis indicates that ion–ion collisions may play an important role in suppressing SBS growth in the Au plasma; as a result, the SBS excited in the filled gas region is dominant. In the early phase of the laser pulse, SBS originates primarily from the high-density plasma at the edges of the interaction beam channel, which is piled up by the heating of the interaction beam. Throughout the duration of the laser pulse, the presence of the TS probe beam might mitigate SBS by perturbing the density distribution around the region overlapping with the interaction beam.
在 "神光三号 "原型激光设备上进行的一项实验中，通过探测受激布里渊散射（SBS）驱动的离子声波，利用集合汤姆逊散射（TS）来研究充满气体的霍室中受激布里渊散射（SBS）的空间增长。实验中同时获得了高质量的时间分辨 SBS 和 TS 光谱，并通过基于射线追踪模型的稳态代码对其进行了分析。分析表明，离子-离子碰撞可能在抑制金等离子体中的 SBS 生长方面发挥了重要作用；因此，在填充气体区域激发的 SBS 占主导地位。在激光脉冲的早期阶段，SBS 主要来自相互作用光束通道边缘的高密度等离子体，这些等离子体是由相互作用光束加热堆积而成的。在整个激光脉冲持续期间，TS 探头光束的存在可能会扰动与相互作用光束重叠区域周围的密度分布，从而缓解 SBS。
{"title":"Study of the spatial growth of stimulated Brillouin scattering in a gas-filled Hohlraum via detecting the driven ion acoustic wave","authors":"Chaoxin Chen, Tao Gong, Zhichao Li, Liang Hao, Yonggang Liu, Xiangming Liu, Hang Zhao, Yaoyuan Liu, Kaiqiang Pan, Qi Li, Sanwei Li, Zhijun Li, Sai Jin, Feng Wang, Dong Yang","doi":"10.1063/5.0173023","DOIUrl":"https://doi.org/10.1063/5.0173023","url":null,"abstract":"In an experiment performed on the Shenguang-III prototype laser facility, collective Thomson scattering (TS) is used to study the spatial growth of stimulated Brillouin scattering (SBS) in a gas-filled Hohlraum by detecting the SBS-driven ion acoustic wave. High-quality time-resolved SBS and TS spectra are obtained simultaneously in the experiment, and these are analyzed by a steady-state code based on the ray-tracing model. The analysis indicates that ion–ion collisions may play an important role in suppressing SBS growth in the Au plasma; as a result, the SBS excited in the filled gas region is dominant. In the early phase of the laser pulse, SBS originates primarily from the high-density plasma at the edges of the interaction beam channel, which is piled up by the heating of the interaction beam. Throughout the duration of the laser pulse, the presence of the TS probe beam might mitigate SBS by perturbing the density distribution around the region overlapping with the interaction beam.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"45 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139083550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Relay, for a better MRE!","authors":"Ke Lan","doi":"10.1063/5.0187709","DOIUrl":"https://doi.org/10.1063/5.0187709","url":null,"abstract":"","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"120 37","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139453919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J.-R. Marquès, L. Lancia, P. Loiseau, P. Forestier-Colleoni, M. Tarisien, E. Atukpor, V. Bagnoud, C. Brabetz, F. Consoli, J. Domange, F. Hannachi, P. Nicolaï, M. Salvadori, B. Zielbauer
We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet [Marquès et al., Phys. Plasmas 28, 023103 (2021)]. In a continuation of this numerical work, we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases: without tailoring, by tailoring only the entrance side of the picosecond laser, and by tailoring both sides of the gas jet. Without tailoring, the acceleration is transverse to the laser axis, with a low-energy exponential spectrum, produced by Coulomb explosion. When the front side of the gas jet is tailored, a forward acceleration appears, which is significantly enhanced when both the front and back sides of the plasma are tailored. This forward acceleration produces higher-energy protons, with a peaked spectrum, and is in good agreement with the mechanism of collisionless shock acceleration (CSA). The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam. The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring. Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet. These parameters are in good agreement with those required for CSA.
