N. Poklonski, I. I. Anikeev, S. A. Vyrko, A. Zabrodskii
A model is proposed for calculating the thermal activation energy of direct current hopping conductivity via nearest neighbors in lightly doped and weakly compensated crystalline semiconductors with hydrogen‐like impurities. The temperature region is considered in which hops of single holes occur only between acceptors randomly distributed over the crystal (or hops of single electrons only between donors). The model is based on the idea of the Coulomb blockade of charge carriers by the field of compensating impurities (trap impurities). The hopping length of a hole between acceptors (or an electron between donors) is assumed to be equal to the critical (percolation) radius of the spherical region per a majority (doping) impurity atom. At a critical radius, an infinite cluster connecting ohmic contacts is formed in the crystal, along which charge carriers move in a hopping manner via majority impurities. The value of is defined as average work on overcoming the electrostatic Coulomb blockade by a charge carrier and its hopping via the electrically conducting cluster to “infinity”. The results of calculating by the proposed model of the Coulomb blockade for the most well‐studied bulk germanium and silicon p‐ and n‐type crystals are consistent with known experimental data.
本文提出了一个模型，用于计算在含有氢类杂质的轻掺杂和弱补偿晶体半导体中通过近邻发生直流跳变导电的热活化能。所考虑的温度区域是：单个空穴的跳变只发生在晶体上随机分布的受体之间（或单个电子的跳变只发生在供体之间）。该模型基于电荷载流子被补偿杂质场（陷阱杂质）库仑阻断的思想。空穴在受体之间（或电子在供体之间）的跳跃长度被假定为等于球形区域中每个多数（掺杂）杂质原子的临界（渗流）半径。在临界半径处，晶体中会形成一个连接欧姆接触的无限簇，电荷载流子通过多数杂质以跳跃的方式沿该簇移动。的值被定义为电荷载流子克服静电库仑阻滞并通过导电簇跳跃到 "无穷大 "的平均功。根据提出的库仑阻滞模型对研究最深入的块状锗和硅 p 型和 n 型晶体进行计算的结果与已知的实验数据一致。
{"title":"Activation Energy of DC Hopping Conductivity of Lightly Doped Weakly Compensated Crystalline Semiconductors","authors":"N. Poklonski, I. I. Anikeev, S. A. Vyrko, A. Zabrodskii","doi":"10.1002/pssb.202400132","DOIUrl":"https://doi.org/10.1002/pssb.202400132","url":null,"abstract":"A model is proposed for calculating the thermal activation energy of direct current hopping conductivity via nearest neighbors in lightly doped and weakly compensated crystalline semiconductors with hydrogen‐like impurities. The temperature region is considered in which hops of single holes occur only between acceptors randomly distributed over the crystal (or hops of single electrons only between donors). The model is based on the idea of the Coulomb blockade of charge carriers by the field of compensating impurities (trap impurities). The hopping length of a hole between acceptors (or an electron between donors) is assumed to be equal to the critical (percolation) radius of the spherical region per a majority (doping) impurity atom. At a critical radius, an infinite cluster connecting ohmic contacts is formed in the crystal, along which charge carriers move in a hopping manner via majority impurities. The value of is defined as average work on overcoming the electrostatic Coulomb blockade by a charge carrier and its hopping via the electrically conducting cluster to “infinity”. The results of calculating by the proposed model of the Coulomb blockade for the most well‐studied bulk germanium and silicon p‐ and n‐type crystals are consistent with known experimental data.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although a memristor model, subjected to electrochemical metallization mechanism, has been proposed based on the spontaneous decay of clusters in the previous work, it does not agree with the human forgetting accurately. Therefore, an improved model is meaningfully presented for the memristor with the cluster spontaneous decay by adding the residual effect. The former is due to the inward contraction of atoms driven by surface energy, while the latter is because of the balance of attractive and repulsive forces between atoms. The model fits well with the actual device. The forgetting is caused by the spontaneous decay. Memory retention is generated due to the added effect, which is also the internal cause of good agreement with the actual forgetting. Additionally, short‐term plasticity is converted to long‐term plasticity through the repeated learning. The efficiency of experiential learning using this model is much higher than that using the previous. It is shown that the physical mechanism of spontaneous decay in the cluster‐based channel is different from that in vacancy‐based or atom‐based channel. The model working under a non‐ideal condition with the temperature influence is discussed. Potential applications based on the model are stated.
