To compare the thermal properties of heterogeneous and homogeneous interfaces, polycrystalline composites are proposed. Thermal properties of heterogeneous and homogeneous interfaces in the composites are investigated using molecular dynamics simulations. The results indicate that when the inflow of heat arises from the same material, phonon scattering at heterogeneous interfaces is stronger than that at homogeneous interfaces. The phonon wave packet simulations indicate that the stronger phonon scattering at heterogeneous interfaces is caused by the combined actions of transmission coefficients and transmission time.Topics: Composites; Nanostructured materials (Nanosci.); Phonon; Solid-solid interface; Thermal properties; Wave function;

The thermophysical properties of Si/Ge hetero-twinned superlattices (SLs) are investigated by nonequilibrium molecular dynamic simulations. The results indicate that the Si/Ge hetero-twinned SLs show low thermal conductivity, which is similar to that of conventional Si/Ge SLs. Analysis with phonon kinetic theory shows that low thermal conductivity in the Si/Ge hetero-twinned SLs is caused by the combined actions of reduced phonon group velocity and reduced relaxation time. Moreover, despite similar thermal conductivity in Si/Ge hetero-twinned SLs and conventional Si/Ge SLs, the phonon group velocity and relaxation time in the two structures are totally different. Our results demonstrate the potential of a new kind of SLs with strong phonon scattering.

Complex logic gate operations using organic microwires as signal transducers based on electrogenerated chemiluminescence (ECL) intensity as the optical readout signal have been developed by taking advantage of the unique ECL reaction between organic semiconductor 9,10-bis(phenylethynyl)anthracene (BPEA) microwires and small molecules. The BPEA microwires, prepared on cleaned-ITO substrate using a simple physical vapor transport (PVT) method, were subsequently used for construction of the ECL sensors. The developed sensor exhibits high ECL efficiency and excellent stability in the presence of co-reactant tripropylamine. Based on the remarkable detection performance of BPEA MWs/TPrA system, the sensors manifested high sensitive ECL response in a wide linear range with low detection limit for the detection of dopamine, proline or methylene blue, which behaves on the basis of molecule-responsive ECL properties based on different ECL reaction mechanisms. Inspired by this, these sensing systems can be utilized to design OR, XOR and INHIBIT logic gates, which would be used for the determination of dopamine, proline and ethylene blue via logic outputs. Importantly, the individual logic gates can be easily brought together through three-input operations to function as integrated logic gates.

A new cubic three dimensional carbon phase has been predicted by first-principles calculations. This phase is constructed by triangle graphene sheets, and dubbed as sc-C96. The investigation on its electronic properties has indicated that sc-C96 possesses a topological nodal line semimetal state, which protected by the combination of time reversal and spatial inversion symmetries, and negligible spin–orbit interaction. Due to the cubic symmetry, the Fermi surface of sc-C96 is constituted of three nodal line circles. From the cohesive energy and phonon spectra, we find that sc-C96 is dynamically stable and may be easily synthesized by polymerizing C96 fullerene molecules at a relatively low pressure conditions (∼1 GPa).

Owing to the outstanding properties of metallic carbon as well as their great potential applications, design and synthesis of metallic carbon have long attracted considerable attention. In this work, a new three-dimensional metallic carbon (dubbed as Tri-C9) has been built by distorting the sp3 hybridization bond. Our first-principles calculations results indicate that Tri-C9 is a metastable metallic carbon, and that the metallic behavior of Tri-C9 originates from the π bonds near Fermi level. This study offers a new way to design all-sp3 hybridized metallic carbon via distorting the sp3-bond. In addition, a feasible synthesis route for Tri-C9 has been proposed by compressing graphite.

