jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Muhammad Avicenna Naradipa | Prayudi Lianto | Gilbert See | Arvind Sundarrajan | Andrivo Rusydi
Source: arXiv (Cornell University) (preprint, 2023-08-06)
Field: Materials Science — Surfaces, Coatings and Films

Unravelling metallic contaminants in complex polyimide heterostructures using deep ultraviolet spectroscopic ellipsometry Metallic contaminants in complex heterostructures are important topics due to their significant roles in determining physical properties as well as device performance. Heterostructures of polyimide via on Al pad and Cu redistribution layer (RDL) on polyimide have shown exotic properties and are important for advanced semiconductor packaging systems. One main problem is significant leakage current variations, which affect the performance of the devices, yet the origin is far from understood. Furthermore, metal contaminations would occur at the buried interfaces and it is particularly challenging to probe them. Until now, the electronic and optical properties of complex polyimide heterostructures and the roles of metallic contaminants, especially in the deep ultraviolet (DUV) have not been studied extensively. Herewith, using spectroscopic ellipsometry (SE) in a broad DUV range supported with finite-difference time-domain (FDTD) calculations, we determine optical properties of contaminants with various concentrations and reveal their influence on device performance of under-bump vias and redistribution layer (RDL) architectures. The complex dielectric function shows varying contamination levels and different metals responsible for chip performance. Metallic contaminants are found embedded within 50 nm in the polyimide and different metals are distinguishable with varying concentrations, in agreement with contact measurements in highly complex structures. Our result shows the potency of spectroscopic ellipsometry in the DUV and paves the way for non-destructive, advanced quality control and metrology applications in integrated advanced electronics packaging systems. Polyimide ; Heterojunction ; Materials science ; Ellipsometry ; Ultraviolet ; Optoelectronics ; Semiconductor ; Layer (electronics) ; Nanotechnology ; Thin film Optical Coatings and Gratings ; Synthesis and properties of polymers ; Copper Interconnects and Reliability
Authors: Yusheng Lei | Ran Ni
Source: arXiv (Cornell University) (preprint, 2023-06-05)
Field: Materials Science — Materials Chemistry

How does a hyperuniform fluid freeze? All phase transitions can be categorised into two different types: continuous and discontinuous phase transitions. Discontinuous phase transitions are normally accompanied with significant structural changes, and nearly all of them have the kinetic pathway of nucleation and growth, if the system does not suffer from glassy dynamics. Here, in a system of barrier-controlled reactive particles, we find that the discontinuous freezing transition of a non-equilibrium hyperuniform fluid into an absorbing state does not have the kinetic pathway of nucleation and growth, and the transition is triggered by long wavelength fluctuations. The transition rate decreases with increasing the system size, which suggests that the metastable hyperuniform fluid is kinetically stable in an infinitely large system. This challenges the common understanding of metastability in discontinuous phase transitions. Moreover, we find that the ``metastable yet kinetically stable'' hyperuniform fluid features a new scaling in the structure factor $S(k \rightarrow 0) \sim k^{1.2}$ in 2D, which is the third dynamic hyperuniform state in addition to the critical hyperuniform state with $S(k \rightarrow 0) \sim k^{0.45}$ and the non-equilibrium hyperuniform fluid with $S(k \rightarrow 0) \sim k^{2}$. Metastability ; Nucleation ; Phase transition ; Scaling ; Kinetic energy ; Phase (matter) ; State (computer science) ; Materials science ; Thermodynamics ; Physics ; Condensed matter physics ; Statistical physics ; Chemical physics ; Mathematics ; Classical mechanics ; Quantum mechanics Material Dynamics and Properties ; Theoretical and Computational Physics ; Stochastic processes and statistical mechanics
Authors: Widana Kaushalya | Alice R. Walker
Source: ChemRxiv (preprint, 2023-08-30)
Field: Chemistry — Physical and Theoretical Chemistry

