Pub Date : 2024-01-09DOI: 10.1088/1361-651x/ad1cd0
Yu Jia, Huadian Zhang, Manoj K. Shukla, Steven Larson, S. Nouranian, A. M. Rajendran, Shan Jiang
This study employs a series of molecular dynamics (MD) simulations, utilizing three commonly used interatomic potentials, i.e., van Beest, Kramer, and van Santen (BKS), Vashishta, and Tersoff to analyze the structural and mechanical characteristics within both void-free and single-void αquartz configurations. Two distinct ensembles, NVT and NPT, were separately applied to investigate the tensile response. The validation of MD results included a comparative study of the three potentials as well as a comparison with experimental microstructural and tension studies. While BKS and Vashishta potentials accurately calculated the bond lengths, density and lattice parameters compared to the experimental values for void-free α-quartz, the results obtained with Tersoff potential exhibited relatively large deviations. The BKS potential offered an accurate description of the mechanical response of α-quartz by successfully predicting stress-strain curves. The Vashishta potential overpredicted Young’s modulus as compared to BKS. The Tersoff potential could capture the elastic deformation but was unable to predict the fracture behavior. The presence of a spherical void significantly reduced mechanical behavior of α-quartz, and the extent of this reduction was highly related to void size. When applying the BKS potential with an NVT ensemble, the ultimate tensile strengths decreased by 19% and 72% with void sizes of 2.5 and 15 Å, respectively. Equivalent stress analysis reveals that the BKS potential can effectively capture greater stress concentration around the void compared to other two potentials. Based on the comparison study, the BKS potential seems to be the most suitable one to describe α-quartz under tension in a realistic manner.
{"title":"Mechanical behavior of alpha quartz with void defects under tension: A molecular dynamics study using different interatomic potentials","authors":"Yu Jia, Huadian Zhang, Manoj K. Shukla, Steven Larson, S. Nouranian, A. M. Rajendran, Shan Jiang","doi":"10.1088/1361-651x/ad1cd0","DOIUrl":"https://doi.org/10.1088/1361-651x/ad1cd0","url":null,"abstract":"\u0000 This study employs a series of molecular dynamics (MD) simulations, utilizing three commonly used interatomic potentials, i.e., van Beest, Kramer, and van Santen (BKS), Vashishta, and Tersoff to analyze the structural and mechanical characteristics within both void-free and single-void αquartz configurations. Two distinct ensembles, NVT and NPT, were separately applied to investigate the tensile response. The validation of MD results included a comparative study of the three potentials as well as a comparison with experimental microstructural and tension studies. While BKS and Vashishta potentials accurately calculated the bond lengths, density and lattice parameters compared to the experimental values for void-free α-quartz, the results obtained with Tersoff potential exhibited relatively large deviations. The BKS potential offered an accurate description of the mechanical response of α-quartz by successfully predicting stress-strain curves. The Vashishta potential overpredicted Young’s modulus as compared to BKS. The Tersoff potential could capture the elastic deformation but was unable to predict the fracture behavior. The presence of a spherical void significantly reduced mechanical behavior of α-quartz, and the extent of this reduction was highly related to void size. When applying the BKS potential with an NVT ensemble, the ultimate tensile strengths decreased by 19% and 72% with void sizes of 2.5 and 15 Å, respectively. Equivalent stress analysis reveals that the BKS potential can effectively capture greater stress concentration around the void compared to other two potentials. Based on the comparison study, the BKS potential seems to be the most suitable one to describe α-quartz under tension in a realistic manner.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"104 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139444733","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}
Considering all possible crystal structures is essential in computer simulations of alloy properties, but using Density Functional Theory (DFT) is computationally impractical. To address this, four structural descriptors were evaluated using machine learning (ML) models to predict formation energy, elasticity and hardness of MoTa alloys. A total of 612 configurations were generated by the Clusters Approach to Statistical Mechanics (CASM) software and their corresponding material properties were calculated by DFT. As input features of ML models, the CORR and SOAP performed best (R2 > 0.90, some up to 0.99), followed by ACSF, while CM performed worst. Furthermore, SOAP shows excellent performance in extrapolation for larger supercell structures of the MoTa alloy system and transfer learning for the MoNb alloy system.
