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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Combinatorial sputter deposition of ultrathick Au-Bi alloy films

We report gold-bismuth alloys are of interest as catalysts and catalytic sensing systems, electrochemical sensors, superconductors, and hohlraums for magnetically assisted inertial confinement fusion implosions. Radiation-hydrodynamics simulations with the Lasnex code of laser-driven hohlraums predict higher x-ray drive from Au-Bi alloys compared with cases of Au-Ta or pure Au and Bi hohlraums. Here, we use direct current magnetron sputtering in Ar gas, with co-sputtering from two elemental targets, to deposit Au-Bi alloys with Bi content of 9–77 at.% and thicknesses up to ~20 µm. Films are characterized by a combination of x-ray diffraction, Rutherford backscattering, scanning electron microscopy, substrate-curvature-based residual stress, and electronic transport measurements. Experiments are complemented by Monte Carlo simulations of ballistic sputtering and gas phase transport of depositing species and Ar gas atoms. Results show that all films are polycrystalline, with three distinct compositional regimes dominated by Au, Au 2 Bi, and Bi crystallographic phases. A metallic behavior of the temperature dependence of electrical resistivity is observed for all the films. Films with Bi content above ~30 at.% exhibit porosity, which is tolerable to hohlraum x-ray drive based on Lasnex simulations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Combinatorial Deposition of Ultrathick Ta-W-Au-Bi High-Entropy Alloys for Next-Generation Hohlraums by Direct-Current Magnetron Sputtering

Hohlraum temperature calculations with the model by J. H. Hammer and M. D. Rosen predict a higher X-ray drive from Ta-W-Au-Bi high-entropy alloys compared to pure Au and recently developed Ta 4 Au and Au-Bi hohlraums. Here, we study the microstructure and properties of 25-75−µm-thick Ta-W-Au-Bi alloy films deposited via combinatorial direct-current magnetron sputtering. All of the films have promising physical properties, including high electrical resistivity, that satisfy the requirements for magnetically assisted inertial confinement fusion experiments. While porosity tends to increase with increasing Bi content, we also found that films with Bi content > 44 at. % exhibited densification close to the substrate/film interface and formed a single-phase alloy. In conclusion, these findings provide a potential path forward for the development of Ta-W-Au-Bi alloys for next-generation hohlraum materials.

Magnetron sputtering↗
DOE OSTI2020

Materials Data on BiAu2 by Materials Project

Au2Bi is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Au1- is bonded to six equivalent Au1- and six equivalent Bi2+ atoms to form a mixture of corner, edge, and face-sharing AuBi6Au6 cuboctahedra. All Au–Au bond lengths are 2.86 Å. All Au–Bi bond lengths are 3.36 Å. Bi2+ is bonded in a 12-coordinate geometry to twelve equivalent Au1- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi3Au by Materials Project

AuBi3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Au is bonded to twelve Bi atoms to form AuBi12 cuboctahedra that share corners with four equivalent AuBi12 cuboctahedra, edges with eight equivalent AuBi12 cuboctahedra, edges with sixteen equivalent BiBi8Au4 cuboctahedra, faces with four equivalent AuBi12 cuboctahedra, and faces with eight equivalent BiBi8Au4 cuboctahedra. There are four shorter (3.36 Å) and eight longer (3.46 Å) Au–Bi bond lengths. There are two inequivalent Bi sites. In the first Bi site, Bi is bonded to four equivalent Au and eight Bi atoms to form distorted BiBi8Au4 cuboctahedra that share corners with twelve equivalent BiBi8Au4 cuboctahedra, edges with eight equivalent AuBi12 cuboctahedra, edges with eight equivalent BiBi8Au4 cuboctahedra, faces with four equivalent AuBi12 cuboctahedra, and faces with ten equivalent BiBi8Au4 cuboctahedra. There are four shorter (3.36 Å) and four longer (3.46 Å) Bi–Bi bond lengths. In the second Bi site, Bi is bonded in a distorted square co-planar geometry to four equivalent Au and eight equivalent Bi atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi4Au by Materials Project

AuBi4 is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight AuBi4 clusters. Au is bonded in a tetrahedral geometry to four equivalent Bi atoms. All Au–Bi bond lengths are 2.76 Å. Bi is bonded in a single-bond geometry to one Au atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi3Au by Materials Project

AuBi3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Au is bonded in a body-centered cubic geometry to eight equivalent Bi atoms. All Au–Bi bond lengths are 3.33 Å. There are two inequivalent Bi sites. In the first Bi site, Bi is bonded in a distorted body-centered cubic geometry to four equivalent Au and four equivalent Bi atoms. All Bi–Bi bond lengths are 3.33 Å. In the second Bi site, Bi is bonded in a body-centered cubic geometry to eight equivalent Bi atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi3Au by Materials Project

AuBi3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Au is bonded to twelve equivalent Bi atoms to form AuBi12 cuboctahedra that share corners with twelve equivalent AuBi12 cuboctahedra, edges with twenty-four equivalent BiBi8Au4 cuboctahedra, faces with six equivalent AuBi12 cuboctahedra, and faces with twelve equivalent BiBi8Au4 cuboctahedra. All Au–Bi bond lengths are 3.41 Å. Bi is bonded to four equivalent Au and eight equivalent Bi atoms to form distorted BiBi8Au4 cuboctahedra that share corners with twelve equivalent BiBi8Au4 cuboctahedra, edges with eight equivalent AuBi12 cuboctahedra, edges with sixteen equivalent BiBi8Au4 cuboctahedra, faces with four equivalent AuBi12 cuboctahedra, and faces with fourteen equivalent BiBi8Au4 cuboctahedra. All Bi–Bi bond lengths are 3.41 Å.

36 MATERIALS SCIENCE↗