Simulations of DNA-coordinated light emission vs. intramolecular electron transfer: electron donor-acceptor systems with benzo[a]pyrene derivatives We apply excited state molecular dynamics to a set of substituted guanine-benzo[a]pyrene diol epoxide-cyano-based molecules with push-pull donor-acceptor behaviour. Changing the position of the cyano group tunes fluorescence and charge transfer properties of these systems. Our work provides new rational design principles for creating fluorescent nucleobase derivatives with desired properties. Intramolecular force ; Nucleobase ; Chemistry ; Fluorescence ; Photochemistry ; Acceptor ; Pyrene ; Excited state ; Guanine ; Molecule ; Electron donor ; Electron acceptor ; Electron ; Electron transfer ; Epoxide ; DNA ; Stereochemistry ; Atomic physics ; Physics ; Organic chemistry Photochemistry and Electron Transfer Studies ; Organic Chemistry Cycloaddition Reactions ; DNA and Nucleic Acid Chemistry
Authors: Xinyu Yang | Shuai Dong
Source: arXiv (Cornell University) (preprint, 2023-12-07)
Field: Materials Science — Materials Chemistry

Oxidation tuning of ferroic transitions in Gd$_2$C monolayer Tuning of ferroic phases provides great opportunities for material functionalities, especially in two-dimensional materials. Here, a $4f$ rare-earth carbide Gd$_2$C monolayer is predicted to be ferromagnetic metal with large magnetization, inherited from its bulk property. Based on first-principles calculations, we propose a strategy that the surface passivation can effectively tune its ferroicity, namely switching among ferromagnetic, antiferromagnetic, and ferroelectric phases. Metal-insulator transition also occurs accompanying these ferroic transitions. Our calculation also suggests that the magneto-optic Kerr effect and second harmonic generation are effective methods to monitor these phase transitions. Monolayer ; Materials science ; Ferromagnetism ; Passivation ; Condensed matter physics ; Antiferromagnetism ; Phase transition ; Ferroelectricity ; Magnetization ; Transition metal ; Kerr effect ; Nanotechnology ; Optoelectronics ; Chemistry ; Magnetic field ; Nonlinear system ; Physics ; Catalysis 2D Materials and Applications ; Graphene research and applications ; Electronic and Structural Properties of Oxides
Authors: Aleksandra Lelević
Source: arXiv (Cornell University) (preprint, 2023-02-01)
Field: Chemistry — Spectroscopy

Facilitating method development for reverse fill/flush flow modulation by using a tunable auxiliary pressure source instead of a fixed bleed capillary The conventional reverse fill/flush flow modulation for comprehensive two-dimensional gas chromatography requires a bleed capillary column to be connected to the outlet of the modulator channel. The purpose of this capillary, that does not contain the stationary phase, is to provide a pressure resistance to the modulator channel flow. In this way, the desired modulator flow can be achieved, and channel over-filling can be avoided. Normally, the length and the internal diameter of the bleed capillary are chosen so as to obtain the modulator flow that is close to the flow of the first separation column. Thus, for any chosen set of chromatographic conditions, the required dimensions of the bleed capillary can be completely different, making the GCxGC method development tedious and generating additional costs in consumables and analyst time. In this work a tunable pressure source generating a suitable backpressure was used instead of the fixed bleed capillary which has the advantage of the possibility to freely adapt the pressure resistance and generate the required modulator channel flow for any conditions. This set-up has been evaluated and compared in terms of the impact on the modulation performance to the set-up involving a fixed bleed capillary demonstrating comparable performance. Capillary action ; Bleed ; Flow (mathematics) ; Modulation (music) ; Channel (broadcasting) ; Chromatography ; Computer science ; Materials science ; Chemistry ; Mechanics ; Acoustics ; Physics ; Telecommunications ; Surgery Analytical Chemistry and Chromatography ; Microfluidic and Capillary Electrophoresis Applications ; Protein purification and stability
Authors: Alexander M. Bier | Julian Büchler | Dirk W. Schubert
Source: Macromolecular Materials and Engineering (article, 2023-12-10)
Field: Materials Science — Polymers and Plastics

