Article
Materials Science, Coatings & Films
Petr Rehak, Jakub Ceska, Miroslav Cerny
Summary: Using a first-principles approach, the effect of oxygen as a substitutional impurity on the cohesion of three transition metal nitride multilayers was investigated. It was found that oxygen prefers to replace nitrogen atoms in interfacial planes and does not reduce the multilayer cohesion. In fact, in the AlN/TiN system, the presence of oxygen was found to increase the cohesion of the interface.
SURFACE & COATINGS TECHNOLOGY
(2023)
Article
Chemistry, Physical
Soulef Jellali, Hela Habli
Summary: This paper focuses on the study of molecules such as francium dimer and a comparative spectroscopic investigation of cationic systems Fr-(Ca+, Sr+, Ba+). Computational methods are used to determine relevant parameters and the accuracy and reliability of the results are discussed. The findings provide insights for future laser cooling applications.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Multidisciplinary
Lede Xian, Ammon Fischer, Martin Claassen, Jin Zhang, Angel Rubio, Dante M. Kennes
Summary: Twisting adjacent layers of van der Waals materials can create flat two-dimensional electronic bands, and this concept can be extended to three spatial dimensions. By applying this approach to various two-dimensional materials like graphitic systems, boron nitride, and WSe2, interesting three-dimensional phases such as quantum magnets and unconventional superconducting states can be induced and controlled.
Article
Chemistry, Physical
Juan J. J. Aucar, Alejandro F. F. Maldonado, Juan I. I. Melo
Summary: In this work, relativistic corrections to the electric field gradient (EFG) are presented, including spin-dependent corrections for the first time. The results show that these new corrections significantly improve the performance of the existing method and are in close agreement with calculations at the four-component Dirac-Hartree-Fock (4c-DHF) level. The accuracy of the EFG values obtained with this new method allows for the analysis of the electronic origin of relativistic effects using well-known nonrelativistic operators.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Jing Shang, Congxin Xia, Chun Tang, Chun Li, Yandong Ma, Yuantong Gu, Liangzhi Kou
Summary: The bending deformation of AgBiP2Se6 monolayers can manipulate the polarization direction and domain size, significantly improving the ferroelectric stability. This mechano-ferroelectric coupling represents a new mechanism for stabilization and polarization flip in 2D ferroelectrics, with potential applications in next-generation non-volatile storage devices.
NANOSCALE HORIZONS
(2021)
Article
Materials Science, Multidisciplinary
Vladimir A. Chernyshev, Calin N. Avram
Summary: In this paper, the structural properties of cubic impurity centers RE3+/RE2+ in fluorite crystals MeF2 were simulated using the ab initio route. The distortions of the crystal lattice near the impurity center were determined by doping with rare-earth ions, and the radial and angular displacements of anions were investigated. The study utilized the MO LCAO approach within the DFT method and compared the results with experimental data, showing satisfactory agreement.
Article
Chemistry, Physical
Alexander V. Bakulin, Alexey S. Kulkov, Svetlana E. Kulkova
Summary: The projector augmented-wave method based on electron density functional theory is used to calculate the absorption energy and migration barriers of hydrogen in doped B2-TiFe. An analytical expression for the temperature-dependent diffusion coefficients of hydrogen in the doped alloy is derived using Landman's method. An approach to estimate the average jump rates of hydrogen for calculating the diffusion coefficient in doped alloys is developed. The effect of impurities on hydrogen diffusion in the alloy is discussed.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Petr Rehak, Monika Vsianska, Miroslav Cerny
Summary: In this paper, the segregation of six sp-impurities to the Sigma 5(310)[001] grain boundary in bcc iron is studied from first principles. It is found that while the vibrational contribution to the crystal energy can be relatively high in some cases, the segregation preference of Al, Ga, In, Sn, Sb, and Te remains constant with increasing temperature. Additionally, the presence of segregated impurity atoms is predicted to reduce the grain boundary cohesion based on calculations of the cleavage energy.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Chemistry, Applied
Thibault Pariat, Pauline M. Verite, Denis Jacquemin, Julien Massue, Gilles Ulrich
Summary: A dual-emissive fluorophore, HBBODipic, with an Excited-State Intramolecular Proton Transfer (ESIPT) process has been described. It has been used for generating panchromatic white-emission and ratiometric detection of substrates.
