Pub Date : 2024-07-14DOI: 10.1088/1361-651x/ad5b7b
Haris Mehmood and Hisham Nasser
Molybdenum Oxide (MoOx) has been used as a hole-extraction film for photovoltaic (PV) applications; however, its interaction with Germanium (Ge)-based solar cells is less understood. For the first time, this paper aims to physically model the Ge solar cell that incorporates MoOx for hole transportation at the front side of the PV device facing the sunlight. However, the charge transportation process within the PV device is influenced by several design parameters that need optimization. A higher work function of MoOx increases the barrier height against minority carriers of electrons which is beneficial for extricating holes at the front interface of MoOx/Ge. A progressive reduction in the recombination of charge carriers has been observed by including a passivation layer of amorphous silicon (i-a-Si:H). Similarly, inserting a passivation and back surface field (BSF) stack of i-a-Si:H strengthens the electric field and likewise reduces the recombination at the rear side of the device. An enhanced doping concentration of BSF assists in the favorable alignment of energy bands for improved charge transportation within the solar cell as the rear passivation maintains the field strength for accelerated movement of charge carriers. However, optimizing the thickness of the front-passivation film is challenging due to the parasitic absorption of light at larger thicknesses. A comparative study with the reference device revealed that the proposed device exhibited a step-increase in the conversion efficiency (η) from 4.23% to 13.10%, with a higher Jsc of 46.4 mA cm−2, Voc of 383 mV, and FF of 74%. The proposed study is anticipated to meet the research gap in the physical device modelling of Ge-based solar cells employing high work function MoOx as a carrier-selective layer that could be conducive to the development of highly efficient multijunction solar cells.
氧化钼（MoOx）已被用作光伏（PV）应用中的空穴萃取薄膜；然而，人们对它与基于锗（Ge）的太阳能电池之间的相互作用了解较少。本文首次旨在建立 Ge 太阳能电池的物理模型，该模型在光伏设备面向阳光的前端加入了用于空穴传输的 MoOx。然而，光伏器件内的电荷传输过程受到多个设计参数的影响，需要进行优化。氧化钼的功函数越高，对电子少数载流子的阻挡高度就越高，这有利于在氧化钼/锗的前端界面挤出空穴。加入非晶硅（i-a-Si:H）钝化层后，电荷载流子的重组逐渐减少。同样，插入 i-a-Si:H的钝化和背表面场（BSF）堆栈可增强电场，并同样减少器件后侧的重组。提高 BSF 的掺杂浓度有助于能带的良好排列，从而改善太阳能电池内部的电荷传输，因为背面钝化可保持电场强度，加速电荷载流子的移动。然而，由于前钝化膜厚度较大时会产生寄生光吸收，因此优化前钝化膜的厚度具有挑战性。与参考器件的比较研究表明，拟议器件的转换效率 (η)从 4.23% 逐步提高到 13.10%，Jsc 为 46.4 mA cm-2，Voc 为 383 mV，FF 为 74%。预计该研究将填补采用高功函数 MoOx 作为载流子选择层的 Ge 基太阳能电池物理器件建模方面的研究空白，有利于开发高效多结太阳能电池。
{"title":"TCAD simulation of germanium-based heterostructure solar cell employing molybdenum oxide as a hole-selective layer","authors":"Haris Mehmood and Hisham Nasser","doi":"10.1088/1361-651x/ad5b7b","DOIUrl":"https://doi.org/10.1088/1361-651x/ad5b7b","url":null,"abstract":"Molybdenum Oxide (MoOx) has been used as a hole-extraction film for photovoltaic (PV) applications; however, its interaction with Germanium (Ge)-based solar cells is less understood. For the first time, this paper aims to physically model the Ge solar cell that incorporates MoOx for hole transportation at the front side of the PV device facing the sunlight. However, the charge transportation process within the PV device is influenced by several design parameters that need optimization. A higher work function of MoOx increases the barrier height against minority carriers of electrons which is beneficial for extricating holes at the front interface of MoOx/Ge. A progressive reduction in the recombination of charge carriers has been observed by including a passivation layer of amorphous silicon (i-a-Si:H). Similarly, inserting a passivation and back surface field (BSF) stack of i-a-Si:H strengthens the electric field and likewise reduces the recombination at the rear side of the device. An enhanced doping concentration of BSF assists in the favorable alignment of energy bands for improved charge transportation within the solar cell as the rear passivation maintains the field strength for accelerated movement of charge carriers. However, optimizing the thickness of the front-passivation film is challenging due to the parasitic absorption of light at larger thicknesses. A comparative study with the reference device revealed that the proposed device exhibited a step-increase in the conversion efficiency (η) from 4.23% to 13.10%, with a higher Jsc of 46.4 mA cm−2, Voc of 383 mV, and FF of 74%. The proposed study is anticipated to meet the research gap in the physical device modelling of Ge-based solar cells employing high work function MoOx as a carrier-selective layer that could be conducive to the development of highly efficient multijunction solar cells.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"11 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141717739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1088/1361-651x/ad5dd4
Atsuo Hirano, Yosuke Tsunemoto and Akiyuki Takahashi
Classical molecular dynamics (MD) is extensively employed to explore the properties, deformations, and fractures of materials at the atomic scale. Identifying local structures is crucial for understanding the mechanisms behind material deformation and fracture. Nevertheless, analyzing the local lattice structure at high temperatures poses challenges due to atomic thermal fluctuations, which act as noise and potentially lead to misjudgment of the local lattice structure. To date, various strategies have been implemented to circumvent this issue. However, they cannot be a solution because it is unable to reproduce phenomena unique to high temperatures, whereas others require significant computational resources. This paper introduces an innovative method to reduce atomic thermal fluctuations using a straightforward algorithm, thereby facilitating accurate identification of local lattice structures even at high temperatures. Our approach incorporates novel degrees of freedom, termed ‘Markers,’ that are linked to atoms. By reducing the thermal fluctuation of these Markers, precise analysis of the local lattice structure becomes feasible. The efficacy of this method is validated through its thermal reducibility and Markers trackabilities to atoms. Utilizing common neighbor analysis, the error rate for structure identification with our method is nearly 0% at temperatures up to 1200 K in Fe, in contrast to approximately 5% without it. Furthermore, the average distance between atoms and Markers remains below 0.1 Å. Applying our method to phase transformations, we successfully observed the transition from face-centered cubic to body-centered cubic structure in Fe at 1200 K. This method holds promise for expanding the capabilities of MD simulations at high temperatures.