Based on the atomic cluster structures and free electron approximation model, it is revealed that the electrochemical potential (ECP) for the system of interest is proportional to the reciprocal of atomic cluster radius squared, i.e., φ = k·(1/r2). Applied to elemental crystals, the correlation between atomic cluster radii and the ECP that we have predicted agrees well with the previously reported results. In addition, some other physicochemical properties associated with the ECP have also been found relevant to the atomic cluster radii of materials. Thus, the atomic cluster radii can be perceived as an effective characteristic parameter to measure the ECP and related properties of materials. Our results provide a better understanding of ECP directly from the atomic structures perspective.

•A linear dependence exists between Zr content and mass density of Al–Zr intermetallics.•The coordinate number of the binary Al–Zr principal clusters varies from 10 to 16.•All Al–Zr alloys studied are conductors, mechanically and thermodynamically stable.•Al2Zr phase has the largest elastic modulus and it is the hardest phase.•The stability of these Al–Zr crystal structures ascends with increasing Zr contents.The cluster characteristics and physical properties of binary Al–Zr intermetallics have been studied in this work by performing first principles calculations. Our investigations indicate that there is a linear dependence between the mass density and Zr-content for these Al–Zr intermetallics. Besides, the coordination number of characteristic principal clusters corresponding to these Al–Zr crystalline phases varies from 10 to 16, and the local atomic structural characteristics of Al–Zr alloys can be properly reflected via the principal clusters. Results on formation energies and elastic constants reveal that these Al–Zr intermetallics are thermodynamically and mechanically stable, among which Al2Zr possesses the largest elastic modulus and the highest hardness. Except for AlZr2 and AlZr3, the other Al–Zr intermetallics are brittle phases by comparison. Furthermore, studies on electric properties suggest that all of these Al–Zr intermetallics studied here are conductive phases.

Cadmium sulfide (CdS) is one of the most significant wide band gap semiconductors, and knowledge of the phase transformation of CdS under high temperature and pressure is especially important for its applications. The pressure–temperature phase diagram and the phase transformation pathways of CdS have been investigated by using density functional theory combined with quasiharmonic approximation. Our results indicated that under ambient conditions, wz-CdS is a stable phase, while under high temperature and pressure, rs-CdS becomes the stable phase. It is also found that zb-CdS is an intermediate phase in transforming from rs-CdS to wz-CdS. Therefore, although there are no zb-CdS phase regions in the CdS pressure–temperature phase diagram, zb-CdS can be found in some prepared experiments.

•With increasing Zr content, the mass density of Cu–Zr intermetallics decreases monotonously.•All Cu–Zr intermetallic compounds considered here are mechanically stable structures.•The heats of formation of the eight Cu–Zr intermetallic compounds are negative.•CuZr2 is a semiconductor with band gap of 0.227 eV, while the other intermetallics are conductors.First-principle calculations have been performed to investigate the structural, mechanical, thermodynamic and electronic properties of eight binary Cu–Zr intermetallic compounds. The results indicated that with increasing Zr concentration, the mass density decreases monotonously. All Cu–Zr intermetallic compounds considered here are mechanically stable structures, and they are ductile materials. Among the eight binary Cu–Zr intermetallic compounds, CuZr is the most ductile phase. Furthermore, the heats of formation of the Cu–Zr intermetallic compounds are negative. Furthermore, CuZr2 is a semiconductor with indirect band gap of 0.227 eV, while the other seven Cu–Zr intermetallic compounds considered here are conductors.

•Water molecule’s adsorption behavior induce 3C-SiC’s surface reconstruction.•The first H is easier decomposing than the second one for most of 3C-SiC surfaces.•H2O is favored to split on the 3C-SiC (1 1 1) surface compared with other surfaces.The reaction mechanism of producing hydrogen via water splitting on the different surfaces of cubic silicon carbide (3C-SiC), the adsorption energy and the activation energy have been studied here by using density functional theory. The results indicated that the adsorption behavior of water molecule could take place on 3C-SiC’s different surfaces and it leads to the surface reconstruction. Besides, the water splitting reaction is found to be a thermally activated process, and the first hydrogen atom is easier decomposing from the adsorbed water molecule than the second one for most of the 3C-SiC surfaces. Furthermore, the water molecule that splitting on 3C-SiC (1 1 1) surface requires relatively small activation energy by contrast with other surfaces. Photon excitation is considered to be essential for the overall water splitting reaction to proceed further.