Article
Chemistry, Physical
Andres Restrepo-Acevedo, Nicolas Osorio, Luis E. Giraldo-Lopez, Richard F. D'Vries, Susana Zacchino, Rodrigo Abonia, Ronan Le Lagadec, Fernando Cuenu-Cabezas
Summary: In this study, three new pyrazole-based azomethine isomers were synthesized using environmentally friendly techniques. The addition of a nitrophenyl group on the pyrazole moiety was found to tune the band gap energy and reactivity, leading to increased antifungal activity against C. albicans for the compound bearing the 2-nitrophenyl substituent. Molecular docking simulations also confirmed the strong binding affinity of the most active compound with a model protein.
JOURNAL OF MOLECULAR STRUCTURE
(2022)
Article
Physics, Applied
Shukai Yao, Babak Anasori, Alejandro Strachan
Summary: 2D rare-earth metal carbides (MXenes) with novel electronic and magnetic properties and potential as scalable 2D magnets were investigated. The effect of the U parameter on the stability and magnetism of different termination sites was studied. It was found that Mo2NdC2O2 and Mo2NdC2(OH)(2) exhibited magnetic properties regardless of termination and Hubbard U value.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Xue Dong, Yu-qian Liu, Xin-bo Liu, Sudip Pan, Zhong-hua Cui, Gabriel Merino
Summary: A new class of beryllium-boron clusters called beryllo-borospherenes are theoretically described in this paper. The addition of beryllium to the B-12 motif leads to significant structural modifications. Beryllium atoms form strong bonds with boron clusters through strong electrostatic and covalent interactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Maria Drosou, Dimitrios A. Pantazis
Summary: The debate over the electronic and geometric structures of the water-oxidizing complex of photosystem II before dioxygen evolution is ongoing. Recent studies have presented contradictory redox formulations for the Mn4CaOx cofactor in the S-3 state, leading to uncertainty about the O-O bond formation in the catalytic cycle. By employing advanced theoretical calculations, researchers were able to evaluate different models for the S-3 state of the oxygen-evolving complex and assess the accuracy of lower-level theoretical approaches.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Enrique M. Arpa, Ines Corral
Summary: Unconjugated pterins are widely present and have various enzymatic functions, potentially participating in singlet oxygen, amino acid, and nucleotide photosensitization. Under UV-A light excitation, some of these pterins degrade, leading to hydrogen peroxide production. This process, occurring in vivo, contributes to oxidative stress and melanocyte destruction in vitiligo. Our study provides mechanistic insights into the formation of transient triplet species that trigger Type I and Type II photosensitizing processes and degradation. Through calculations, we demonstrate that 6-biopterin degradation in vitiligo patients' skin produces 6-formylpterin and subsequently 6-carboxypterin. The changes in photosensitizing potential with pH are attributed to modulation of excited-state redox potentials.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Jacek Piechota, Stanislaw Krukowski, Petro Sadovyi, Bohdan Sadovyi, Sylwester Porowski, Izabella Grzegory
Summary: The study investigated the dissolution of molecular nitrogen in liquid gallium and iron through ab initio calculations and experiments, revealing fundamental differences in N bonding between the two solvents. It was found that the nitrogen solubility in iron is much higher than in gallium, indicating that liquid iron may be a prospective solvent for gallium nitride crystallization from metallic solutions.
Article
Chemistry, Multidisciplinary
Chuanxu Ma, Zhongcan Xiao, Alexander A. Puretzky, Hao Wang, Ali Mohsin, Jingsong Huang, Liangbo Liang, Yingdong Luo, Benjamin J. Lawrie, Gong Gu, Wenchang Lu, Kunlun Hong, Jerzy Bernholc, An-Ping Li
Article
Chemistry, Physical
Chenyi Zhou, Wenhan Xu, Bing Zhang, Yunhe Zhang, Chen Shen, Qinfei Xu, Xin Liu, Florian Bertram, Jerzy Bernholc, Zhenhua Jiang, Yingshuang Shang, Haibo Zhang
Summary: Researchers have demonstrated a polymer with high energy density discharge performance, which can achieve excellent capacitance performance at higher temperatures. The unique structure of this polymer, characterized by curled and densely packed chains, can be produced using existing industrial processes and is suitable for large-scale applications.
