Formation Mechanism and Binding Energy for Body-Centered Cubic Structure of He^＋9 Cluster

The formation mechanism for the body-centered cubic structure of cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between the nuclei at the center and an apex of the body-centered cubic structure. The result of the calculation shows that the curve has a minimal energy . The binding energy of with respect to was calculated to be 0.8857 a.u. This means that the cluster ofmay be formed in the body-centered cubic structure of .

Metastable Face-Centered Cubic Structure and Structural Transition of Sn on 2H-NbSe2(0001)

Surface structures and properties of Sn islands grown on superconducting substrate 2H-NbSe2（0001）are studied using low temperature scanning tunneling microscopy or spectroscopy.The pure face-centered cubic（fee）structure of Sn surface is obtained.Superconductivity is also detected on the fcc-Sn（111）surface,and the size of superconducting gap on the Sn surface is nearly the same as that on the superconducting substrate.Furthermore,phase transition occurs from fcc-Sn（111）toβ-Sn（001）by keeping the sample at room temperature for a certain time.Due to the strain relaxation on theβ-Sn islands,both the in-plane unit cell and out-of-plane structures distort,and the height of surface atoms varies periodically to form a universal ripple structure.

Interstitially carbon-alloyed refractory high-entropy alloys with a body-centered cubic structure

The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)structure.Here we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤20.It is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=20.Moreover,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi level.All these features are consistent with the expectation that carbon atoms occupy the interstitial site.For x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice site.In addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution phase.Our study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.

Electrochemical performances of Mg_(45)M_5Co_(50)(M=Pd, Zr) ternary hydrogen storage electrodes

In order to improve the discharge capacity and cyclic life of Mg-Co-based alloy, ternary Mg45M5Co50 （M=Pd, Zr） alloys were synthesized via mechanical alloying. TEM analysis demonstrates that these alloys all possess body-centered cubic （BCC） phase in nano-crystalline. Electrochemical experiments show that Mg45Zr5Co50 electrode exhibits the highest capacity （425 mA·h/g） among the Mg45M5Co50 （M=Mg, Pd, Zr） alloys. And Mg45Pd5Co50 electrode lifts not only the initial discharge capacity （379 mA·h/g）, but also the discharge kinetics, e.g., exchange current density and hydrogen diffusion ability from that of Mg50Co50. It could be concluded that the electrochemical performances were enhanced by substituting Zr and Pd for Mg in Mg-Co-based alloy.

A model for dynamic recovery of bcc structure

GENERALLY the following two processes will take place simultaneously during hot deformation: one is work hardening caused by the increase of dislocation density on account of slip deforma-tion; the other is softening caused by the process of recovery and recrystallization. The overalleffect of the development of the two contrary processes is influenced by deformation tempera-ture, rate and quantities. Among them temperature controls the rate of self-diffusion, whichaffects the proceeding of recovery and recrystallization as well. During recovery the dislocationdensity is mainly determined by deformation rate (ε) and strain quantities (ε).