经典分子动力学（MD）被广泛用于探索材料在原子尺度上的特性、变形和断裂。识别局部结构对于理解材料变形和断裂背后的机理至关重要。然而，在高温条件下分析局部晶格结构是一项挑战，因为原子热波动是一种噪声，有可能导致对局部晶格结构的误判。迄今为止，人们已经实施了各种策略来规避这一问题。然而，这些方法都无法解决这一问题，因为它们无法再现高温下的特有现象，而其他方法则需要大量的计算资源。本文介绍了一种创新方法，利用一种简单的算法来减少原子热波动，从而即使在高温下也能准确识别局部晶格结构。我们的方法包含了与原子相连的新自由度，称为 "标记"。通过减少这些标记的热波动，就可以对局部晶格结构进行精确分析。这种方法的有效性通过其热还原性和标记与原子的可跟踪性得到了验证。利用共邻分析，在温度高达 1200 K 的铁元素中，使用我们的方法进行结构识别的错误率几乎为 0%，而不使用这种方法的错误率约为 5%。此外，原子与 Markers 之间的平均距离保持在 0.1 Å 以下。将我们的方法应用于相变，我们成功观测到铁在 1200 K 时从面心立方结构向体心立方结构的转变。
{"title":"Atomic thermal fluctuation reduction method for robust local lattice structure identification in finite-temperature molecular dynamics","authors":"Atsuo Hirano, Yosuke Tsunemoto and Akiyuki Takahashi","doi":"10.1088/1361-651x/ad5dd4","DOIUrl":"https://doi.org/10.1088/1361-651x/ad5dd4","url":null,"abstract":"Classical molecular dynamics (MD) is extensively employed to explore the properties, deformations, and fractures of materials at the atomic scale. Identifying local structures is crucial for understanding the mechanisms behind material deformation and fracture. Nevertheless, analyzing the local lattice structure at high temperatures poses challenges due to atomic thermal fluctuations, which act as noise and potentially lead to misjudgment of the local lattice structure. To date, various strategies have been implemented to circumvent this issue. However, they cannot be a solution because it is unable to reproduce phenomena unique to high temperatures, whereas others require significant computational resources. This paper introduces an innovative method to reduce atomic thermal fluctuations using a straightforward algorithm, thereby facilitating accurate identification of local lattice structures even at high temperatures. Our approach incorporates novel degrees of freedom, termed ‘Markers,’ that are linked to atoms. By reducing the thermal fluctuation of these Markers, precise analysis of the local lattice structure becomes feasible. The efficacy of this method is validated through its thermal reducibility and Markers trackabilities to atoms. Utilizing common neighbor analysis, the error rate for structure identification with our method is nearly 0% at temperatures up to 1200 K in Fe, in contrast to approximately 5% without it. Furthermore, the average distance between atoms and Markers remains below 0.1 Å. Applying our method to phase transformations, we successfully observed the transition from face-centered cubic to body-centered cubic structure in Fe at 1200 K. This method holds promise for expanding the capabilities of MD simulations at high temperatures.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"31 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141587983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1088/1361-651x/ad4d0d
Stefan Bauer, Peter Benner, Tristan Bereau, Volker Blum, Mario Boley, Christian Carbogno, C Richard A Catlow, Gerhard Dehm, Sebastian Eibl, Ralph Ernstorfer, Ádám Fekete, Lucas Foppa, Peter Fratzl, Christoph Freysoldt, Baptiste Gault, Luca M Ghiringhelli, Sajal K Giri, Anton Gladyshev, Pawan Goyal, Jason Hattrick-Simpers, Lara Kabalan, Petr Karpov, Mohammad S Khorrami, Christoph T. Koch, Sebastian Kokott, Thomas Kosch, Igor Kowalec, Kurt Kremer, Andreas Leitherer, Yue Li, Christian H Liebscher, Andrew J Logsdail, Zhongwei Lu, Felix Luong, Andreas Marek, Florian Merz, Jaber R Mianroodi, Jörg Neugebauer, Zongrui Pei, Thomas A R Purcell, Dierk Raabe, Markus Rampp, Mariana Rossi, Jan-Michael Rost, James Saal, Ulf Saalmann, Kasturi Narasimha Sasidhar, Alaukik Saxena, Luigi Sbailò, Markus Scheidgen, Marcel Schloz, Daniel F Schmidt, Simon Teshuva, Annette Trunschke, Ye Wei, Gerhard Weikum, R Patrick Xian, Yi Yao, Junqi Yin, Meng Zhao and Matthias Scheffler
Science is and always has been based on data, but the terms ‘data-centric’ and the ‘4th paradigm’ of materials research indicate a radical change in how information is retrieved, handled and research is performed. It signifies a transformative shift towards managing vast data collections, digital repositories, and innovative data analytics methods. The integration of artificial intelligence and its subset machine learning, has become pivotal in addressing all these challenges. This Roadmap on Data-Centric Materials Science explores fundamental concepts and methodologies, illustrating diverse applications in electronic-structure theory, soft matter theory, microstructure research, and experimental techniques like photoemission, atom probe tomography, and electron microscopy. While the roadmap delves into specific areas within the broad interdisciplinary field of materials science, the provided examples elucidate key concepts applicable to a wider range of topics. The discussed instances offer insights into addressing the multifaceted challenges encountered in contemporary materials research.
