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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Ce IV 70 oxosulfate rings, frameworks, supramolecular assembly and redox activity

M IV molecular oxo-clusters (M=Zr, Hf, Ce, Th, U, Np, Pu) are prolific in bottoms-up material design, catalysis, and elucidating reaction pathways in nature and in synthesis. Here we introduce Ce 70 , a wheel-shaped oxo-cluster, [Ce IV 70 -(OH) 36 (O) 64 (SO 4 ) 60 (H 2 O) 10 ] 4- . Ce 70 crystallizes into intricate high pore volume frameworks with divalent transition metals and Ce-monomer linkers. Eight crystal-structures feature four framework types in which the Ce 70 -rings are linked as propellers, in offset-stacks, in a tartan pattern, and as isolated rings. In this work, small-angle X-ray scattering of Ce 70 dissolved in butylamine, with and without added cations (Ce IV , alkaline earths, Mn II ), shows the metals‘ differentiating roles in ring linking, leading to supramolecular assemblies. The large acidic pores and abundant terminal sulfates provide ion-exchange behavior, demonstrated with U IV and Nd III . Frameworks featuring Ce III/IV -monomer linkers demonstrate both oxidation and reduction. Furthermore, this study opens the door to mixed-metal, highly porous framework catalysts, and new clusters for metal-organic framework design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Hypereutectic Al-Ce-X (X=Mn, Cr, V, Mo, W) alloys fabricated by laser powder-bed fusion

Here, we characterize the microstructures and high-temperature mechanical properties of Al-2Ce and ternary Al-2Ce-1X (at.%) alloys fabricated by laser powder-bed fusion (LPBF), where X = Mn, Cr, V, Mo, and W are slow-diffusing transition metals. All ternary alloys show a hypereutectic microstructure in the as-LPBF state, containing an interconnected network of eutectic Al 11 Ce 3 phases (~10 vol.%) and an additional population of submicron, equiaxed Al 20 CeX 2 primary precipitates (~10 vol.%) which are isomorphous among these five alloys. Similar microstructures are present in arc-melted rods and atomized powders but are coarser due to the slower cooling rates in these processes. The hardness of the as-LPBF ternary Al-Ce-X alloys (1300–1400 MPa) is higher than that of the binary Al-Ce alloy (~1100 MPa) due to the higher volume fraction of strengthening phases. Furthermore, during exposure at 400 °C for up to three months, greater hardness retention is achieved in the ternary Al-Ce-X alloys (65–75%) than in the binary Al-Ce alloy (~55%), which is attributed to the extreme coarsening resistance of the Al 20 CeX 2 precipitates imparted by the very slow-diffusing ternary solute. These coarsening-resistant Al 20 CeX 2 precipitates also substantially improve alloy creep resistance, increasing the threshold stress for dislocation creep at 300°C from ~32 MPa for the binary Al-Ce alloy to ~77–100 MPa for the ternary Al-Ce-X alloys, and at 400°C from <10 MPa for the binary Al-Ce alloy to >40 MPa for the ternary Al-Ce-V alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Phase stability in cast and additively manufactured Al-rich Al-Cu-Ce alloys

Additively manufactured (AM) eutectic Al alloy systems have been studied extensively for advantageous thermal stability and mechanical properties due to their refined microstructures. Al-Cu-Ce alloys are one subset of these AM eutectic alloys. Here we studied phase stability in AM Al-Cu-Ce alloys and compared it to that of conventionally cast ones. A new phase, Al 8 Cu 3 Ce, was identified in the microstructures of both AM and cast Al-Cu-Ce alloys. This Al 8 Cu 3 Ce phase was not previously included on experimental or thermodynamically calculated phase diagrams of the Al-Cu-Ce system. Therefore, we performed additional thermodynamic modeling of the system. These models were experimentally validated with cast and subsequently heat-treated Al-Cu-Ce alloys. We found that despite the refined microstructure of the AM alloys, the phases formed were consistent with the cast alloys, suggesting that AM processing did not significantly alter the formation and stability of phases from that in the conventional alloys. In conclusion, this work has resolved inconsistent previous descriptions of the Al-Cu-Ce ternary phase diagram in the Al-rich region and resulted in the addition of the Al 8 Cu 3 Ce as an equilibrium phase above 500 °C.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Earth's partial pressure of CO2 over the past 120 Ma; evidence from Ce anomalies in the deep (greater than 600 m) Pacific Ocean, 1