在对合金特性进行计算机模拟时，必须考虑所有可能的晶体结构，但使用密度泛函理论（DFT）在计算上并不现实。为了解决这个问题，我们使用机器学习（ML）模型对四种结构描述符进行了评估，以预测钼钽合金的形成能、弹性和硬度。统计力学聚类方法（CASM）软件共生成了 612 种构型，并通过 DFT 计算了其相应的材料属性。作为 ML 模型的输入特征，CORR 和 SOAP 表现最好（R2 > 0.90，有些高达 0.99），其次是 ACSF，而 CM 表现最差。此外，SOAP 在对 MoTa 合金体系的较大超晶胞结构进行外推以及对 MoNb 合金体系进行迁移学习方面表现出色。
{"title":"Structural descriptors evaluation for MoTa mechanical properties prediction with machine learning","authors":"Tingpeng Tao, Shu Li, Dechuang Chen, Shuai Li, Dongrong Liu, Xin Liu, Minghua Chen","doi":"10.1088/1361-651x/ad1cd1","DOIUrl":"https://doi.org/10.1088/1361-651x/ad1cd1","url":null,"abstract":"\u0000 Considering all possible crystal structures is essential in computer simulations of alloy properties, but using Density Functional Theory (DFT) is computationally impractical. To address this, four structural descriptors were evaluated using machine learning (ML) models to predict formation energy, elasticity and hardness of MoTa alloys. A total of 612 configurations were generated by the Clusters Approach to Statistical Mechanics (CASM) software and their corresponding material properties were calculated by DFT. As input features of ML models, the CORR and SOAP performed best (R2 > 0.90, some up to 0.99), followed by ACSF, while CM performed worst. Furthermore, SOAP shows excellent performance in extrapolation for larger supercell structures of the MoTa alloy system and transfer learning for the MoNb alloy system.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"26 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139444131","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 : 2023-12-29DOI: 10.1088/1361-651x/ad16ef
Pan Zheng, Yiru Huang, Lei Zhang
The A4BX6 molecular halide perovskites have received attention owing to their interesting optoelectronic properties at the molecular scale; however, a comprehensive dataset of their atomic structures and electronic properties and associated data-driven investigation are still unavailable now, which makes it difficult for inverse materials design for semiconductor applications (e.g. wide band gap semiconductor). In this manuscript, we employ data-driven methods to predict band gaps of A4BX6 molecular halide perovskites via machine learning. A large virtual design database including 246 904 A4BX6 perovskite samples is predicted via machine learning, based on the model trained using 2740 first-principles results of A4BX6 molecular halide perovskites. In addition, symbolic regression-based machine learning is employed to identify more physically intuitive descriptors based on the starting first-principles dataset of A4BX6 molecular halide perovskites. In addition, different ranking methods are employed to offer a comprehensive feature importance analysis for the halide perovskite materials. This study highlights the efficacy of machine learning-assisted compositional design of A4BX6 perovskites, and the multi-dimensional database established here is valuable for future experimental validation toward perovskite-based wide band gap semiconductor materials.