Optimization of Fiber Laydown During the Fiber Spinning Process by Utilizing the Coanda‐Effect Abstract The laydown of aerodynamically stretched fibers during fiber spinning is a key feature of the non‐woven quality. The desired properties of the produced non‐woven are mostly determined by the mechanical properties of the single fiber and the homogeneity of the spunbond. While the former is studied widely, the homogeneity is mostly studied by simulations and not experimentally. Cloudiness or formation of non‐wovens is a known phenomenon that describes deviations from the ideal laydown. Thin areas have a huge impact on the mechanical properties of the spunbond; And subsequently, the investigation of the fiber laydown is of great interest. This work presents an experimental approach to optimize the fiber laydown of a pilot plant fiber spinning device consisting of two aerodynamic stretching devices (aspirators) that stretch eight single fibers each. Due to fiber accumulation on the lay‐down belt under each of the aspirators, a metal rod is placed in‐between to deflect the fibers into the center utilizing the Coanda‐effect to achieve a broad homogeneous fiber distribution. Spinning ; Materials science ; Homogeneity (statistics) ; Fiber ; Composite material ; Aerodynamics ; Homogeneous ; Mechanics ; Computer science ; Thermodynamics Textile materials and evaluations ; Plant Surface Properties and Treatments ; Rheology and Fluid Dynamics Studies
Authors: H. R. A. Jones | Ya. V. Pavlenko | Y. Lyubchik | M. S. Bessell | N. F. Allard | D. J. Pinfield
Source: arXiv (Cornell University) (preprint, 2023-04-18)
Field: Chemistry — Spectroscopy

A blue depression in the optical spectra of M dwarfs A blue depression is found in the spectra of M dwarfs from 4000 to 4500A. This depression shows an increase toward lower temperatures though is particularly sensitive to gravity and metallicity. It is the single most sensitive feature in the optical spectra of M dwarfs. The depression appears as centered on the neutral calcium resonance line at 4227A and leads to nearby features being weaker by about two orders of magnitude than predicted. We consider a variety of possible causes for the depression including temperature, gravity, metallicity, dust, damping constants, and atmospheric stratification. We also consider relevant molecular opacities which might be the cause identifying AlH, SiH, and NaH in the spectral region. However, none of these solutions are satisfactory. In the absence of a more accurate determination of the broadening of the calcium line perturbed by molecular hydrogen, we find a promising empirical fit using a modified Lorentzian line profile for the calcium resonance line. Such fits provide a simplistic line-broadening description for this calcium resonance line and potentially other un-modelled resonance lines in cool high-pressure atmospheres. Thus we claim the most plausible cause of the blue depression in the optical spectra of M dwarfs is a lack of appropriate treatment of line broadening for atomic calcium. The broad wings of the calcium resonance line develop at temperatures below about 4000K and are analogous to the neutral sodium and potassium features which dominate the red optical spectra of L dwarfs. Spectral line ; Metallicity ; Astrophysics ; Brown dwarf ; Resonance (particle physics) ; Line (geometry) ; Surface gravity ; Chemistry ; Physics ; Atomic physics ; Astronomy ; Stars ; Geometry Spectroscopy and Laser Applications ; Stellar, planetary, and galactic studies ; Atmospheric Ozone and Climate
Authors: Andrew O’Hara | Benjamin Plotkin-Swing | Niklas Dellby | Juan Carlos Idrobo | Ondrej L. Krivanek | Tracy C. Lovejoy | Sokrates T. Pantelides
Source: arXiv (Cornell University) (preprint, 2023-10-20)
Field: Materials Science — Materials Chemistry

High-temperature phonons in h-BN: momentum-resolved vibrational spectroscopy and theory Vibrations in materials and nanostructures at sufficiently high temperatures result in anharmonic atomic displacements, which leads to new phenomena such as thermal expansion and multiphonon scattering processes, with a profound impact on temperature-dependent material properties including thermal conductivity, phonon lifetimes, nonradiative electronic transitions, and phase transitions. Nanoscale momentum-resolved vibrational spectroscopy, which has recently become possible on monochromated scanning-transmission-electron microscopes, is a unique method to probe the underpinnings of these phenomena. Here we report momentum-resolved vibrational spectroscopy in hexagonal boron nitride at temperatures of 300, 800, and 1300 K across three Brillouin zones (BZs) that reveals temperature-dependent phonon energy shifts and demonstrates the presence of strong Umklapp processes. Density-functional-theory calculations of temperature-dependent phonon self-energies reproduce the observed energy shifts and identify the contributing mechanisms. Phonon ; Anharmonicity ; Brillouin zone ; Spectroscopy ; Condensed matter physics ; Materials science ; Boron nitride ; Thermal conductivity ; Molecular physics ; Chemistry ; Physics ; Nanotechnology ; Quantum mechanics Thermal properties of materials ; Boron and Carbon Nanomaterials Research ; Graphene research and applications
Authors: Agrawal | Rathore | Kumar
Source: Bulgarian Chemical Communications (article, 2023-08-25)
Field: Materials Science — Materials Chemistry