It was found that Ce serves as a chemical tracer of paleo-oceanic redox conditions. It was shown that the unoxidized and soluble Ce(3+) in modern seawater exhibits a negative anomaly relative to the other soluble REE(3+). An expression of soluble Ce(3+) in seawater that was approximately 1900X greater than the average observed in Ce in 600-5000 m Pacific seawater was derived. Since Ce(CO3)(+) and Ce(CO3)2(-) complexes greatly exceed the Ce(PO4) complexes in seawater, the formulations of using carbonate complexes were followed and it was found that the calculated Ce and observed concentrations in the deep 600-5000 m Pacific Ocean agree within the uncertainties of the thermodynamic data. As expected, the calculated Ce concentrations are a strong function of pH and found to be lesser functions of CO3(2-) activities.

Liu, Y.-G↗
DOE OSTI2020

Materials Data on Ce(GePt)2 by Materials Project

Ce(PtGe)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Pt and eight Ge atoms. There are four shorter (3.34 Å) and four longer (3.35 Å) Ce–Pt bond lengths. There are four shorter (3.30 Å) and four longer (3.35 Å) Ce–Ge bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Ge atoms. All Pt–Ge bond lengths are 2.55 Å. In the second Pt site, Pt is bonded in a 5-coordinate geometry to four equivalent Ce and five Ge atoms. There are one shorter (2.46 Å) and four longer (2.52 Å) Pt–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Pt atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Ce and five Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SnIr)2 by Materials Project

Ce(IrSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Ir and eight Sn atoms. There are four shorter (3.40 Å) and four longer (3.50 Å) Ce–Ir bond lengths. There are four shorter (3.38 Å) and four longer (3.56 Å) Ce–Sn bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.59 Å) and four longer (2.66 Å) Ir–Sn bond lengths. In the second Ir site, Ir is bonded to four equivalent Ce and four equivalent Sn atoms to form distorted IrCe4Sn4 tetrahedra that share corners with twelve equivalent SnCe4Ir4 tetrahedra, edges with two equivalent SnCe4Ir4 tetrahedra, edges with four equivalent IrCe4Sn4 tetrahedra, and faces with four equivalent IrCe4Sn4 tetrahedra. All Ir–Sn bond lengths are 2.64 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Ir atoms. In the second Sn site, Sn is bonded to four equivalent Ce and four equivalent Ir atoms to form distorted SnCe4Ir4 tetrahedra that share corners with twelve equivalent IrCe4Sn4 tetrahedra, edges with two equivalent IrCe4Sn4 tetrahedra, edges with four equivalent SnCe4Ir4 tetrahedra, and faces with four equivalent SnCe4Ir4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(PRh)2 by Materials Project

Ce(RhP)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Rh and eight P atoms. There are four shorter (3.19 Å) and four longer (3.21 Å) Ce–Rh bond lengths. There are four shorter (3.12 Å) and four longer (3.15 Å) Ce–P bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 9-coordinate geometry to four equivalent Ce and five P atoms. There are four shorter (2.35 Å) and one longer (2.36 Å) Rh–P bond lengths. In the second Rh site, Rh is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent P atoms. All Rh–P bond lengths are 2.47 Å. There are two inequivalent P sites. In the first P site, P is bonded in a 8-coordinate geometry to four equivalent Ce and four equivalent Rh atoms. In the second P site, P is bonded in a 9-coordinate geometry to four equivalent Ce and five Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(ClO)3 by Materials Project

Ce(OCl)3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ce is bonded in a 1-coordinate geometry to three O and five Cl atoms. There are one shorter (2.04 Å) and two longer (2.38 Å) Ce–O bond lengths. There are a spread of Ce–Cl bond distances ranging from 2.79–2.98 Å. There are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Ce atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Ce and one Cl atom. The O–Cl bond length is 2.32 Å. There are two inequivalent Cl sites. In the first Cl site, Cl is bonded in a distorted trigonal planar geometry to one Ce and two equivalent O atoms. In the second Cl site, Cl is bonded in a water-like geometry to two equivalent Ce atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(AsRh)2 by Materials Project