•Twin indeed can influence elastic properties of face-centered-cubic (FCC) metals.•For most of the FCC metals studied here, twin can enhance the elastic modulus.•The effect of twin on face-centered-cubic metals’ elastic modulus is limited.•Twin boundary enhancing elastic stiffness is not a universal law for FCC metals.It has usually been reported that the elastic stiffness of polycrystals is lower than that of the corresponding monocrystals. Recent experimental results made by Tanigaki et al. (2013) indicate that twin boundaries can improve the elastic stiffness of synthesized nano-polycrystalline diamonds. These researches imply that it may be a universal law for the twin boundary enhancing elastic stiffness. To verify this hypothesis, the elastic properties of ten face-centered-cubic (FCC) structure metals’ perfect crystals and twin crystals have been studied by using first-principles calculations. Our research findings indicated that twins cannot always enhance the elastic stiffness of FCC structure metals. These results further clarify the fact that twin boundary enhancing elastic stiffness is not a universal law.

•These Ni–Zr alloys' mass density and bulk modulus decrease as Zr-content increase.•Ni5Zr is the most stiffness phase and NiZr2 is the most ductile phase among them.•The structural stability of these Ni–Zr alloys ascends with Zr-content increase.•These Ni–Zr intermetallics are conductive phases and thermodynamically stable.The structural, mechanical, thermodynamic and electronic properties of binary Ni–Zr intermetallic compounds have been investigated by performing first-principles calculations. The results indicated that the structural parameters of these Ni–Zr intermetallic compounds agree well with the available experimental and other theoretical values. With increasing of Zr-content, the mass density and bulk modulus of these Ni–Zr intermetallic compounds decrease. Besides, Ni5Zr is the most stiffness phase and NiZr2 is the most ductile phase among these binary Ni–Zr intermetallic compounds. The structural stability of these Ni–Zr alloys ascends with Zr-content increasing. Furthermore, all the binary Ni–Zr intermetallic compounds considered in this work are conductive phases, and they are thermodynamically stable.

First principles calculations have been performed to study the structural, heats of formation, elastic properties, and densities of states of eight Mg–AE (AE = Ca, Sr, Ba) intermetallic compounds. The obtained results indicate that with increasing atom weight and concentration of AE, the bulk moduli decrease monotonously, and the larger the electronegativity difference is, the smaller the elastic modulus would be. Based on the ratios of shear moduli to bulk moduli, it has been found that Mg2Ca, Mg38Sr9, Mg2Sr, Mg17Ba2 and Mg23Ba6 behave in a brittle manner, and Mg17Sr2, Mg23Sr6 and Mg2Ba behave in a ductile manner. Our calculations of the densities of states, heats of formation, and elastic constants of all the eight Mg compounds indicate that they are all conductors, thermodynamically and mechanically stable.Graphical abstractHighlights► Mg–X (X = Ca, Sr, Ba) system intermetallic compounds have been investigated. ► With increasing atom weight of X, the bulk moduli decrease monotonously. ► Mg–X intermetallic compounds are all conductors. ► Mg–X intermetallic compounds are all thermodynamically and mechanically stable.

Structural, elastic and electronic properties, as well as heats of formation, of seven Ca–Zn intermetallic compounds have been studied by using first principles methods. It was found that with increasing Zn concentration, the bulk moduli and shear moduli of Ca–Zn intermetallic compounds increase monotonically. Our results also indicate that Ca3Zn, Ca5Zn3, and CaZn are ductile, while CaZn2, CaZn5, CaZn11, and CaZn13 are brittle. Furthermore, calculations of the electronic properties and heats of formation indicate that seven Ca–Zn intermetallic compounds, considered in this work, are all conductors and thermodynamically stable.Graphical abstractCalculated heats of formation compared to experimental and theoretical data for Ca–Zn system intermetallic compounds.Highlights► Ca–Zn system intermetallic compounds have been studied. ► Ca–Zn intermetallic compounds are all conductors. ► Ca–Zn intermetallic compounds are all stable.

