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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Morphological and chemical characteristics of oxide scales formed on δ-phase plutonium metal alloys II: 2.0 at% Ga

The focused ion-beam scanning electron microscopy (FIB-SEM) and three-dimensional (3D) microscopy were applied to characterize the subsurface morphological features of oxide scales formed on an ~2.0 at. % Ga plutonium (Pu) metal alloy. Using the FIB-SEM technique, a number of morphological features formed in the interior of the oxide scale from Pu metal’s environmental exposure were observed and identified. Auger electron spectroscopy (AES) was utilized to characterize the cross-sectional composition and chemistry of the oxide scale. The oxide scale formed during inert storage and operational environments was found to be highly variable in thickness and morphology, presenting some regions with a thin (<400 nm), dense oxide layer and others with a thick (>2 µm) scale with substantial lateral cracking. After subsequent exposure to dry air environment, the oxide scale became thicker (~4 µm) and slightly more porous. The changes following aging in a moist air environment were observed to be more severe, with the formation of a highly porous internal structure containing significant lateral and transverse cracking. In comparison to the scale formed on an ~3.5 at. % Ga-Pu metal alloy, the oxide morphology of the lower gallium alloy investigated here exhibited greater variation in thickness and a noteworthy dependence on the presence of water vapor, particularly in terms of the internal porosity formed during growth of the oxide.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu3Ga by Materials Project

Pu3Ga is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pu is bonded to eight equivalent Pu and four equivalent Ga atoms to form distorted PuPu8Ga4 cuboctahedra that share corners with twelve equivalent PuPu8Ga4 cuboctahedra, edges with eight equivalent GaPu12 cuboctahedra, edges with sixteen equivalent PuPu8Ga4 cuboctahedra, faces with four equivalent GaPu12 cuboctahedra, and faces with fourteen equivalent PuPu8Ga4 cuboctahedra. All Pu–Pu bond lengths are 2.92 Å. All Pu–Ga bond lengths are 2.92 Å. Ga is bonded to twelve equivalent Pu atoms to form GaPu12 cuboctahedra that share corners with twelve equivalent GaPu12 cuboctahedra, edges with twenty-four equivalent PuPu8Ga4 cuboctahedra, faces with six equivalent GaPu12 cuboctahedra, and faces with twelve equivalent PuPu8Ga4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa2 by Materials Project

PuGa2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Pu is bonded to twelve equivalent Ga atoms to form a mixture of edge and face-sharing PuGa12 cuboctahedra. All Pu–Ga bond lengths are 3.16 Å. Ga is bonded in a 9-coordinate geometry to six equivalent Pu and three equivalent Ga atoms. All Ga–Ga bond lengths are 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa3 by Materials Project

PuGa3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pu is bonded to twelve equivalent Ga atoms to form a mixture of corner and face-sharing PuGa12 cuboctahedra. There are six shorter (2.97 Å) and six longer (3.06 Å) Pu–Ga bond lengths. Ga is bonded in a 4-coordinate geometry to four equivalent Pu and six equivalent Ga atoms. There are four shorter (2.84 Å) and two longer (2.87 Å) Ga–Ga bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa3 by Materials Project

PuGa3 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Pu sites. In the first Pu site, Pu is bonded to twelve Ga atoms to form PuGa12 cuboctahedra that share corners with nine PuGa12 cuboctahedra, edges with twelve equivalent GaPu4Ga8 cuboctahedra, faces with seven PuGa12 cuboctahedra, and faces with nine equivalent GaPu4Ga8 cuboctahedra. There are a spread of Pu–Ga bond distances ranging from 3.01–3.08 Å. In the second Pu site, Pu is bonded to twelve Ga atoms to form PuGa12 cuboctahedra that share corners with six equivalent GaPu4Ga8 cuboctahedra, corners with nine PuGa12 cuboctahedra, edges with nine equivalent GaPu4Ga8 cuboctahedra, faces with three equivalent GaPu4Ga8 cuboctahedra, and faces with seven PuGa12 cuboctahedra. There are a spread of Pu–Ga bond distances ranging from 3.01–3.08 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded in a 4-coordinate geometry to four Pu and six Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.81–2.93 Å. In the second Ga site, Ga is bonded to four Pu and eight Ga atoms to form distorted GaPu4Ga8 cuboctahedra that share corners with two equivalent PuGa12 cuboctahedra, corners with six equivalent GaPu4Ga8 cuboctahedra, edges with seven PuGa12 cuboctahedra, edges with eight equivalent GaPu4Ga8 cuboctahedra, faces with four PuGa12 cuboctahedra, and faces with nine equivalent GaPu4Ga8 cuboctahedra. There are a spread of Ga–Ga bond distances ranging from 2.99–3.08 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa by Materials Project

PuGa crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are three inequivalent Pu sites. In the first Pu site, Pu is bonded in a 12-coordinate geometry to eight equivalent Ga atoms. All Pu–Ga bond lengths are 3.13 Å. In the second Pu site, Pu is bonded in a 8-coordinate geometry to eight equivalent Ga atoms. There are four shorter (3.13 Å) and four longer (3.19 Å) Pu–Ga bond lengths. In the third Pu site, Pu is bonded in a 8-coordinate geometry to eight equivalent Ga atoms. There are four shorter (3.12 Å) and four longer (3.20 Å) Pu–Ga bond lengths. Ga is bonded in a distorted q6 geometry to eight Pu and two equivalent Ga atoms. Both Ga–Ga bond lengths are 2.70 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa4 by Materials Project

PuGa4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Pu is bonded in a 11-coordinate geometry to thirteen Ga atoms. There are a spread of Pu–Ga bond distances ranging from 2.97–3.13 Å. There are three inequivalent Ga sites. In the first Ga site, Ga is bonded in a 9-coordinate geometry to three equivalent Pu and six Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.58–2.91 Å. In the second Ga site, Ga is bonded to four equivalent Pu and eight Ga atoms to form a mixture of distorted edge, face, and corner-sharing GaPu4Ga8 cuboctahedra. There are four shorter (3.02 Å) and two longer (3.06 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 3-coordinate geometry to three equivalent Pu and eight Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa by Materials Project

PuGa crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Pu sites. In the first Pu site, Pu is bonded in a 5-coordinate geometry to one Pu and eight equivalent Ga atoms. The Pu–Pu bond length is 2.29 Å. There are four shorter (2.93 Å) and four longer (3.25 Å) Pu–Ga bond lengths. In the second Pu site, Pu is bonded in a 8-coordinate geometry to eight equivalent Ga atoms. All Pu–Ga bond lengths are 3.00 Å. Ga is bonded in a 10-coordinate geometry to eight Pu and two equivalent Ga atoms. Both Ga–Ga bond lengths are 2.55 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa6 by Materials Project

PuGa6 crystallizes in the tetragonal P4/nbm space group. The structure is three-dimensional. Pu is bonded to twelve Ga atoms to form a mixture of edge and face-sharing PuGa12 cuboctahedra. There are four shorter (3.10 Å) and eight longer (3.18 Å) Pu–Ga bond lengths. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded in a 4-coordinate geometry to one Pu and three Ga atoms. There are one shorter (2.56 Å) and two longer (2.62 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 9-coordinate geometry to four equivalent Pu and five Ga atoms. The Ga–Ga bond length is 2.41 Å.

36 MATERIALS SCIENCE↗