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Anomalous elastic softening in ferroelectric hafnia under pressure

Physical Review B 2025年第6期111卷 064106-064106页

作者： Alejandro Alvarez Niaz Abdolrahim Sobhit Singh Materials Science Program University of Rochester Rochester New York 14627 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Laboratory for Laser Energetics University of Rochester Rochester New York 14627 USA Center for Coherence and Quantum Optics University of Rochester Rochester New York 14627 USA

This study employs first-principles density-functional theory (DFT) calculations to explore the elastic and mechanical properties of ferroelectric hafnia (HfO2) in its polar orthorhombic Pca21 phase under varying hydrostatic pressure conditions up to 30 GPa. Utilizing a plane-wave basis set and Perdew-Burke-Ernzerhof generalized-gradient approximation for solids in our DFT calculations, we investigate both pure and yttrium-substituted HfO2. Our findings reveal an anomalous reduction in the C33 component of the elastic tensor with increasing pressure, which becomes significant above 15 GPa and signals a potential pressure-driven structural phase transition at higher pressure. The analysis of atomic displacements under pressure sheds light on the unusual mechanical behavior and phase stability of this material. Additionally, we observe a transition from an indirect band gap to a direct band gap with increasing pressure, which could have significant implications for optical applications. The effects of yttrium substitution on the mechanical and electronic properties are further examined, revealing that yttrium substitution softens the elastic response of this material and reduces the electronic band gap. These results enhance our understanding of elastic and mechanical responses of ferroelectric hafnia and its potential for applications in microelectronics, piezoelectric devices, and nonvolatile ferroelectric random-access memories. Further experimental validation is recommended to confirm our predictions and explore the practical implications of the observed phase transitions and electronic behavior of the ferroelectric hafnia under high-pressure conditions.

关键词： Ferroelectricity

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Ab initio phonon transport across grain boundaries in graphene using machine learning based on small dataset

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Physical Review materials 2022年第4期6卷 044004-044004页

作者： Amirreza Hashemi Ruiqiang Guo Keivan Esfarjani Sangyeop Lee Computational Modeling and Simulation Program University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Materials Science and Engineering University of Virginia Charlottesville Virginia 22904 USA Department of Physics University of Virginia Charlottesville Virginia 22904 USA Department of Physics and Astronomy University of Pittsburgh Pittsburgh Pennsylvania 15261 USA

Establishing the structure-property relationship for grain boundaries (GBs) is critical for developing next-generation functional materials but has been severely hampered due to its extremely large configurational space. Atomistic simulations with low computational cost and high predictive power are strongly desirable, but the conventional simulations using empirical interatomic potentials and density functional theory suffer from the lack of predictive power and high computational cost, respectively. A machine learning interatomic potential (MLIP) recently emerged but often requires extensive size of the training dataset, making it a less feasible approach. Here, we demonstrate that an MLIP trained with a rationally designed small training dataset can predict thermal transport across GBs in graphene with ab initio accuracy at an affordable computational cost. We employed a rational approach based on the structural unit model to find a small set of GBs that can represent the entire configurational space and thus can serve as a cost-effective training dataset for the MLIP. Only 5 GBs were found to be enough to represent the entire configurational space of graphene GBs. Using the atomistic Green's function approach and the MLIP, we revealed that the structure-thermal resistance relation in graphene does not follow the common understanding that large dislocation density causes larger thermal resistance. In fact, thermal resistance is nearly independent of dislocation density at room temperature and is higher when the dislocation density is small at sub-room temperature. We explain this intriguing behavior with the buckling near a GB causing a strong scattering of flexural phonon modes. In this paper, we show that a machine learning technique combined with conventional wisdom (e.g., structural unit model) can extend the recent success of ab initio thermal transport simulation, which has been mostly limited to single crystals, to complex yet practically important polycry

关键词： Phonons Graphene Landauer formula Machine learning

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Detection of toxic chemicals in hand sanitizers using near-infrared spectroscopy

Detection of toxic chemicals in hand sanitizers using near-i...

