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Fluorite-type materials in the monolayer limit 单层极限中的萤石型材料
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-19 DOI: 10.1103/physrevmaterials.8.094002
Shota Ono, Ravinder Pawar
The 2H, 1T, and their distorted structures are known as prototype structures of AB2 monolayers. Here, we study a puckered (PCK) structure that is truncated from the (110) surface of fluorite-type materials. 53 fluorite-type materials are investigated based on first-principles approach. The formation energy calculations indicate that seven systems form the PCK structure in the monolayer limit, while other systems form either 1T, 2H, or distorted 1T structures. The PCK structures of PbF2 and Ga2Au exhibit negative Poisson's ratio (NPR) in the out-of-plane direction. We explain the NPR by an analytical model assuming a constant interatomic distance under the in-plane strain. In addition, we demonstrate that the appearance of NPR is correlated with non-ionic character of the system, which is based on the surface energy calculations and the Born effective charge analyses. We also find that PRh2 in the PCK structure is highly distorted.
众所周知,2H、1T 及其扭曲结构是 AB2 单层的原型结构。在此,我们研究了一种从萤石型材料 (110) 表面截断的皱褶(PCK)结构。我们基于第一原理方法研究了 53 种萤石型材料。形成能计算表明,有七个体系在单层极限下形成 PCK 结构,而其他体系则形成 1T、2H 或扭曲的 1T 结构。PbF2 和 Ga2Au 的 PCK 结构在平面外方向呈现负泊松比(NPR)。我们通过假定面内应变下原子间距离恒定的分析模型来解释负泊松比。此外,我们还基于表面能计算和 Born 有效电荷分析,证明了 NPR 的出现与体系的非离子特性相关。我们还发现 PCK 结构中的 PRh2 高度扭曲。
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引用次数: 0
Magnetization dependent anisotropic topological properties in EuCuP EuCuP 中与磁化有关的各向异性拓扑特性
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-19 DOI: 10.1103/physrevmaterials.8.094202
Jian Yuan, Xianbiao Shi, Hong Du, Wei Xia, Xia Wang, Jinguang Cheng, Baotian Wang, Ruidan Zhong, Shihao Zhang, Yanfeng Guo
The correlation between magnetism and nontrivial topological band structure serves as a unique venue for discovering exotic topological properties. Combining magnetotransport measurements and first-principles calculations, we unveil herein that the hexagonal EuCuP holds a topologically trivial state in the paramagnetic structure, while strong magnetization dependent anisotropic topological states in the spin-polarization structures. Specifically, it hosts a trivial topological state in the in-plane spin-polarization structure, while a Weyl semimetal state in the out-of-plane spin-polarization structure. Our scaling analysis suggests that the intrinsic Berry curvature in the spin-polarization structures can account for the observed large anisotropic anomalous Hall effect. First-principles calculations show that the magnetization and the spin-orbit coupling simultaneously play essential roles for the appearance of the four pairs of Weyl points in the out-of-plane spin-polarization structure. Our work therefore establishes in EuCuP the intimate relation between magnetism and the nontrivial topological states, which would be instructive for future study on this key issue of topological physics.
磁性与非琐碎拓扑带状结构之间的相关性是发现奇异拓扑特性的独特途径。结合磁传输测量和第一原理计算,我们在此揭示了六方 EuCuP 在顺磁结构中具有拓扑琐碎态,而在自旋极化结构中具有强磁化依赖的各向异性拓扑态。具体来说,它在面内自旋极化结构中具有拓扑三要态,而在面外自旋极化结构中具有韦尔半金属态。我们的缩放分析表明,自旋极化结构中的内在贝里曲率可以解释观察到的巨大各向异性反常霍尔效应。第一原理计算表明,磁化和自旋轨道耦合同时对平面外自旋极化结构中出现四对韦尔点起着至关重要的作用。因此,我们的工作在 EuCuP 中建立了磁性与非奇异拓扑态之间的密切关系,这对今后研究拓扑物理的这一关键问题具有指导意义。
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引用次数: 0
Impact of grain boundary energy anisotropy on grain growth 晶界能量各向异性对晶粒生长的影响
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-19 DOI: 10.1103/physrevmaterials.8.093403
S. Kiana Naghibzadeh, Zipeng Xu, David Kinderlehrer, Robert Suter, Kaushik Dayal, Gregory S. Rohrer
A threshold dynamics model of grain growth that accounts for the anisotropy in the grain boundary energy has been used to simulate experimentally observed grain growth of polycrystalline Ni. The simulation reproduces several aspects of the observed microstructural evolution that are not found in the results of simulations assuming isotropic properties. For example, the relative areas of the lowest-energy twin boundaries increase as the grains grow and the average grain boundary energy decreases with grain growth. This decrease in energy occurs because the population of higher-energy grain boundaries decreases while the population of lower-energy boundaries increases as the total grain boundary area decreases. This phenomenon emerges from the assumption of anisotropic grain boundary energies without modification of the energy minimizing algorithm. These findings are consistent with the observation that, in addition to the decrease in grain boundary area, additional energy is dissipated during grain growth by a decrease in the average grain boundary energy.