{"title":"First-principles and machine learning investigation on A4BX6 halide perovskites","authors":"Pan Zheng, Yiru Huang, Lei Zhang","doi":"10.1088/1361-651x/ad16ef","DOIUrl":"https://doi.org/10.1088/1361-651x/ad16ef","url":null,"abstract":"The A<sub>4</sub>BX<sub>6</sub> molecular halide perovskites have received attention owing to their interesting optoelectronic properties at the molecular scale; however, a comprehensive dataset of their atomic structures and electronic properties and associated data-driven investigation are still unavailable now, which makes it difficult for inverse materials design for semiconductor applications (e.g. wide band gap semiconductor). In this manuscript, we employ data-driven methods to predict band gaps of A<sub>4</sub>BX<sub>6</sub> molecular halide perovskites via machine learning. A large virtual design database including 246 904 A<sub>4</sub>BX<sub>6</sub> perovskite samples is predicted via machine learning, based on the model trained using 2740 first-principles results of A<sub>4</sub>BX<sub>6</sub> molecular halide perovskites. In addition, symbolic regression-based machine learning is employed to identify more physically intuitive descriptors based on the starting first-principles dataset of A<sub>4</sub>BX<sub>6</sub> molecular halide perovskites. In addition, different ranking methods are employed to offer a comprehensive feature importance analysis for the halide perovskite materials. This study highlights the efficacy of machine learning-assisted compositional design of A<sub>4</sub>BX<sub>6</sub> perovskites, and the multi-dimensional database established here is valuable for future experimental validation toward perovskite-based wide band gap semiconductor materials.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"8 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139094110","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 : 2023-12-19DOI: 10.1088/1361-651x/ad111f
Yunhai Liu, Benteng Che, Xiaowen Wang, Yiyao Luo, Hu Zhang, Ligao Liu, Penghui Xu
In order to further explore the influence of temperature on the face-centered cubic (FCC) single-phase crystal CoCrFeNiAl0.1, we conducted a series of Nano-indentation experiments on CoCrFeNiAl0.1 at different temperatures. At room temperature, the effects of indentation can convert a portion of CoCrFeNiAl0.1’s FCC phase into a funnel-shaped hexagonal close-packed (HCP) phase, resulting less deformation on the sides of the indenter. What we analyzed shows that CoCrFeNiAl0.1’s HCP phase has excellent heat resistance and mechanics, allowing CoCrFeNiAl0.1 to maintain great properties in high-temperature environments. However, if T ⩾ 1500 K, high temperature will decrease the number of the HCP phases and dislocation density, leading to an accelerated decline in material strength. This research can provide a theoretical relationship between temperature and microstructural evolution for the research and application of CoCrFeNiAl0.1 in high-temperature environments.
{"title":"Exploring the effects of temperature on the mechanical properties of high-entropy alloy (CoCrFeNiAl0.1) based on molecular dynamics simulation","authors":"Yunhai Liu, Benteng Che, Xiaowen Wang, Yiyao Luo, Hu Zhang, Ligao Liu, Penghui Xu","doi":"10.1088/1361-651x/ad111f","DOIUrl":"https://doi.org/10.1088/1361-651x/ad111f","url":null,"abstract":"In order to further explore the influence of temperature on the face-centered cubic (FCC) single-phase crystal CoCrFeNiAl<sub>0.1</sub>, we conducted a series of Nano-indentation experiments on CoCrFeNiAl<sub>0.1</sub> at different temperatures. At room temperature, the effects of indentation can convert a portion of CoCrFeNiAl<sub>0.1</sub>’s FCC phase into a funnel-shaped hexagonal close-packed (HCP) phase, resulting less deformation on the sides of the indenter. What we analyzed shows that CoCrFeNiAl<sub>0.1</sub>’s HCP phase has excellent heat resistance and mechanics, allowing CoCrFeNiAl<sub>0.1</sub> to maintain great properties in high-temperature environments. However, if <italic toggle=\"yes\">T</italic> ⩾ 1500 K, high temperature will decrease the number of the HCP phases and dislocation density, leading to an accelerated decline in material strength. This research can provide a theoretical relationship between temperature and microstructural evolution for the research and application of CoCrFeNiAl<sub>0.1</sub> in high-temperature environments.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"18 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055808","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 : 2023-12-15DOI: 10.1088/1361-651x/ad104e
Aparna Thankappan