CHEMISTRY OF MATERIALS
(2022)
Article
Multidisciplinary Sciences
Xiaoshi Qian, Donglin Han, Lirong Zheng, Jie Chen, Madhusudan Tyagi, Qiang Li, Feihong Du, Shanyu Zheng, Xingyi Huang, Shihai Zhang, Junye Shi, Houbing Huang, Xiaoming Shi, Jiangping Chen, Hancheng Qin, Jerzy Bernholc, Xin Chen, Long-Qing Chen, Liang Hong, Q. M. Zhang
Summary: A new class of EC polymer has been developed, showing significantly enhanced performance under lower electric fields compared to state-of-the-art materials. This improvement is achieved by increasing the number of polar entities in the polymer through the conversion of a small number of chlorofluoroethylene groups into covalent double bonds. The polymer displays high-entropy polar phases with low energy barrier for electric-field-induced switching, maintaining performance for over one million cycles at low fields suitable for practical EC cooling applications.
Article
Physics, Applied
Hancheng Qin, Wenchang Lu, J. Bernholc
Summary: The precise atomic structure of metal contacts plays a significant role in the performance of nanoscale electronic devices. Researchers used a DFT-based method to evaluate different metal contacts with graphene or graphene nanoribbons, finding that surface metal contacts unbound to graphene had lower resistance with titanium (Ti) contacts compared to gold (Au), calcium (Ca), iridium (Ir), platinum (Pt), and strontium (Sr). However, as an edge contact, titanium had higher resistance than gold. Additionally, bridging oxygen atoms at the titanium and gold edge contacts reduced transmission by over 30%.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Xin Chen, Hancheng Qin, Xiaoshi Qian, Wenyi Zhu, Bo Li, Bing Zhang, Wenchang Lu, Ruipeng Li, Shihai Zhang, Lei Zhu, Fabrice Domingues Dos Santos, J. Bernholc, Q. M. Zhang
Summary: Introducing a small amount of fluorinated alkyne monomers enhances the polarization change in ferroelectric polymers, leading to a strong electromechanical coupling effect.
Article
Polymer Science
Xin Chen, Hancheng Qin, Wenyi Zhu, Bing Zhang, Wenchang Lu, J. Bernholc, Q. M. Zhang
Summary: Recently, it was discovered that converting chlorofluoroethylene (CFE) into fluorinated alkyne (FA) in P(VDF-TrFE-CFE) polymeric materials can result in P(VDF-TrFE-CFE-FA) tetrapolymers with exceptional electromechanical response at ultralow electric fields. This effect is attributed to the conversion of bulky CFE into small-size FA defects, which weakens the relaxor behavior and allows for a diffused critical endpoint transition region. The near 2 mol % FA content in the tetrapolymers enables a small change in the electric field to induce a large electroactuation, presenting new opportunities for novel applications.
Article
Physics, Applied
Xin Chen, Hancheng Qin, Yang Liu, Yen-Ting Lin, Bing Zhang, Wenchang Lu, Seong H. H. Kim, J. Bernholc, Qing Wang, Q. M. Zhang
Summary: The origin of dielectric constant enhancement in high-temperature polymer dilute nanocomposites is investigated. Trace nanofiller loadings can greatly enhance the dielectric constant without affecting breakdown strength and dielectric loss. The interface regions between the polymers and trace nanofillers play a crucial role in the observed enhancement.
APPLIED PHYSICS LETTERS
(2023)
Article
Polymer Science
Zhubing Han, Hancheng Qin, Xin Chen, Wenhan Xu, Yang Liu, J. Bernholc, Qing Wang
Summary: The incorporation of comonomers in PVDF-based ferroelectric polymers has been widely used to modify their structures and properties. Previous studies have shown that large-sized comonomers can induce relaxor ferroelectricity, but this study demonstrates that a small-sized comonomer can preferentially adopt a polar all-trans conformation, resulting in terpolymers with robust ferroelectricity and enhanced transition temperature and coercive field. This work systematically investigates the effects of comonomer size on the microstructures and properties of ferroelectric polymers.
