The thermal conductance across the one-dimensional (1D) interface between a MoS2 monolayer and Au electrode (edge-contact) has been investigated using molecular dynamics simulations.Although the thermal conductivity of monolayer MoS2 is 2-3 orders of magnitude lower than that of graphene,the covalent bonds formed at the interface enable interfacial thermal conductance (ITC) that is comparable to that of a graphene-metal interface.Each covalent bond at the interface serves as an independent channel for thermal conduction,allowing ITC to be tuned linearly by changing the interfacial bond density (controlling S vacandes).In addition,different Au surfaces form different bonding configurations,causing large ITC variations.Interestingly,the S vacancies in the central region of MoS2 only slightly affect the ITC,which can be explained by a mismatch of the phonon vibration spectra.Further,at room temperature,ITC is primarily dominated by phonon transport,and electron-phonon coupling plays a negligible role.These results not only shed light on the phonon transport mechanisms across 1D metal-MoS2 interfaces,but also provide guidelines for the design and optimization of such interfaces for thermal management in MoS2-based electronicdevices. 相似文献
Heterojunction interfaces in perovskite solar cells play an important role in enhancing their photoelectric properties and stability.Till date,the precise lattice arrangement at TiO2/CH3NH3PbI3 heterojunction interfaces has not been investigated clearly.Here,we examined a TiO2/CH3NH3PbI3 interface and found that a heavy atomic layer exists in such interfaces,which is attributed to the vacancies of methylammonium (MA) cation groups.Further,first-principles calculation results suggested that an MA cation-deficient surface structure is beneficial for a strong heterogeneous binding between TiO2 and CH3NH3PbI3 to enhance the interface stability.Our research is helpful for further understanding the detailed interface atom arrangements and provides references for interfacial modification in perovskite solar cells. 相似文献
Recently,the eutectic high-entropy alloy(EHEA),AlCoCrFeNi2.1,can reach a good balance of strength and ductility.The dual-phase alloy exhibits a eutectic lamellar microstructure with large numbers of interfaces.However,the role of the interfaces in plastic deformation have not been revealed deeply.In the present work,the orientation relationship(OR)of the interfaces has been clarified as the Kurdjumov-Sachs(KS)interfaces presenting〈111〉B2 〈110〉FCCand {110} B2{111}FCC independent of their morphologies.There exist three kinds of interfaces in the EHEA,namely,The dominating interface and the secondary interface are both non-slip planes and atomistic-scale faceted,facilitating the nucleation and slip transmission of the dislocations.The formation mechanism of the preferred interfaces is revealed using the atomistic geometrical analysis according to the criteria of the low interfacial energy based on the coincidence-site lattice(CSL)theory.In particular,the ductility of the dual-phase alloy originates from the KS interface-induced slip continuity across interfaces,which provides a high slip-transfer geometric factor.Moreover,the strengthening effect can be attributed to the interface resistance for the dislocation transmission due to the mismatches of the moduli and lattice parameters at the interfaces. 相似文献
In general,packaging materials which encapsulate light emitting diodes(LEDs)and microelectronic devices offer barrier protection against several environmental hazards such as water and ionic contaminants.However,these encapsulants may provide pathways for water and ionic contaminants to reach the metal/polymer interfaces and provoke local corrosion of electronics,which is a major reliability concern for polymer encapsulated LEDs and microelectronics.As the water and corrosive constituents play a crucial role in their reliability,water uptake kinetics,interfacial ion transport and delamination behaviour of silicone coated copper model system,mimicking a typical microelectronics packaging system,is explored in the present work.Electrochemical impedance spectroscopy(EIS)integrated with attenuated total reflection Fourier transform infrared(ATR-FTIR)spectroscopy studies revealed that water diffusion inside the silicone network is Fickian in nature and the evolution of the observed time constants are related to the diffusion and interfacial reactions.A decrease of impedance magnitude with time was observed in EIS measurements concurrently