Goos-Hänchen shift in monolayer graphene with electrostatic barriers We analysed the electron transport and Goos-Hnchen (GH) lateral shifts in graphene.We discuss recent studies on the GH shift in monolayer graphene.We describe the theoretical framework for calculating the GH shift and its electronic analogue in monolayer graphene.Further we discuss the enhancement in the GH shift corresponding to the resonant positions arising due to quasi-bound states formation in the presence of well-formed in the double barrier structure. Monolayer ; Graphene ; Bilayer graphene ; Electrostatics ; Graphene nanoribbons Graphene research and applications ; Quantum optics and atomic interactions ; Plasmonic and Surface Plasmon Research
Authors: Stefan R. Anton | Denis E. Tranca | Stefan G. Stanciu | Radu Hristu | Cosmin Karl Bănică | Eugeniu Vasile | Zhaoyi Hu | Engang Fu | George A. Stanciu
Source: Coatings (article, 2023-11-07)
Field: Materials Science — Materials Chemistry

Characterization of Nanoporous Copper Using Scanning Probe Techniques This study explores the mechanical and optical properties of nanoporous copper (NPC) films dealloyed in acid and base using qualitative and quantitative measurements. Two types of NPC films (NPC 1 and NPC 2) were prepared by dealloying precursor films in different corrosive solutions. The films were characterized using atomic force microscopy (AFM) and scattering scanning near-field optical microscopy (s-SNOM). The AFM analysis revealed distinct nanoporous structures in both films, with NPC 2 showing larger pore sizes and the presence of copper aggregations on the surface. Rugosity measures showed that NPC 2 had higher rugosity than NPC 1 and indicated fundamental differences in the height distributions of the surface nano-topography. The Minkowski connectivity analysis highlighted differences in connectedness and topological characteristics between the two samples. The analysis of the GLCM features showed clear distinctions in ASM, Contrast, Dissimilarity, Energy, and Homogeneity between NPC 1 and NPC 2. The s-SNOM results demonstrated altered optical properties, with NPC 1 showing higher contrast at 1550 nm, while NPC 2 exhibited reversed-phase contrast at 561 nm. The phase contrast at 638 nm indicated a red-shifted optical absorption peak in NPC 2 compared to NPC 1. Copper ; Materials science ; Atomic force microscopy ; Nanoporous ; Optical microscope ; Confocal laser scanning microscopy ; Rugosity ; Microscopy ; Phase contrast microscopy ; Analytical Chemistry (journal) ; Optics ; Nanotechnology ; Chemistry ; Scanning electron microscope ; Biomedical engineering ; Composite material ; Metallurgy Nanoporous metals and alloys ; Anodic Oxide Films and Nanostructures ; Copper-based nanomaterials and applications
Authors: Jiawen Luo | Fengwei Chen | Tao Jiang | Zhiqiang Zhan | Xuemin Wang | Qi Yang | Ruijiao Zou | Jia Li | Yong Zeng | Weidong Wu | Lixin Xu
Source: Physica Scripta (article, 2023-03-20)
Field: Chemistry — Spectroscopy