{"title":"Roadmap on data-centric materials science","authors":"Stefan Bauer, Peter Benner, Tristan Bereau, Volker Blum, Mario Boley, Christian Carbogno, C Richard A Catlow, Gerhard Dehm, Sebastian Eibl, Ralph Ernstorfer, Ádám Fekete, Lucas Foppa, Peter Fratzl, Christoph Freysoldt, Baptiste Gault, Luca M Ghiringhelli, Sajal K Giri, Anton Gladyshev, Pawan Goyal, Jason Hattrick-Simpers, Lara Kabalan, Petr Karpov, Mohammad S Khorrami, Christoph T. Koch, Sebastian Kokott, Thomas Kosch, Igor Kowalec, Kurt Kremer, Andreas Leitherer, Yue Li, Christian H Liebscher, Andrew J Logsdail, Zhongwei Lu, Felix Luong, Andreas Marek, Florian Merz, Jaber R Mianroodi, Jörg Neugebauer, Zongrui Pei, Thomas A R Purcell, Dierk Raabe, Markus Rampp, Mariana Rossi, Jan-Michael Rost, James Saal, Ulf Saalmann, Kasturi Narasimha Sasidhar, Alaukik Saxena, Luigi Sbailò, Markus Scheidgen, Marcel Schloz, Daniel F Schmidt, Simon Teshuva, Annette Trunschke, Ye Wei, Gerhard Weikum, R Patrick Xian, Yi Yao, Junqi Yin, Meng Zhao and Matthias Scheffler","doi":"10.1088/1361-651x/ad4d0d","DOIUrl":"https://doi.org/10.1088/1361-651x/ad4d0d","url":null,"abstract":"Science is and always has been based on data, but the terms ‘data-centric’ and the ‘4th paradigm’ of materials research indicate a radical change in how information is retrieved, handled and research is performed. It signifies a transformative shift towards managing vast data collections, digital repositories, and innovative data analytics methods. The integration of artificial intelligence and its subset machine learning, has become pivotal in addressing all these challenges. This Roadmap on Data-Centric Materials Science explores fundamental concepts and methodologies, illustrating diverse applications in electronic-structure theory, soft matter theory, microstructure research, and experimental techniques like photoemission, atom probe tomography, and electron microscopy. While the roadmap delves into specific areas within the broad interdisciplinary field of materials science, the provided examples elucidate key concepts applicable to a wider range of topics. The discussed instances offer insights into addressing the multifaceted challenges encountered in contemporary materials research.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"14 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1361-651x/ad5a2b
Bhoomi S Shah, Jiten P Tailor, Sunil H Chaki and M P Deshpande
In the realm of photovoltaic applications, scientists and technocrats are striving to maximize the solar cell input photon energy conversion to electricity. However, achieving optimal cell efficiency requires significant time and energy investment for each variation and optimization. To overcome this issue authors simulated and studied the fabricated cell for optimizing conditions, which can save time and efforts for the relatively better outcomes. The family of transition metal chalcogenides holds promise as a material that yield improved outcomes in optoelectronic applications, particularly in photovoltaics. These materials are employed in experimental investigations aimed at enhancing solar cell parameters, resulting in the development of the FTO/ZnO/ZrS2/MoS2/CuO/Au composite cell. Numerical simulations utilizing SCAPS-1D software is conducted, focusing on the significance of CuO as a hole transport layer (HTL), and ZnO as an electron transport layer (ETL). The investigation examines into the impact of various factors, including thickness, bandgap, and carrier densities for both HTL and ETL, on fundamental solar cell parameters. The study indicates that device parameters are influenced by factors such as recombination rate, photogenerated current, charge carrier length, and built-in-voltage. Optimized parameters for HTL, including thickness, bandgap, and carrier concentration, are determined to be 0⋅35 μm, 1⋅2 eV, and 1⋅0 × 1020 cm–3, respectively. For ETL, the optimized parameters are found to be 0⋅05 μm, 3⋅1 eV, and 1⋅0 × 1018 cm–3, respectively. With these optimized parameters, the efficiency of the solar cell reached 20⋅64%, accompanied by open circuit voltage, short circuit current density, and fill factor values of 0.836 V, 36.021 mA⋅cm–2, and 68⋅54%, respectively. The simulated results indicate that addition of two extra layers and the use of efficient binary materials in heterojunction formation can effectively enhance device parameters, offering advantages such as low-cost and large-scale fabrication.
