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SSRN 2023年

作者： Baraldi, Rafael Bispo da Silva, Douglas de Gouveia, Guilherme Lisboa Garcia, Amauri Spinelli, José Eduardo Department of Materials Engineering Federal University of São Carlos UFSCar SP São Carlos13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil Department of Manufacturing and Materials Engineering University of Campinas SP Campinas13083-860 Brazil

Microstructures are the strategic link between cast alloys processing and their properties. The investigation of α-Al morphologies is regarded as critical for broadening the potential applications of cast Al-Ce alloys. These alloys are anticipated to offer high-temperature strength. Moreover, Ce is the most abundant rare-earth element in the Earth’s crust. A central task is changing the Ce content (4.0, 6.0 and 10.1 wt.% Ce) and observing the morphologies, particularly when extremely high cooling rates - 102 to 103 K/s - are attained during cast-centrifugal Cu-mold operations. In the present contribution, rapid solidification of the Al-4wt.% Ce alloy led to generation of high cooling rate cells. A eutectic mixture of Al11Ce3 fibers and lamellae filled the intercellular spacings. Using the Hunt-Lu model, an experimental cell spacing of roughly 6.3 μm was obtained with a suitable equivalence to the modeling outcomes, corresponding to a solidification velocity of 3.1 mm/s and a cooling rate of approximately 155 K/s. © 2023, The Authors. All rights reserved.

关键词： Cells

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Influence of Treatment Time on the Synthesis of Copper Oxide Films by Cathode Cage Plasma Deposition

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SSRN 2023年

作者： de Carvalho, Júlio F.S. Monção, Renan M. de Sousa, Ediones M. da Luz Lima, Cleânio Costa, Carla L.S.C. Garcia, Ramón R.P. Feitor, Michelle C. de Carvalho Costa, Thércio H. Libório, Maxwell S. de Sousa, Rômulo R.M. Federal University of Piauí Graduate Program in Materials Science and Engineering PI Teresina Brazil Federal University of Piauí Physics Postgraduate Program PI Teresina Brazil Federal university of Rio Grande do Norte Department of Materials Science and Engineering RN Natal Brazil Federal University of Rio Grande do Norte Department of Mechanical Engineering RN Natal Brazil Federal university of Rio Grande do Norte School of Science and Technology RN Natal Brazil

Copper oxide is a valuable p-type semiconductor for photovoltaic applications. In this work, plasma deposition with cathodic cage (CCPD) of copper oxide (CuO+Cu2O) films on glass was performed to evaluate the microstructural, morphological, chemical, and bandgap changes as a function of the treatment time variation (2, 3, 4, and 5 hours). The samples were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive System (EDS), X-ray Diffraction (XRD), and Raman Spectroscopy to identify morphologies, chemical composition, and crystalline phases of the deposited films, and the absorption spectrum optics was used to calculate the bandgap width. All films showed bandgap energies around 2.60 eV. However, the sample treated with a time of 3h presented a compact coating with 1.46 µm of thickness and bandgap energy equal to 2.57 eV, being the best result. © 2023, The Authors. All rights reserved.

关键词： Energy gap

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Transforming organic chemistry research paradigms: moving from manual efforts to the intersection of automation and artificial intelligence

arXiv

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arXiv 2023年

作者： Liu, Chengchun Chen, Yuntian Mo, Fanyang School of Materials Science and Engineering Peking University Beijing China Ningbo Institute of Digital Twin Eastern Institute of Technology Ningbo China Preferred Program Shenzhen Graduate School Peking University Shenzhen China

Organic chemistry is undergoing a major paradigm shift, moving from a labor-intensive approach to a new era dominated by automation and artificial intelligence (AI). This transformative shift is being driven by technological advances, the ever-increasing demand for greater research efficiency and accuracy, and the burgeoning growth of interdisciplinary research. AI models, supported by computational power and algorithms, are drastically reshaping synthetic planning and introducing groundbreaking ways to tackle complex molecular synthesis. In addition, autonomous robotic systems are rapidly accelerating the pace of discovery by performing tedious tasks with unprecedented speed and precision. This article examines the multiple opportunities and challenges presented by this paradigm shift and explores its far-reaching implications. It provides valuable insights into the future trajectory of organic chemistry research, which is increasingly defined by the synergistic interaction of automation and AI. Copyright © 2023, The Authors. All rights reserved.

