Article
Chemistry, Multidisciplinary
Ekaterina Selezneva, Alexandre Vercouter, Guillaume Schweicher, Vincent Lemaur, Katharina Broch, Aleandro Antidormi, Kazuo Takimiya, Veaceslav Coropceanu, Jean-Luc Bredas, Claudio Melis, Jerome Cornil, Henning Sirringhaus
Summary: The study investigates the lattice thermal conductivity in polycrystalline thin films of Cn-DNTT-Cn semiconductors and finds that thermal conductivity is more isotropic than charge transport, with long terminal alkyl chains significantly reducing in-plane thermal conductivity. Vibrational mode analysis reveals strong localization of intermolecular vibrational modes in C8-DNTT-C8.
ADVANCED MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Lin Yang, Yi Tao, Yanglin Zhu, Manira Akter, Ke Wang, Zhiliang Pan, Yang Zhao, Qian Zhang, Ya-Qiong Xu, Renkun Chen, Terry T. Xu, Yunfei Chen, Zhiqiang Mao, Deyu Li
Summary: This study observed length-dependent thermal conductivity in ultrathin van der Waals crystal NbSe3 nanowires, providing experimental evidence for superdiffusive phonon transport. Contrary to the classical size effect due to phonon-boundary scattering, the observed thermal conductivity showed an enhancement as the characteristic size of the nanowires decreased.
NATURE NANOTECHNOLOGY
(2021)
Article
Physics, Applied
Yirui Lu, Lei Yan, Shafqat Hussain, Mengtao Sun, Zhenglong Zhang, Hairong Zheng
Summary: Tip enhanced Raman spectra of AB-stacked bilayer graphene and twisted bilayer graphene nanofragments have been studied. A unique Raman band G(r)(+) is observed and can be tuned by the twisted angle.
APPLIED PHYSICS LETTERS
(2022)
Article
Polymer Science
Weixuan Wang, Wei Zhou, Hengyi Shi, Dongyi He, Yunsong Pang, Xiaoliang Zeng, Chuanchang Li
Summary: The rapid development of electronic devices has led to higher requirements for thermal interface materials in terms of thermal conductivity, softness, and stability. However, achieving softness, stability, and thermal conductivity simultaneously is still challenging. In this study, a strategy of introducing free-movable polymer chains was proposed to prepare thermally conductive gels with high thermal conductivity, good softness, and increased stretchability. The high thermal conductivity was attributed to the addition of microscale spherical Aluminum, while the good softness was due to the free-movable poly (ethylene propylene diene) that reduced the interaction between polymer networks. The thermally conductive gels showed excellent heat-dissipation ability and thermal stability after 1000 heating-cooling cycles, demonstrating their potential applications in the thermal management of electronic devices.
Article
Chemistry, Physical
Haina Wang, Frank H. Stillinger, Salvatore Torquato
Summary: The Zhang-Torquato conjecture states that any realizable set of pair statistics, whether from a nonequilibrium or equilibrium system, can be achieved by equilibrium systems involving up to two-body interactions. The study shows that the unit-step function g(2) can be easily realized within a certain range of densities. For higher dimensions, the maximum terminal packing fraction can be achieved, and the large-r behaviors of the effective potentials are given by approximate expressions based on known conditions. These findings are important for the design of novel nanoparticle systems with density-dependent effective potentials, including exotic hyperuniform states of matter.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Nathalia L. Costa, Keshav Sharma, Yoong Ahm Kim, Go Bong Choi, Morinobu Endo, Newton M. Barbosa Neto, Alexandre R. Paschoal, Paulo T. Araujo
Summary: The temperature dependence of the Raman C-band frequency of linear carbon chains can be used to evaluate their thermal properties within the Debye formalism, providing universal relations for quantities such as internal energy, heat capacity, coefficient of thermal expansion, thermal strain, and Gruneisen parameter in terms of the number of carbon atoms and temperature.
PHYSICAL REVIEW LETTERS
(2021)
Article
Thermodynamics
H. L. Shi, M. R. Song, J. Yang, Q. Z. Han, Y. H. Ren, Z. T. Jiang
Summary: This study investigates the thermal conductivity and interfacial thermal conductivity of complex graphene nanoribbons with various parameters and temperatures. The results show that interfacial thermal conductivity is fundamentally important for heat transport performance, with certain factors affecting the thermal and interfacial conductivity differently. Placing polyethylene molecules at the interfaces can enhance the interfacial thermal conductivity.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Materials Science, Composites
Yongdong Wu, Chenxu Zhang, Wendian Tu, Guoping Du, Xiaoliang Zeng, Rong Sun, Yonglun Xu, Linlin Ren
Summary: A decoupling strategy is proposed to fabricate a thermal interface material with high thermal conductivity and excellent compliance by introducing pendent chains into polymer networks. The compliance of the material is improved with the increasing content of pendent chains. The resulting sample shows potential application in chip cooling and reduces temperature by almost 24 degrees C compared to commercial TIMs. Our work presents a promising way for thermal interface materials design with high thermal conductivity and excellent compliance.