{"title":"Learning Model Based on Electrochemical Metallization Memristor with Cluster Residual Effect","authors":"Quanhai Sun, Guanyu Chen","doi":"10.1002/pssb.202400170","DOIUrl":"https://doi.org/10.1002/pssb.202400170","url":null,"abstract":"\u0000Although a memristor model, subjected to electrochemical metallization mechanism, has been proposed based on the spontaneous decay of clusters in the previous work, it does not agree with the human forgetting accurately. Therefore, an improved model is meaningfully presented for the memristor with the cluster spontaneous decay by adding the residual effect. The former is due to the inward contraction of atoms driven by surface energy, while the latter is because of the balance of attractive and repulsive forces between atoms. The model fits well with the actual device. The forgetting is caused by the spontaneous decay. Memory retention is generated due to the added effect, which is also the internal cause of good agreement with the actual forgetting. Additionally, short‐term plasticity is converted to long‐term plasticity through the repeated learning. The efficiency of experiential learning using this model is much higher than that using the previous. It is shown that the physical mechanism of spontaneous decay in the cluster‐based channel is different from that in vacancy‐based or atom‐based channel. The model working under a non‐ideal condition with the temperature influence is discussed. Potential applications based on the model are stated.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141641503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An extension of the tight‐binding approximation model using the discrete fractional Fourier transform is proposed. The quantum state between localized and delocalized states is formulated, where the intermediate state is continuously parameterized. The mixed features of the localized molecular‐like state and delocalized wave‐like state are confirmed when the wavefunction and band diagram of the intermediate state are represented. The proposed model is expected to be used to represent the quantum state with localized/delocalized features in, for example, organic semiconductors.
{"title":"Extending the Tight‐Binding Model by Discrete Fractional Fourier Transform","authors":"T. Miyadera, Yuji Yoshida, M. Chikamatsu","doi":"10.1002/pssb.202400176","DOIUrl":"https://doi.org/10.1002/pssb.202400176","url":null,"abstract":"An extension of the tight‐binding approximation model using the discrete fractional Fourier transform is proposed. The quantum state between localized and delocalized states is formulated, where the intermediate state is continuously parameterized. The mixed features of the localized molecular‐like state and delocalized wave‐like state are confirmed when the wavefunction and band diagram of the intermediate state are represented. The proposed model is expected to be used to represent the quantum state with localized/delocalized features in, for example, organic semiconductors.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141650537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. McEwen, E. Rocco, Vincent Meyers, Alireza Lanjani, Shadi Omranpour, O. Andrieiev, M. Vorobiov, D. Demchenko, M. Reshchikov, F. Shahedipour-Sandvik
Despite recent advances in growth and characterization of GaN:Be, reliable conductive p‐type GaN:Be remains elusive. In this work, GaN is co‐doped with Be and Mg to improve the incorporation and ionization efficiency of both Be and Mg. Be and Mg are found to interact in complex ways rendering GaN:Be,Mg semi‐insulating. Rather than improving Be and Mg incorporation efficiency, there is an apparent mutual inhibition of incorporation when Be and Mg are co‐dopants. Furthermore, photoluminescence measurements indicate that the BeGa acceptor is reduced in particular, relative to the total [Be]. The same effect is not observed for Mg. From this, it is concluded that Mg preferentially incorporates into Ga lattice sites over Be, and excess Be that cannot incorporate into substitutional sites instead occupies interstitial sites. The interstitial Be acts as donor defect, which compensate Mg acceptors. This provides an explanation for the observed reduction in BeGa‐related luminescence intensity (without an associated decrease in [Be]) in GaN:Be with significant [Mg] content.