关键词： Automation

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In situ structural determination of 3d and 5d perovskite oxides under high pressure by synchrotron x-ray diffraction

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Physical Review B 2023年第13期108卷 134106-134106页

作者： Jie Chen Jiaming He Yanyao Zhang Stella Chariton Vitali Prakapenka Kazunari Yamaura Jung-Fu Lin J. B. Goodenough J.-S. Zhou Materials Science and Engineering Program Mechanical Engineering University of Texas at Austin Austin Texas 78712 USA Department of Earth and Planetary Sciences Jackson School of Geosciences The University of Texas at Austin Austin Texas 78712 USA Center for Advanced Radiation Sources The University of Chicago Illinois 60637 USA Research Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Graduate School of Chemical Sciences and Engineering Hokkaido University North 10 West 8 Kita-ku Sapporo Hokkaido 060–0810 Japan

In contrast to the Mott transition found in RNiO3 (R= rare earths), the metal-insulator transition temperature in the perovskite NaOsO3 is not sensitive to pressure. The peculiarity may be correlated to how the crystal structure of NaOsO3 responds to high pressure, which has been rarely studied so far. The pressure-induced bond-length shrinking can increase the orbital overlap integral and therefore the electron bandwidth. However, in the orthorhombic perovskite structure, the pressure-induced bending in the bond angle Os-O-Os may compensate for the bandwidth broadening due to the bond-length shrinking in some circumstances. A recent structural study on polycrystalline NaOsO3 indicated that orthorhombic distortion is enlarged under high pressure. But, how the local structure changes under pressure remains unknown. Moreover, a highly unusual phase transition from the orthorhombic phase (Pbnm) to a polar phase (Pbn21) occurs at around 18 GPa [Sereika et al., npj Quantum Mater. 5, 66 (2020)]. Motivated by these concerns, we have done a more comprehensive structural study on NaOsO3 using single-crystal diffraction with synchrotron radiation at high pressures up to 41 GPa. Diffraction patterns over the entire pressure range can be refined well with the Pbnm structural model. Moreover, the refinement results reveal in detail how the local structures change under pressure corresponding to the enhanced orthorhombic distortion from the lattice parameters. We have carried out a systematic study for understanding the pressure effect on the orthorhombic perovskites in the context of the influences of the charge distributions in the ABO3 formula, i.e., A3+B3+O3, A2+B4+O3, and A1+B5+O3 and the B-site cations from the 3d to the 4d and 5d row of elements. To fulfill this purpose, we have revisited two families of 3d perovskites: RCrO3 and RFeO3.

关键词： Phase transitions Crystal structures X-ray diffraction

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Deep peak property learning for efficient chiral molecules ECD spectra prediction

arXiv

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arXiv 2024年

作者： Li, Hao Long, Da Yuan, Li Tian, Yonghong Wang, Xinchang Mo, Fanyang School of Electronic and Computer Engineering Peking University Shenzhen China -Preferred Program Peking University Shenzhen Graduate School Shenzhen China College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China Peng Cheng Laboratory Shenzhen China School of Materials Science and Engineering Peking University Beijing China

Chiral molecule assignation is crucial for asymmetric catalysis, functional materials, and the drug industry. The conventional approach requires theoretical calculations of electronic circular dichroism (ECD) spectra, which is time-consuming and costly. To speed up this process, we have incorporated deep learning techniques for the ECD prediction. We first set up a large-scale dataset of Chiral Molecular ECD spectra (CMCDS) with calculated ECD spectra. We further develop the ECDFormer model, a Transformer-based model to learn the chiral molecular representations and predict corresponding ECD spectra with improved efficiency and accuracy. Unlike other models for spectrum prediction, our ECDFormer creatively focused on peak properties rather than the whole spectrum sequence for prediction, inspired by the scenario of chiral molecule assignation. Specifically, ECDFormer predicts the peak properties, including number, position, and symbol, then renders the ECD spectra from these peak properties, which significantly outperforms other models in ECD prediction, Our ECDFormer reduces the time of acquiring ECD spectra from 1-100 hours per molecule to 1.5s. Copyright © 2024, The Authors. All rights reserved.

关键词： Forecasting

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Microstructure, Properties and Crystallographic Orientation of Novel Austenitic Fe-26mn-0.4c Steel Under Hot Torsion Process

SSRN

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SSRN 2023年

作者： da Silva Lima, Marcos Natan França Schmalz, Guilherme Luis Loureiro, Rodrigo de Carvalho Paes Ferreira, João Carlos Rodrigues, Samuel Filgueiras Muñoz, Jessica Calvo Cabrera Marrero, José María de Abreu, Hamilton Ferreira Gomes Department of Metallurgical and Materials Engineering Federal University of Ceará Campus do Pici bloco 729 Fortaleza Ceará60020-181 Brazil Graduate Program in Materials Engineering Federal Institute of Education Science and Technology of Maranhão Sao Luis65030-005 Brazil Department Materials Science and Metallurgical Engineering Universitat Politècnica de Catalunya: Catalunya Bl. I Barcelona08930 Spain