{"title":"SCAPS 1D based study of hole and electron transfer layers to improve MoS2–ZrS2 solar cell efficiency","authors":"Bhoomi S Shah, Jiten P Tailor, Sunil H Chaki and M P Deshpande","doi":"10.1088/1361-651x/ad5a2b","DOIUrl":"https://doi.org/10.1088/1361-651x/ad5a2b","url":null,"abstract":"In the realm of photovoltaic applications, scientists and technocrats are striving to maximize the solar cell input photon energy conversion to electricity. However, achieving optimal cell efficiency requires significant time and energy investment for each variation and optimization. To overcome this issue authors simulated and studied the fabricated cell for optimizing conditions, which can save time and efforts for the relatively better outcomes. The family of transition metal chalcogenides holds promise as a material that yield improved outcomes in optoelectronic applications, particularly in photovoltaics. These materials are employed in experimental investigations aimed at enhancing solar cell parameters, resulting in the development of the FTO/ZnO/ZrS2/MoS2/CuO/Au composite cell. Numerical simulations utilizing SCAPS-1D software is conducted, focusing on the significance of CuO as a hole transport layer (HTL), and ZnO as an electron transport layer (ETL). The investigation examines into the impact of various factors, including thickness, bandgap, and carrier densities for both HTL and ETL, on fundamental solar cell parameters. The study indicates that device parameters are influenced by factors such as recombination rate, photogenerated current, charge carrier length, and built-in-voltage. Optimized parameters for HTL, including thickness, bandgap, and carrier concentration, are determined to be 0⋅35 μm, 1⋅2 eV, and 1⋅0 × 1020 cm–3, respectively. For ETL, the optimized parameters are found to be 0⋅05 μm, 3⋅1 eV, and 1⋅0 × 1018 cm–3, respectively. With these optimized parameters, the efficiency of the solar cell reached 20⋅64%, accompanied by open circuit voltage, short circuit current density, and fill factor values of 0.836 V, 36.021 mA⋅cm–2, and 68⋅54%, respectively. The simulated results indicate that addition of two extra layers and the use of efficient binary materials in heterojunction formation can effectively enhance device parameters, offering advantages such as low-cost and large-scale fabrication.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"103 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.1088/1361-651x/ad5a2a
Huiming Wang, Jianfeng Jin, Dongxin Wang, Demei Xu, Kaiqi Guo, Peijun Yang and Gaowu Qin
Beryllium has some unique properties and plays a key role in many special applications. However, Beryllium (α-Be) is of close-packed hexagonal (HCP) crystal structure, which has a strong anisotropic feature and limits its applications. In this work, diffusion behaviors of the self-interstitial atom (SIA) in α-Be at the temperature of 300–1100 K are studied using molecular dynamics simulations. It is observed that the diffusion mechanisms are not only dominated by the SIA jumps among the BO and BS sites on the basal plane, but also by the jumps among the C and O sites along the c-axis, which strongly depend on temperature. Diffusion behaviors of SIA can be divided into two stages with the temperature of 300–800 K and 800–1100 K, respectively, in which diffusion coefficient component of the c-axis (Dc) is higher than that of the basal plane (Db) at first and then becomes closer to the Db after 800 K, in consistent with diffusion mechanisms. When the temperature rises from 300 K to 1100 K, the total diffusion coefficient of SIA (Dt) increases gradually from 0.34 × 10−4 cm2 s−1 to 1.13 × 10−4 cm2 s−1. With the temperature increasing from 300 K to 1100 K, the anisotropy factor (η = Dc/Db) of SIA diffusion drastically decreases from 1.76 to 1.01 in α-Be, while the η increases from 0.21 to 0.70 in α-Zr with the temperature from 500 K to 1100 K.