{"title":"Collisionless shock acceleration of protons in a plasma slab produced in a gas jet by the collision of two laser-driven hydrodynamic shockwaves","authors":"J.-R. Marquès, L. Lancia, P. Loiseau, P. Forestier-Colleoni, M. Tarisien, E. Atukpor, V. Bagnoud, C. Brabetz, F. Consoli, J. Domange, F. Hannachi, P. Nicolaï, M. Salvadori, B. Zielbauer","doi":"10.1063/5.0178253","DOIUrl":"https://doi.org/10.1063/5.0178253","url":null,"abstract":"We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet [Marquès et al., Phys. Plasmas 28, 023103 (2021)]. In a continuation of this numerical work, we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases: without tailoring, by tailoring only the entrance side of the picosecond laser, and by tailoring both sides of the gas jet. Without tailoring, the acceleration is transverse to the laser axis, with a low-energy exponential spectrum, produced by Coulomb explosion. When the front side of the gas jet is tailored, a forward acceleration appears, which is significantly enhanced when both the front and back sides of the plasma are tailored. This forward acceleration produces higher-energy protons, with a peaked spectrum, and is in good agreement with the mechanism of collisionless shock acceleration (CSA). The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam. The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring. Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet. These parameters are in good agreement with those required for CSA.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"41 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139031811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philip Dalladay-Simpson, Bartomeu Monserrat, Li Zhang, Federico Gorelli
Evidence for metallization in dense oxygen has been reported for over 30 years [Desgreniers et al., J. Phys. Chem. 94, 1117 (1990)] at a now routinely accessible 95 GPa [Shimizu et al., Nature 393, 767 (1998)]. However, despite the longevity of this result and the technological advances since, the nature of the metallic phase remains poorly constrained [Akahama et al., Phys. Rev. Lett. 74, 4690 (1995); Goncharov et al., Phys. Rev. B 68, 224108 (2003); Ma, Phys. Rev. B 76, 064101 (2007); and Weck et al., Phys. Rev. Lett. 102, 255503 (2009)]. In this work, through Raman spectroscopy, we report the distinct vibrational characteristics of metallic ζ-O2 from 85 to 225 GPa. In comparison with numerical simulations, we find reasonable agreement with the C2/m candidate structure up to about 150 GPa. At higher pressures, the C2/m structure is found to be unstable and incompatible with experimental observations. Alternative candidate structures, C2/c and Ci, with only two molecules in the primitive unit cell, are found to be stable and more compatible with measurements above 175 GPa, indicative of the dissociation of (O2)4 units. Further, we report and discuss a strong hysteresis and metastability with the precursory phase ϵ-O2. These findings will reinvigorate experimental and theoretical work into the dense oxygen system, which will have importance for oxygen-bearing chemistry, prevalent in the deep Earth, as well as fundamental physics.
{"title":"Distinct vibrational signatures and complex phase behavior in metallic oxygen","authors":"Philip Dalladay-Simpson, Bartomeu Monserrat, Li Zhang, Federico Gorelli","doi":"10.1063/5.0160060","DOIUrl":"https://doi.org/10.1063/5.0160060","url":null,"abstract":"Evidence for metallization in dense oxygen has been reported for over 30 years [Desgreniers et al., J. Phys. Chem. 94, 1117 (1990)] at a now routinely accessible 95 GPa [Shimizu et al., Nature 393, 767 (1998)]. However, despite the longevity of this result and the technological advances since, the nature of the metallic phase remains poorly constrained [Akahama et al., Phys. Rev. Lett. 74, 4690 (1995); Goncharov et al., Phys. Rev. B 68, 224108 (2003); Ma, Phys. Rev. B 76, 064101 (2007); and Weck et al., Phys. Rev. Lett. 102, 255503 (2009)]. In this work, through Raman spectroscopy, we report the distinct vibrational characteristics of metallic ζ-O2 from 85 to 225 GPa. In comparison with numerical simulations, we find reasonable agreement with the C2/m candidate structure up to about 150 GPa. At higher pressures, the C2/m structure is found to be unstable and incompatible with experimental observations. Alternative candidate structures, C2/c and Ci, with only two molecules in the primitive unit cell, are found to be stable and more compatible with measurements above 175 GPa, indicative of the dissociation of (O2)4 units. Further, we report and discuss a strong hysteresis and metastability with the precursory phase ϵ-O2. These findings will reinvigorate experimental and theoretical work into the dense oxygen system, which will have importance for oxygen-bearing chemistry, prevalent in the deep Earth, as well as fundamental physics.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"40 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Q. Wang, J. J. Honrubia, Y. Yin, X. H. Yang, F. Q. Shao
The Brown–Preston–Singleton (BPS) stopping power model is added to our previously developed hybrid code to model ion beam–plasma interaction. Hybrid simulations show that both resistive field and ion scattering effects are important for proton beam transport in a solid target, in which they compete with each other. When the target is not completely ionized, the self-generated resistive field effect dominates over the ion scattering effect. However, when the target is completely ionized, this situation is reversed. Moreover, it is found that Ohmic heating is important for higher current densities and materials with high resistivity. The energy fraction deposited as Ohmic heating can be as high as 20%–30%. Typical ion divergences with half-angles of about 5°–10° will modify the proton energy deposition substantially and should be taken into account.