尽管最近在氮化镓：铍的生长和表征方面取得了进展，但可靠的导电 p 型氮化镓：铍仍然遥遥无期。在这项工作中，GaN 与 Be 和 Mg 共同掺杂，以提高 Be 和 Mg 的掺入和电离效率。研究发现，铍和镁以复杂的方式相互作用，使 GaN:Be,Mg 成为半绝缘体。当 Be 和 Mg 作为共掺杂剂时，不但不会提高 Be 和 Mg 的掺入效率，反而会明显地相互抑制掺入。此外，光致发光测量结果表明，相对于总[Be]而言，BeGa 受体的减少尤为明显。镁则没有观察到同样的效应。由此得出的结论是，镁优先于铍掺入镓晶格位点，而不能掺入取代位点的多余铍则占据了间隙位点。间隙铍作为供体缺陷，补偿了镁的受体。这就解释了为什么在[镁]含量较高的氮化镓：铍中观察到与铍相关的发光强度降低（而[铍]含量没有相应降低）。
{"title":"Incorporation and Interaction of Co‐Doped Be and Mg in GaN Grown by Metal‐Organic Chemic Vapor Deposition","authors":"B. McEwen, E. Rocco, Vincent Meyers, Alireza Lanjani, Shadi Omranpour, O. Andrieiev, M. Vorobiov, D. Demchenko, M. Reshchikov, F. Shahedipour-Sandvik","doi":"10.1002/pssb.202400211","DOIUrl":"https://doi.org/10.1002/pssb.202400211","url":null,"abstract":"Despite recent advances in growth and characterization of GaN:Be, reliable conductive p‐type GaN:Be remains elusive. In this work, GaN is co‐doped with Be and Mg to improve the incorporation and ionization efficiency of both Be and Mg. Be and Mg are found to interact in complex ways rendering GaN:Be,Mg semi‐insulating. Rather than improving Be and Mg incorporation efficiency, there is an apparent mutual inhibition of incorporation when Be and Mg are co‐dopants. Furthermore, photoluminescence measurements indicate that the BeGa acceptor is reduced in particular, relative to the total [Be]. The same effect is not observed for Mg. From this, it is concluded that Mg preferentially incorporates into Ga lattice sites over Be, and excess Be that cannot incorporate into substitutional sites instead occupies interstitial sites. The interstitial Be acts as donor defect, which compensate Mg acceptors. This provides an explanation for the observed reduction in BeGa‐related luminescence intensity (without an associated decrease in [Be]) in GaN:Be with significant [Mg] content.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141649719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrical conductivity σ and magnetization M of (KBFO) nanoparticles (NPs) are systematically examined using a microscopic model and Green's function theory. KBFO is characterized by a narrow bandgap and relatively weak electrical conductivity σ, which presents a problem in carrier transportation and collection. Therefore, ways to enhance σ are found. The first is reducing the NP size. The second one is doping at the Fe and Bi sites with different ions which cause a compressive strain, that is, their ionic radius is smaller than that of the host ion. It is shown that doping with Al at the Fe site as well as with Ru or La ions at the Bi site leads to enhancing the electrical conductivity σ. The magnetization M increases with increasing concentration of all dopants.