铍具有一些独特的性质，在许多特殊应用中发挥着关键作用。然而，铍（α-Be）为密堆积六方（HCP）晶体结构，具有很强的各向异性，限制了其应用。本文利用分子动力学模拟研究了 300-1100 K 温度下 α-Be 中自间隙原子（SIA）的扩散行为。结果表明，扩散机制不仅受基底面上 BO 和 BS 位点之间的 SIA 跃迁的支配，而且还受沿 c 轴的 C 和 O 位点之间的跃迁的支配，而这些跃迁与温度密切相关。SIA 的扩散行为可分为两个阶段，温度分别为 300-800 K 和 800-1100 K，其中 c 轴的扩散系数分量（Dc）最初高于基底面的扩散系数分量（Db），800 K 之后则逐渐接近于 Db，这与扩散机制一致。当温度从 300 K 上升到 1100 K 时，SIA 的总扩散系数（Dt）从 0.34 × 10-4 cm2 s-1 逐渐增加到 1.13 × 10-4 cm2 s-1。随着温度从 300 K 升至 1100 K，SIA 扩散的各向异性因子（η = Dc/Db）在 α-Be 中从 1.76 急剧下降至 1.01，而在α-Zr 中，随着温度从 500 K 升至 1100 K，η 从 0.21 增至 0.70。
{"title":"Molecular dynamics insights on the self-interstitial diffusion in α-Beryllium","authors":"Huiming Wang, Jianfeng Jin, Dongxin Wang, Demei Xu, Kaiqi Guo, Peijun Yang and Gaowu Qin","doi":"10.1088/1361-651x/ad5a2a","DOIUrl":"https://doi.org/10.1088/1361-651x/ad5a2a","url":null,"abstract":"Beryllium has some unique properties and plays a key role in many special applications. However, Beryllium (α-Be) is of close-packed hexagonal (HCP) crystal structure, which has a strong anisotropic feature and limits its applications. In this work, diffusion behaviors of the self-interstitial atom (SIA) in α-Be at the temperature of 300–1100 K are studied using molecular dynamics simulations. It is observed that the diffusion mechanisms are not only dominated by the SIA jumps among the BO and BS sites on the basal plane, but also by the jumps among the C and O sites along the c-axis, which strongly depend on temperature. Diffusion behaviors of SIA can be divided into two stages with the temperature of 300–800 K and 800–1100 K, respectively, in which diffusion coefficient component of the c-axis (Dc) is higher than that of the basal plane (Db) at first and then becomes closer to the Db after 800 K, in consistent with diffusion mechanisms. When the temperature rises from 300 K to 1100 K, the total diffusion coefficient of SIA (Dt) increases gradually from 0.34 × 10−4 cm2 s−1 to 1.13 × 10−4 cm2 s−1. With the temperature increasing from 300 K to 1100 K, the anisotropy factor (η = Dc/Db) of SIA diffusion drastically decreases from 1.76 to 1.01 in α-Be, while the η increases from 0.21 to 0.70 in α-Zr with the temperature from 500 K to 1100 K.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"43 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-26DOI: 10.1088/1361-651x/ad5a2c
M Mohammed Shoaib Hussain, N Syed Kaleemullah, G Ajay and M Mohamed Sheik Sirajuddeen
First principles calculations were employed to study the structural, electronic and optical properties of Indium based cubic perovskite materials, specifically focusing on InBeF3 and InCaF3 compounds. The generalized gradient approximation Perdew–Burke–Ernzerhof (GGA_PBE) approximation and Tran–Blaha modified Becke–Johnson (TB-mBJ) approximations were used to study and compare the electronic and optical properties. The compound InBeF3 is predicted to have an indirect band gap of 2.51 eV in GGA_PBE and 2.96 eV in TB-mBJ. InCaF3 is found to have a direct wide band gap of 3.61 eV in GGA_PBE and 4.37 eV in TB-mBJ approximation. The partial density of states predicts the significance of In-5p and F-2p states in the conduction and valence bands, respectively. The dielectric constants decrease under the TB-mBJ approximation, with InCaF3 demonstrating lower values owing to its larger band gap. Optical activity analysis indicates transparency for both compounds with notable absorption peaks, suggesting potential applications in transparent coatings. Refractive indices decrease with photon energy, with values dropping below 1.0 in the TB-mBJ approximation, indicating superluminal behavior in wave propagation. The drop in refractive index value below1.0 is earlier for InCaF3 than InBeF3. Examination of the extinction coefficient reveals UV absorption peaks, indicating potential for optoelectronic applications. From this study it can be noticed that the compounds under study can be used for optoelectronic applications, supported by their predicted structural and optical properties study.