一种考虑到晶界能量各向异性的晶粒生长阈值动力学模型被用来模拟实验观察到的多晶镍的晶粒生长。模拟再现了观察到的微结构演变的几个方面,而这些方面在假设各向同性的模拟结果中是找不到的。例如,能量最低的孪晶边界的相对面积随着晶粒的长大而增大,平均晶界能量随着晶粒的长大而减小。能量下降的原因是,随着晶粒边界总面积的减少,高能量晶粒边界的数量减少,而低能量边界的数量增加。这种现象产生于各向异性晶界能量假设,无需修改能量最小化算法。这些发现与以下观察结果是一致的:除了晶界面积的减小之外,在晶粒生长过程中,平均晶界能量的减小也会耗散额外的能量。
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引用次数: 0
Intrinsic origins of broad luminescence in melt-grown ZnGa2O4 single crystals 熔融生长的 ZnGa2O4 单晶宽发光的内在原因
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-18 DOI: 10.1103/physrevmaterials.8.094604
Ymir K. Frodason, Augustinas Galeckas, Vegard S. Olsen, Philip M. Weiser, Zbigniew Galazka, Chris G. Van de Walle, Lasse Vines
This work explores the luminescence properties of melt-grown ZnGa2O4 single crystals using photoluminescence spectroscopy and first-principles calculations. The photoluminescence spectra consist of numerous overlapping broad bands in the spectral range between 1.4 and 3.9 eV, which can be divided into low- (1.4–2.7 eV) and high-energy (2.7–3.9 eV) parts. When using below-gap excitation, the photoluminescence spectrum shows distinct orange and ultraviolet luminescence bands peaking at 1.99 and 3.36 eV, respectively. The results are interpreted by using configuration coordinate diagrams derived from hybrid functional calculations for self-trapped holes, as well as for the most stable native defects and their complexes. The calculations show that self-trapped holes, Zn antisites, and Zn-Ga antisite pairs give rise to strongly overlapping luminescence lines that are compatible with the high-energy side of the broad emission. For the low-energy side, we suggest Zn vacancies and their complexes with Ga antisites as potential intrinsic origins. The calculated Zn vacancy lineshape fits well with the orange luminescence band. Ga vacancies are unlikely to be the origin of the observed visible and ultraviolet emission, as the calculated luminescence lines occur in the infrared region. Moreover, complexes between the Ga vacancy and one or two Ga antisites, which would show luminescence at higher energies, are only metastable. It is more favorable for a Ga antisite to jump into the Ga vacancy, replacing the Ga antisite and vacancy with a Zn vacancy.