Ce(RhAs)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Rh and eight As atoms. There are four shorter (3.30 Å) and four longer (3.32 Å) Ce–Rh bond lengths. There are four shorter (3.25 Å) and four longer (3.29 Å) Ce–As bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent As atoms. All Rh–As bond lengths are 2.56 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to four equivalent Ce and five As atoms. There are one shorter (2.42 Å) and four longer (2.47 Å) Rh–As bond lengths. There are two inequivalent As sites. In the first As site, As is bonded in a 8-coordinate geometry to four equivalent Ce and four equivalent Rh atoms. In the second As site, As is bonded in a 9-coordinate geometry to four equivalent Ce and five Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(AlAu)2 by Materials Project

Ce(AuAl)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight Au and eight Al atoms. There are four shorter (3.38 Å) and four longer (3.42 Å) Ce–Au bond lengths. There are four shorter (3.39 Å) and four longer (3.43 Å) Ce–Al bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded to four equivalent Ce and four equivalent Al atoms to form distorted AuCe4Al4 tetrahedra that share corners with twelve equivalent AlCe4Au4 tetrahedra, edges with two equivalent AlCe4Au4 tetrahedra, edges with four equivalent AuCe4Al4 tetrahedra, and faces with four equivalent AuCe4Al4 tetrahedra. All Au–Al bond lengths are 2.59 Å. In the second Au site, Au is bonded in a 5-coordinate geometry to four equivalent Ce and five Al atoms. There are one shorter (2.51 Å) and four longer (2.61 Å) Au–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ce and four equivalent Au atoms to form distorted AlCe4Au4 tetrahedra that share corners with twelve equivalent AuCe4Al4 tetrahedra, edges with two equivalent AuCe4Al4 tetrahedra, edges with four equivalent AlCe4Au4 tetrahedra, and faces with four equivalent AlCe4Au4 tetrahedra. In the second Al site, Al is bonded in a 5-coordinate geometry to four equivalent Ce and five Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SbPd)2 by Materials Project

Ce(PdSb)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Pd and eight Sb atoms. There are four shorter (3.44 Å) and four longer (3.59 Å) Ce–Pd bond lengths. There are four shorter (3.51 Å) and four longer (3.58 Å) Ce–Sb bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 8-coordinate geometry to four equivalent Ce and four equivalent Sb atoms. All Pd–Sb bond lengths are 2.70 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to four equivalent Ce and five Sb atoms. There are one shorter (2.58 Å) and four longer (2.68 Å) Pd–Sb bond lengths. There are two inequivalent Sb sites. In the first Sb site, Sb is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Pd atoms. In the second Sb site, Sb is bonded in a 9-coordinate geometry to four equivalent Ce and five Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SnRh)2 by Materials Project

Ce(RhSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Rh and eight Sn atoms. There are four shorter (3.45 Å) and four longer (3.48 Å) Ce–Rh bond lengths. There are four shorter (3.44 Å) and four longer (3.53 Å) Ce–Sn bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Sn atoms. All Rh–Sn bond lengths are 2.64 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.57 Å) and four longer (2.67 Å) Rh–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded to four equivalent Ce and four equivalent Rh atoms to form a mixture of distorted face and edge-sharing SnCe4Rh4 tetrahedra. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(GaPd)2 by Materials Project

