Scattering of e± with Al, Ni, Cu, Ag, Pt, and Au atoms including the relativistic effect at 1 eV ≤ E ≤1 MeV

Theoretical study on structural stability and optoelectronic properties of metal-adsorbed two-dimensional GaN

Structure of Y3TaNi6+xAl26: a filled-up substitution variant of the BaHg11 type

Angular distributions of atoms sputtered from NiAl{1 1 0} and Ni{1 0 0}

The self-encapsulation kinetics of Ag/Al bilayers were studied both experimentally and theoretically as part of the effort to introduce Ag as an alternative metallization scheme for future ultra-large-scale-integrated technologies. Theoretical modeling was based on an analytical solution of a modified diffusion equation, which incorporated the diffusion of Al atoms through the Ag layers during the Ag/Al bilayer encapsulation progress. The amount of segregated Al atoms was monitored by both Rutherford backscattering spectrometry and film resistivity measurements, and correlated well with the theoretical predictions. These findings showed that the kinetics of the self-encapsulation could be significantly affected by both (i) the chemical affinity between Al and Ag atoms, and (ii) the interfacial energy between the metal layer (Ag) and the newly formed AlxOyNz diffusion barriers. Higher anneal temperatures were shown to accelerate the encapsulation process, and hence, achieved a lower resistivity in the underneath Ag layer. This model, in addition, confirmed the self-passivating characteristics of AlxOyNz diffusion barriers formed by Ag/Al bilayers annealed between 500 and 725 °C.

This study investigated the interface energy, work of adhesion, and electronic structural properties at the Ag/Au/M(Cu,Ni) interface, employing the first-principles method based on density functional theory. First, the structures of various binary and ternary interfaces were optimized. Subsequently, the total density of states (TDOS), partial density of states (PDOS), charge distribution, and bonding characteristics of these interfaces were investigated. Additionally, the interface energy and work of adhesion of these interfaces were calculated. The results indicated that the Ag/Au/Ni interface exhibited higher stability and bonding strength compared to the Ag/Au/Cu interface. The contribution of the PDOS of atoms at the Ag/Au/M(Cu,Ni) interface to the TDOS can be primarily attributed to d-orbital electrons, while s- and p-orbit electrons had minimal influence on PDOS.Notably, d-d orbital hybridization emerged between the d-orbit electrons in Cu and Ni atoms and those in Ag and Au atoms, enhancing structural stability. Two distinct peaks in the TDOS of Ag/Ni, Au/Ni, and Ag/Au/Ni interfaces appeared near the Fermi level, corresponding to d-d orbital hybridization involving Ni, Ag, and Au atoms. At the Ag/Au/Cu and Ag/Au/Ni interfaces, resonance peaks corresponding to the s and p orbits of Ag and the s and p orbits of Au, as well as the d orbits of Ag and Au, indicated the presence of a relatively strong metallic bond between Ag and Au atoms. Furthermore, the Ag/Ni and Au/Ni systems exhibited greater average electron transfer compared to the Ag/Cu and Au/Cu systems. Moreover, atomic bond lengths at the Ag/Au/Ni interface were significantly less than those at the Ag/Au/Cu interface, indicating higher stability of the Ag/Au/Ni interface compared to the Ag/Au/Cu interface.

The effect of systematic Ni atom addition on the chemical ordering properties of the nanoalloys has been studied for PtNi@Ag core–shell systems in which Ag atoms full occupy the shell of the icosahedral structure. We concentrate only on the chemical ordering optimization within a given geometric structure and we have core–shell system compositions (Pt13-nNinAg42 and Pt55-nNinAg92 for PtNi@Ag) with size of 55 and 147. Local relaxations were performed by using Monte Carlo Basin-Hopping algorithm within Gupta potential. Results show that it is energetically favourable to substitute Ni atoms for Pt13-nNinAg42 and Pt55-nNinAg92 systems. Excess energy variations were calculated to compare the relative stability. The atomic mixing degrees of Pt, Ni and Ag atoms were discussed by using order parameter (R) indicator. It is observed that the Ni atoms prefer to locate with closer to Pt atoms than Ag atoms due to tendency of occupying the core regions of the icosahedral structures. The local pressures of the atoms were also examined to clarify the composition effect on atomic stress and pressure. It is also observed that in trimetallic PtNi@Ag core–shell nanoalloys, the strain on the core atoms can be released by substituting Pt atoms with Ni atoms.

Dissolution and segregation of monolayer Cu, Ni and Co atoms on the [formula omitted] surface induced by thermal annealing

The short range order and physical properties of Ni-Al-Cr alloys are studied by using the cluster-plus-glue-atom model. In the formula [Al-Ni<sub>12</sub>]Al<sub><i>x</i></sub>Cr<sub>3–<i>x</i></sub>, <i>x</i> = 0, 0.5, 1.0, 1.5, 2.0, 2.5, Al atom is selected as the center of cluster, then twelve Ni atoms which are arranged at the nearest neighboring sites constructe a cluster, and Al atoms and Cr atoms which are located at second neighboring sites are glue atoms. The results of formation energy show that the configurations of cluster-plus-glue-atoms model are more stable than the other configurations with all compositions. The results of difference charge density show that the charge density transfer of Ni-Al-Cr system is mainly accumulated between Ni and Al atoms or between Ni and Cr atoms. It means that Ni-Al and Ni-Cr are more easily bonded than Ni-Ni and Al-Cr. The electronic band structures indicate that Ni-Al-Cr alloy has conductor properties. The hybrid effects between Ni-3d and Al-3p or Ni-3d and Cr-3d are obvious, which verifies that there are strong interactions between Ni and Al atoms or between Ni and Cr atoms.