这项研究利用光致发光光谱和第一原理计算探讨了熔融生长的 ZnGa2O4 单晶的发光特性。光致发光光谱由 1.4 至 3.9 eV 光谱范围内的许多重叠宽带组成,可分为低能(1.4-2.7 eV)和高能(2.7-3.9 eV)两部分。当使用低于隙激发时,光致发光光谱显示出明显的橙色和紫外发光带,峰值分别为 1.99 和 3.36 eV。利用混合函数计算得出的配置坐标图解释了自俘获空穴以及最稳定的原生缺陷及其复合物的结果。计算结果表明,自俘获空穴、Zn 反异质体和 Zn-Ga 反异质体对会产生强烈重叠的发光线,这些发光线与宽发射的高能侧相符。对于低能侧,我们建议将锌空位及其与镓反相石的复合物作为潜在的内在来源。计算得出的 Zn 空位线形与橙色发光带非常吻合。镓空位不太可能是观测到的可见光和紫外线发射的来源,因为计算出的发光线出现在红外区域。此外,镓空位与一个或两个镓对位体之间的络合物会在更高能量下发光,但这种络合物只能是稳定的。一个 Ga 反杂质跃迁到 Ga 空位中,用一个 Zn 空位取代 Ga 反杂质和空位,这对 Ga 空位更有利。
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引用次数: 0
Subjugating extensive magnetostructural temperature window and giant magnetocaloric effect in B-doped (MnNiSi)0.67(Fe2Ge)0.33 hexagonal system 掺 B (锰镍硅)0.67(铁2锗)0.33 六方体系中的广泛磁结构温度窗口与巨磁效应的共轭
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-18 DOI: 10.1103/physrevmaterials.8.094407
J. Sridhar Mohanty, Saheli Samanta, Kalyan Mandal
Coupled first-order magnetostructural transformations (FOMSTs) with narrow widths governed by low external stimuli play a crucial role in magnetic refrigeration for ferromagnetic hexagonal systems. In this work, we report a family of magnetocaloric materials named boron (B)-doped (MnNiSi)0.67(Fe2Ge)0.33 compounds that are devoid of rare-earth elements. Our results show that varying B concentrations up to 5 at. % can tailor the robust FOMSTs between the low-temperature ferromagnetic orthorhombic phase and the high-temperature paramagnetic hexagonal phase in a wider temperature regime. A dramatic change in hysteresis (ΔThys) from ∼25 K for x=0 to ∼8 (9) K as well as increases in the saturation magnetization for specific 2 (3) at. % of B dopants is pronounced. Henceforth, the origin of the reducing hysteresis is illustrated based on the geometrical compatibility conditions (λ21) between the austenite and martensite phases using temperature-dependent powder x-ray diffraction analysis. Moreover, we found the samples performed with good functional stability from the thermal cycling run. The branch of these B doping materials exhibits robust features of a large magnetocaloric effect (MCE) over an extensive temperature range (∼71 K) and temperature-averaged magnetic entropy change at a lower magnetic field change of 2 T. These several tangible benefits, such as reduced ΔThys, geometrical compatibility, and robust MCE properties are first reported in the studied hexagonal system. Therefore, our results offer a viable approach to improve the cascading of these materials towards the application of cooling technology.
在铁磁性六方体系的磁制冷过程中,由低外部刺激控制的窄宽度耦合一阶磁结构转变(FOMST)起着至关重要的作用。在这项研究中,我们报告了一系列不含稀土元素的磁致冷材料,它们被命名为掺硼(B)的 (MnNiSi)0.67(Fe2Ge)0.33 化合物。我们的研究结果表明,改变硼的浓度(最高可达 5 at.当 x=0 时,磁滞(ΔThys)从 ∼25 K 急剧下降到 ∼8 (9) K,同时饱和磁化率在特定的 2 (3) at.B掺杂剂的百分比明显增加。因此,我们利用随温度变化的粉末 X 射线衍射分析,根据奥氏体和马氏体相之间的几何相容性条件 (λ2∼1) 来说明还原磁滞的起源。此外,我们还发现样品在热循环运行中具有良好的功能稳定性。这些掺 B 材料的分支在很大的温度范围(∼ 71 K)内表现出强大的磁致效应(MCE),并在较低的磁场变化 2 T 时表现出温度平均磁熵变化。因此,我们的研究结果为改进这些材料的级联以应用冷却技术提供了一种可行的方法。
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引用次数: 0
Ductile-to-brittle transition criterion of metallic glasses 金属玻璃的韧性到脆性转变标准
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-17 DOI: 10.1103/physrevmaterials.8.093608
X. T. Li, Z. Q. Liu, Z. J. Zhang, P. Zhang, Z. F. Zhang
In principle, the ductile-to-brittle transition (DBT) of metallic glasses may be dominated by the competition between shearing and cracking at different stress states. In response to this issue, we propose a new and concise criterion for DBT, named as the shearing-cracking (S-C) criterion, which can accurately predict the critical transition behaviors in metallic glasses induced by variations in both stress state (extrinsic factor) and Poisson's ratio (intrinsic factor). Furthermore, the S-C criterion provides a reasonable explanation for the peculiar phenomenon in metallic glasses that there are rare experimental cases of tensile fracture angle within the range of 60 to 90. Importantly, the S-C criterion offers theoretical guidance for toughness enhancement in metallic glasses from both intrinsic and extrinsic factors, thus facilitating the advancement of engineering applications involving metallic glasses.