Article
Chemistry, Physical
Yang Liu, Yao Zhou, Hancheng Qin, Tiannan Yang, Xin Chen, Li Li, Zhubing Han, Ke Wang, Bing Zhang, Wenchang Lu, Long-Qing Chen, J. Bernholc, Qing Wang
Summary: This article introduces a composite material of poly(vinylidene fluoride) and TiO2, which exhibits superior performance in terms of piezoelectric activity and mechanical energy density driven by Joule heating. The interconversion between electrical and mechanical energies is crucial for ferroelectric materials to be used in transducers, actuators, and sensors. The composite material demonstrates a strain over 8% and an output mechanical energy density of 11.3 J cm(-3) at an electric field of 40 MV m(-1), outperforming conventional ferroelectric ceramics and crystals.
Article
Materials Science, Multidisciplinary
Felix Lupke, Anh D. Pham, Yi-Fan Zhao, Ling-Jie Zhou, Wenchang Lu, Emil Briggs, Jerzy Bernholc, Marek Kolmer, Jacob Teeter, Wonhee Ko, Cui-Zu Chang, Panchapakesan Ganesh, An-Ping Li
Summary: The study investigates the local signatures of thickness-dependent topology in MnBi2Te4 thin films using scanning tunneling microscopy and spectroscopy. Theoretical calculations reveal a topological quantum phase transition beyond a film thickness of one monolayer, with alternating quantum anomalous Hall effect and axion insulating states, and localized electronic states at step edges.
Article
Chemistry, Multidisciplinary
Chuanxu Ma, Zhongcan Xiao, Peter Bonnesen, Liangbo Liang, Alexander A. Puretzky, Jingsong Huang, Marek Kolmer, Bobby G. Sumpter, Wenchang Lu, Kunlun Hong, Jerzy Bernholc, An-Ping Li
Summary: This study investigates the cyclodehydrogenation reaction mechanism in the on-surface synthesis of graphene nanoribbons using isotopic labeling. A reaction pathway involving conrotatory electrocyclization and a [1,9]-sigmatropic D shift, followed by H/D eliminations, is identified and substantiated by experiments and simulations. The research not only helps clarify the reaction process in GNR synthesis, but also presents a rational strategy for designing precise hydrogen/deuterium isotope labeling patterns in on-surface reactions.
Article
Materials Science, Multidisciplinary
Qiyan Zhang, Xin Chen, Bing Zhang, Tian Zhang, Wengchang Lu, Zhe Chen, Ziyu Liu, Seong H. Kim, Brian Donovan, Ronald J. Warzoha, Enrique D. Gomez, J. Bernholc, Q. M. Zhang
Summary: This research demonstrates a strategy to reduce weak points in polymers by utilizing interchain electrostatic forces in polymer blends, leading to significant enhancements in dielectric breakdown strength.
Article
Chemistry, Multidisciplinary
Bing Zhang, Xin Chen, Wenchang Lu, Q. M. Zhang, J. Bernholc
Summary: The weakening of hydrogen bonds between nanoparticles and polymer chains reduces the dielectric enhancement in the composite material. Multiscale simulations showed that the attachment of solvated highly dipolar polymers to oxide nanoparticles results in deposition of nanoparticle-polymer blobs during solution casting. The increased free volume in the nanocomposite enables easier reorientation of monomer dipoles with an applied electric field, leading to a higher dielectric permittivity.
Article
Chemistry, Inorganic & Nuclear
Jiayong Zhang, Yongqiang Cheng, Alexander I. Kolesnikov, Jerry Bernholc, Wenchang Lu, Anibal J. Ramirez-Cuesta
Summary: The anharmonic phonon behavior in zirconium hydrides and deuterides has been investigated using inelastic neutron scattering and lattice dynamics calculations within the framework of density functional theory. The study found that anharmonicity in these materials originates from deviations of hydrogen potentials from quadratic behavior in certain directions and is apparent for higher-order excited vibrational states. Convolution of the eigenfrequencies with the instrument resolution qualitatively describes the anharmonic peaks in the experimental data.
Article
Materials Science, Multidisciplinary
A. Lusakowski, P. Boguslawski, T. Story
Summary: This study found that incorporating Mn into Pb1-xSnxTe alloy can shift the topological phases towards higher Sn contents, inducing perturbations in band energies and widening the Weyl region when the Mn spin polarization is finite. The research also proposed a new method to calculate topological indices for systems with finite spin polarization, based on the concept of the Chern number, to identify the distinct topological phases of the alloy.