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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Radiation-Induced Defect Formation Kinetics in Inconel–Cu Multimetallic Layered Composites

This study investigates the stability of Inconel–Cu Multimetallic Layered Composites (MMLCs) in nuclear reactor applications using Molecular Dynamics simulations. The focus is on understanding the underlying mechanisms governing the properties of MMLCs for advanced nuclear reactors, specifically, the mechanochemistry of the interface between Inconel and copper alloys. The selection of Inconel–Cu MMLCs is primarily due to copper’s superior thermal conductivity, enhancing heat management within reactors by preventing hotspots and ensuring uniform temperature distribution. This research examines Incoloy 800H and two Inconel variants (718 and 625), assessing their stability at 1000 K after exposure to 10 keV collision cascades up to 0.12 dpa. Notable findings include defect clustering on the {1 2 0} family of planes of Inconel and Cu, with Stacking Faults and Lomer–Cottrell locks on the Inconel side.

Ramesh, Rajesh↗
DOE OSTI2026

Intermediate Bandgap (IB) Cu 3 VS x Se 4−x Nanocrystals as a New Class of Light Absorbing Semiconductors

A new family of highly uniform, cubic-shaped Cu 3 VS x Se 4−x (CVSSe; 0 ≤ x ≤ 4) nanocrystals based on earth-abundant materials with intermediate bandgaps (IB) in the visible range is reported, synthesized via a hot-injection method. The IB transitions and optical band gap of the novel CVSSe nanocrystals are investigated using ultraviolet-visible spectroscopy, revealing tunable band gaps that span the visible and near-infrared regimes. The composition-dependent relationships among the crystal phase, optical band gap, and photoluminescence properties of the novel IB semiconductors with progressive substitution of Se by S are examined in detail. High-resolution transmission electron microscopy and scanning electron microscopy characterization confirm the high crystallinity and uniform size (~19.7 nm × 17.2 nm for Cu 3 VS 4 ) of the cubic-shaped nanocrystals. Density functional theory (DFT) calculations based on virtual crystal approximation support the experimental findings, showing good agreement in lattice parameters and band gaps across the CVSSe series and lending confidence that the targeted phases and compositions have been successfully realized. A current conversion efficiency, i.e., incident photon-to-current efficiency, of 14.7% was achieved with the p-type IB semiconductor Cu 3 VS 4 . These novel p-type IB semiconductor nanocrystals hold promise for enabling thin film solar cells with efficiencies beyond the Shockley–Queisser limit by allowing sub-band-gap photon absorption through intermediate-band transitions, in addition to the conventional direct-band-gap transition.

Cu3VSxSe4−x↗
DOE OSTI2021

Fleetite, Cu 2 RhIrSb 2 , a New Species of Platinum-Group Mineral from the Miass Placer Zone, Southern Urals, Russia

Fleetite, Cu 2 RhIrSb 2 , a new species of platinum-group mineral (PGM), was discovered intergrown with an Os–Ir–Ru alloy in the Miass Placer Zone (Au–PGE), southern Urals, Russia. A single grain 50 μm across was found. Osmium, ruthenium, and iridium are the main associated minerals; also present are Pt–Fe alloys, laurite, Sb-rich irarsite, Rh-rich tolovkite, kashinite, anduoite, ferronickelplatinum, heazlewoodite, PGE-bearing pentlandite and digenite, as well as micrometric inclusions of forsterite (Fo 93.7 ), chromite–magnesiochromite, and Mg-rich edenite. In reflected light, fleetite is light gray; it is opaque, isotropic, non-pleochroic, and non-bireflectant. We report reflectance values measured in air. A mean of seven point-analyses (wavelength-dispersive spectrometry) gave Cu 13.93, Ni 8.60, Fe 0.10, Ir 28.07, Rh 7.91, Ru 1.96, Sb 39.28, total 99.85 wt.%, corresponding to (Cu 1.41 Ni 0.58 Fe 0.01 ) Σ2.00 (Rh 0.49 Ni 0.36 Ru 0.12 ) Σ0.97 Ir 0.95 Sb 2.08 on the basis of six atoms per formula unit, taking into account the structural results. The calculated density is 10.83 g/cm 3 . Single-crystal X-ray studies show that fleetite is cubic, space group Fdm (#227), a = 11.6682(8) Å, V = 1588.59(19) Å 3 , and Z = 16. A least-squares refinement of X-ray powder-diffraction data gave a = 11.6575(5) Å and V = 1584.22(19) Å 3 . The strongest five reflections in the powder pattern [d in Å(I)(hkl)] are: 6.70(75)(111), 4.13(100)(220), 3.52(30)(311), 2.380(50)(422), 2.064(40)(440). Results of synchrotron micro-Laue diffraction experiments are consistent [a = 11.66(2) Å]. The crystal structure of fleetite was solved and refined to R = 0.0340 based upon 153 reflections with F o > 4σ(F o ). It is isotypic with Pd 11 Bi 2 Se 2 and best described as intermetallic, with all metal atoms in 12-fold coordination. Fleetite and other late exotic phases were formed by reaction of the associated alloy phases with a fluid phase enriched in Sb, As, and S in circulation in the cooling ophiolite source-rock. The mineral is named after Michael E. Fleet (1938–2017) in recognition of his significant contributions to the Earth Sciences.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Multimodal X-ray Microscopy: The Kinetics of Cu in CdTe Absorbers