原则上,金属玻璃的韧性到脆性转变(DBT)可能由不同应力状态下的剪切和开裂竞争所主导。针对这一问题,我们提出了一种新的、简明的 DBT 准则,即剪切-开裂(S-C)准则,它可以准确预测金属玻璃中由应力状态(外因)和泊松比(内因)变化引起的临界转变行为。此外,S-C 准则还能合理解释金属玻璃中拉伸断裂角在 60∘ 至 90∘ 范围内的罕见实验现象。重要的是,S-C 准则为从内在和外在因素提高金属玻璃的韧性提供了理论指导,从而促进了涉及金属玻璃的工程应用的发展。
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引用次数: 0
Anisotropic mechanical behavior of cesium tin iodide perovskite subjected to uniaxial tension 单轴拉伸下碘化铯锡包晶石的各向异性力学行为
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-16 DOI: 10.1103/physrevmaterials.8.093607
Amith Adoor Cheenady, Krishna Rajan
Lead-based metal halide perovskites (MHPs) have wide-ranging applications as solar cells, field-effect transistors, diodes, and photodetectors. However, their poor stability and concerns about toxicity have enabled lead-free tin-based MHPs to emerge as a promising alternative. We utilize molecular dynamics (MD) simulations to investigate the anisotropic mechanical behavior of single-crystal cubic CsSnI3, a promising lead-free MHP, under uniaxial tension. Among the three investigated crystal orientations, [111] is found to be the strongest and to exhibit the highest ultimate strain while [100] is the weakest. While shear strain localization and amorphization precede fracture along [100], fracture directly follows strain localization along [110] and [111]. We also investigated the influence of a crystal defect, in the form of an embedded rectangular crack, on the anisotropic mechanical behavior of cubic CsSnI3. The presence of crystal defects is found to substantially reduce the anisotropy in mechanical properties, with very similar crack growth behavior and almost identical stress-strain response noted along starkly different crystal orientations of loading. Finally, the ultimate strengths and ultimate strains of cubic CsSnI3 determined here are comparable to or higher than those of cubic CsPbI3 and MAPbI3 determined in prior MD-based investigations. Thus, our study supports the applicability of cubic CsSnI3 as a lead-free alternative to commonly used cubic MHPs, while the sensitivity to crystal defects revealed here underlines the importance of defect control for obtaining robust devices with reliable properties.
铅基金属卤化物过氧化物(MHPs)可广泛应用于太阳能电池、场效应晶体管、二极管和光电探测器。然而,由于其稳定性较差以及对毒性的担忧,无铅锡基 MHPs 成为了一种有前途的替代品。我们利用分子动力学(MD)模拟研究了单晶立方 CsSnI3(一种很有前途的无铅 MHP)在单轴拉力下的各向异性机械行为。在所研究的三种晶体取向中,[111]是最强的,表现出最高的极限应变,而[100]是最弱的。沿[100]方向的剪切应变局部化和非晶化发生在断裂之前,而沿[110]和[111]方向的应变局部化则直接导致断裂。我们还研究了嵌入式矩形裂纹形式的晶体缺陷对立方体 CsSnI3 各向异性力学行为的影响。结果发现,晶体缺陷的存在大大降低了机械特性的各向异性,在截然不同的加载晶体方向上,裂纹生长行为非常相似,应力-应变响应也几乎相同。最后,本研究测定的立方 CsSnI3 的极限强度和极限应变与之前基于 MD 研究测定的立方 CsPbI3 和 MAPbI3 相当或更高。因此,我们的研究支持立方 CsSnI3 作为常用立方 MHPs 的无铅替代品的适用性,而此处揭示的晶体缺陷敏感性则强调了控制缺陷对于获得性能可靠的稳健器件的重要性。
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引用次数: 0
Low-density diamondlike amorphous carbon at nanostructured metal-diamond interfaces 纳米结构金属-金刚石界面上的低密度金刚石状无定形碳
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-16 DOI: 10.1103/physrevmaterials.8.096001
Brendan McBennett, Yuka Esashi, Nicholas W. Jenkins, Albert Beardo, Yunzhe Shao, Emma E. Nelson, Theodore H. Culman, Begoña Abad, Michael Tanksalvala, Travis D. Frazer, Samuel Marks, Weilun Chao, Sadegh Yazdi, Joshua L. Knobloch, Henry C. Kapteyn, Margaret M. Murnane