Perovskite solar cells (PSCs) have garnered extensive research interest due to their potential for efficient, flexible, and cost-effective solar energy production, making them suitable for wearable and low-cost applications. In this study, we successfully synthesized layered copper-based perovskite materials, and subsequently conducted simulations using the Solar Cell Capacitance Simulator SCAPS-1D. This study introduces, a PSC structure with (CH3NH3)2CuCl4 as the active layer. By employing a two-step chemical method, we have successfully synthesized (CH3NH3)2CuCl4, and its optical band gap was determined using Tauc’s extrapolation method. Utilizing the experimentally determined bandgap as the simulation input, we predicted a solar architecture consisting of glass substrate/fluorine-doped tin oxide/TiO2/(CH3NH3)2CuCl4/spiro-OMeTAD/Pt, which exhibited an impressive conversion efficiency of 27.93% along with a fill factor of 62.04%, Jsc of 34.39 mA cm−2, and Voc of 1.31 V. Through the software, we conducted a comprehensive study on the impact of back metal contact, hole transport layer, electron transport layer, layer thickness, temperature, and defect density on the overall device performance. These results unveil the development of an environmentally friendly PSC based on methylammonium copper.
{"title":"Numerical simulation of solar cell performance with copper-based layered perovskite using SCAPS-1D software","authors":"Aparna Thankappan","doi":"10.1088/1361-651x/ad104e","DOIUrl":"https://doi.org/10.1088/1361-651x/ad104e","url":null,"abstract":"Perovskite solar cells (PSCs) have garnered extensive research interest due to their potential for efficient, flexible, and cost-effective solar energy production, making them suitable for wearable and low-cost applications. In this study, we successfully synthesized layered copper-based perovskite materials, and subsequently conducted simulations using the Solar Cell Capacitance Simulator SCAPS-1D. This study introduces, a PSC structure with (CH<sub>3</sub>NH<sub>3</sub>)<sub>2</sub>CuCl<sub>4</sub> as the active layer. By employing a two-step chemical method, we have successfully synthesized (CH<sub>3</sub>NH<sub>3</sub>)<sub>2</sub>CuCl<sub>4</sub>, and its optical band gap was determined using Tauc’s extrapolation method. Utilizing the experimentally determined bandgap as the simulation input, we predicted a solar architecture consisting of glass substrate/fluorine-doped tin oxide/TiO<sub>2</sub>/(CH<sub>3</sub>NH<sub>3</sub>)<sub>2</sub>CuCl<sub>4</sub>/spiro-OMeTAD/Pt, which exhibited an impressive conversion efficiency of 27.93% along with a fill factor of 62.04%, <italic toggle=\"yes\">J</italic>\u0000<sub>sc</sub> of 34.39 mA cm<sup>−2</sup>, and <italic toggle=\"yes\">V</italic>\u0000<sub>oc</sub> of 1.31 V. Through the software, we conducted a comprehensive study on the impact of back metal contact, hole transport layer, electron transport layer, layer thickness, temperature, and defect density on the overall device performance. These results unveil the development of an environmentally friendly PSC based on methylammonium copper.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"23 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138687888","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 : 2023-12-14DOI: 10.1088/1361-651x/ad15a9
Jerry Howard, Krista Carlson, L. Mushongera
Metallic glasses (MGs) are an emerging class of materials possessing multiple desirable properties including high strength, hardness, and corrosion resistance when compared to their crystalline counterparts. However, most previously studied MGs are not useful in high temperature environments because they undergo the glass transition phenomenon and crystallize below the melting point. In addition, bulk MGs are typically found in multi-component systems, meaning that searching compositional space with a reasonable resolution using computational or experimental methods can be costly. In this study, an in-house developed genetic algorithm-based tool was used to locate alloy compositions with high glass forming ability (GFA) and high-temperature stability in the Ta-Ni-Co-B alloy system. GFA was predicted using an empirical predictive parameter known as P_HSS. High-temperature stability was predicted using the CALPHAD method to calculate liquidus temperature. Justification for the use of P_HSS to predict GFA of high-temperature MGs, as well as the use of liquidus temperature as a predictor of general high-temperature stability, was given in the form of a meta-analysis of previously reported MG compositions. The predictions made using this algorithm were analyzed and are presented herein. While high-temperature stability was the property of interest for this research, this framework could be used in the future to locate alloys with other application-specific material properties. This genetic algorithm-based tool enables the coupling of empirical parameters and CALPHAD to efficiently search multi-component space to locate glass-forming alloys with desirable properties.
