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A model describing size-dependent melting temperature and thermal conductivity of nanosemiconductors is proposed based on Lindermann's melting criterion and Debye model. By the atomic thermal vibration consideration and by introducing intrinsic size effect of phonon velocity and mean free path combined with surface scattering effect, the model predicts that the melting temperature and thermal conductivity of nanosemiconductors decrease as the size reduces. The size effect depends on such material parameters as the vibration entropy, mean free path, the characteristic crystal size and surface roughness. The predictions are in agreement with experimental results of Si nanoparticles, nanowires and thin films.

Impact welding has been carried out using a projectile having a diameter of 11 and 5 mm at an impact velocity of 200 m/s or more. A large projectile regardless of the slenderness ratio, was welded to a stainless steel target. However, only a small projectile with a slenderness ratio less than 1.2 was welded to the same target. In order to examine the effect of the diameter of the projectile on the weldability, the temperature elevating process in two cylindrical projectiles subjected to a longitudinal impact was evaluated numerically using LS-DYNA. The numerical results indicated that since the deformation mechanism of a projectile with a slenderness ratio less than 1.0 is different of that of the projectile with the slenderness ratio more than 1.5, the small projectile with the slenderness ratio less than 1.0 can be welded to the target.

The high-pressure melting curve of semiconductors with defects has been studied using statistical moment method (SMM). In agreement with experiments and with DFT calculations we obtain a negative slope for the high-pressure melting curve. We have derived a new equation for the melting curve of the defect semiconductors. The melting was investigated at different high pressures, and the SMM calculated melting temperature of Si, AlP, AlAs and GaP crystals with defects being in good agreement with previous experiments.

Molecular dynamics (MDs) simulations were used to explore the thermal stability of Au nanoparticles (NPs) with decahedral, cuboctahedral, icosahedral and Marks NPs. According to the calculated cohesive energy and melting temperature, the Marks NPs have a higher cohesive energy and melting temperature compared to these other shapes. The Lindemann index, radial distribution function, deformation parameters, mean square displacement and self-diffusivity have been used to characterize the structure variation during heating. This work may inspire researchers to prepare Marks NPs and apply them in different fields.

The band structure of Al${}_x$Ga${}_{1-x}$Sb semiconducting ternary alloys and their related properties such as elastic constants, microhardness, transition pressure to the first phase, acoustic wave velocities and melting temperature have been investigated. The calculations are performed using a pseudopotential approach within the virtual crystal approximation which includes the effect of compositional disorder as an effective potential. Generally, our results are found to be in good accord with the experimental results. The composition dependence of all features of interest showed a monotonic behavior and suggests that the stiffness, hardness and structural stability becomes better in Al${}_x$Ga${}_{1-x}$Sb for higher Al concentrations. The bulk sound speeds and melting temperature are found to become larger when increasing the Al content.

The structural and electronic properties of mono-vacancy (MV) defect in graphene-based Möbius strip (GMS) are studied in the framework of density functional theory (DFT) combined with the molecular dynamics (MD) simulations. Two kinds of MV defects are observed: the 59-type MV (a configuration with one pentagon and one nonagon ring) located at the curved areas of Möbius strip, and the 5566-type MV (a configuration with two pentagon and two hexagon rings) with one sp³ hybridized carbon appeared in the twisted areas. The 5566-type MV defect is the most stable configuration at 0 K, while the DFT-MD calculations show that it is unstable at room-temperature and will transform into a 59-type MV. Additionally, the melting behavior of GMSs is investigated through empirical potential MD simulations, and we find that their melting temperatures are about 2750 K, which is lower than that of carbon nanotubes and graphene.

A series of Cu–34Mn–6Ni–$x$Sn (wt.%) braze fillers that were used for brazing stainless steel (SS) were prepared. The microstructures, melting temperatures, wettability and mechanical properties of the braze fillers were investigated. An Sn-rich phase was formed in braze fillers with an Sn content above 6 wt.% (including) because of the segregation performance of Sn. The melting temperatures of braze fillers decreased markedly with an increase in Sn content. The addition of 6 wt.% Sn resulted in the highest wettability of braze fillers on the SS. With an increase in Sn content, the tensile strength and hardness increased, whereas the plasticity and toughness of the braze fillers decreased owing to the solid solution and segregation of Sn.

In this study, structural, electronic, magnetic, elastic and thermal properties of Co-based Quaternary Heusler alloys (QHAs) CoYTiZ ($\mathrm{\text{Z}}=\mathrm{\text{Al}}$, Ga, Si, Ge) have been investigated by Wien2k code. The calculations have been performed using full-potential linearized augmented plane wave (FP-LAPW) method. Generalized Gradient Approximation (GGA) method has been adopted. Structural properties have been explored for three different Wyckoff positions. From the geometry optimization calculations, it is concluded that all these alloys are stable in Type-III crystal structure. Moreover, magnetic phase optimization revealed ferro-magnetic (FM) phase as stable one. Results of electronic properties have shown metallic character for CoYTiAl, CoYTiGa, CoYTiGe while nearly half metal (HM) character for CoYTiSi. Magnetic moment obeys Slater Pauling rule (SP) for these alloys. To check out the mechanical stability, elastic properties have been investigated. Elastic parameters have shown the ductile nature of these alloys. The values for melting temperature ($T_{\mathrm{\text{melt}}})$ have confirmed the thermal stability of the studied alloys.