Next-generation nanoelectronic, energy, and quantum technologies require increasingly stringent thermal, optical, mechanical, and electrical properties of component materials, often surpassing the limits of widely used materials such as silicon. Diamond, an ultrawide bandgap semiconductor, is a promising material for these applications because of its very high stiffness, thermal conductivity, and electron mobility. However, incorporating diamond into devices that require high-quality metal-diamond interfaces is challenging. In this work, we use a suite of electron microscopy measurements to reveal an ultrathin amorphous carbon layer that emerges at metal-diamond interfaces after electron beam lithography. Using extreme ultraviolet scatterometry, we nondestructively determine lower bounds on the layer's Young's modulus and thermal conductivity, which at >230GPa and >1.1 W/(mK) are indicative of a diamondlike form of amorphous carbon with high sp3 bonding. However, extreme ultraviolet coherent diffractive imaging reflectometry and energy-dispersive x-ray spectroscopy measurements indicate a low and likely inhomogeneous density in the range of 12g/cm3. The low density of such a stiff and conductive layer could indicate that it contains nanometer-scale voids or atomic-scale vacancies. The appearance of this unusual layer illustrates the nanofabrication challenges for diamond and highlights the need for better techniques to characterize surfaces and interfaces in nanoscale devices.
下一代纳米电子、能源和量子技术对元件材料的热学、光学、机械和电学特性的要求越来越严格,往往超过了硅等广泛使用的材料的极限。金刚石是一种超宽带隙半导体,具有极高的硬度、热导率和电子迁移率,是一种很有前途的应用材料。然而,将金刚石应用到需要高质量金属-金刚石界面的设备中具有挑战性。在这项工作中,我们利用一套电子显微镜测量方法揭示了电子束光刻后在金属-金刚石界面上出现的超薄无定形碳层。利用极紫外散射测量法,我们非破坏性地确定了该层的杨氏模量和热导率的下限,230GPa 和 1.1 W/(mK) 的杨氏模量和热导率表明该层是一种具有高 sp3 键的类似金刚石的无定形碳。然而,极紫外相干衍射成像反射测量法和能量色散 X 射线光谱法的测量结果表明,密度很低,而且很可能不均匀,在 1-2 克/立方厘米的范围内。如此坚硬的导电层密度如此之低,可能表明其中含有纳米级空隙或原子级空位。这种不寻常层的出现说明了金刚石的纳米制造所面临的挑战,并突出表明需要更好的技术来表征纳米级器件的表面和界面。
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引用次数: 0
Role of local structure in the optical and electronic properties of oxygen vacancies in different crystal phases of Ga2O3 局部结构在 Ga2O3 不同晶相中氧空位的光学和电子特性中的作用
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-16 DOI: 10.1103/physrevmaterials.8.094603
Chaiyawat Kaewmeechai, Jack Strand, Alexander Shluger
We investigate the structural, electronic, and optical properties of oxygen vacancies (VO) in crystalline α, β, and εGa2O3 using density functional theory (DFT) calculations with the PBE0-TC-LRC functional. Our results reveal that the charge transition levels (CTLs) associated with VO exhibit significant variations depending on the crystal phase and the coordination environment of surrounding atoms. In particular, VOs surrounded by tetrahedral Ga atoms (T-Ga) exhibit deeper CTLs compared to those surrounded by octahedral Ga atoms (O-Ga). We also observe distinct atomic relaxations, with larger displacements of T-Ga atoms compared to O-Ga atoms in the vicinity of VOs. Using linear-response time-dependent DFT, we investigate the optical transitions of VO and identify two distinct types of transitions: defect state to conduction band state and valence band to defect state. These results can be used to better understand the optical properties of VO defects in Ga2O3 films.