{"title":"Predicting multi-component, high-temperature metallic glasses by coupling empirical models, CALPHAD, and a genetic algorithm","authors":"Jerry Howard, Krista Carlson, L. Mushongera","doi":"10.1088/1361-651x/ad15a9","DOIUrl":"https://doi.org/10.1088/1361-651x/ad15a9","url":null,"abstract":"\u0000 Metallic glasses (MGs) are an emerging class of materials possessing multiple desirable properties including high strength, hardness, and corrosion resistance when compared to their crystalline counterparts. However, most previously studied MGs are not useful in high temperature environments because they undergo the glass transition phenomenon and crystallize below the melting point. In addition, bulk MGs are typically found in multi-component systems, meaning that searching compositional space with a reasonable resolution using computational or experimental methods can be costly. In this study, an in-house developed genetic algorithm-based tool was used to locate alloy compositions with high glass forming ability (GFA) and high-temperature stability in the Ta-Ni-Co-B alloy system. GFA was predicted using an empirical predictive parameter known as P_HSS. High-temperature stability was predicted using the CALPHAD method to calculate liquidus temperature. Justification for the use of P_HSS to predict GFA of high-temperature MGs, as well as the use of liquidus temperature as a predictor of general high-temperature stability, was given in the form of a meta-analysis of previously reported MG compositions. The predictions made using this algorithm were analyzed and are presented herein. While high-temperature stability was the property of interest for this research, this framework could be used in the future to locate alloys with other application-specific material properties. This genetic algorithm-based tool enables the coupling of empirical parameters and CALPHAD to efficiently search multi-component space to locate glass-forming alloys with desirable properties.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"12 10","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138972695","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 : 2023-12-14DOI: 10.1088/1361-651X/ad15aa
Jingting Sun, Z. Yuan, Meiling Tang, Peng Zheng, Yan He, Ying Wang
In order to reveal the friction behaviour and wear mechanism of nanoscale textures on the friction pair of 304 stainless steel, molecular dynamics simulations were firstly used to investigate the effects of smooth and textured surfaces on the tribological properties of the stainless steel substrate, and then focus on the effects of sliding velocity and depth on the surface morphology, mechanical force, friction coefficient, anisotropy, stress, temperature and dislocations of the textured substrate. The results show that the temperature, friction, stress, and dislocation line length of the textured surface are relatively smaller than those of the non-textured surface, and the textured surface has a smaller and more stable friction factor, which ultimately leads to a reduction of the friction factor by about 0.090. When the sliding distance is 120 Å, the number of defective atoms in the textured substrate is reduced by 12.9%, and its anisotropy is more stable. At the same indentation depth, the average friction coefficient, temperature and anisotropy increase significantly with increasing sliding velocity. The average friction coefficient is maximum when the sliding velocity is increased to 400 m s−1, with a value of about 0.833. The sliding friction, friction coefficient, dislocation line length, number of defect atoms, number of stacked atoms, stress, temperature and anisotropy factor increase with increasing depth of abrasive indentation. The average friction coefficient is minimum at a sliding depth of 4 Å, with a value of about 0.556, and the number of defective atoms is reduced by 83.2%. This indicates that textured surface treatment of 304 stainless steel and selection of appropriate sliding parameters can effectively reduce the wear during the friction process and improve the wear resistance of the substrate.