{"title":"A DFT study on structural, electronic, and optical properties of cubic perovskite semiconductors InXF3 (X = Be and Ca) for optoelectronic applications","authors":"M Mohammed Shoaib Hussain, N Syed Kaleemullah, G Ajay and M Mohamed Sheik Sirajuddeen","doi":"10.1088/1361-651x/ad5a2c","DOIUrl":"https://doi.org/10.1088/1361-651x/ad5a2c","url":null,"abstract":"First principles calculations were employed to study the structural, electronic and optical properties of Indium based cubic perovskite materials, specifically focusing on InBeF3 and InCaF3 compounds. The generalized gradient approximation Perdew–Burke–Ernzerhof (GGA_PBE) approximation and Tran–Blaha modified Becke–Johnson (TB-mBJ) approximations were used to study and compare the electronic and optical properties. The compound InBeF3 is predicted to have an indirect band gap of 2.51 eV in GGA_PBE and 2.96 eV in TB-mBJ. InCaF3 is found to have a direct wide band gap of 3.61 eV in GGA_PBE and 4.37 eV in TB-mBJ approximation. The partial density of states predicts the significance of In-5p and F-2p states in the conduction and valence bands, respectively. The dielectric constants decrease under the TB-mBJ approximation, with InCaF3 demonstrating lower values owing to its larger band gap. Optical activity analysis indicates transparency for both compounds with notable absorption peaks, suggesting potential applications in transparent coatings. Refractive indices decrease with photon energy, with values dropping below 1.0 in the TB-mBJ approximation, indicating superluminal behavior in wave propagation. The drop in refractive index value below1.0 is earlier for InCaF3 than InBeF3. Examination of the extinction coefficient reveals UV absorption peaks, indicating potential for optoelectronic applications. From this study it can be noticed that the compounds under study can be used for optoelectronic applications, supported by their predicted structural and optical properties study.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"5 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-25DOI: 10.1088/1361-651x/ad585f
Doruk Aksoy, Jian Luo, Penghui Cao and Timothy J Rupert
The discovery of complex concentrated alloys (CCA) has unveiled materials with diverse atomic environments, prompting the exploration of solute segregation beyond dilute alloys. However, the vast number of possible elemental interactions means a computationally prohibitive number of simulations are needed for comprehensive segregation energy spectrum analysis. Data-driven methods offer promising solutions for overcoming such limitations for modeling segregation in such chemically complex environments (CCEs), and are employed in this study to understand segregation behavior of a refractory CCA, NbMoTaW. A flexible methodology is developed that uses composable computational modules, with different arrangements of these modules employed to obtain site availabilities at absolute zero and the corresponding density of states beyond the dilute limit, resulting in an extremely large dataset containing 10 million data points. The artificial neural network developed here can rely solely on descriptions of local atomic environments to predict behavior at the dilute limit with very small errors, while the addition of negative segregation instance classification allows any solute concentration from zero up to the equiatomic concentration for ternary or quaternary alloys to be modeled at room temperature. The machine learning model thus achieves a significant speed advantage over traditional atomistic simulations, being four orders of magnitude faster, while only experiencing a minimal reduction in accuracy. This efficiency presents a powerful tool for rapid microstructural and interfacial design in unseen domains. Scientifically, our approach reveals a transition in the segregation behavior of Mo from unfavorable in simple systems to favorable in complex environments. Additionally, increasing solute concentration was observed to cause anti-segregation sites to begin to fill, challenging conventional understanding and highlighting the complexity of segregation dynamics in CCEs.
复杂浓缩合金（CCA）的发现揭示了具有多种原子环境的材料，促使人们探索稀合金以外的溶质偏析问题。然而，大量可能的元素相互作用意味着要进行全面的偏析能谱分析，需要进行大量的模拟计算，其计算量令人望而却步。本研究采用数据驱动方法来了解难熔 CCA NbMoTaW 的偏析行为。本研究开发了一种灵活的方法，使用可组合的计算模块，通过对这些模块进行不同的排列组合来获得绝对零度时的位点利用率以及稀释极限以外的相应状态密度，从而获得包含 1 千万个数据点的超大数据集。这里开发的人工神经网络可以完全依赖于对局部原子环境的描述来预测稀释极限的行为，误差非常小，而增加负偏析实例分类后，可以对室温下三元或四元合金从零到等原子浓度的任何溶质浓度进行建模。因此，与传统原子模拟相比，机器学习模型在速度上具有显著优势，快了四个数量级，而精度却只降低了很少。这种效率为在未知领域快速进行微结构和界面设计提供了强大的工具。在科学上，我们的方法揭示了钼的偏析行为从简单系统中的不利转变为复杂环境中的有利。此外，我们还观察到溶质浓度的增加会导致反偏析位点开始填充，这挑战了人们的传统认识，凸显了 CCE 中偏析动力学的复杂性。
{"title":"A machine learning framework for the prediction of grain boundary segregation in chemically complex environments","authors":"Doruk Aksoy, Jian Luo, Penghui Cao and Timothy J Rupert","doi":"10.1088/1361-651x/ad585f","DOIUrl":"https://doi.org/10.1088/1361-651x/ad585f","url":null,"abstract":"The discovery of complex concentrated alloys (CCA) has unveiled materials with diverse atomic environments, prompting the exploration of solute segregation beyond dilute alloys. However, the vast number of possible elemental interactions means a computationally prohibitive number of simulations are needed for comprehensive segregation energy spectrum analysis. Data-driven methods offer promising solutions for overcoming such limitations for modeling segregation in such chemically complex environments (CCEs), and are employed in this study to understand segregation behavior of a refractory CCA, NbMoTaW. A flexible methodology is developed that uses composable computational modules, with different arrangements of these modules employed to obtain site availabilities at absolute zero and the corresponding density of states beyond the dilute limit, resulting in an extremely large dataset containing 10 million data points. The artificial neural network developed here can rely solely on descriptions of local atomic environments to predict behavior at the dilute limit with very small errors, while the addition of negative segregation instance classification allows any solute concentration from zero up to the equiatomic concentration for ternary or quaternary alloys to be modeled at room temperature. The machine learning model thus achieves a significant speed advantage over traditional atomistic simulations, being four orders of magnitude faster, while only experiencing a minimal reduction in accuracy. This efficiency presents a powerful tool for rapid microstructural and interfacial design in unseen domains. Scientifically, our approach reveals a transition in the segregation behavior of Mo from unfavorable in simple systems to favorable in complex environments. Additionally, increasing solute concentration was observed to cause anti-segregation sites to begin to fill, challenging conventional understanding and highlighting the complexity of segregation dynamics in CCEs.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"227 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-24DOI: 10.1088/1361-651x/ad585e
Luyu Wang, Xinxin Liu and Zhibin Gao
High-entropy alloys (HEAs) are currently the subject of extensive research. Despite this, the effects of rapid cooling on their performance have yet to be investigated. This study uses ab initio molecular dynamics to investigate the CrCoFeNiMnAlx (x =0, 0.5 and 1) HEAs under a rapid cooling process. It has been observed that the three HEAs all form metallic glass at 300 K under a constant cooling rate of 1.25 × 102 K ps−1, mainly composed of icosahedron and face-centered cubic clusters. Secondly, the glass transition temperatures (Tg) are predicted to be 1658 K for CrCoFeNiMn, 1667 K for CrCoFeNiMnAl0.5, and 1687 K for CrCoFeNiMnAl, respectively. It can be seen the Tg of HEAs increases with the content of Al increasing. Eventually, a relationship between structure and dynamics is established by using the five-fold local symmetry parameters and shear viscosity, which proves that structural evolution is the fundamental reason for dynamic deceleration. The present results contribute to understanding the evolution of the local structure of CrCoFeNiMnAlx and provide a new perspective for studying the structural mechanism of dynamic retardation in HEAs.