with water absorption bands shifting towards lower wavenumber in ATR-FTIR measurements,implying the growth of strong hydrogen bonding between water molecules and the silicone network.The estimated diffusion constant of water using the capacitance method was in the order of 7×10-12m2s-1and the water absorption volume fraction was in the range of 0%to 0.30%.Scanning Kelvin probe studies elucidated the ion transport process occurring at the silicone/copper interface in a humid atmosphere.The interfacial ion transport process is controlled by the interfacial electrochemical reactions at the cathodic delamination front and the estimated average delamination rate is 0.43 mm h-1/2.This work demonstrates that exploring ion and water transport in the silicone coating and along the silicone/copper interface is of pivotal importance as part of a detailed reliability assessment of the polymer encapsulated LEDs and microelectronics. 相似文献
Understanding the interface between strengthening precipitates and matrix in alloys, especially at the atomic level, is a critical issue for tailoring the precipitate strengthening to achieve desired mechanical properties. Using high-resolution scanning transmission electron microscopy, we here clarify the semicoherent interfaces between the matrix and long-period stacking ordered(LPSO) phases, including 18 R and 14 H, in Mg–Zn–Y alloys. The LPSO/Mg interface features the unique configuration of the Shockley partial dislocations, which produces a near zero macroscopic strain because the net Burgers vectors equal zero. The 18 R/Mg interface characterizes a dissociated structure that can be described as a narrow slab of 54 R. There are two dislocation arrays accompanied to the 18 R/54 R and 54 R/Mg interface, resulting a slight deviation(about 2.3°). The 14 R/Mg interface exhibits the dislocation pairs associated with solute atoms. We further evaluate the stability and morphology of the corresponding interfaces based on elastic interaction, via calculating the mutual strong interactions between dislocation arrays, as well as that between the dislocations and solute atoms. The synchronized migration of interfacial dislocations and solute atoms, like move-drag behavior, dominates the lateral growth of LPSO phases in Mg alloys. 相似文献
Cell attachment and spreading on Ti-based alloy surfaces is a major parameter in implant technology. Ti-39Nb-13Ta-4.6Zr alloy is a new β type Ti alloy developed for biomedical application. This alloy has low modulus and high strength, which indicates that it can be used for medical purposes such as surgical implants. To evaluate the biocompatibility and effects of the surface morphology of Ti-39Nb-13Ta-4.6Zr on the cellular behaviour, the adhesion and proliferation of rat gingival fibroblasts were studied with substrates having different surface roughness and the results were also compared with commercial pure titanium and Ti-6Al-4V. The results indicate that fibroblast shows similar adhesion and proliferation on the smooth surfaces of commercial pure titanium (Cp Ti), Ti-39Nb-13Ta-4.6Zr, and Ti-6Al-4V, suggesting that Ti-39Nb-13Ta-4.6Zr has similar biocompatibility to Cp Ti and Ti-6Al-4V. The fibroblast adhesion and spreading was lower on rough surfaces of Cp Ti, Ti-39Nb-13Ta-4.6Zr and Ti-6Al-4V than on smooth ones. Surface roughness appeared to be a dominant factor that determines the fibroblast adhesion and proliferation. 相似文献
By studying a cluster model containing Ni region (phase), NiaAI region (phase) and Ni/Ni3Al region (interface) with a first-principles method, the occupation behavior and the ductility effect of zirconium in a Ni-Ni3Al system were investigated. It is found that zirconium has a stronger segregation tendency to Ni region than to Ni3Al region. The bond order analyses based on Rice-Wang model and the maximum theoretical shear stress model, however, show that zirconium has different degrees of ductility effect in these three regions, which originates from its different ability to increase the Griffith work of interracial cleavage 2γint and to decrease the maximum theoretical shear stress τmax. In addition, it is revealed in this paper that the distinct behavior of zirconium from boron to restrain hydrogen-induced embrittlement can be attributed to their different influences on the crystalline and electronic structures in Ni-Ni3Al alloys. 相似文献