Frequency regulation of Terahertz quantum cascade lasers by changing barrier thickness Abstract Terahertz (THz) sources with different frequency are important to gas detection. THz quantum cascade lasers (QCLs) based on resonant phonon structure with different frequency emission by changing transition barrier thickness are hereby presented. By theoretically calculation, a 0.19 nm thickening change of transition barrier would cause an approximately 350 GHz regulation range in frequency, and is then confirmed by experimental results. The corresponding far field beam profile keeps almost unchanged. With the increase of the transition barrier thickness, the output power only decreases by 15%, but the threshold current density decreases 24%. This simple method contributes to a satisfactory gas-detection approach with a stability of relative high output power. Terahertz radiation ; Cascade ; Laser ; Materials science ; Range (aeronautics) ; Quantum ; Optoelectronics ; Physics ; Optics ; Chemistry Spectroscopy and Laser Applications ; Terahertz technology and applications ; Atmospheric Ozone and Climate
Authors: N. O. Vambold | G. A. Sazhaev | I. Leonov
Source: arXiv (Cornell University) (preprint, 2023-10-11)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Interplay between electron correlations, magnetic state, and structural confinement in LaNiO3 ultrathin films We report a theoretical study of the effects of electron correlations and structural confinement on the electronic properties and magnetic state of LaNiO3 (LNO) thin films epitaxially deposited on the (001) LaAlO3 (LAO) substrate. Using the DFT+U method we compute the electronic band structure, magnetic properties, and phase stability of the 1.5 unit-cell-thick NiO2-terminated LNO thin films. Our results reveal complex diversity of the electronic states caused by the effects of structural confinement, interfacial charge transfer and electronic correlations. Our calculations suggest the appearance of in-plane (110) charge disproportionation of the Ni ions in the interface NiO2 layer of the antiferromagnetically ordered LNO thin films. Moreover, the electronic states of both the AFM and FM LNO/LAO show a large orbital polarization of the Ni ions in the surface NiO2 layers. We propose the crucial importance of oxygen defects to explain the metal-to-insulator phase transition experimentally observed in a few-unit-cell-thick LNO/LAO thin films. Condensed matter physics ; Materials science ; Thin film ; Electronic structure ; Electron ; Epitaxy ; Nanotechnology ; Layer (electronics) ; Physics Magnetic and transport properties of perovskites and related materials ; Electronic and Structural Properties of Oxides ; Advanced Condensed Matter Physics
Authors: Murilo Henrique Moreira | Fernando Penteado Schmidt | André L.F. Cardoso | Rodolfo Foster Klein-Gunnewiek | V. C. Pandolfelli
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2023-01-02)
Field: Chemistry — Organic Chemistry

Microwave thermogravimetry as a tool to evaluate the drying of refractory castables – The effects of volumetric heating Refractory castables present special features that render them unique and the most appropriate solution for lining specific high-temperature industrial equipment. Hydraulic bonded monolithics develop mechanical strength at room temperatures due to the hydration of some of its constituents, such as calcium aluminate cement. Their most significant drawback is the drying step, which takes place before firing and requires several hours of slow heating rates and plateaus to reduce the likelihood of facing explosive spalling. This phenomenon is a result of water vapor pressurization, as well as thermomechanical stresses. As an alternative to reduce the time and CO<sub>2</sub> generation, microwave heating can be a promising solution as the volumetric nature of the temperature increase can make this process safer. Besides this benefit, the likelihood of using green energy and the higher efficiency of this method add to the potential benefits. The present work analyses the mass loss of refractory castables by proposing a microwave thermogravimetry equipment. The results suggest that water removal occurs at earlier temperatures and, in total, nine-fold less energy consumption estimation Numerical model results showed the distinct thermal gradients and the resulting drying profiles, highlighting the importance of properly controlling the microwave power during drying. Thus, these findings indicate that the microwave process might be a valid strategy for a safer, greener and faster drying of castable refractories. Thermogravimetry ; Refractory (planetary science) ; Materials science ; Microwave heating ; Microwave ; Composite material ; Process engineering ; Chemical engineering ; Computer science ; Engineering Microwave-Assisted Synthesis and Applications ; Materials Engineering and Processing ; Advanced ceramic materials synthesis
Authors: Ф. З. Утяшев | Р. Ю. Сухоруков | А. К. Галимов | Л. В. Гаврилина
Source: Проблемы машиностроения и надежности машин (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

Комбинация сдвиговой и ротационной деформаций – эффективный процесс получения ультрамелкозернистых полуфабрикатов из жаропрочных сплавов Superplastic deformation of ultrafine-grained semifinished products is used in production of turbine engine disks from heat-resistant superalloys based on nickel, iron, and titanium. This technology is based on gatorizing, which is implemented using powerful horizontal hydraulic presses for the manufacture of ultrafine-grained bars and vacuum-forming complexes for the manufacture of discs from bars in an oxidizing-free atmosphere. This article discusses the theoretical and practical prerequisites for the development of an effective deformation for obtaining an ultrafine-grained structure in superalloys. The technological advantages of using combined methods are shown, combining shear and rotational strain components for the formation of an ultrafine-grained structure in large-sized billets. Using the example of upsetting (or tension) with torsion, the stress–strain state of the material and the energy–power parameters of deformation, as well as the design and technological features of the equipment ensuring the refinement of the bars and disks structure, are determined. Environmental science Titanium Alloys Microstructure and Properties