我们使用 PBE0-TC-LRC 函数进行密度泛函理论(DFT)计算,研究了晶体 α、β 和 ε-Ga2O3 中氧空位(VO)的结构、电子和光学性质。我们的研究结果表明,与 VO 相关的电荷转移水平(CTLs)会因晶体相和周围原子的配位环境而发生显著变化。特别是,与被八面体镓原子(O-Ga)包围的 VO 相比,被四面体镓原子(T-Ga)包围的 VO 显示出更深的 CTL。我们还观察到不同的原子弛豫,与 VO 附近的 O-Ga 原子相比,T-Ga 原子的位移更大。利用线性响应时间相关 DFT,我们研究了 VO 的光学跃迁,并确定了两种不同类型的跃迁:缺陷态到传导带态和价带到缺陷态。这些结果可用于更好地理解 Ga2O3 薄膜中 VO 缺陷的光学特性。
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引用次数: 0
Structure and migration of heavily irradiated grain boundaries and dislocations in Ni in the athermal limit 热极限镍中严重辐照晶界和位错的结构与迁移
IF 3.4 3区 材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY Pub Date : 2024-09-16 DOI: 10.1103/physrevmaterials.8.093606
Ian Chesser, Peter M. Derlet, Avanish Mishra, Sarah Paguaga, Nithin Mathew, Khanh Dang, Blas Pedro Uberuaga, Abigail Hunter, Saryu Fensin
The microstructural evolution at and near preexisting grain boundaries (GBs) and dislocations in materials under high radiation doses is still poorly understood. In this work, we use the creation relaxation algorithm (CRA) developed for atomistic modeling of high-dose irradiation in bulk materials to probe the athermal limit of saturation of GB and dislocation core regions under irradiation in fcc Ni. We find that, upon continuously subjecting a single dislocation or GB to Frenkel pair creation in the athermal limit, a local steady-state disordered defect structure is reached with excess properties that fluctuate around constant values. Case studies are given for a straight screw dislocation which elongates into a helix under irradiation and several types of low- and high-angle GBs, which exhibit coupled responses such as absorption of extrinsic dislocations, roughening, and migration. A positive correlation is found between the initial GB energy and the local steady-state GB energy under irradiation across a wide variety of GB types. Metastable GB structures with similar density in the defect core region but different initial configurations are found to converge to the same limiting structure under CRA. The mechanical responses of pristine and irradiated dislocations and GB structures are compared under an applied shear stress. Irradiated screw and edge dislocations are found to exhibit a hardening response, migrating at larger flow stresses than their pristine counterparts. Mobile GBs are found to exhibit softening or hardening responses depending on GB character. Although some GBs recover their initial pristine structures upon migration outside of the radiation zone, many GBs sustain different flow stresses corresponding to altered mobile core structures.
在高剂量辐照下,材料中预存在晶界(GB)和位错处及其附近的微观结构演变仍然鲜为人知。在这项工作中,我们利用为大块材料高剂量辐照的原子模型而开发的创造弛豫算法(CRA),来探测在辐照下 fcc Ni 中晶界和位错核心区域饱和的热极限。我们发现,在热极限条件下,当单个位错或 GB 不断受到弗伦克尔对的产生作用时,就会出现局部稳态无序缺陷结构,其过剩性质围绕恒定值波动。本研究给出了在辐照下拉长成螺旋状的直螺旋位错和几种低角度和高角度 GB 的案例研究,它们表现出了耦合反应,如外位错吸收、粗化和迁移。在各种类型的 GB 中,发现初始 GB 能量与辐照下的局部稳态 GB 能量之间存在正相关。研究发现,在 CRA 作用下,缺陷核心区域密度相似但初始构型不同的可迁移 GB 结构会趋同于相同的极限结构。比较了原始位错和辐照位错以及 GB 结构在外加剪应力下的机械响应。结果发现,辐照螺钉位错和边缘位错表现出硬化响应,与原始位错相比,它们在更大的流动应力下发生迁移。移动 GB 显示出软化或硬化反应,这取决于 GB 的特性。虽然有些 GB 在迁移到辐射区之外时会恢复其最初的原始结构,但许多 GB 会维持不同的流动应力,这与已改变的移动核心结构相对应。
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Physical Review Materials
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