{"title":"Resistive field generation in intense proton beam interaction with solid targets","authors":"W. Q. Wang, J. J. Honrubia, Y. Yin, X. H. Yang, F. Q. Shao","doi":"10.1063/5.0172035","DOIUrl":"https://doi.org/10.1063/5.0172035","url":null,"abstract":"The Brown–Preston–Singleton (BPS) stopping power model is added to our previously developed hybrid code to model ion beam–plasma interaction. Hybrid simulations show that both resistive field and ion scattering effects are important for proton beam transport in a solid target, in which they compete with each other. When the target is not completely ionized, the self-generated resistive field effect dominates over the ion scattering effect. However, when the target is completely ionized, this situation is reversed. Moreover, it is found that Ohmic heating is important for higher current densities and materials with high resistivity. The energy fraction deposited as Ohmic heating can be as high as 20%–30%. Typical ion divergences with half-angles of about 5°–10° will modify the proton energy deposition substantially and should be taken into account.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"53 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138546926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Since the discovery of hydride superconductors, a significant challenge has been to reduce the pressure required for their stabilization. In this context, we propose that alloying could be an effective strategy to achieve this. We focus on a series of alloyed hydrides with the AMH6 composition, which can be made via alloying A15 AH3 (A = Al or Ga) with M (M = a group ⅢB or IVB metal), and study their behavior under pressure. Seven of them are predicted to maintain the A15-type structure, similar to AH3 under pressure, providing a platform for studying the effects of alloying on the stability and superconductivity of AH3. Among these, the A15-type phases of AlZrH6 and AlHfH6 are found to be thermodynamically stable in the pressure ranges of 40–150 and 30–181 GPa, respectively. Furthermore, they remain dynamically stable at even lower pressures, as low as 13 GPa for AlZrH6 and 6 GPa for AlHfH6. These pressures are significantly lower than that required for stabilizing A15 AlH3. Additionally, the introduction of Zr or Hf increases the electronic density of states at the Fermi level compared with AlH3. This enhancement leads to higher critical temperatures (Tc) of 75 and 76 K for AlZrH6 and AlHfH6 at 20 and 10 GPa, respectively. In the case of GaMH6 alloys, where M represents Sc, Ti, Zr, or Hf, these metals reinforce the stability of the A15-type structure and reduce the lowest thermodynamically stable pressure for GaH3 from 160 GPa to 116, 95, 80, and 85 GPa, respectively. Particularly noteworthy are the A15-type GaMH6 alloys, which remain dynamically stable at low pressures of 97, 28, 5, and 6 GPa, simultaneously exhibiting high Tc of 88, 39, 70, and 49 K at 100, 35, 10, and 10 GPa, respectively. Overall, these findings enrich the family of A15-type superconductors and provide insights for the future exploration of high-temperature hydride superconductors that can be stabilized at lower pressures.
{"title":"Design of high-temperature superconductors at moderate pressures by alloying AlH3 or GaH3","authors":"Xiaowei Liang, Xudong Wei, Eva Zurek, Aitor Bergara, Peifang Li, Guoying Gao, Yongjun Tian","doi":"10.1063/5.0159590","DOIUrl":"https://doi.org/10.1063/5.0159590","url":null,"abstract":"Since the discovery of hydride superconductors, a significant challenge has been to reduce the pressure required for their stabilization. In this context, we propose that alloying could be an effective strategy to achieve this. We focus on a series of alloyed hydrides with the AMH6 composition, which can be made via alloying A15 AH3 (A = Al or Ga) with M (M = a group ⅢB or IVB metal), and study their behavior under pressure. Seven of them are predicted to maintain the A15-type structure, similar to AH3 under pressure, providing a platform for studying the effects of alloying on the stability and superconductivity of AH3. Among these, the A15-type phases of AlZrH6 and AlHfH6 are found to be thermodynamically stable in the pressure ranges of 40–150 and 30–181 GPa, respectively. Furthermore, they remain dynamically stable at even lower pressures, as low as 13 GPa for AlZrH6 and 6 GPa for AlHfH6. These pressures are significantly lower than that required for stabilizing A15 AlH3. Additionally, the introduction of Zr or Hf increases the electronic density of states at the Fermi level compared with AlH3. This enhancement leads to higher critical temperatures (Tc) of 75 and 76 K for AlZrH6 and AlHfH6 at 20 and 10 GPa, respectively. In the case of GaMH6 alloys, where M represents Sc, Ti, Zr, or Hf, these metals reinforce the stability of the A15-type structure and reduce the lowest thermodynamically stable pressure for GaH3 from 160 GPa to 116, 95, 80, and 85 GPa, respectively. Particularly noteworthy are the A15-type GaMH6 alloys, which remain dynamically stable at low pressures of 97, 28, 5, and 6 GPa, simultaneously exhibiting high Tc of 88, 39, 70, and 49 K at 100, 35, 10, and 10 GPa, respectively. Overall, these findings enrich the family of A15-type superconductors and provide insights for the future exploration of high-temperature hydride superconductors that can be stabilized at lower pressures.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"31 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138537070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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