The results of molecular dynamics calculations on the interfacial energies and atomic structures of Ag/Ni and Cu/Ni interfaces are presented. Calculation on Ag/Ni interfaces with low-index planes shows that those containing the (111) plane have the lowest energies, which is in agreement with the experiments. Comparing surface energy with interfacial energy, it is found the order of the interfacial energies of Ag/Ni and Cu/Ni containing the planes fall in the same order as solid-vapor surface energies of Ag, Cu and Ni. In this MD simulation, the relaxed atomic structure and dislocation network of (110)Ag||(110)Ni interface are coincident to HREM observations. 相似文献
The structure of α-Fe metal magnetic recording particles coated with silane coupling agents have been studied by TEM, FT-IR, EXAFS, Mossbauer. The results show that a close, uniform, firm and ultra thin layer, which is beneficial to the magnetic and chemical stability, has been formed by the cross-linked chemical bond Si-O-Si. And the organic molecule has chemically bonded to the particle surface, which has greatly affected the surface Fe atom electronic structure. Furthermore, the covalent bond between metal particle surface and organic molecule has obvious effect on the near edge structure of the surface Fe atoms. 相似文献
Although half-Heusler compounds are quite promising for thermoelectric power generation, there is only limited research on the interfacial structure between metal electrode and half-Heusler compounds for device applications. This work reports on the characteristics of Nb_(0.8)Ti_(0.2)Fe Sb/Ti junction and its evolution behavior during 973 K. The Nb_(0.8)Ti_(0.2)Fe Sb/Ti interface consists of one Ti_(0.9)Fe_(0.1) layer and one Fe-poor layer.There is an Ohmic contact and a low contact resistivity(0.15■ cm~(-2)) in this junction, on account of the matching of working functions between Nb_(0.8)Ti_(0.2)Fe Sb and Ti_(0.9)Fe_(0.1) interlayer. The high doping of Ti high carrier concentration in Nb Fe Sb matrix leads to a high carrier concentration, which results in inducing a large tunneling current at this interface. After aging treatment at 973 K, the Fe-poor layer and the Ti0.9 Fe0.1 layer continues to expand, resulting in the increase of the thickness of the interfacial layer and the contact resistivity. The interfacial electrical is only 1.9■cm~(-2) after 25 days' aging. The thickness of the interface layer has a good linear relation with the square root of aging time, which firmly indicates that the growth of the layer is determined by mutual diffusion of Fe and Ti atoms across the interface. The low contract resistivity and long-time thermal stability demonstrate the great potential of Nb_(0.8)Ti_(0.2)Fe Sb/Ti thermoelectric junction in high efficiency half-Heusler TE devices. 相似文献
First-principles calculations were performed to study the adhesion and the interfacial electronic structure of aluminum/molybdenum semi-boride (Al/Mo2B) interface. The work of adhesion (Wad) was calculated for both terminations of the Mo2B surface and it was found that Mo-terminated has larger Wad than the B-terminated one. It was shown that interfacial Al and B atoms form polar covalent bonds, while bonding of interfacial Al and Mo atoms mainly presents metallic character. 相似文献
We demonstrate that the atomic structures, electronic states, and bonding nature of the interface between SrTiO3 substrate and anatase TiO2 thin films could be related and technologically manipulated at the atomic level. Applying advanced transmission electron
microscopy, the grown anatase TiO2 thin films are found to make a clean and direct contact to the SrTiO3 substrates in an epitaxial, coherent, and atomically abrupt way. The atomic-resolution microscopic images reveal that the
interface comprises SrO-terminated SrTiO3 and Ti-terminated TiO2 with the interfacial Ti of TiO2 sitting above the hollow site, which is confirmed theoretically to be the most energetically favorable. Quantitatively, the
first-principles calculations predict that the oxygen sublattice at the interface undergoes a notable reconstruction, i.e.,
the interfacial O atoms of TiO2 are displaced largely toward the SrO plane of the SrTiO3, flattening the originally zigzag TiO2 atomic chains. Consequently, the interfacial layers suffer a remarkable modification in the charge accumulation and also
a deviation in the density of states from their bulk counterparts, indicating that the substrate can have an impact on the
deposited thin films electronically. Using several analytic methods, the SrTiO3/TiO2 interface is found to take on a metallic nature, and the interfacial bonding is determined to be of a mixed covalent and