The behavior of solar cells is very often limited by inhomogeneously distributed nanoscale defects. This is the case throughout the entire lifecycle of the solar cell, from the distribution of elements and defects during solar cell growth as well as the charge-collection and recombination during operation, to degradation and failure mechanisms due to impurity diffusion, crack formation, and irradiation- and heat-induced cell damage This has been known for a while in the field of crystalline silicon, but inhomogeneities are far more abundant in polycrystalline materials, and are the limiting factor in thin-film solar cells where grain sizes are often on the order of the diffusion length. We showed that the high penetration of hard X-rays combined with the high sensitivity to elemental distribution, structure, and spatial resolution offers a unique avenue for highly correlative studies at the nanoscale. We presented results on Cu-doped CdTe, where carrier collection is directly correlated to the kinetics of Cu inside the absorber and the particular Cu-phases at the ZnTe/CdTe interface. We complemented the results with modeling using PVRD-FASP and PyCDTS, where the X-ray beam induced profile can be reproduced by the equilibrium defect concentrations proposed by the solvers.

Bertoni, Mariana↗
DOE OSTI2020

Materials Data on Cu(PO3)2 by Materials Project

Cu(PO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cu2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.92–2.49 Å. P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Cu2+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cu2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(IO3)2 by Materials Project

Cu(IO3)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Cu2+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.97–2.51 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Cu2+ and two equivalent I5+ atoms. There are one shorter (1.83 Å) and one longer (2.59 Å) O–I bond lengths. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one I5+ atom. The O–I bond length is 1.86 Å. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Cu2+ and one I5+ atom. The O–I bond length is 1.88 Å. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cu2+ and one I5+ atom. The O–I bond length is 1.87 Å. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one I5+ atom. The O–I bond length is 1.86 Å. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Cu2+ and two equivalent I5+ atoms. There are one shorter (1.83 Å) and one longer (2.73 Å) O–I bond lengths. There are two inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 6-coordinate geometry to four O2- atoms. In the second I5+ site, I5+ is bonded in a 4-coordinate geometry to four O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(PtS2)2 by Materials Project

Cu(PtS2)2 is Spinel-like structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are three inequivalent Pt+3.50+ sites. In the first Pt+3.50+ site, Pt+3.50+ is bonded to six S2- atoms to form PtS6 octahedra that share corners with six equivalent CuS4 tetrahedra and edges with six PtS6 octahedra. There are a spread of Pt–S bond distances ranging from 2.40–2.43 Å. In the second Pt+3.50+ site, Pt+3.50+ is bonded to six S2- atoms to form distorted PtS6 octahedra that share corners with two equivalent PtS6 octahedra, corners with four equivalent CuS4 tetrahedra, and edges with six PtS6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are four shorter (2.34 Å) and two longer (2.93 Å) Pt–S bond lengths. In the third Pt+3.50+ site, Pt+3.50+ is bonded to six S2- atoms to form PtS6 octahedra that share corners with two equivalent PtS6 octahedra, corners with four equivalent CuS4 tetrahedra, and edges with six PtS6 octahedra. The corner-sharing octahedral tilt angles are 3°. There are four shorter (2.40 Å) and two longer (2.45 Å) Pt–S bond lengths. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with ten PtS6 octahedra and an edgeedge with one CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Cu–S bond distances ranging from 2.31–2.39 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to two equivalent Pt+3.50+ and two equivalent Cu1+ atoms. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to four Pt+3.50+ atoms. In the third S2- site, S2- is bonded to three Pt+3.50+ and one Cu1+ atom to form a mixture of distorted corner and edge-sharing SCuPt3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(BO2)2 by Materials Project