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Applied Industrial Spectroscopy, AIS 2021 - Part of Optical Sensors and Sensing Congress 2021

作者： Chowdhury, Aminur Rashid Burney, Umar Hutter, Dan Lee, Tse-Ang Hutter, Tanya Department of Mechanical Engineering University of Texas at Austin AustinTX United States Materials Science and Engineering Program Texas Materials Institute University of Texas at Austin AustinTX United States University of Texas at Austin AustinTX United States

Many alcohol-based hand sanitizer products contain toxic ethanol substitutes. In this work, we demonstrate the application of near-infrared spectroscopy for the detection of methanol and 1-propanol in hand sanitizer u... 详细信息

ISBN: (纸本)9781557528209

关键词： Infrared devices

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Evidence of magnetoelectronic electromagnon mediated transport in flexoelectronic heterostructures

arXiv

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arXiv 2023年

作者： Katailiha, Anand Lou, Paul C. Bhardwaj, Ravindra G. Beyermann, Ward P. Kumar, Sandeep Department of Mechanical Engineering University of California RiversideCA92521 United States Department of Physics and Astronomy University of California RiversideCA92521 United States Materials Science and Engineering Program University of California RiversideCA92521 United States

The superposition of atomic vibrations and flexoelectronic effect gives rise to a cross correlation between free charge carriers and temporal magnetic moment of phonons in conducting heterostructures under an applied strain gradient. The resulting dynamical coupling is expected to give rise to quasiparticle excitations called as magnetoelectronic electromagnon that carries electronic charge and temporal magnetic moment. Here, we report experimental evidence of magnetoelectronic electromagnon in the freestanding degenerately doped p-Si based heterostructure thin film samples. These quasiparticle excitations give rise to long-distance (>100µm) spin transport;demonstrated using spatially modulated transverse magneto-thermoelectric and non-local resistance measurements. The magnetoelectronic electromagnons are non-reciprocal and give rise to large magnetochiral anisotropy (0.352 A-1T-1) that diminishes at lower temperatures. The superposition of non-reciprocal magnetoelectronic electromagnons gives rise to longitudinal and transverse modulations in charge carrier density, spin density and magnetic moment;demonstrated using the Hall effect and edge dependent magnetoresistance measurements, which can also be called as inhomogeneous magnetoelectronic multiferroic effect. These quasiparticle excitations are analogues to photons where time dependent polarization and temporal magnetic moment replaces electric and magnetic field, respectively and most likely topological because it manifests topological Nernst effect. Hence, the magnetoelectronic electromagnon can potentially give rise to quantum interference and entanglement effects in conducting solid state system at room temperature in addition to efficient spin transport. © 2023, CC BY.

关键词： Magnetic moments

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Direct observation of structural phase transformations during continuous phosphorus deposition on Cu(111)

arXiv

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arXiv 2024年

作者： David, Jiří Jeřábek, František Procházka, Pavel Černý, Miroslav Ciobanu, Cristian V. Průša, Stanislav Šikola, Tomáš Kodambaka, Suneel Kolíbal, Miroslav Institute of Physical Engineering Brno University of Technology Technická 2 Brno616 69 Czech Republic CEITEC BUT. Brno University of Technology Purkyňova 123 Brno612 00 Czech Republic Department of Mechanical Engineering Materials Science Program Colorado School of Mines GoldenCO80401 United States Department of Materials Science and Engineering Virginia Polytechnic Institute State University BlacksburgVA24061 United States

Blue phosphorene - two-dimensional, hexagonal-structured, semiconducting phosphorus - has gained attention as it is considered easier to synthesize on metal surfaces than its allotrope, black phosphorene. Recent studies report different structures of phosphorene, for example, on Cu(111), but the underlying mechanisms of their formation are not known. Here, using a combination of in situ ultrahigh vacuum low-energy electron microscopy and in vacuo scanning tunneling microscopy, we determine the time-evolution of the surface structure and morphology during the deposition of phosphorus on single-crystalline Cu(111). We find that during early stages of deposition, phosphorus intermixes with Cu, resulting in copper phosphide structures. With increasing surface concentration of phosphorus, the phosphide phase disappears and a blue phosphorene layer forms, followed by self-assembly of highly ordered phosphorus clusters that eventually grow into multilayer islands. We attribute the unexpected transformation of stable phosphide to a phosphorene layer, and the previously unreported multilayer growth, to the presence of a large concentration of P2 dimers on the surface. Our results constitute direct evidence for a new growth mode leading to a phosphorene layer via an intermediary phase, which could underpin the growth of other 2D materials on strongly interacting substrates. © 2024, CC BY-SA.