利用微观模型和格林函数理论系统地研究了（KBFO）纳米粒子（NPs）的电导率σ和磁化率M。KBFO 具有带隙窄、导电率 σ 相对较弱的特点，这给载流子的运输和收集带来了问题。因此，人们找到了增强 σ 的方法。首先是减小 NP 尺寸。第二种方法是在铁和铋位点掺入不同的离子，这些离子会产生压缩应变，即它们的离子半径小于宿主离子的离子半径。研究表明，在铁位点掺入 Al 离子以及在铋位点掺入 Ru 或 La 离子可提高导电率 σ。磁化 M 随所有掺杂剂浓度的增加而增大。
{"title":"Theoretical Study of Magnetization and Electrical Conductivity of Ion‐Doped KBiFe2O5 Nanoparticles","authors":"A. Apostolov, I. Apostolova, J. Wesselinowa","doi":"10.1002/pssb.202400252","DOIUrl":"https://doi.org/10.1002/pssb.202400252","url":null,"abstract":"The electrical conductivity σ and magnetization M of (KBFO) nanoparticles (NPs) are systematically examined using a microscopic model and Green's function theory. KBFO is characterized by a narrow bandgap and relatively weak electrical conductivity σ, which presents a problem in carrier transportation and collection. Therefore, ways to enhance σ are found. The first is reducing the NP size. The second one is doping at the Fe and Bi sites with different ions which cause a compressive strain, that is, their ionic radius is smaller than that of the host ion. It is shown that doping with Al at the Fe site as well as with Ru or La ions at the Bi site leads to enhancing the electrical conductivity σ. The magnetization M increases with increasing concentration of all dopants.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the structure, morphological, and roughness properties of electrodeposited nickel thin films grown on different substrates, that is, silicon, copper, and gold. X‐ray diffraction analysis reveals that the Ni coatings exhibit a face‐centered‐cubic phase, regardless of the substrate used, although the texture is mainly influenced by the substrate. Atomic force microscopy images show that larger grains are obtained with gold substrates, while smaller ones are observed with copper and silicon substrates, in agreement with scanning electron microscopy. The results demonstrate that both topological and fractal characteristics of the Ni thin films are significantly influenced by the type of substrate. Statistical parameters are quantified to compare the surface morphology of the different samples. Fractal analysis reveals that the fractal dimensions of all surfaces range between 2 and 3, indicating self‐affinity. Fractal succolarity and lacunarity are measured to assess the penetration of a liquid into the surface and the distribution of gaps in the Ni film surfaces, respectively. Minkowski functionals are utilized for topological analysis to characterize the internal structure of the Ni thin films. The observed differences in roughness characteristics provide evidence that the type of substrate affects the nucleation and growth of surface features during electrodeposition.
{"title":"Role of Substrate on the Fractal Characteristics of Nanostructure Surfaces of Electrodeposited Nickel Thin Films","authors":"Maryam Nasehnejad, G. Nabiyouni","doi":"10.1002/pssb.202400109","DOIUrl":"https://doi.org/10.1002/pssb.202400109","url":null,"abstract":"This study investigates the structure, morphological, and roughness properties of electrodeposited nickel thin films grown on different substrates, that is, silicon, copper, and gold. X‐ray diffraction analysis reveals that the Ni coatings exhibit a face‐centered‐cubic phase, regardless of the substrate used, although the texture is mainly influenced by the substrate. Atomic force microscopy images show that larger grains are obtained with gold substrates, while smaller ones are observed with copper and silicon substrates, in agreement with scanning electron microscopy. The results demonstrate that both topological and fractal characteristics of the Ni thin films are significantly influenced by the type of substrate. Statistical parameters are quantified to compare the surface morphology of the different samples. Fractal analysis reveals that the fractal dimensions of all surfaces range between 2 and 3, indicating self‐affinity. Fractal succolarity and lacunarity are measured to assess the penetration of a liquid into the surface and the distribution of gaps in the Ni film surfaces, respectively. Minkowski functionals are utilized for topological analysis to characterize the internal structure of the Ni thin films. The observed differences in roughness characteristics provide evidence that the type of substrate affects the nucleation and growth of surface features during electrodeposition.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The discovery of polar metals challenges long‐standing assumptions about the incompatibility between polar order and metallicity. However, despite recent progress, the mechanism allowing the coexistence of these supposedly forbidden properties remains unclear. Herein, carriers are introduced by constructing a symmetric polar/nonpolar interface in the KNbO3/BaTiO3 (KNO/BTO) superlattice (SL), enabling the coexistence of ferroelectric and metallic properties. A first‐principles analysis of the evolution of polar distortion and metallicity in the KNO/BTO SL under biaxial strain in the face to explore the dependence of the two at the microscopic level is performed. It is found that compressive strain enhances polarization distortion while reducing conductivity from three dimensions to two dimensions, indicating a weak coupling mechanism between carriers and polarization. Furthermore, it is shown that the presence of holes strengthens the TiO (NbO) covalent bonds, resulting in an unexpected enhancement of the polarization properties of the KNO/BTO SL. Therefore, it is proposed using the carrier screening effect and covalent bonding synergies as a framework for understanding the interaction between ferroelectricity and free carriers, rather than just a single factor therein. These results provide new theoretical insights for designing robust polar metals in perovskite ferroelectrics.