为了揭示纳米级纹理对304不锈钢摩擦副的摩擦行为和磨损机理，首先利用分子动力学模拟研究了光滑表面和纹理表面对不锈钢基体摩擦学性能的影响，然后重点研究了滑动速度和深度对纹理基体表面形貌、机械力、摩擦系数、各向异性、应力、温度和位错的影响。结果表明，纹理表面的温度、摩擦力、应力和位错线长度相对小于非纹理表面，纹理表面的摩擦系数更小、更稳定，最终导致摩擦系数降低了约 0.090。当滑动距离为 120 Å 时，纹理基底中的缺陷原子数量减少了 12.9%，其各向异性也更加稳定。在相同的压痕深度下，随着滑动速度的增加，平均摩擦系数、温度和各向异性都显著增加。当滑动速度增加到 400 m s-1 时，平均摩擦系数最大，约为 0.833。滑动摩擦力、摩擦系数、位错线长度、缺陷原子数、堆积原子数、应力、温度和各向异性因子随磨料压痕深度的增加而增加。平均摩擦系数在滑动深度为 4 Å 时最小，值约为 0.556，缺陷原子数减少了 83.2%。这表明，对 304 不锈钢进行纹理表面处理并选择适当的滑动参数，可有效减少摩擦过程中的磨损，提高基体的耐磨性。
{"title":"Study on the surface microtexture microscopic friction and wear characteristics of 304 stainless steel","authors":"Jingting Sun, Z. Yuan, Meiling Tang, Peng Zheng, Yan He, Ying Wang","doi":"10.1088/1361-651X/ad15aa","DOIUrl":"https://doi.org/10.1088/1361-651X/ad15aa","url":null,"abstract":"In order to reveal the friction behaviour and wear mechanism of nanoscale textures on the friction pair of 304 stainless steel, molecular dynamics simulations were firstly used to investigate the effects of smooth and textured surfaces on the tribological properties of the stainless steel substrate, and then focus on the effects of sliding velocity and depth on the surface morphology, mechanical force, friction coefficient, anisotropy, stress, temperature and dislocations of the textured substrate. The results show that the temperature, friction, stress, and dislocation line length of the textured surface are relatively smaller than those of the non-textured surface, and the textured surface has a smaller and more stable friction factor, which ultimately leads to a reduction of the friction factor by about 0.090. When the sliding distance is 120 Å, the number of defective atoms in the textured substrate is reduced by 12.9%, and its anisotropy is more stable. At the same indentation depth, the average friction coefficient, temperature and anisotropy increase significantly with increasing sliding velocity. The average friction coefficient is maximum when the sliding velocity is increased to 400 m s−1, with a value of about 0.833. The sliding friction, friction coefficient, dislocation line length, number of defect atoms, number of stacked atoms, stress, temperature and anisotropy factor increase with increasing depth of abrasive indentation. The average friction coefficient is minimum at a sliding depth of 4 Å, with a value of about 0.556, and the number of defective atoms is reduced by 83.2%. This indicates that textured surface treatment of 304 stainless steel and selection of appropriate sliding parameters can effectively reduce the wear during the friction process and improve the wear resistance of the substrate.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"44 6","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971447","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 : 2023-12-12DOI: 10.1088/1361-651x/ad1493
G. Benabdellah, Djaafri toufik, Mohamed Mokhtari, Muhammad Salman Khan, A. Tawfeek, Hijaz Ahmad
The structural, electronic, magnetic, elastic, and thermoelectric properties of NiVxSc1-xSb half Heusler alloys with different compositions were investigated employing a self-consistent first-principles-based calculation that uses the full-potential linearized-augmented-plane-wave method. The structural characteristics, such as the bulk modulus and lattice constants, are examined with various vanadium concentrations. The accurately modified Becke Johnson potential was used to calculate the band gap energies. The equilibrium lattice parameter of NiScSb type-I structure has the lowest energy and seems to be most stable among the other configurations with a lattice constant value of 6.04 Å, which deviates from the experimental results by up to 0.5%. The bulk modulus rises as the lattice constant decreases. The ground states of the studied alloy structures are dynamically stable, as concluded by the non-existence of negative phonon frequency. The band structure of NiScSb (for x = 0) was predicted as a non-magnetic semiconductor with an indirect band nature, and an energy gap value of 0.244 eV along (Γ-point > X). This tendency was further supported by the symmetrical shape of the curves that reflect the densities of states for these configuration channels. The thermoelectric characteristics of these various combinations were also thoroughly investigated and discussed.