The structural properties, heats of formation, elastic properties, and electronic structures of Ni–Ta intermetallic compounds are investigated in detail based on density functional theory. Our results indicate that all Ni–Ta intermetallic compounds calculated here are mechanically stable except for P21/m-Ni3Ta and hc-NiTa2. Furthermore, we found that Pmmn-Ni3Ta is the ground state stable phase of Ni3Ta polymorphs. The polycrystalline elastic modulus has been deduced by using the Voigt–Reuss–Hill approximation. All Ni–Ta intermetallic compounds in our study, except for NiTa, are ductile materials by corresponding G/K values and poisson's ratio. The calculated heats of formation demonstrated that Ni2Ta are thermodynamically unstable. Our results also indicated that all Ni–Ta intermetallic compounds analyzed here are conductors. The density of state demonstrated the structure stability increases with the Ta concentration.Graphical abstractMechanical properties and formation heats of Ni–Ta intermetallic compounds are discussed in detail in this paper.Highlights► Ni–Ta intermetallic compounds are investigated by first principle calculations. ► P21/m-Ni3Ta and hc-NiTa2 are mechanically unstable phases. ► Pmmn-Ni3Ta is ground stable phase of Ni3Ta polymorphs. ► All Ni–Ta intermetallic compounds are conducting materials.

The mechanical stabilities of K4 carbon and K4-like NaC2 have been studied by performing first-principle calculations. Total energies as functions of isotropic deformations and volume-conserving tetragonal and trigonal deformations have been calculated. For K4 carbon, the total energy shows a minimum for isotropic and trigonal deformations, but exhibits maxima for tetragonal deformation. In contrast, the total energy of K4-like NaC2 shows a minimum under all three deformations. These results indicate that K4 carbon is not a metastable phase, but that K4-like NaC2 is a metastable phase. In addition, the heat of formation of K4-like NaC2 is discussed.Highlights► Mechanical stability of K4 carbon and K4-like NaC2 has been studied. ► K4 carbon is not a metastable phase. ► K4-like NaC2 is a metastable phase.

Relative stability of nanosized β-C3N4 and graphitic C3N4 has been studied by using first principles calculations. It has been demonstrated that the relative stability sequence changes with increasing size of the nanostructure. When the number of C3N4 molecules in the C3N4 nanostructure is less than a threshold number, the β-C3N4 nanostructure is in the stability phase. When the number of C3N4 molecules in the C3N4 nanostructure exceeds the threshold number, the graphitic C3N4 is in the stability phase. In addition, size-dependence electronic properties of β-C3N4 and graphitic C3N4 nanostructures have also been analyzed in this work.Highlights► Relative stability of nanosized C3N4 has been studied. ► Nanosized β-C3N4 becomes more stable than the g-C3N4 phase. ► Electronic properties of nanosized C3N4 have been analyzed.

A novel polymorph of boron nitride (BN) with a body-centered tetragonal structure (bct-BN) has been predicted using first-principles calculations. The structural, vibrational, and mechanical calculations indicated that bct-BN is mechanically stable at zero pressure. When pressure is above 6 GPa, bct-BN becomes energetically more stable than h-BN. The bct-BN appears to be an intermediate phase between h-BN and w-BN due to a low energy barrier from h-BN to w-BNvia bct-BN. Our results also indicated that the structure of unknown E-BN phase might be bct-BN.