COMPOSITES COMMUNICATIONS
(2023)
Letter
Materials Science, Multidisciplinary
Guangxin Lv, Elynn Jensen, Christopher M. Evans, David G. Cahill
Summary: Polymer materials with enhanced thermal conductivity are highly sought after for thermal management of electronic devices. This study successfully developed epoxy resins with a thermal conductivity of 0.52 W/(m K), which is 2.5 times higher than common polymers. It was found that the thermal conductivity and density of these epoxy resins have a positive correlation with crystallinity.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Ivy Maria, Raagya Arora, Moinak Dutta, Subhajit Roychowdhury, Umesh V. Waghmare, Kanishka Biswas
Summary: In this study, the researchers investigated the intrinsic lattice shearing in TlBiSe2 induced by dual 6s2 lone pairs, and found that the structure shuttles between different energetically accessible low-symmetry structures, which strongly suppresses the lattice thermal conductivity. By utilizing metavalent bonding and cooperative movement of the constituent atoms, a low thermal conductivity and a high thermoelectric performance were achieved in TlBiSeS.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Joakim Brorsson, Arsalan Hashemi, Zheyong Fan, Erik Fransson, Fredrik Eriksson, Tapio Ala-Nissila, Arkady Krasheninnikov, Hannu-Pekka Komsa, Paul Erhart
Summary: High-order force constant expansions, combined with GPU-accelerated molecular dynamics simulations, provide an accurate, transferable, and efficient approach for sampling the dynamical properties of materials.
ADVANCED THEORY AND SIMULATIONS
(2022)
Article
Polymer Science
Haoting Zheng, Kun Wu, Yingjie Zhan, Kunxin Wang, Jun Shi
Summary: A series of PVA composite films incorporating different hydrogen bond acceptors were prepared and their thermal properties were investigated. The results showed that the addition of these acceptors significantly enhanced the in-plane thermal conductivity of the films due to the strong intermolecular interaction. FT-IR and WXAD analysis confirmed the role of a particular acceptor, TBB, as a thermal bridge, promoting regular internal structure formation. Mechanical testing and molecular dynamics simulations further supported the findings and revealed that strong intermolecular interactions effectively restricted molecular chain activity and reduced free volume, leading to improved thermal conductivity.
JOURNAL OF POLYMER SCIENCE
(2023)
Article
Chemistry, Physical
Natalya A. A. Zimbovskaya, Abraham Nitzan
Summary: In this study, the effect of chain configuration on phonon heat transport in a single polymer chain is analyzed theoretically based on recent molecular dynamic simulations. It is found that when the chain is strongly compressed and tangled, multiple random bends act as scattering centers for vibrational phonon modes, resulting in diffusive heat transport. As the chain straightens up, the number of scatterers decreases and the heat transport becomes more ballistic. A model of a long atomic chain is introduced to simulate the changes in chain configuration, and the phonon thermal conductance exhibits a threshold-like transition from diffusive to ballistic transport as the scatterers are gradually removed.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Polymer Science
Yafei Wang, Zhicheng Chang, Ke Gao, Ziwei Li, Guanyi Hou, Jun Liu, Liqun Zhang
Summary: The study found that MoS2 and BN fillers enhance thermal conductivity with increasing sizes but have different effects on the composites; the introduction of hybrid BN/MoS2 filler effectively reduces voids in the composites and increases thermal conductivity; there exists an optimal loading ratio of the two fillers, reaching the maximum thermal conductivity of the composite.
Article
Engineering, Environmental
Ting Gu, Zhu Zeng, Shuang Wu, De-xiang Sun, Cheng-shou Zhao, Yong Wang
Summary: The blowout growth of microelectronic devices calls for improvement in thermal conductivity and electromagnetic interference (EMI) shielding performance of packaging materials. A scalable production strategy was proposed to prepare PLLA composite films with high thermal conductivity and excellent EMI shielding efficiency. The films showed superior properties compared to conventional PLLA films and have potential applications in large-scale production of green electronic products.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Nanoscience & Nanotechnology
A. Savin, M. A. Mazo
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2020)
Article
Physics, Condensed Matter
A. V. Savin
PHYSICS OF THE SOLID STATE
(2020)
Article
Materials Science, Multidisciplinary
A. V. Savin, Yu. A. Kosevich
Summary: This study models the mechanical conformations and thermal dynamics of graphene-based polymer nanocarpets, showing that they maintain a flat shape on a flat substrate and exhibit resistance to thermal vibrations. The heat capacity of the nanocarpets increases monotonically with temperature, with the most significant growth occurring at T=450K.