高熵合金（HEAs）是目前广泛研究的课题。尽管如此，快速冷却对其性能的影响仍有待研究。本研究采用 ab initio 分子动力学方法研究了快速冷却过程中的 CrCoFeNiMnAlx（x =0、0.5 和 1）高熵合金。结果表明，在 1.25 × 102 K ps-1 的恒定冷却速率下，三种 HEA 在 300 K 时均形成金属玻璃，主要由二十面体和面心立方晶簇组成。其次，预测铬钴铁镍锰、铬钴铁镍锰铝和铬钴铁镍锰铝的玻璃化转变温度（Tg）分别为 1658 K、1667 K 和 1687 K。由此可见，随着铝含量的增加，HEA 的 Tg 也在增加。最后，利用五重局部对称参数和剪切粘度建立了结构与动力学之间的关系，证明了结构演变是动态减速的根本原因。本研究结果有助于理解铬钴铁镍锰铝氧化物局部结构的演变，并为研究 HEA 动态减速的结构机理提供了一个新的视角。
{"title":"The property of CrCoNiFeMnAl x (x=0, 0.5, and 1) high-entropy alloys on rapid cooling: insights from ab initio molecular dynamics","authors":"Luyu Wang, Xinxin Liu and Zhibin Gao","doi":"10.1088/1361-651x/ad585e","DOIUrl":"https://doi.org/10.1088/1361-651x/ad585e","url":null,"abstract":"High-entropy alloys (HEAs) are currently the subject of extensive research. Despite this, the effects of rapid cooling on their performance have yet to be investigated. This study uses ab initio molecular dynamics to investigate the CrCoFeNiMnAlx (x =0, 0.5 and 1) HEAs under a rapid cooling process. It has been observed that the three HEAs all form metallic glass at 300 K under a constant cooling rate of 1.25 × 102 K ps−1, mainly composed of icosahedron and face-centered cubic clusters. Secondly, the glass transition temperatures (Tg) are predicted to be 1658 K for CrCoFeNiMn, 1667 K for CrCoFeNiMnAl0.5, and 1687 K for CrCoFeNiMnAl, respectively. It can be seen the Tg of HEAs increases with the content of Al increasing. Eventually, a relationship between structure and dynamics is established by using the five-fold local symmetry parameters and shear viscosity, which proves that structural evolution is the fundamental reason for dynamic deceleration. The present results contribute to understanding the evolution of the local structure of CrCoFeNiMnAlx and provide a new perspective for studying the structural mechanism of dynamic retardation in HEAs.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"29 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-19DOI: 10.1088/1361-651x/ad56a6
Vladimir N Danilin, Alexander S Aleshchenko, Andrei V Danilin and Alexander N Koshmin
The main process parameters of direct and indirect extrusion of aluminum alloys were studied using FE-modeling in this article. The subject of the study was the use of billets taper heating and variable pressing rate as compared to the standard extrusion conditions. Extrusion of AA2024 grade alloy and experimental Al-2%Cu-1.5%Mn-1%Mg-1%Zn alloy was considered. The flow stress-on-strain dependences within the 350 °C–450 °C range at strain rates of 0.1–10 s−1 were determined for the experimental alloy. Considering the time of billet transportation to the extrusion equipment, its optimum temperature gradient was determined to be 500 °C at the front end and 140 °C at the tail end. Direct extrusion of taper heated billets at the variable rate and elongation of 7 allowed increasing the process performance by 5.6 times (from 1.8 mm s−1 to an average of 10 mm s−1, in case uniformly heated billets are extruded at the constant rate). In case of pressing at high elongations (15 and 25), the performance increase was about 2 times. It was found that the use of taper heating, both in case of grade alloy and model alloy extrusion, in all the considered conditions, allows achieving a significant increase in performance. However, these results are considered to be most effective in case of direct extrusion at small elongation ratios.