{"title":"Probing the Interplay between Ferroelectricity and Metallicity in KNbO3/BaTiO3 Superlattices through Strain Engineering","authors":"Gang Li, Ningjie Ma, Minghua Tang, Z. Long","doi":"10.1002/pssb.202400066","DOIUrl":"https://doi.org/10.1002/pssb.202400066","url":null,"abstract":"The discovery of polar metals challenges long‐standing assumptions about the incompatibility between polar order and metallicity. However, despite recent progress, the mechanism allowing the coexistence of these supposedly forbidden properties remains unclear. Herein, carriers are introduced by constructing a symmetric polar/nonpolar interface in the KNbO3/BaTiO3 (KNO/BTO) superlattice (SL), enabling the coexistence of ferroelectric and metallic properties. A first‐principles analysis of the evolution of polar distortion and metallicity in the KNO/BTO SL under biaxial strain in the face to explore the dependence of the two at the microscopic level is performed. It is found that compressive strain enhances polarization distortion while reducing conductivity from three dimensions to two dimensions, indicating a weak coupling mechanism between carriers and polarization. Furthermore, it is shown that the presence of holes strengthens the TiO (NbO) covalent bonds, resulting in an unexpected enhancement of the polarization properties of the KNO/BTO SL. Therefore, it is proposed using the carrier screening effect and covalent bonding synergies as a framework for understanding the interaction between ferroelectricity and free carriers, rather than just a single factor therein. These results provide new theoretical insights for designing robust polar metals in perovskite ferroelectrics.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141367321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander Reznik, Vyacheslav Konstantinov, E. Ganykina, Askar Rezvanov
Structural, mechanical, and electrophysical properties of rhombohedral hafnium oxide (r‐HfO2) with space group R3, as well as properties of HfO2, ZrO2, and Hf0.5Zr0.5O2 with space group Pca21 are studied using quantum chemical calculations. The characteristic diffraction peak of 2θ r‐HfO2 is close to the characteristic diffraction peaks of tetragonal (t‐HfO2) and orthorhombic (f‐HfO2) hafnium oxide. The value of bulk modulus is 231 GPa, which is larger than one of the orthorhombic structures. The values of high intensity peaks of Raman spectrum are 670 and 540 cm−1. The bandgap width is 5.8 eV and the average value of dielectric constant is 35.34, which is higher than one of orthorhombic hafnium oxide.
{"title":"First‐Principles Calculation of Basic Properties of Rhombohedral Hafnium Oxide with Space Group R3","authors":"Alexander Reznik, Vyacheslav Konstantinov, E. Ganykina, Askar Rezvanov","doi":"10.1002/pssb.202400105","DOIUrl":"https://doi.org/10.1002/pssb.202400105","url":null,"abstract":"Structural, mechanical, and electrophysical properties of rhombohedral hafnium oxide (r‐HfO2) with space group R3, as well as properties of HfO2, ZrO2, and Hf0.5Zr0.5O2 with space group Pca21 are studied using quantum chemical calculations. The characteristic diffraction peak of 2θ r‐HfO2 is close to the characteristic diffraction peaks of tetragonal (t‐HfO2) and orthorhombic (f‐HfO2) hafnium oxide. The value of bulk modulus is 231 GPa, which is larger than one of the orthorhombic structures. The values of high intensity peaks of Raman spectrum are 670 and 540 cm−1. The bandgap width is 5.8 eV and the average value of dielectric constant is 35.34, which is higher than one of orthorhombic hafnium oxide.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141370393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gui‐Zhu Ran, Qi-Jun Liu, Zheng‐Tang Liu, Ya‐Le Tao
The first‐principles computational methods based on density functional theory are used to study B6O, including its structural, elastic, electronic, and optical properties. The results show that the obtained structural and mechanical parameters are in good agreement with the experimental values. The elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and mechanical stability of rhombohedral B6O are studied. The results show that B6O has mechanical stability, anisotropy, and brittleness. The electronic structure of B6O is analyzed by band structure and density of states. Besides, the chemical bond is systematically explained in terms of Mulliken population and charge density. Finally, the optical characteristics of B6O are examined, encompassing aspects such as the complex dielectric function, conductivity, reflectivity, refractive index, absorption spectrum, and loss function.