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
A. Savin
Summary: The study shows that two OH groups covalently attached to opposite vertices of a hexagon on the graphene sheet form a energetically more advantageous structure, leading to the formation of C-4(OH). The attached oxygen atoms on the outer surface of the graphene sheet form a hexagonal lattice, and the hydroxyl groups can form hydrogen bond chains in various ways.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Alexander Savin
Summary: Research shows that a multilayer packaging of identical single-walled carbon nanotubes with a diameter of over 2.5 nm on a flat substrate is a multistable system, with thickness decreasing as the portion of collapsed nanotubes increases. All stationary states of the package are stable to thermal fluctuations at 300 K.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Acoustics
A. Savin, E. A. Korznikova, S. Dmitriev
Summary: The study investigates the linear and nonlinear dynamic excitations in CNT bundle and reveals the existence of compressive solitons and discrete breathers in the bundle. It also uncovers new channels of energy localization and transport, which are crucial for the use of CNT bundles in various technologies.
JOURNAL OF SOUND AND VIBRATION
(2022)
Article
Chemistry, Physical
Alexander V. Savin, Yuri S. Kivshar
Summary: In this study, molecular dynamics simulations were used to investigate the dynamics of ACN molecules on a flat surface of hexagonal boron nitride. It was found that ACN molecules exhibited chirality and formed stable secondary structures on the substrate. The structure of the hydrogen-bond chains depended on the isomeric composition of the molecules.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Alexander V. Savin
Summary: This study demonstrates using molecular dynamics that the motion of carbon nanoparticles on a thermalized graphene sheet lying on a flat substrate can be described as particles moving in a viscous medium with a constant coefficient of friction. The value of this coefficient depends on the temperature and particle size, and there are two types of effective friction: diffusion and ballistic.
Article
Materials Science, Multidisciplinary
Alexander Savin, Yuri S. Kivshar
Summary: The study of thermal transport in low-dimensional materials, especially graphene, has attracted significant attention recently. In this study, we numerically investigate the phonon transport in low-dimensional carbon structures, focusing on the hydrodynamic regime revealed by the observation of second sound. Our simulations show that accurate modeling of such graphene systems requires semiquantum molecular dynamics simulations to consider the quantum statistics of thermalized phonons. We find that second sound is attributed to the maximum group velocity of bending optical oscillations in carbon structures, and it disappears for temperatures above 200 K, being replaced by diffusive dynamics of thermal waves. Furthermore, our results suggest that second sound has a velocity of about 6 km/s in low-dimensional structures, with stronger hydrodynamic effects observed in carbon nanotubes compared to carbon nanoribbons.
Article
Physics, Fluids & Plasmas
Alexander Savin, Ilsiya R. Sunagatova, Sergey Dmitriev
Summary: The paper analyzes rotorbreathers in a chain of coupled linear elastic rotators and finds that the frequency of angular rotation of rotorbreathers cannot exceed the optical band of the phonon spectrum, but is instead in the spectrum gap. By selecting appropriate initial conditions, the radial oscillations of rotorbreathers can be minimized.
Article
Materials Science, Multidisciplinary
Alexander Savin
Summary: In this study, natural and resonant oscillations of suspended circular graphene membranes were simulated using full-atomic models. The presence of various substrates was found to affect the frequency distribution of membrane vibrations and the pattern of resonant frequencies changing with radius.
Article
Physics, Condensed Matter
A. V. Savin, O. I. Savina
Summary: The stationary states of a single-walled carbon nanotube array on a flat substrate formed by a molecular crystal are investigated, showing that the assembly form of nanotubes is energetically influenced by the interaction with the substrate. Acoustic supersonic solitons are found to exist only in small-diameter nanotubes, while vibrations are confined to end nanotubes or those forming structural defects in the chain.
PHYSICS OF THE SOLID STATE
(2021)
Article
Physics, Multidisciplinary
A. V. Savin, A. P. Klinov
Article
Materials Science, Multidisciplinary
A. Savin, E. A. Korznikova, S. Dmitriev
Article
Physics, Condensed Matter
A. V. Savin, O. I. Savina
PHYSICS OF THE SOLID STATE
(2020)