Ce(PdGa)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 4-coordinate geometry to eight Pd and eight Ga atoms. There are four shorter (3.27 Å) and four longer (3.41 Å) Ce–Pd bond lengths. There are four shorter (3.32 Å) and four longer (3.34 Å) Ce–Ga bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded to four equivalent Ce and four equivalent Ga atoms to form distorted PdCe4Ga4 tetrahedra that share corners with twelve equivalent GaCe4Pd4 tetrahedra, edges with two equivalent GaCe4Pd4 tetrahedra, edges with four equivalent PdCe4Ga4 tetrahedra, and faces with four equivalent PdCe4Ga4 tetrahedra. All Pd–Ga bond lengths are 2.54 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to four equivalent Ce and five Ga atoms. There are one shorter (2.49 Å) and four longer (2.55 Å) Pd–Ga bond lengths. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded to four equivalent Ce and four equivalent Pd atoms to form distorted GaCe4Pd4 tetrahedra that share corners with twelve equivalent PdCe4Ga4 tetrahedra, edges with two equivalent PdCe4Ga4 tetrahedra, edges with four equivalent GaCe4Pd4 tetrahedra, and faces with four equivalent GaCe4Pd4 tetrahedra. In the second Ga site, Ga is bonded in a 9-coordinate geometry to four equivalent Ce and five Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(ZnAu2)2 by Materials Project

Ce(Au2Zn)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded to twelve Au atoms to form a mixture of distorted edge and face-sharing CeAu12 cuboctahedra. There are four shorter (3.02 Å) and eight longer (3.35 Å) Ce–Au bond lengths. There are five inequivalent Au sites. In the first Au site, Au is bonded in a 11-coordinate geometry to three equivalent Ce, four Au, and four equivalent Zn atoms. There are two shorter (2.80 Å) and two longer (2.89 Å) Au–Au bond lengths. All Au–Zn bond lengths are 2.89 Å. In the second Au site, Au is bonded in a 11-coordinate geometry to three equivalent Ce, four Au, and four equivalent Zn atoms. There are two shorter (2.80 Å) and two longer (2.89 Å) Au–Au bond lengths. All Au–Zn bond lengths are 2.89 Å. In the third Au site, Au is bonded in a 11-coordinate geometry to three equivalent Ce, four Au, and four equivalent Zn atoms. Both Au–Au bond lengths are 2.89 Å. All Au–Zn bond lengths are 2.89 Å. In the fourth Au site, Au is bonded in a 11-coordinate geometry to three equivalent Ce, four Au, and four equivalent Zn atoms. Both Au–Au bond lengths are 2.80 Å. All Au–Zn bond lengths are 2.89 Å. In the fifth Au site, Au is bonded in a 11-coordinate geometry to three equivalent Ce, four Au, and four equivalent Zn atoms. The Au–Au bond length is 2.80 Å. All Au–Zn bond lengths are 2.89 Å. Zn is bonded in a 10-coordinate geometry to eight Au and two equivalent Zn atoms. Both Zn–Zn bond lengths are 2.70 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4‐Amino‐1,2,4‐triazole

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH 2 -1,2,4-Triaz), 5-amino-tetrazole (5-NH 2 -HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1 : 1 and 1 : 3 ratios with CeCl 3 ⋅ 7H 2 O, [C 2 mim] 3 [CeCl 6 ] ([C 2 mim] + =1-ethyl-2-methylimidazolium), and Ce(NO 3 ) 3 ⋅ 6H 2 O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH 2 -1,2,4-Triaz is structure directing via η 2 μ 2 κ 2 bridging, with the formation of the dinuclear complexes [Ce 2 Cl 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 (H 2 O) 8 ]Cl 4 ⋅ 4H 2 O, [Ce 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 4 (4-NH 2 -1,2,4-Triaz) 2 (Cl) 6 ], and [4-NH 2 -1,2,4-HTriaz][Ce 2 (μ 2 -4-NH 2 -1,2,4-Triaz) 2 (μ 2 -NO 3 )(NO 3 ) 6 (H 2 O) 2 ]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 2 (μ 3 -Cl) 2 (Cl) 6 (μ 2 -4-NH 2 -1,2,4-Triaz) 12 ] ⋅ 7H 2 O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M 6 X 8 core, and the first reported Ce(III) hexanuclear complex of this type.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Combining solution-, precipitation- and load-transfer strengthening in a cast Al-Ce-Mn- Sc -Zr alloy

