Article
Chemistry, Multidisciplinary
Adriano Diaz Fattorini, Caroline Cheze, Inaki Lopez Garcia, Christian Petrucci, Marco Bertelli, Flavia Righi Riva, Simone Prili, Stefania M. S. Privitera, Marzia Buscema, Antonella Sciuto, Salvatore Di Franco, Giuseppe D'Arrigo, Massimo Longo, Sara De Simone, Valentina Mussi, Ernesto Placidi, Marie-Claire Cyrille, Nguyet-Phuong Tran, Raffaella Calarco, Fabrizio Arciprete
Summary: In this study, a Ge-rich Ge-Sb-Te alloy was deposited on silicon substrates using physical vapor deposition. The electronic properties of the alloy were investigated, and it was found to have similar electrical parameters to conventional alloys but with enhanced thermal stability.
Review
Materials Science, Multidisciplinary
Isaac Chang, Qing Cai
Summary: The eutectic solidification of binary and ternary alloys has been extensively studied, leading to the development of high entropy alloys with superior properties. However, there is a knowledge gap in understanding the solidification behavior of high order multicomponent eutectic alloys. The hardness of Al-based eutectic alloys increases significantly with an increasing number of constituents, offering new opportunities for developing ultrahigh strength alloys.
PROGRESS IN MATERIALS SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Caroline Cheze, Flavia Righi Riva, Giulia Di Bella, Ernesto Placidi, Simone Prili, Marco Bertelli, Adriano Diaz Fattorini, Massimo Longo, Raffaella Calarco, Marco Bernasconi, Omar Abou El Kheir, Fabrizio Arciprete
Summary: In this study, the electronic properties of PCM double-layered heterostructures deposited on silicon substrates were characterized. The composition evolution and interdiffusion of the heterostructure interface were obtained using XPS and UPS. The final composition of the GGST layer was found to be close to GST212, and the density of states calculated by density functional theory was in agreement with experimental results. Differences in the crystallization process were discussed based on the photoemission results.
Article
Chemistry, Physical
I Pethes, P. Jovari, S. Michalik, T. Wagner, V Prokop, I Kaban, D. Szaraz, A. Hannon, M. Krbal
Summary: Short range order and topology of GexS100-x glasses with a composition range of 20 <= x <= 42 at% were investigated using neutron diffraction, X-ray diffraction, and Ge K-edge extended X-ray absorption fine structure (EXAFS) measurements. The experimental data sets were analyzed using the reverse Monte Carlo simulation method. It was observed that both Ge and S atoms in the glasses satisfied the Mott-rule, with Ge and S atoms having 4 and 2 neighbors, respectively. The chemically ordered network model described the structure of these glasses, with Ge-S bonds being preferred and S-S bonds only present in S-rich glasses. Ge-Ge bonds were found to be necessary in Ge-rich glasses, and the connections between Ge atoms, such as edge-sharing GeS4/2 tetrahedra, were analyzed. The frequency of primitive rings was also calculated.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Zhen Yang, Haonan Hu, Qiuli Li, Zheng Zhang, Lei Niu, Jian Wu, Tengxiu Wei, Yuanhuan Sun, Yiming Fang, Xunsi Wang, Zhiyong Yang, Jinfeng Zhou, Rongping Wang
Summary: By preparing GexSe10Te90-x glasses with varying Te contents and measuring their properties, it was found that the glasses exhibit different optical characteristics depending on the composition, with the nonlinear optical refractive index showing significant variations. These Te-based glasses show potential for applications as mid- and far-infrared nonlinear optical devices.
Article
Nanoscience & Nanotechnology
Frank Czerwinski
Summary: The strength retention of Al-Ce binary alloys at high temperatures was assessed compared to A380 alloy and pure Al. The Al11Ce3 eutectic and proeutectic phases were found to have limited effectiveness in strengthening Al-Ce alloys at room temperature and retaining their strength at increased temperatures. Despite the high hardness retention ratio of Al-Ce alloys, the yield stress decreased with testing temperatures.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Dandan Dong, Zhiming Cao, Guang Han, Chuang Dong
Summary: This study explains the composition of eutectic Ti57Cu43 by introducing the dual-cluster model, identifying a basic unit for multicomponent Ti-Cu-based BMGs and proposing a mechanism for the formation of typical BMGs by replacing atoms in the basic unit with alloying ones.