关键词： Self assembly

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Bioactivity and cytotoxicity of LiF-modified bioactive glass ceramics for bone regeneration

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Ceramics International 2025年

作者： Selli, Neslihan Tamsü Başaran, Neslihan Kesmez, Ömer Yavaş, Adem Demir, Feride Ertürk, A. Tamer Department of Materials Science and Engineering Gebze Technical University Kocaeli Gebze41400 Turkey Department of Chemistry Faculty of Science Akdeniz University Antalya07058 Turkey Food Technology Program Food Processing Department Çine Vocational School Aydin Adnan Menderes University Aydin Turkey Agricultural Biotechnology and Food Safety Research and Application Center Aydin Adnan Menderes University Aydin Turkey Mechanical Engineering Department Kocaeli University Umuttepe Campus Kocaeli Izmit41001 Turkey

Bioactive glasses and glass-ceramics have drawn significant attention due to their excellent bone-bonding capabilities and biocompatibility. This study investigates the effects of lithium fluoride (LiF) addition on the microstructure, mechanical properties, and biocompatibility of novel bioactive glass compositions. Glasses with varying LiF contents (1, 2, and 3 wt%) were synthesized using the melt-quenching method and subsequently heat-treated to obtain bioactive glass-ceramics. X-ray diffraction (XRD) analysis revealed an increase in the intensity of hydroxyapatite, fluorapatite, and diopside phases with increasing LiF content, suggesting enhanced crystallization. Vickers hardness measurements showed a significant improvement, with the highest hardness (730 MPa) observed in the K3 composition. Scanning Electron Microscopy (SEM) was used to examine the microstructural morphology, while Energy-Dispersive X-ray Spectroscopy (EDX) was employed to analyze the elemental composition of the samples. Furthermore, in vitro bioactivity assessments in simulated body fluid (SBF) confirmed the apatite-forming ability of all compositions. Cytotoxicity evaluations demonstrated enhanced cell viability in LiF-containing compositions, with K3 exhibiting the highest biocompatibility. The findings suggest that LiF addition optimizes crystallization, mechanical performance, and biocompatibility, making these modified bioactive glass-ceramics promising candidates for biomedical applications. © 2025

关键词： Energy dispersive spectroscopy

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Oxygen Non-Stoichiometry and Point Defect Equilibria in (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-δ

Oxygen Non-Stoichiometry and Point Defect Equilibria in (La1...

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243rd ECS Meeting

作者： Bishop, Sean R. Zhang, Dawei Liu, Cijie Li, Wei Salinas, Perla A. Smith, Andrew I. Coker, Eric N. De Santiago, Héctor A. Liu, Xingbo McDaniel, Anthony H. Luo, Jian Sandia National Laboratories AlbuquerqueNM87123 United States Program of Materials Science and Engineering University of California La Jolla San DiegoCA92093 United States Department of Mechanical and Aerospace Engineering Benjamin M. Statler College of Engineering and Mineral Resources West Virginia University MorgantownWV26506 United States Sandia National Laboratories LivermoreCA94550 United States Department of NanoEngineering University of California La Jolla San DiegoCA92093 United States

ISBN: (纸本)9781607685395

In this work, the A-site of the common SOFC cathode La0.8Sr0.2MnO3-δ (LSM) is modified with additional lanthanide and alkali elements, resulting in the composition (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-δ. We show that the amount of oxygen released during reduction measured by thermo-gravimetric analysis is significantly greater for this "high entropy" perovskite oxide (HEPO) in comparison with La2/3Sr1/3MnO3-δ, the latter having the same amount of total acceptor dopant and with a similar average A-site radius. The origins of enhanced reduction will be discussed. © The Electrochemical Society.

关键词： Thermogravimetric analysis

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Real-time temperature correction for magnetoresistive biosensors integrated with temperature modulator

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Biosensors and Bioelectronics: X 2023年 14卷 100356页

作者： Kim, Songeun Wang, Shan X. Lee, Jung-Rok Division of Mechanical and Biomedical Engineering Ewha Womans University Seoul03760 Korea Republic of Graduate Program in Smart Factory Ewha Womans University Seoul03760 Korea Republic of Department of Materials Science and Engineering Stanford University StanfordCA93405 United States Department of Electrical Engineering Stanford University StanfordCA93405 United States

Magnetoresistance-based biosensors utilize changes in electrical resistance upon varying magnetic fields to measure biological molecules or events involved with magnetic tags. However, electrical resistance fluctuates with temperature. To decouple unwanted temperature-dependent signals from the signal of interest, various methods have been proposed to correct signals from magnetoresistance-based biosensors. Yet, there is still a need for a temperature correction method capable of instantaneously correcting signals from all sensors in an array, as multiple biomarkers need to be detected simultaneously with a group of sensors in a central laboratory or point-of-care setting. Here we report a giant magnetoresistive biosensor system that enables real-time temperature correction for individual sensors using temperature correction coefficients obtained through a temperature sweep generated by an integrated temperature modulator. The algorithm with individual temperature correction coefficients obviously outperformed that using the average temperature correction coefficient. Further, temperature regulation did not eliminate temperature-dependent signals completely. To demonstrate that the method can be used in biomedical applications where large temperature variations are involved, binding kinetics experiments and melting curve analysis were conducted with the temperature correction method. The method successfully removed all temperature-dependent artifacts and thus produced more precise kinetic parameters and melting temperatures of DNA hybrids. © 2023 The Authors