{"title":"Investigating the electronic structure, elastic, magnetic, and thermoelectric nature of NiVXSc1-XSb quaternary half-Heusler alloys","authors":"G. Benabdellah, Djaafri toufik, Mohamed Mokhtari, Muhammad Salman Khan, A. Tawfeek, Hijaz Ahmad","doi":"10.1088/1361-651x/ad1493","DOIUrl":"https://doi.org/10.1088/1361-651x/ad1493","url":null,"abstract":"\u0000 The structural, electronic, magnetic, elastic, and thermoelectric properties of NiVxSc1-xSb half Heusler alloys with different compositions were investigated employing a self-consistent first-principles-based calculation that uses the full-potential linearized-augmented-plane-wave method. The structural characteristics, such as the bulk modulus and lattice constants, are examined with various vanadium concentrations. The accurately modified Becke Johnson potential was used to calculate the band gap energies. The equilibrium lattice parameter of NiScSb type-I structure has the lowest energy and seems to be most stable among the other configurations with a lattice constant value of 6.04 Å, which deviates from the experimental results by up to 0.5%. The bulk modulus rises as the lattice constant decreases. The ground states of the studied alloy structures are dynamically stable, as concluded by the non-existence of negative phonon frequency. The band structure of NiScSb (for x = 0) was predicted as a non-magnetic semiconductor with an indirect band nature, and an energy gap value of 0.244 eV along (Γ-point > X). This tendency was further supported by the symmetrical shape of the curves that reflect the densities of states for these configuration channels. The thermoelectric characteristics of these various combinations were also thoroughly investigated and discussed.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"36 23","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139008865","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 : 2023-12-08DOI: 10.1088/1361-651x/ad0e79
Junliang Zhao, Chen Li, Jing Wang
A two-dimensional model of nanosecond laser drilling 316L stainless steel was established with the consideration of laser focus, which was indeed different from the original two-phase flow model without laser focus, especially in the temperature field, velocity field, surface morphology and hole depth. Simulation and experiment of drilling holes with different laser repetition frequencies (100 kHz, 50 kHz and 20 kHz) were carried out. The results show that manufacturing process could divide into three stages: high-efficiency phase, stabilization stage and low-efficiency phase. Meanwhile, the limited number of pulses at 100 kHz, 50 kHz and 20 kHz were obtained, and the values were approximately 289, 367 and 492, respectively. More, the values at 10 kHz and 200 kHz obtained by modeling were very close to those calculated by the fitted equation. All the research provides theoretical, simulation and experimental basis for designing and optimizing parameters on laser surface manufacturing.