Using molecular dynamics simulations, strain rate, temperature and size dependent mechanical properties of < 001 > orientation diamond nanowires are investigated. It is found that, for the same cross-sectional areas, strain rates have almost no effect on yield strength and Young's modulus, provided strain rates are within the range from 0.001 to 0.025 ps− 1. Our calculated results have also indicated that, at the temperature ranging from 100 to 500 K, diamond nanowires' yield strength, Young's modulus, fracture strength and fracture strain are all decreasing with increasing temperature. Furthermore, at the temperature of 300 K, yield strength, Young's modulus, fracture strength and fracture strain increase dramatically with increasing cross sectional area. Finally, orientation dependent diamond nanowires mechanical properties are studied.Stress–strain responses with temperature ranging from 100 to 500 K for DNWs with cross sectional area of 4.58 nm2.Research Highlights► Mechanical properties of diamond nanowires have been studied by MD simulation. ► Yield strength and Young's modulus are decreasing with increasing temperature. ► Fracture strength and fracture strain are decreasing with increasing temperature.

First principle calculations are used to determine the pressure dependent phase stability transformations for GaS polytypes at pressures up to 1000 GPa. Our results indicate that the relative stability sequence changes with the increase in pressure. With the increase in pressure, the phase stability sequence is β-GaS, GaS-II, rocksalt GaS, CsCl structure of GaS and β-GaS, and the corresponding transformation pressures are 2, 19, 75 and 680 GPa. Finally, we discuss the influence of pressure dependence of these GaS polytypes on their electronic properties.

•The atomic cluster structural features of CMAs described by the cluster-plus-glue-atom model were outlined.•The cluster structure related composition rules, as reflected by the cluster line composition rule and the cluster formula composition rule, were reviewed.•The cluster structure related physicochemical properties, including mechanical properties, electronic properties and other properties derived from the cluster-plus-glue-atom model were outlined.Complex metallic alloys (CMAs) are important engineering materials with great scientific and technological significance. Accurate description and better understanding of the atomic structure and structure-related properties is essential for CMAs’ future design and practical application. Atomic-level structure of CMAs remains as a mystery to be uncovered due to their complicated atomic configuration. Since atomic clusters are advocated as basic building blocks of materials, various cluster-based models have been developed during the past decades, among which the “cluster-plus-glue-atom” model has been proven as an effective one to describe the atomic structural features of CMAs. Meanwhile, many intriguing rules correlating the atomic cluster structure with the composition and physicochemical property of CMAs have been revealed in light of the cluster-plus-glue-atom model. Besides, the cluster-plus-glue-atom model has exerted profound influence on the theoretical design of CMAs with desired properties. In this review article, the atomic cluster structural features of CMAs described by the cluster-plus-glue-atom model, and the cluster structure related composition rules, physicochemical properties, together with their correlations have been outlined.

A novel polymorph of boron nitride (BN) with a body-centered tetragonal structure (bct-BN) has been predicted using first-principles calculations. The structural, vibrational, and mechanical calculations indicated that bct-BN is mechanically stable at zero pressure. When pressure is above 6 GPa, bct-BN becomes energetically more stable than h-BN. The bct-BN appears to be an intermediate phase between h-BN and w-BN due to a low energy barrier from h-BN to w-BNvia bct-BN. Our results also indicated that the structure of unknown E-BN phase might be bct-BN.

Cadmium sulfide (CdS) is one of the most significant wide band gap semiconductors, and knowledge of the phase transformation of CdS under high temperature and pressure is especially important for its applications. The pressure–temperature phase diagram and the phase transformation pathways of CdS have been investigated by using density functional theory combined with quasiharmonic approximation. Our results indicated that under ambient conditions, wz-CdS is a stable phase, while under high temperature and pressure, rs-CdS becomes the stable phase. It is also found that zb-CdS is an intermediate phase in transforming from rs-CdS to wz-CdS. Therefore, although there are no zb-CdS phase regions in the CdS pressure–temperature phase diagram, zb-CdS can be found in some prepared experiments.