Here, a cast Al-9Ce-0.75Mn-0.18Sc-0.12Zr (wt%) alloy is designed to combine three strengthening phases: (i) micron-scale Al 11 Ce 3 platelets formed during eutectic solidification, (ii) nano-scale L1 2 -Al 3 (Sc,Zr) precipitates formed during aging, and (iii) Mn in solid solution in the α-Al matrix. Microstructural analyses by SEM, TEM, and atom-probe tomography reveal that Mn remains in solid solution in the as-cast alloy, providing solution strengthening with no influence on the eutectic Al-Al 11 Ce 3 microstructure, which provides precipitation- and load-transfer strengthening. During long-term over-aging at 400 °C, Mn-rich precipitates grow at the Al-Al 11 Ce 3 interface, with no effect on the microhardness. However, after short aging at 350 °C, a high number density of fine L1 2 -Al 3 (Sc,Zr) nanoprecipitates form in the Al matrix (with a coarser size at the Al-Al 11 Ce 3 interface), providing precipitation strengthening. The synergistic combination of the three strengthening mechanisms (solution, precipitation, and load transfer) in our Al-Ce-Mn-Sc-Zr alloy results in higher microhardness after aging at 350 and 400 °C, and higher creep resistance at 300 °C, as compared to alloys with two strengthening mechanisms: an Al-10Ce-0.93Mn control alloy (without precipitation strengthening from Sc and Zr), Al-Ce-Sc-Zr (without solution strengthening from Mn), and Al-Mn-Zr-Er (without load-transfer strengthening from Ce). Furthermore, these dual-strengthened alloys are more creep resistant than alloys with a single strengthening mechanism (Al-Ce, Al-Mn, and Al-Sc-Zr), confirming that the three mechanisms can be combined in pairs or all together.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Primary solidification of ternary compounds in Al-rich Al–Ce–Mn alloys

Primary solidification of ternary compounds Al 20 Mn 2 Ce and Al 10 Mn 2 Ce were analyzed through the coupling of the thermodynamic modeling and classic nucleation theory. Thermodynamic models of Al 20 Mn 2 Ce and Al 10 Mn 2 Ce were developed using the CALPHAD approach based on first-principles calculated enthalpy of formation and experimental data obtained from this work and the literature. The analysis suggested that despite the larger thermodynamic driving force for nucleation of Al 10 Mn 2 Ce, nucleation is preferred for the Al 20 Mn 2 Ce phase in the highly undercooled liquid due to its smaller interfacial energy. Therefore, manufacturing methods with rapid cooling rates will favor primary solidification of Al 20 Mn 2 Ce for Al-rich Al–Ce–Mn alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Thin film combinatorial sputtering of Al-Ce alloys: Investigating the phase separation of as-deposited solid solutions and determining the coefficient of thermal expansion

Al x Ce 100–x thin films with a composition range of ~75.0 < x < 99.5 at% (36.5 < x < 97.5 wt%) were synthesized via combinatorial co-sputtering from an Al and an Al 50 Ce 50 target. The crystal structure, phase fraction, film morphology, electrical resistivity, and temperature-dependent coefficients of thermal expansion (CTE) are all correlated to the Al x Ce 100–x composition. The as-deposited films form a metastable solid-solution, and annealing leads to the formation of the thermodynamically stable two-phase system of Al and the α-Al 11 Ce 3 intermetallic. Temperature dependent x-ray diffraction (XRD) reveals that the two phases expand independently of one another, and the thin film Al temperature-dependent CTE is similar to bulk Al. The thin film Al 11 Ce 3 intermetallic phase has a nearly constant CTE of ~1.5 × 10 –5 /°C within the temperature range studied (25–550 °C). To confirm the thin film Al 11 Ce 3 results, bulk stoichiometric Al 11 Ce 3 and +/- 1 wt% Ce samples were prepared and the CTE of each was measured with the same conditions. A Rietveld analysis of the bulk data enabled an estimation of the CTE in each of the 3 orthorhombic lattice parameters, which displayed anisotropic behavior. The thin film and bulk CTE measurements were in very good agreement. Estimations of the temperature dependent CTE of the two-phase alloys are made via the Reuss and Voigt models. Finally, by demonstrating the efficacy of the approach, more complex multi-component rapid materials discovery of low CTE Al-alloys can be pursued via the combinatorial thin film synthesis and XRD measurement.

36 MATERIALS SCIENCE↗