关键词： Kinetics

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Performance Enhancement of Plate Heat Exchangers Using MWCNTs-SiO2 Hybrid Nanofluids: A CFD Analysis on Heat Transfer and Pressure Drop Characteristics

Research Square

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Research Square 2024年

作者： Heris, Saeed Zeinali Zolfagharian, Nima Mousavi, Seyed Borhan Nami, Shamin Hosseini School of Safety Science & Engineering Xi’an University of Science and Technology 58 Yanta Mid. Rd. Shaanxi Xi’an710054 China Faculty of Chemical and Petroleum Engineering University of Tabriz Tabriz Iran J. Mike Walker ‘66 Mechanical Engineering Department Texas A&M University College StationTX77843 United States School of Chemical Biological and Materials Engineering The University of Oklahoma NormanOK73019 United States

Heat exchangers play a vital role in numerous sectors like power generation and automotive manufacturing. Enhancing the energy efficiency of these exchangers stands as a significant hurdle. Utilizing nanofluids emerges as an optimal solution to augment heat transfer rates, leveraging their superior thermal conductivity while addressing economic constraints linked with traditional heat exchanger technologies. The motivation for this study is to consider the comprehensive synergistic features of MWCNTs, SiO2, and hybrid MWCNTs–SiO2 EG-based nanofluids in plate heat exchangers. This was achieved by simulating a plate heat exchanger using CFD (Fluent and Gambit softwares) considering the comparison of two SiO2, MWCNTs, and their hybrid forms at different mass concentrations. The Reynolds-Averaged Navier-Stokes (RANS) method was employed to model turbulent flows, and the nanoparticles were compared in both single-phase and two-phase states, with their properties derived from experimental studies. Moreover, Nusselt number, convective heat transfer coefficient, and pressure drop variations were computed at different Reynolds numbers. The findings indicated an increase in the Nusselt number with the incorporation of the hybrid nanofluid, achieving a maximum enhancement of 11.19% in comparison to EG at a Reynolds number of 240 and a concentration of 0.86 wt.%. Noticeably, the pressure drop remained negligible at lower Reynolds numbers, exhibiting marginal variations up to 0.3% at higher Reynolds numbers. At a concentration of 0.86 wt.% and a Reynolds number of 480, the introduction of MWCNTs, hybrid, and SiO2 nano-additives resulted in respective increases in the heat transfer coefficient by 21.02%, 10.76%, and 2.16% and corresponding alterations in pressure drop of 0.11%, 0.04%, and 0.02%. © 2024, CC BY.

关键词： Reynolds number

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Opto-thermoelectric pulling of light-absorbing particles

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Light(science & Applications) 2020年第1期9卷 1686-1696页

作者： Linhan Lin Pavana Siddhartha Kollipara Abhay Kotnala Taizhi Jiang Yaoran Liu Xiaolei Peng Brian A.Korgel Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084People’s Republic of China McKetta Department of Chemical Engineering The University of Texas at AustinAustinTX 78712USA Department of Electrical and Computer Engineering The University of Texas at AustinAustinTX 78712USA

Optomechanics arises from the photon momentum and its exchange with low-dimensional *** is well known that optical radiation exerts pressure on objects,pushing them along the light ***,optical pulling of an object against the light path is still a counter-intuitive ***,we present a general concept of optical pulling-opto-thermoelectric pulling(OTEP)—where the optical heating of a light-absorbing particle using a simple plane wave can pull the particle itself against the light *** irradiation orientation-directed pulling force imparts self-restoring behaviour to the particles,and three-dimensional(3D)trapping of single particles is achieved at an extremely low optical intensity of 10^(−2)mWμm^(−2).Moreover,the OTEP force can overcome the short trapping range of conventional optical tweezers and optically drive the particle flow up to a macroscopic *** concept of selfinduced opto-thermomechanical coupling is paving the way towards freeform optofluidic technology and lab-on-achip devices.

关键词： absorbing light trapping

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