{"title":"Numerical simulation of nanosecond laser drilling of 316L stainless steel: addition of laser focus and analysis of manufacturing process","authors":"Junliang Zhao, Chen Li, Jing Wang","doi":"10.1088/1361-651x/ad0e79","DOIUrl":"https://doi.org/10.1088/1361-651x/ad0e79","url":null,"abstract":"A two-dimensional model of nanosecond laser drilling 316L stainless steel was established with the consideration of laser focus, which was indeed different from the original two-phase flow model without laser focus, especially in the temperature field, velocity field, surface morphology and hole depth. Simulation and experiment of drilling holes with different laser repetition frequencies (100 kHz, 50 kHz and 20 kHz) were carried out. The results show that manufacturing process could divide into three stages: high-efficiency phase, stabilization stage and low-efficiency phase. Meanwhile, the limited number of pulses at 100 kHz, 50 kHz and 20 kHz were obtained, and the values were approximately 289, 367 and 492, respectively. More, the values at 10 kHz and 200 kHz obtained by modeling were very close to those calculated by the fitted equation. All the research provides theoretical, simulation and experimental basis for designing and optimizing parameters on laser surface manufacturing.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"35 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138687753","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 : 2023-12-07DOI: 10.1088/1361-651x/ad104f
Chongyao Yang, Wei Wu, Kwang-Leong Choy
Recently perovskite solar cells (PSCs) have caught much attention. Oxygen atom (O1) and molecule (O2) are important dopants to influence the stability of the structural, electronic and optical properties, thus the performance of PSCs. RbPbX3-type perovskites have fantastic chemical stability and good power conversion efficiency. Here we have studied the effects of interstitial O1 and O2 on the structural properties, and hence the electronic structure of RbPbI3 from first principles. We have included the van der Waals (vdW) forces into our density-functional-theory calculations. The formation of dopant level within the pristine band gap has been found when incorporating oxygen. The defect level, dominated by oxygen and iodine, is above the valence band maximum by 0.5–1.3 eV, depending on the location of the defects in the bulk. In addition, we can see the bandwidths of the defect levels are very narrow, which could trap the electron and affect the transport properties. In addition, a metallic state has been found in our calculations for interstitial oxygen molecule when there are strong O–O, O–Pb, and O–I bonds, indicating the complex nature of oxygen-doped PSCs. The comparison between the defect formation energies when doping oxygen atom and molecules is consistent with the previous report about oxygen-molecule passivation of PSCs. Our work has therefore provided important theoretical insight to the effect of oxygen dopants on the electronic structure of RbPbI3.
{"title":"First-principles studies of oxygen interstitial dopants in RbPbI3 halide for perovskite solar cells","authors":"Chongyao Yang, Wei Wu, Kwang-Leong Choy","doi":"10.1088/1361-651x/ad104f","DOIUrl":"https://doi.org/10.1088/1361-651x/ad104f","url":null,"abstract":"Recently perovskite solar cells (PSCs) have caught much attention. Oxygen atom (O<sub>1</sub>) and molecule (O<sub>2</sub>) are important dopants to influence the stability of the structural, electronic and optical properties, thus the performance of PSCs. RbPbX<sub>3</sub>-type perovskites have fantastic chemical stability and good power conversion efficiency. Here we have studied the effects of interstitial O<sub>1</sub> and O<sub>2</sub> on the structural properties, and hence the electronic structure of RbPbI<sub>3</sub> from first principles. We have included the van der Waals (vdW) forces into our density-functional-theory calculations. The formation of dopant level within the pristine band gap has been found when incorporating oxygen. The defect level, dominated by oxygen and iodine, is above the valence band maximum by 0.5–1.3 eV, depending on the location of the defects in the bulk. In addition, we can see the bandwidths of the defect levels are very narrow, which could trap the electron and affect the transport properties. In addition, a metallic state has been found in our calculations for interstitial oxygen molecule when there are strong O–O, O–Pb, and O–I bonds, indicating the complex nature of oxygen-doped PSCs. The comparison between the defect formation energies when doping oxygen atom and molecules is consistent with the previous report about oxygen-molecule passivation of PSCs. Our work has therefore provided important theoretical insight to the effect of oxygen dopants on the electronic structure of RbPbI<sub>3</sub>.","PeriodicalId":18648,"journal":{"name":"Modelling and Simulation in Materials Science and Engineering","volume":"6 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138687750","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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