Influence Of Au Research Articles

Mechanosynthesis of Fe1-YAuYNX nitride (X = 0.25): Influence of Au on process, microstructure and aging

Grinding of Fe2N, Fe and Au powder mixture gives rise to bcc-like single phase Fe1-YAuyN0.25 solid solution, 0≤Y≤25. Aging of this product leads to a γ-type nitride. Compounds are studied by Mössbauer spectroscopy, X-ray diffraction, scanning electron microscopy and thermal analysis. The role of Au atoms on the micromechanisms taking place during mechanosynthesis, magnetic properties, and nitrogen distribution and redistribution is discussed.

Strengthening of glass through surface crystallization of β-spodumene ss

Compositions close to spodumene with additional flux were investigated regarding surface crystallization for strengthening of glass articles. The influence of Au, TiO 2, P 2O 5 and ZnO was determined. After a general characterization, nucleation and crystallization rates and the activation energies for viscosity of the starting glasses were determined. Further, the activation energy for crystallization and the Avrami exponents were calculated from the results of differential thermal analysis. Transformation with time and temperature was investigated, showing that crystallization of the β-eucryptite solid solution starts at temperatures around Tg. At higher temperatures, the β-spodumene solid solution is the predominant crystalline phase. The base composition was chosen for further investigation of crystalline growth. Glass rods were drawn under industrial conditions. Due to a crystallized surface layer with an extremely low expansion coefficient, the flexural strength of the initial glass increased fourfold to a maximum of 800 MPa.

Effects of Au and Ag additions on the formation of the Bi(2223) phase

The influence of Au as well as Ag additions on the formation of the Bi(2223) phase is studied. By means of DTA measurements, it is found that the onset temperature of partial melting in the Au added precursor powders is not affected up to 10 wt.% Au in the mixture, whereas 0.5 wt.% Ag is sufficient for lowering this temperature by 12°C. The lattice parameters of the Bi(2223) phase remain constant regardless of the proportion of Au or Ag added in the samples. EDX analysis failed to detect either Au or Ag in the Bi(2223) crystals formed in the sintered samples.

The influence of Au and Pr on the superconductivity-related gap in RBa 2Cu 3O 7−δ

The superconductivity-related self-energies of phonons in the high- T c superconductor RBa 2Cu 3O 7−δ (R = rare earth) have recently made possible the determination of a value of the superconducting gap. 1 The addition of impurities has the apparent effect of shifting this gap value to higher energies. We interpret these results in terms of a symmetrization of the gap at the Fermi surface by the impurities.

Influence of Au and Ag at the interface of sputtered giant magnetoresistance Fe/Cr multilayers

Multilayer films consisting of 20-AA Fe and 15-AA Cr with amounts of Au and Ag varying from 0 to 4 AA deposited at alternate Fe/Cr interfaces have been RF-diode-sputtered, and their magnetic and magnetotransport properties have been measured. When no noble metal is included, the films exhibit strong antiparallel coupling between adjacent Fe layers, with saturation fields as large as 7 kOe, and giant magnetoresistance (GMR) of 6% at 300 K, similar to that of MBE (molecular beam epitaxy)-grown films reported by others. The interruption of intimate contact between Fe and Cr at the interface resulting from noble-metal deposition gives rise to a substantial decrease in the magnitude of the GMR and the interfacial coupling. This suggests that the mechanism of GMR is associated with Fe and Cr in contact, as is required by models invoking spin-dependent impurity scattering. The results also suggest that the antiparallel coupling arises from direct exchange. >

Influence of Au as an impurity in Ni-silicide growth

The growth of Ni silicides in Ni films on Si and in lateral diffusion couples with Ni films on Si patterns on Al2O3 is strongly influenced by the presence of 1–2 at. % Au in Ni. During silicide formation, Au accumulates at the silicide/ Ni and silicide/Si interface and retards phase formation at temperatures below the Au/Si eutectic. At temperatures of 400–500 °C (above the eutectic), the growth rate is enhanced by over two orders of magnitude. We believe the increase is due to the segregation of Au at the Ni-silicide grain boundaries and the transport of Si in the Au-Si liquid. The growth rate is independent of temperature from 600–800 °C and is limited by the diffusion of Si in the Au-Si liquid at a value of 10−5 cm2/sec.