We have used a method for determining volume dependence of the Grüneisen parameter in the Lindemann law to study the pressure dependence of melting temperatures in case of 10 metals viz. Cu, Mg, Pb, Al, In, Cd, Zn, Au, Ag and Mn. The reciprocal gamma relationship has been used to estimate the values of Grüneisen parameters at different volumes. The results for melting temperatures of metals at high pressures obtained in this study using the Lindemann law of melting are compared with the available experimental data and also with the values calculated from the instability model based on a thermal equation of state. The analytical model used in this study is much simpler than the accurate DFT calculations and molecular dynamics.

A simplified model that describes the size and shape dependence of melting thermodynamics of full free nanocrystals was established. Critical sizes of Fe, Co, Ni magnetic nanocrystals when the crystals keep their crystallinity were calculated and the corresponding minimum melting temperature was predicted. Theoretical predictions were consistent with experimental results.

A model is developed to account for the size-dependent melting temperature of pure metallic and bimetallic nanowires, where the effects of the contributions of all surface atoms to the surface area, lattice and surface packing factors and the cross-sectional shape of the nanowires are considered. As the size decreases, the melting temperature functions of pure metallic and bimetallic nanowires decrease almost with the same size-dependent trend. Due to the inclusion of the above effects, the present model can also be applied to investigate the melting temperature depression rate of different low-dimensional system, accurately. The validity of the model is verified by the data of experiments and molecular dynamics simulations.

Size-dependent melting temperature of metallic nanoparticles is studied theoretically based on cohesive energy. Three factors are introduced in the present model. The k factor, i.e. efficiency of space filling of crystal lattice is defined as the ratio between the volume of the atoms in a crystal cell and that of the crystal cell. The β factor is defined as the ratio between the cohesive energy of surface atom and interior atom of a crystal. The q_s factor represents the packing fraction on a surface crystalline plane. Considering the β, q_s and k factors, the relationship between melting temperature and nanoparticle size is discussed. The obtained model is compared with the reported experimental data and the other models.

The study of the melting transition for large molecular weight DNA which had been irradiated with various doses of γ-rays can yield information on the structural and dynamical behaviour of DNA, leading to a better understanding of changes induced by external agents. In order to interpret the accumulated experimental data, a theoretical description capable of correlating thermal changes to those induced by ionizing radiation, is required. The theoretical ideas proposed here, based on first principles and certain assumptions, allow for a quantitative analysis of the melting data and the subsequent evaluation of a very small number of parameters which can be used to interpret the observed variations in experimental quantities (such as UV absorbance) which are related to structural variations.

A newly developed AMBER compatible force field with coupled backbone torsion potential terms (AMBER03^2D) is utilized in a folding simulation of a mini-protein Trp-cage. Through replica exchange and direct molecular dynamics (MD) simulations, a multi-step folding mechanism with a synergetic folding of the hydrophobic core (HPC) and the α-helix in the final stage is suggested. The native structure has the lowest free energy and the melting temperature predicted from the specific heat capacity C_v is only 12 K higher than the experimental measurement. This study, together with our previous study, shows that AMBER03^2D is an accurate force field that can be used for protein folding simulations.

In this paper we have studied the variation of normalized per-atom pair cohesive (binding) energy and melting temperature with size and number of atom-pairs in the BN nano-crystal by simple model approach. In small nano-particles, large proportions of their atoms reside either at or near the surface, and those in clusters are basically all on the surface. So, we have to study the surface configuration in detail that leads the constancy of the crystals. Even for bulk materials, parameters that ensure this constancy involving normalized cohesive energy, surface reconstruction, iconicity, bulk structure, hybridization and charge balance, melting point. It is worthwhile to say that many of these factors are quite interdependent. These all factors influence the whole cohesive energy of crystals and give important information about the deflections from inverse size dependence. The per-atom-pair binding energy and melting temperature of BN nano-crystal is a quadratic function of the inverse of the crystal size. The binding energy and melting temperature comes near their bulk value with increasing the crystal size and same as the bulk material when the crystal size is above than 100 nm.

This paper studies the effect of atoms number $(N)$ of bulk Ag: $N=2916$ atoms (Ag${}_{2916}$), 4000 atoms (Ag${}_{4000}$), 5324 atoms (Ag${}_{5324})$, 6912 atoms (Ag${}_{6912})$ at temperature $T=300$K, 400K, 500K, 600K, 700K, 800K, 900K, 1000K on bulk Ag${}_{5324}$ and annealing time $t$ = 200 ps on the structure and phase transition of Ag bulk by Molecular Dynamics (MD) method with Sutton–Chen (SC) pair interaction potential, periodic boundary conditions. The structural results are analyzed through the Radial Distribution Function (RDF), the total energy of the system ($E_{tot})$, the size $(l)$, the phase transition (determined by the relationship between $E_{tot}$ and $T$), and combined with the Common Neighbors Analysis (CNA) method. The obtained results show that the first peak’s position ($r)$ of the RDF has negligible change value, $r=2.78$Å, which is completely consistent with the experimental results. For bulk Ag, there are always four types of structure: FCC, HCP, BCC, Amor and glass transition temperature $T_g=500$K. When decreasing the temperature, bulk Ag changes from liquid state to crystalline state, when increasing the annealing time at $T_g=500$K, bulk Ag changes from amorphous phase to crystalline phase state, leading to the increase of FCC, HCP, BCC structures and the decrease of Amor structure. The obtained results will be used as guide for future experiments.

We present a simple model for the melting curve of a two-dimensional electron solid in a magnetic field and compare it with recent experiments on the phase diagram of 2-D electrons on cryogenic substrates and in GaAs/GaAlAs heterojunctions.