CuB2O4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. there are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a rectangular see-saw-like geometry to four equivalent O2- atoms. All Cu–O bond lengths are 2.02 Å. In the second Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.92–2.00 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.49 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. All B–O bond lengths are 1.49 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two B3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Cu2+ and two equivalent B3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to one Cu2+ and two equivalent B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Cu2+ and two B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(NO3)2 by Materials Project

Cu(NO3)2 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Cu2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.97–2.40 Å. There are three inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.23 Å) and two longer (1.29 Å) N–O bond length. In the second N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of N–O bond distances ranging from 1.24–1.29 Å. In the third N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.23 Å) and two longer (1.29 Å) N–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one N5+ atom. In the second O2- site, O2- is bonded in a water-like geometry to one Cu2+ and one N5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one N5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one N5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Cu2+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(TeO3)4 by Materials Project

Cu(TeO3)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Cu2+ is bonded in a 3-coordinate geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 1.96–2.54 Å. There are four inequivalent Te+5.50+ sites. In the first Te+5.50+ site, Te+5.50+ is bonded to six O2- atoms to form corner-sharing TeO6 octahedra. The corner-sharing octahedra tilt angles range from 32–40°. There are a spread of Te–O bond distances ranging from 1.95–2.05 Å. In the second Te+5.50+ site, Te+5.50+ is bonded to six O2- atoms to form corner-sharing TeO6 octahedra. The corner-sharing octahedra tilt angles range from 35–42°. There are a spread of Te–O bond distances ranging from 1.94–2.06 Å. In the third Te+5.50+ site, Te+5.50+ is bonded to six O2- atoms to form corner-sharing TeO6 octahedra. The corner-sharing octahedra tilt angles range from 32–42°. There are a spread of Te–O bond distances ranging from 1.96–2.03 Å. In the fourth Te+5.50+ site, Te+5.50+ is bonded to six O2- atoms to form corner-sharing TeO6 octahedra. The corner-sharing octahedra tilt angles range from 33–41°. There are a spread of Te–O bond distances ranging from 1.94–2.05 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Cu2+ and two Te+5.50+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two Te+5.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two Te+5.50+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two Te+5.50+ atoms. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cu2+ and two Te+5.50+ atoms. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms. In the eleventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Cu2+ and two Te+5.50+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(PO3)3 by Materials Project

Cu(PO3)3 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Cu3+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cu–O bond distances ranging from 1.99–2.09 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CuO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–49°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CuO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–56°. There is two shorter (1.51 Å) and two longer (1.61 Å) P–O bond length. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CuO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–45°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cu3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to one Cu3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cu3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(Mo3Se4)2 by Materials Project

Cu(Mo3Se4)2 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Mo+2.50+ is bonded to five Se2- atoms to form a mixture of edge and corner-sharing MoSe5 square pyramids. There are a spread of Mo–Se bond distances ranging from 2.54–2.64 Å. Cu1+ is bonded in a distorted linear geometry to eight Se2- atoms. There are two shorter (2.34 Å) and six longer (3.29 Å) Cu–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 1-coordinate geometry to three equivalent Mo+2.50+ and one Cu1+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to four equivalent Mo+2.50+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(HgN)2 by Materials Project

Cu(HgN)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Cu2+ is bonded in a square co-planar geometry to four N3- atoms. There are two shorter (2.09 Å) and two longer (2.10 Å) Cu–N bond lengths. Hg2+ is bonded in a linear geometry to two N3- atoms. There are one shorter (2.23 Å) and one longer (2.24 Å) Hg–N bond lengths. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a square co-planar geometry to two equivalent Cu2+ and two equivalent Hg2+ atoms. In the second N3- site, N3- is bonded in a square co-planar geometry to two equivalent Cu2+ and two equivalent Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(AgO)2 by Materials Project