An experimental austenitic twin-induced plasticity (TWIP) steel was deformed under hot torsion tests. Two different total equivalent strains were employed in order to raise its yield strength while keeping reasonable toughness. The material was strained isothermally at 900 °C with a low strain rate of 0.05 s–1. The effects of torsional deformation on the microstructure, texture and mechanical properties of TWIP-FeMnCCr steel were investigated and compared with the as-received samples. X-Ray Diffraction (XRD) measurements were performed to identify the phases present in the metal before and after the thermomechanical process. Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), Orientation distribution function (ODF) analysis and tensile experiments complemented the investigation of this research. The main deformation mechanism changed from conventional sliding inside the grain to nucleated twinning from the grain boundaries, which led to the decrease of the grains to less than 1 μm (UFG - Ultrafine Grains). The results indicate that the deformation mechanisms transition dependent on grain size is associated with the discontinuous flow profile of the material. This was due to changes in the density of dislocations within the grain and the movement of dislocations around the yield point. No martensitic transformation was detected during the strain and neither from the twinning mechanism in the microstructure after the torsion deformation. The best balance between high strength and good ductility (920 MPa and 52%) was obtained after the total equivalent strain of 2.6. It was verified that the employed thermomechanical schedule affects the displacement of the substructure with the formation of subgrains influencing the hardening behavior, texture and yield strength of the metal. © 2023, The Authors. All rights reserved.

关键词： Textures

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Shark Skin Denticles: From Morphological Diversity to Multi-functional Adaptations and Applications

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Advanced Functional materials 2024年第35期34卷

作者： Ghimire, Ashish Dahl, Rikke Beckmann Shen, Sheng-Feng Chen, Po-Yu Dept. of Materials Science and Engineering National Tsing Hua University Hsinchu300044 Taiwan Biodiversity Research Center Academia Sinica Taipei115201 Taiwan Dept. of Life Science National Taiwan Normal University Taipei116059 Taiwan Biodiversity Program Taiwan International Graduate Program Academia Sinica and National Taiwan Normal University Taiwan

The energy crisis of the 1970s sparked growing concern over minimizing fuel consumption in water, land, and air transportation. Researchers fascinated by sharks' effortless swimming abilities investigated shark skin denticles and uncovered functions beyond drag reduction, such as antifouling, protection, and bioluminescence. Over the past five decades, significant progress has been made in comprehending drag reduction and antifouling functions of denticle structures;however, the investigation of other functions remains limited. Recent discoveries of diverse denticle morphologies have ignited a keen interest in obtaining morphogroups that can aid other functional studies. This work integrates advances in antifouling, hydrodynamics, aerodynamics, bioluminescence, and protective functions to provide a holistic understanding of their diverse roles. Additionally, this work also dictates multi-functional adaptations of denticles and contributes to the relatively less-explored but essential aspects, such as protective functions and denticle morphogroups. By examining these functions together, this work aims to uncover potential synergies and interactions, facilitating the development of multifunctional materials inspired by shark skin denticles. © 2024 Wiley-VCH GmbH.

关键词： Hydrodynamics

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Early and advanced crystallization stages in lithia-alumina-silica glasses nucleated by ZrO2

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Ceramics International 2025年

作者： Revelo, Raúl Julián Souza, Mauricio Lima Pena, Rafaella Bartz Yoshida, Satoshi Zanotto, Edgar Dutra Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil São Carlos Institute of Physics University of São Paulo SP São Carlos13566-590 Brazil Materials Integration Laboratories AGC Inc 1-1 Suehiro-Cho Tsurumi-Ku Kanagawa Yokohama230-0045 Japan

ZrO2 is one of the most effective and widely used nucleating agents in various families of glass-ceramics;however, its detailed mechanism remains a subject of debate. Understanding its nucleation mechanism requires a thorough analysis of microstructural evolution and the identification of factors influencing this process. This study investigates the effects of ZrO2 incorporation on the internal nucleation and microstructural evolution in stoichiometric LAS (Li2O·Al2O3·nSiO2) glass-ceramics of varying composition. Glasses with different SiO2 molar ratios (n = 2, 4, 5, and 6) were prepared with ZrO2 additions of 3.0 and 3.5 mol%. Several thermal treatments were employed, followed by characterization using XRD, SEM, STEM, and Raman spectroscopy. The results indicate that a minimum of 3.5 mol% ZrO2 is required to induce internal nucleation in LAS glasses with n = 4, 5, and 6. In these compositions, Zr-enriched regions formed through liquid-liquid phase separation serve as preferential sites for ZrO2 crystal precipitation, which subsequently induces the nucleation of β-quartz solid solution. Upon further treatment at higher temperatures, this metastable phase transforms into β-spodumene or its solid solution. As expected, increasing SiO2 content enhances glass network polymerization, as evidenced by the increased presence of Q3 species in Raman spectroscopy, leading to higher characteristic temperatures of glass transition and peak crystallization in DSC analyses. A higher SiO2 content results in fewer but larger crystals, whereas a lower SiO2 content promotes a higher number density of crystals within the glass matrix. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Glass ceramics