Microscopic phase-field simulation of atomic site occupation in ordering process of NiAl 9Fe 6 alloy

Effects of Ag or Al addition to CuZr-based metallic alloys on glass formation and structural evolution: A molecular dynamics simulation study

A model is proposed to describe the temperature dependence of the aluminum oxynitride (AlxOyNz) diffusion barrier formation during a silver self-encapsulation process. These barrier layers form in the temperature range of 500-725 °C during anneals of the Ag/Al bilayers on oxidized Si substrates in an ammonia ambient. Experimental results show that temperature has a significant effect on the kinetics of this process. In this investigation, the diffusion of Al atoms through the Ag layers during self-encapsulation process is modeled using an analytical solution to a modified diffusion equation. This model shows that higher anneal temperatures will minimize the retardation effect byi) reducing the chemical affinity between Al and Ag atoms, andii) allowing more Al atoms to surmount the interfacial energy barrier between the metal layer (Ag) and the newly formed AlxOyNzdiffusion barriers. The theoretical predictions on the amount of segregated Al atom correlate well with experimental results from Rutherford backscattering spectrometry. This model in addition confirms the self-passivation characteristics of AlxOyNzdiffusion barriers formed by Ag/Al bilayers annealed between 500∼725 °C.

Effect of the Ni coating thickness on laser welding-brazing of Mg/steel

Mobility of point defects in CoCrFeNi-base high entropy alloys

While the dimension of solder bumps keeps shrinking to meet higher performance requirements, the formation of interfacial compounds may be affected more profoundly by the other side of metallization layer due to a smaller bump height. In this study, cross interactions on the formation of intermetallic compounds (IMCs) were investigated in eutectic SnPb, SnAg3.5, SnAg3.8Cu0.7, and SnSb5 solders jointed to Cu/Cr–Cu/Ti on the chip side and Au/Ni metallization on the substrate side. It is found that the Cu atoms on the chip side diffused to the substrate side to form (Cux,Ni1−x)6Sn5 or (Niy,Cu1−y)3Sn4 for the four solders during the reflow for joining flip chip packages. For the SnPb solder, Au atoms were observed on the chip side after the reflow, yet few Ni atoms were detected on the chip side. In addition, for SnAg3.5 and SnSn5 solders, the Ni atoms on the substrate side migrated to the chip side during the reflow to change binary Cu6Sn5 into ternary (Cux,Ni1−x)6Sn5 IMCs, in which the Ni weighed approximately 21%. Furthermore, it is intriguing that no Ni atoms were detected on the chip side of the SnAg3.8Cu0.7 joint. The possible driving forces responsible for the diffusion of Au, Ni, and Cu atoms are discussed in this paper.

Сrystal structure of the ternary erbium and silver aluminide ErAg 0 . 77 Al 2 . 23 has been studied using powder X-ray diffraction data: space group R-3m , Pearson symbol h R36 , lattice parameters a = 0.55049(1) nm, c = 2.61415(6) nm, final residual values are R I = 0,0450; R P = 0,0314; wR P = 0,0430. Samples were prepared by an arc melting under purified argon atmosphere with nonconsumable tungsten electrode and water-cooled copper hearth of the elemental components with certified purities of 99.999 wt.% Er, 99.95 wt.% Ag and 99.99 wt.% Al. All samples were re-melted twice to ensure homogeneity, and then heat treated in evacuated silica tubes at 600 o C during 700 hours. Annealed alloys were quenched in cold water without breaking the tubes. Phase analysis of the prepared samples and crystal structure determination of new compound were carried out using X-ray powder diffraction patterns recorded on a automatic powder diffractometer Huber Imaging Plate Guinier Camera G670 (Cu K α1 -radiation, l = 0.154056 nm; 3.503 ≤ 2 θ ≤ 99.99°; step 0,01° of 2 θ , scan time is 250 sec per step). Refinement of the atomic positional and displacement parameters in the crystal structure of the compounds was carried out by the full profile Rietveld method in the range 2 θ =3.50­–99.99 o (Cu K α1 -radiation) using the WinCSD program package. Existence of the new ternary aluminide ErAg 0 . 77 Al 2 . 23 with the rhombohedral structure of the PuNi 3 -type was found in the two three-component samples of the starting compositions Er 0 . 25 Ag 0 . 20 Al 0 . 55 and Er 0 . 25 Ag 0 . 17 Al 0 . 58 . In both samples new aluminide was in thermodynamic equilibrium with the small admixtures of the earlier known ternary phases ErAg 2 . 5 Al 2 . 5 (DyAg 2 . 4 Al 2 . 6 -type structure) and Er 8 Ag 17 Al 49 (Yb 8 Cu 17 Al 49 -type structure). Partially ordered distribution of the smaller atoms Ag and Al was observed in the crystal structure of new intermetallide, in particular Wyckoff site 6 с is fully occupied by Ag atoms, whereas Wyckoff sites 3 b and 18 h are occupied by the statistical mixtures of Ag and Al atoms with a predominant content of aluminum atoms leading to the next formulas ErAg 0 . 77(1) Al 2 . 23(1) or Er(Ag 0 . 26 Al 0 . 74 ) 3 . Interatomic distances in the ErAg 0 . 77 Al 2 . 23 crystal structure are in good correlation with the respective sums of the atomic radii of the components indicating predominance of the metallic bonding. Structure type PuNi 3 (or NbBe 3 ) can be considered as formed from the structural units of the CaCu 5 and MgZn 2 structure types. Keywords: crystal structure, X-ray powder diffraction, aluminide, erbium, silver.