本文使用 FE 模型研究了铝合金直接和间接挤压的主要工艺参数。与标准挤压条件相比，研究的主题是使用坯料锥形加热和可变加压速率。研究考虑了 AA2024 等级合金和试验性 Al-2%Cu-1.5%Mn-1%Mg-1%Zn 合金的挤压。在应变速率为 0.1-10 s-1 时，确定了实验合金在 350 °C-450 °C 范围内的流动应力-应变相关性。考虑到坯料运输到挤压设备的时间，确定其最佳温度梯度为前端 500 ℃，尾端 140 ℃。以可变速率和 7 的伸长率直接挤压锥形加热坯料，可将加工性能提高 5.6 倍（从 1.8 mm s-1 提高到平均 10 mm s-1，如果以恒定速率挤压均匀加热的坯料）。如果以高伸长率（15 和 25）进行挤压，性能提高约 2 倍。研究发现，在等级合金和模型合金挤压中，在所有考虑的条件下使用锥形加热都能显著提高性能。然而，这些结果被认为在小伸长率的直接挤压情况下最为有效。
{"title":"Simulation of taper heating and variable pressing rate to improve extrusion performance for high-strength aluminum alloys","authors":"Vladimir N Danilin, Alexander S Aleshchenko, Andrei V Danilin and Alexander N Koshmin","doi":"10.1088/1361-651x/ad56a6","DOIUrl":"https://doi.org/10.1088/1361-651x/ad56a6","url":null,"abstract":"The main process parameters of direct and indirect extrusion of aluminum alloys were studied using FE-modeling in this article. The subject of the study was the use of billets taper heating and variable pressing rate as compared to the standard extrusion conditions. Extrusion of AA2024 grade alloy and experimental Al-2%Cu-1.5%Mn-1%Mg-1%Zn alloy was considered. The flow stress-on-strain dependences within the 350 °C–450 °C range at strain rates of 0.1–10 s−1 were determined for the experimental alloy. Considering the time of billet transportation to the extrusion equipment, its optimum temperature gradient was determined to be 500 °C at the front end and 140 °C at the tail end. Direct extrusion of taper heated billets at the variable rate and elongation of 7 allowed increasing the process performance by 5.6 times (from 1.8 mm s−1 to an average of 10 mm s−1, in case uniformly heated billets are extruded at the constant rate). In case of pressing at high elongations (15 and 25), the performance increase was about 2 times. It was found that the use of taper heating, both in case of grade alloy and model alloy extrusion, in all the considered conditions, allows achieving a significant increase in performance. However, these results are considered to be most effective in case of direct extrusion at small elongation ratios.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"179 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-06DOI: 10.1088/1361-651x/ad4c82
Izumi Takahara, Kiyou Shibata, Teruyasu Mizoguchi
Crystal orbital overlap population (COOP) is one of the effective tools for chemical-bonding analysis, and thus it has been utilized in the materials development and characterization. In this study, we developed a code to perform the COOP-based chemical-bonding analysis based on the wave function obtained from a first principles all-electron calculation with numeric atom-centered orbitals. The chemical-bonding analysis using the developed code was demonstrated for F2, Si, CaC6, and metals including Ti and Nb. Furthermore, we applied the method to analyze the chemical-bonding changes associated with a Li intercalation in three representative layered materials: graphite, MoS2, and ZrNCl, because of their great industrial importance, particularly for the applications in battery and superconducting materials. The COOP analysis provided some insights for understanding the intercalation mechanism and the stability of the intercalated materials from a chemical-bonding viewpoint.
晶体轨道重叠群（COOP）是化学键分析的有效工具之一，因此在材料开发和表征中得到了广泛应用。在本研究中，我们开发了一种代码，以第一原理全电子计算获得的波函数为基础，利用数值原子中心轨道进行基于 COOP 的化学键分析。使用开发的代码对 F2、Si、CaC6 以及包括 Ti 和 Nb 在内的金属进行了化学键分析。此外，由于石墨、MoS2 和 ZrNCl 这三种具有代表性的层状材料在工业上的重要性，特别是在电池和超导材料中的应用，我们应用该方法分析了与锂插层相关的化学键变化。COOP 分析为从化学键角度理解插层材料的插层机理和稳定性提供了一些启示。
{"title":"Crystal orbital overlap population based on all-electron ab initio simulation with numeric atom-centered orbitals and its application to chemical-bonding analysis in Li-intercalated layered materials","authors":"Izumi Takahara, Kiyou Shibata, Teruyasu Mizoguchi","doi":"10.1088/1361-651x/ad4c82","DOIUrl":"https://doi.org/10.1088/1361-651x/ad4c82","url":null,"abstract":"Crystal orbital overlap population (COOP) is one of the effective tools for chemical-bonding analysis, and thus it has been utilized in the materials development and characterization. In this study, we developed a code to perform the COOP-based chemical-bonding analysis based on the wave function obtained from a first principles all-electron calculation with numeric atom-centered orbitals. The chemical-bonding analysis using the developed code was demonstrated for F<sub>2</sub>, Si, CaC<sub>6</sub>, and metals including Ti and Nb. Furthermore, we applied the method to analyze the chemical-bonding changes associated with a Li intercalation in three representative layered materials: graphite, MoS<sub>2</sub>, and ZrNCl, because of their great industrial importance, particularly for the applications in battery and superconducting materials. The COOP analysis provided some insights for understanding the intercalation mechanism and the stability of the intercalated materials from a chemical-bonding viewpoint.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"56 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141546735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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