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Surface Roughness-Induced Changes in Important Physical Features of CoFeSm Thin Films on Glass Substrates during Annealing

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materials 2023年第21期16卷 6989-6989页

作者： Fern, Chi-Lon Liu, Wen-Jen Chang, Yung-Huang Chiang, Chia-Chin Chen, Yuan-Tsung Lu, Pei-Xin Su, Xuan-Ming Lin, Shih-Hung Lin, Ko-Wei Department of Materials Science and Engineering National Chung Hsing University Taichung40227 Taiwan Department of Materials Science and Engineering I-Shou University Kaohsiung84001 Taiwan Bachelor Program in Industrial Technology National Yunlin University of Science and Technology 123 University Road Section 3 Yunlin Douliou64002 Taiwan Department of Mechanical Engineering National Kaohsiung University of Science and Technology Kaohsiung80778 Taiwan Graduate School of Materials Science National Yunlin University of Science and Technology 123 University Road Section 3 Yunlin Douliou64002 Taiwan Department of Electronic Engineering National Yunlin University of Science and Technology 123 University Road Section 3 Yunlin Douliou64002 Taiwan

Co60Fe20Sm20 thin films were deposited onto glass substrates in a high vacuum setting. The films varied in thickness from 10 to 50 nm and underwent annealing processes at different temperatures: room temperature (RT), 100, 200, and 300 °C. Our analysis encompassed structural, magnetic, electrical, nanomechanical, adhesive, and optical properties in relation to film thickness and annealing temperature. X-ray diffraction (XRD) analysis did not reveal characteristic peaks in Co60Fe20Sm20 thin films due to insufficient growth-driving forces. Electrical measurements indicated reduced resistivity and sheet resistance with increasing film thickness and higher annealing temperatures, owing to hindered current-carrier transport resulting from the amorphous structure. Atomic force microscope (AFM) analysis showed a decrease in surface roughness with increased thickness and annealing temperature. The low-frequency alternating current magnetic susceptibility (χac) values increased with film thickness and annealing temperature. Nanoindentation analysis demonstrated reduced film hardness and Young’s modulus with thicker films. Contact angle measurements suggested a hydrophilic film. Surface energy increased with greater film thickness, particularly in annealed films, indicating a decrease in contact angle contributing to this increase. Transmittance measurements have revealed intensified absorption and reduced transmittance with thicker films. In summary, the surface roughness of CoFeSm films at different annealing temperatures significantly influenced their magnetic, electrical, adhesive, and optical properties. A smoother surface reduced the pinning effect on the domain walls, enhancing the χac value. Additionally, diminished surface roughness led to a lower contact angle and higher surface energy. Additionally, smoother surfaces exhibited higher carrier conductivity, resulting in reduced electrical resistance. The optical transparency decreased due to the smoother surface of C

关键词： Thin films

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Microstructural Effect on the Corrosion Behavior of N- and P-Type Bismuth Tellurides Fabricated by Induction Melting

SSRN

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SSRN 2023年

作者： El-Makaty, Farah M. Nawaz, Muddasir Shakoor, R. Abdul Hammuda, Abdelmagid Youssef, Khaled M. Mechanical and Industrial Engineering Department Qatar University Doha2713 Qatar Qatar University Doha2713 Qatar Materials Science and Technology Graduate Program College of Arts and Sciences Qatar University Doha2713 Qatar

Numerous efforts have been made to understand and enhance the thermoelectric properties of bismuth telluride alloys. However, limited studies have been reported to investigate the corrosion behavior of these alloys and their suitability for industrial applications. This paper examines the corrosion behavior of three different bismuth telluride alloys prepared by induction melting: pristine Bi2Te3, n-type Bi2Te2.55Se0.45, and p-type Bi0.6Sb1.4Te3. The electrochemical response of the samples is tested in 3.5 wt.% NaCl solution at room temperature. Potentiodynamic polarization curves (Tafel plots) revealed that the n-type sample formed a passive layer compared to the pristine and the p-type samples, which showed pitting corrosion. The different trends observed in the samples were related to their evolved microstructures, where fingerprint-like features in the pristine and the p-type samples showed high susceptibility to pitting corrosion. In contrast, a unique needle-like microstructure of the n-type samples acted as nucleation sites for passive layer formation causing higher corrosion resistance in this sample. © 2023, The Authors. All rights reserved.

关键词： Microstructure

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