Article
Chemistry, Physical
Xuyao Zhang, Weiguo Li, Jiasen Xu, Ruozhen Zhang, Pan Dong, Yanli Ma, Haibo Kou
Summary: In this study, a theoretical model for the temperature-dependent surface tension (TDST) of binary liquid alloys (BLAs) was developed based on broken-bond rules. The model, combined with the classical ideal solution model, offers a simple method for predicting the surface tension of BLAs with different component concentrations.
SURFACES AND INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Y. H. Zhou, S. F. Liu, D. Chen, Q. F. Wu, B. Xiao, F. He, Z. J. Wang, T. Yang, J. J. Kai
Summary: In this study, the irradiation behavior of two types of EHEAs (Fe42 and Fe47) with different phase designs was investigated using He ion irradiation. The results showed that the phase composition of the alloys remained relatively stable up to a certain level of irradiation, but the long-range order of the B2 phase in Fe42 alloy was disrupted to a greater extent. It was also found that the Fe47 alloy with an ordered B2 phase exhibited better radiation resistance, with smaller and fewer helium bubbles formed. This work provides a new strategy for designing EHEAs with excellent resistance to irradiation at elevated temperatures.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Huajie Zhang, Jinfu Li
Summary: Alloying Si with Ge enhances its electrochemical performance, leading to higher efficiency Li-ion batteries. In this study, Sr was added to the Al-Si-Ge eutectic ribbons as a modifier, resulting in porous coral-like SiGe particles with numerous fibrous branches. The Sr-modified SiGe anode exhibited excellent capacity of 1166.6 mA h g(-1) at 0.1 A g(-1) after 100 cycles, along with a fantastic initial coulombic efficiency of 83.62%. Additionally, it showed superior rate performance with a reversible capacity of 675.3 mA h g(-1) at a current density of 8 A g(-1). This research demonstrates that modification treatments commonly used in metallurgy hold promise for synthesizing high-performance battery electrodes and other energy storage materials.
Article
Materials Science, Multidisciplinary
Ruobing Wang, Zhitang Song, Wenxiong Song, Tianjiao Xin, Shilong Lv, Sannian Song, Jun Liu
Summary: In this study, we demonstrate a phase-change memory (PCM) based on In0.9Ge2Sb2Te5 (IGST) alloy, which shows improved thermal stability and reliability compared to traditional Ge2Sb2Te5 storage devices. The introduction of In can enhance the nucleation centers of the device, boosting set speed and endurance. Matching stable phase-change octahedrons could be a feasible way to achieve practical PCMs.
Article
Materials Science, Ceramics
W. Li, L. T. Kong, J. F. Li
Summary: The study found that adding Ge to Al90Y10 amorphous alloys induces more severe chemical heterogeneity compared to adding Si, resulting in a faster decrease in crystallization onset temperature. Ge addition reduces precipitation of metastable phases but promotes direct crystallization into stable phases. Additionally, adding Si can cause the primary crystallization of α-Al to split into two stages.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2022)
Article
Chemistry, Physical
Payam Kalhor, Khashayar Ghandi, Hamad Ashraf, Zhiwu Yu
Summary: The study used ATR-FTIR spectroscopy to investigate the structural and interactive properties of zinc chloride-ethylene glycol mixtures, revealing that EG is most significantly affected by ZnCl2 to form a new complex, while the ZnCl2-4EG deep eutectic solvent exhibits unique interaction characteristics.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Byung-Hyun Kim, Sang-Pil Kim, Joonhee Kang, Yong-Chae Chung, Kyung-Suk Kim, Kwang-Ryeol Lee
Summary: The study investigated the composition modulation by Ar bombardment on the Co0.5Cu0.5 alloy and the CoAl B2 phase using molecular dynamics simulation. The results showed that Ar bombardment induces surface composition modulation in a layer-by-layer mode and the rearrangement of substrate atoms plays a significant role in the observed modulation.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Feipeng Yang, Jianying Wang, Tao Wen, Xinhai Ai, Xixi Dong, Hailin Yang, Shouxun Ji
Summary: The traditional wrought Al-Mg-Si alloys fabricated via laser powder bed fusion (LPBF) are prone to hot cracks, unless adding grain refiners in as-LPBFed Al alloys. In this work, the Al-9.6 wt.% Mg-4.9 wt.% Si alloy with low solidification range and hot-cracking susceptibility was successfully processed by LPBF. The as-LPBFed alloys have reached a high relative density of 99.3% at the VED of 129.6 J/mm(3). The microstructures were featured by fine a-Al grains and cellular eutectic Mg2Si, accompanied by a high number density of dislocations, coherent GP zone and alpha-Al-12(Fe, Mn)(3) Si phases. The as-LPBFed Al-13.3Mg(2)Si alloy exhibited the high ultimate tensile strength of 557 MPa, yield strength of 439 MPa and elongation of 2.9%. In addition to the grain refinement and dislocation strengthening, the strength enhancement is mainly ascribed to the dispersion strengthening from the divorced nanosized eutectic Mg2Si. The results demonstrate that manipulation of alloys at near eutectic composition is effective to achieve high strength Al-Mg-Si alloys processed by LPBF.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Physics, Condensed Matter