ionic character. This combined experimental and theoretical investigation gains insight into the complex atomic and electronic
structures of the buried interface, which are fundamental for relating the atomic-scale structures to their properties on
a quantum level. 相似文献
The mechanism for the adhesion of polyacrylic acid (PAA) coatings to oxidized metal surfaces has been studied. The work entailed studies of the mechanical and chemical interactions occurring at the interfaces between PAA polyelectrolyte macromolecules and iron (III) orthophosphate dihydrate or zinc phosphate hydrate (hopeite) crystalline films that were deposited on the metal surfaces. With respect to mechanical interactions, it was determined that the surface topography of the highly crystallized hopeite layers consisted of an open microstructure. This resulted in enhanced wettability of the oxide film by the polyelectrolyte macromolecules, thereby increasing the mechanical interlocking bond forces. Studies of the interfacial chemical reactions indicated that the conformation changes in the PAA macromolecules relate directly to the frequency of the magnitude of acid-base and divalent metallic ion crosslinking interactions between the proton-donating pendent COOH groups in PAA molecules and polar OH groups at hydrated oxide surface sites. Namely, the presence of numerous free nucleophilic ions existing on the deposited oxide film leads to a substantial increase in the coil-up and entanglement macromolecule density. These entangled complex macromolecules at the interfaces result in a decrease in the degree of chemisorption at the oxide film surfaces, whereas regularly oriented COOH groups produce strong interfacial chemisorption with the polar OH groups. Since the polyelectrolyte macromolecules have hydrophilic pendent COOH groups, the polymer structure which appears best for use as an adhesive and coating should have only enough hydrophilic COOH groups to occupy all available polar OH groups at the oxide metal surface sites. 相似文献
Recent studies have indicated that two-dimensional (2D) MoS2 exhibits low in-plane and inter-plane thermal conductivities. This poses a significant challenge to heat management in MoS2-based electronic devices. To address this challenge, we have designed MoS2-graphene interfaces that fully utilize graphene, a 2D material that exhibits very high thermal conductivity. First, we performed ab initio atomistic simulations to understand bonding and structural stability at the interfaces. The interfaces that we designed, which were connected via strong covalent bonds between Mo and C atoms, were energetically stable. We then performed molecular dynamics simulations to investigate interfacial thermal conductance in these materials. Surprisingly, the interfacial thermal conductance was high and comparable to those of covalently bonded graphene-metal interfaces. Importantly, each interfacial Mo–C bond served as an independent thermal channel, enabling modulation of the interfacial thermal conductance by controlling the Mo vacancy concentration at the interface. The present work provides a viable heat management strategy for MoS2-based electronic devices.
Emerging next-generation soft electronics will require versatile properties functioning under mechanical compliance, which will involve the use of different types of materials. As a result, control over material interfaces (particularly soft/hard interfaces) has become crucial and is now attracting intensive worldwide research efforts. A series of material and structural interface designs has been devised to improve interfacial adhesion, preventing failure of electromechanical properties under mechanical deformation. Herein, different soft/hard interface design strategies at multiple length scales in the context of flexible hybrid electronics are reviewed. The crucial role of soft ligands and/or polymers in controlling the morphologies of active nanomaterials and stabilizing them is discussed, with a focus on understanding the soft/hard interface at the atomic/molecular scale. Larger nanoscopic and microscopic levels are also discussed, to scrutinize viable intrinsic and extrinsic interfacial designs with the purpose of promoting adhesion, stretchability, and durability. Furthermore, the macroscopic device/human interface as it relates to real-world applications is analyzed. Finally, a perspective on the current challenges and future opportunities in the development of truly seamlessly integrated soft wearable electronic systems is presented. 相似文献