Cu(AgO)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ag1+ is bonded in a linear geometry to two O2- atoms. There are one shorter (2.13 Å) and one longer (2.14 Å) Ag–O bond lengths. Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.02 Å) and two longer (2.03 Å) Cu–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a square co-planar geometry to two equivalent Ag1+ and two equivalent Cu2+ atoms. In the second O2- site, O2- is bonded in a square co-planar geometry to two equivalent Ag1+ and two equivalent Cu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(SnS2)4 by Materials Project

Cu(SnS2)4 is beta indium sulfide-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Cu2+ is bonded to four equivalent S2- atoms to form CuS4 tetrahedra that share corners with twelve equivalent SnS6 octahedra. The corner-sharing octahedral tilt angles are 57°. All Cu–S bond lengths are 2.33 Å. Sn+3.50+ is bonded to six S2- atoms to form SnS6 octahedra that share corners with three equivalent CuS4 tetrahedra and edges with six equivalent SnS6 octahedra. There are three shorter (2.60 Å) and three longer (2.67 Å) Sn–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Cu2+ and three equivalent Sn+3.50+ atoms. In the second S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Sn+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(N3Cl)2 by Materials Project

Cu(N3Cl)2 crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. Cu2+ is bonded in an octahedral geometry to six N atoms. There are a spread of Cu–N bond distances ranging from 1.87–1.93 Å. There are five inequivalent N sites. In the first N site, N is bonded in a single-bond geometry to one Cu2+ and four equivalent Cl1- atoms. There are three shorter (2.71 Å) and one longer (2.72 Å) N–Cl bond lengths. In the second N site, N is bonded in a single-bond geometry to one Cu2+ and four equivalent Cl1- atoms. All N–Cl bond lengths are 2.70 Å. In the third N site, N is bonded in a single-bond geometry to one Cu2+ and four equivalent Cl1- atoms. All N–Cl bond lengths are 2.70 Å. In the fourth N site, N is bonded in a single-bond geometry to one Cu2+ and four equivalent Cl1- atoms. All N–Cl bond lengths are 2.98 Å. In the fifth N site, N is bonded in a single-bond geometry to one Cu2+ and four equivalent Cl1- atoms. All N–Cl bond lengths are 2.98 Å. Cl1- is bonded in a 8-coordinate geometry to twelve N atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu(AgO)2 by Materials Project

Cu(AgO)2 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ag1+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. There are two shorter (2.27 Å) and two longer (2.66 Å) Ag–O bond lengths. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.97 Å. O2- is bonded to four equivalent Ag1+ and two equivalent Cu2+ atoms to form a mixture of distorted corner and edge-sharing OCu2Ag4 octahedra. The corner-sharing octahedra tilt angles range from 0–10°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Prediction of the Al-rich part of the Al-Cu phase diagram using cluster expansion and statistical mechanics

In this work, the thermodynamic properties of α-Al and other phases (GP zones, θ'', θ' and θ) in the Al-rich part of the Al-Cu system have been obtained by means of the cluster expansion formalism in combination with statistical mechanics. This information was used to build the Al-rich part of the Al-Cu phase-diagram taking into account vibrational entropic contributions for θ', as those of the other phases were negligible. The simulation predictions of the phase boundaries between α-Al and either θ'', θ' or θ phases as a function of temperature are in good agreement with experimental data and extend the phase boundaries to a wider temperature range. The DFT calculations reveal the presence of a number of metastable Guinier-Preston-zone type configurations that may coexist with α-Al and θ'' at low temperatures. They also demonstrate that θ' is the stable phase below 550K but it is replaced by θ above this temperature due to the vibrational entropic contribution to the Gibbs energy of θ'. This work shows how the combination of cluster expansion and statistical mechanics can be used to expand our knowledge of the phase diagram of metallic alloys and to provide Gibbs free energies of different phases that can be used as input in mesoscale simulations of precipitation.

36 MATERIALS SCIENCE↗