J. Kalikka, K. Konstantinou, J. Akola, R. O. Jones
Summary: Molecular dynamics simulations were used to study the as-deposited (AD) surface of amorphous selenium, revealing differences in defects and ring distributions compared to the earlier melt-quenched (MQ) structures. The presence of defects in the AD structures influenced Bader charges and band gap edge states in electronic structures. Dominance of rings found in previous AD simulations was not observed in this study.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Energy & Fuels
David Kleiven, Jaakko Akola, Andrew A. Peterson, Tejs Vegge, Jin Hyun Chang
Summary: Cluster expansion has become increasingly popular in recent years, with a new strategy proposed here to construct a training set based on relevance in Monte Carlo sampling for statistical analysis and reduction of expected error, resulting in increased reproducibility of the model. This method can also be applied to other machine learning approaches where sampling relevant configurational space with a small set of training data is desired, particularly in cases involving first-principles calculations.
JOURNAL OF PHYSICS-ENERGY
(2021)
Article
Materials Science, Multidisciplinary
Konstantinos Konstantinou, Felix C. Mocanu, Jaakko Akola, Stephen R. Elliott
Summary: In this study, a computational approach was used to investigate the effects of electric fields on the atomic and electronic structures of amorphous phase-change materials. By applying homogeneous electric fields, defects were removed from the band gap and transformed into delocalized electronic states, leading to engineered structural relaxation for optimized glass design.
Review
Physics, Condensed Matter
R. O. Jones
Summary: This article is a complement to the previous review on chemical bonds, focusing on condensed matter physics and the structure and properties of phase change materials. It discusses new concepts such as "electron-rich," "hypervalent," and "three-centre" bonds, as well as the bond in metals and the "Peierls" distortion.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Materials Science, Multidisciplinary
Jaakko Akola, Konstantinos Konstantinou, R. O. Jones
Summary: Density functional/molecular dynamics simulations were performed to study the migration of silver atoms and the formation of conductive filaments in a chalcogenide electrolyte under an electric field. The simulations showed significant atomic diffusion and the formation of conductive clusters at the platinum electrode. The electronic structure analysis revealed changes in the dissolved silver atoms upon cluster formation. Despite the presence of conductive silver wires, the electrolyte as a whole does not conduct.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Condensed Matter
Mohammad Alidoust, Erling Rothmund, Jaakko Akola
Summary: This paper explores the application of machine-learned multi-orbital tight-binding models in intermetallic compounds Mg2Si, Mg2Ge, Mg2Sn, and Mg2Pb. The results demonstrate the accuracy of the model in describing the electronic characteristics, especially under different strain conditions. The study also reveals significant effects of compressive and tensile strain on the band structures and band gaps of these compounds.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Chemistry, Multidisciplinary
Robert O. Jones, Stephen R. Elliott, Richard Dronskowski
Summary: Phase-change memory materials (PCMs) have unique properties and significant applications. Recent research has focused on improving the materials by investigating their bonding mechanisms. Metavalent bonding, which combines characteristics of both metallic and covalent bonding, is proposed as a new mechanism applicable to PCMs and halide perovskite materials. However, it is discovered that PCMs violate the octet rule and possess two types of covalent bonds: two-center, two-electron (2c-2e) bonds and electron-rich, multicenter bonds (3c-4e bonds, hyperbonds) involving lone-pair electrons.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Erkka J. Frankberg, Aloshious Lambai, Jiahui Zhang, Janne Kalikka, Sergei Khakalo, Boris Paladino, Mattia Cabrioli, Nidhin G. Mathews, Turkka Salminen, Mikko Hokka, Jaakko Akola, Antti Kuronen, Erkki Levanen, Fabio Di Fonzo, Gaurav Mohanty