{"title":"Geometrical, Electronic, and Optical Properties of Rhombohedral B6O from First‐Principles Calculation","authors":"Gui‐Zhu Ran, Qi-Jun Liu, Zheng‐Tang Liu, Ya‐Le Tao","doi":"10.1002/pssb.202400152","DOIUrl":"https://doi.org/10.1002/pssb.202400152","url":null,"abstract":"The first‐principles computational methods based on density functional theory are used to study B6O, including its structural, elastic, electronic, and optical properties. The results show that the obtained structural and mechanical parameters are in good agreement with the experimental values. The elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and mechanical stability of rhombohedral B6O are studied. The results show that B6O has mechanical stability, anisotropy, and brittleness. The electronic structure of B6O is analyzed by band structure and density of states. Besides, the chemical bond is systematically explained in terms of Mulliken population and charge density. Finally, the optical characteristics of B6O are examined, encompassing aspects such as the complex dielectric function, conductivity, reflectivity, refractive index, absorption spectrum, and loss function.","PeriodicalId":20107,"journal":{"name":"physica status solidi (b)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141266469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiu Xu, H. Guan, Shaosong Huang, Zhihong Zhong, Atsushi Yabuuchi, Koichi Sato
The effects of hydrogen on the mechanical properties of CrNiCo and CrFeNiCo medium‐entropy alloys (MEAs) and CrFeMnNiCo high‐entropy alloys (HEAs) are investigated. Although their total elongation is less than that of the commonly used stainless steel (SS) 316L (SS316L), the tensile strengths of HEAs and MEAs are 150–350 MPa higher than that of SS316L. Hydrogen charging up to 1400 appm (nominal concentration) does not affect the tensile strength of SS316L; however, it decreases the elongation by less than 20%. In contrast, hydrogen increases the tensile strength of MEAs and HEA, but has little effect on elongation. Among the MEAs and HEAs, CrNiCo exhibits the highest tensile strength and total elongation. No brittle fracture due to hydrogen is observed on the fracture surfaces of the H‐charged samples. However, nanotwin structures are more common in H‐charged MEAs and HEAs than in H‐uncharged MEAs and HEA. Additionally, the calculation results based on the first‐principles reveal for the first time that single vacancies or tiny vacancy clusters do not trap H in MEAs compared to HEAs, such that cracks due to H are unlikely to occur. Thus, the hydrogen embrittlement resistance of MEAs may be improved.
研究了氢对铬镍钴和铬铁镍钴中熵合金（MEAs）以及铬铁镍钴高熵合金（HEAs）机械性能的影响。虽然它们的总伸长率低于常用的不锈钢 (SS) 316L (SS316L)，但 HEAs 和 MEAs 的抗拉强度比 SS316L 高 150-350 兆帕。充氢至 1400 appm（标称浓度）不会影响 SS316L 的拉伸强度，但会使伸长率降低不到 20%。相比之下，氢会增加 MEA 和 HEA 的抗拉强度，但对伸长率影响不大。在 MEA 和 HEA 中，CrNiCo 的抗拉强度和总伸长率最高。在带氢样品的断裂面上没有观察到氢导致的脆性断裂。然而，与充氢的 MEA 和 HEA 相比，充氢的 MEA 和 HEA 中的纳米孪晶结构更为常见。此外，基于第一性原理的计算结果首次表明，与 HEA 相比，单个空位或微小空位簇不会在 MEA 中捕获 H，因此不太可能出现 H 导致的裂纹。因此，MEA 的抗氢脆性能可能会得到改善。
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