Summary: This research discovers the significant plasticity of amorphous aluminum oxide (a-Al2O3) at room temperature and verifies its plasticity mechanism at both micro and macro scales. This finding has important implications for the development of engineering materials.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Sander o. Hanslin, Hannes Jonsson, Jaakko Akola
Summary: Transition metal dichalcogenides (TMDs) are inexpensive and abundant alternatives to precious metals as catalyst materials. Experimental measurements show that MoS2 has significant electrocatalytic activity for the hydrogen evolution reaction (HER). However, the activity varies depending on the preparation method. To understand the mechanism and active sites for HER, calculations were performed on transition metal doped basal plane of MoS2 under electrochemical conditions, taking into account electrode potential and solvent effects.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Sander O. Hanslin, Hannes Jonsson, Jaakko Akola
Summary: This study employs a grand-canonical approach to calculate the kinetics of the hydrogen evolution reaction on intrinsic sites of MoS2. The results reveal that certain edge configurations, particularly S-deficient edges on the Mo-termination, exhibit significantly higher activity. The findings suggest that catalyst design for transition metal dichalcogenides should focus on modifying the metal sites rather than activating the chalcogen sites.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Konstantinos Konstantinou, Felix C. Mocanu, Jaakko Akola
Summary: Understanding the relation between structural disorder and localized states in phase-change memory materials is crucial for technological advances and fundamental understanding. Using computational simulations, this study investigates the impact of antisite defects on the spatial localization of electronic states in recrystallized models of Ge2Sb2Te5, identifying that specific defective atomic environments induce electron localization.
Article
Chemistry, Physical
Andrew M. Teale, Trygve Helgaker, Andreas Savin, Carlo Adamo, Balint Aradi, Alexei Arbuznikov, Paul W. Ayers, Evert Jan Baerends, Vincenzo Barone, Patrizia Calaminici, Eric Cances, Emily A. Carter, Pratim Kumar Chattaraj, Henry Chermette, Ilaria Ciofini, T. Daniel Crawford, Frank De Proft, John F. Dobson, Claudia Draxl, Thomas Frauenheim, Emmanuel Fromager, Patricio Fuentealba, Laura Gagliardi, Giulia Galli, Jiali Gao, Paul Geerlings, Nikitas Gidopoulos, Peter M. W. Gill, Paola Gori-Giorgi, Andreas Gorling, Tim Gould, Stefan Grimme, Oleg Gritsenko, Hans Jorgen Aagaard Jensen, Erin R. Johnson, Robert O. Jones, Martin Kaupp, Andreas M. Koster, Leeor Kronik, Anna Krylov, Simen Kvaal, Andre Laestadius, Mel Levy, Mathieu Lewin, Shubin Liu, Pierre-Francois Loos, Neepa T. Maitra, Frank Neese, John P. Perdew, Katarzyna Pernal, Pascal Pernot, Piotr Piecuch, Elisa Rebolini, Lucia Reining, Pina Romaniello, Adrienn Ruzsinszky, Dennis R. Salahub, Matthias Scheffler, Peter Schwerdtfeger, Viktor N. Staroverov, Jianwei Sun, Erik Tellgren, David J. Tozer, Samuel B. Trickey, Carsten A. Ullrich, Alberto Vela, Giovanni Vignale, Tomasz A. Wesolowski, Xin Xu, Weitao Yang
Summary: This paper provides an informal review and discussion on the history, present status, and future of density-functional theory (DFT) by 70 workers in the field. The format of a roundtable discussion allowed participants to express their views through 302 individual contributions to a preset list of 26 questions. Supported by a bibliography of 777 entries, the paper offers a comprehensive snapshot of DFT in 2022.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Konstantinos Konstantinou, Stephen R. Elliott, Jaakko Akola
Summary: This study demonstrates that excess electrons and holes in glassy Ge2Sb2Te5 can be spontaneously trapped, forming deep traps and midgap states. The trapping of these charge carriers is facilitated by specific structural motifs in the amorphous phase-change material. These findings provide insights into the origin of charge trapping and have implications for resistance drift and athermal melting in electronic-memory devices.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Mohammad Alidoust, Erlend E. Isachsen, Klaus Halterman, Jaakko Akola
Summary: The study compares the dispersive permittivity tensor of materials using a low-energy model and density functional theory, revealing general agreement in low-strain and low-frequency regimes but significant discrepancies in other areas. It suggests a need for revisiting and improving the random phase approximation used in widely-used DFT packages. The study highlights the pivotal role phosphorene can play in optoelectronics devices and emphasizes the importance of reliable predictions for precise device design.
