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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ce(Al4Fe)2 by Materials Project

CeFe2Al8 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to thirteen Al atoms. There are a spread of Ce–Al bond distances ranging from 3.13–3.33 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 9-coordinate geometry to nine Al atoms. There are a spread of Fe–Al bond distances ranging from 2.34–2.58 Å. In the second Fe site, Fe is bonded in a 9-coordinate geometry to nine Al atoms. There are a spread of Fe–Al bond distances ranging from 2.33–2.57 Å. There are nine inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–3.09 Å. In the second Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and six Al atoms. There are a spread of Al–Al bond distances ranging from 2.64–2.82 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to four equivalent Fe and four Al atoms. Both Al–Al bond lengths are 2.66 Å. In the fourth Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–3.00 Å. In the fifth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and six Al atoms. Both Al–Al bond lengths are 2.84 Å. In the sixth Al site, Al is bonded in a 1-coordinate geometry to three Fe and four Al atoms. Both Al–Al bond lengths are 3.02 Å. In the seventh Al site, Al is bonded in a distorted linear geometry to two equivalent Ce, two Fe, and eight Al atoms. In the eighth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms. Both Al–Al bond lengths are 2.90 Å. In the ninth Al site, Al is bonded in a distorted linear geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(In2Pd)2 by Materials Project

CePd2In4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to four Pd and ten In atoms. There are two shorter (3.25 Å) and two longer (3.36 Å) Ce–Pd bond lengths. There are a spread of Ce–In bond distances ranging from 3.25–3.69 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to two equivalent Ce and seven In atoms. There are a spread of Pd–In bond distances ranging from 2.74–3.06 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to two equivalent Ce and seven In atoms. There are a spread of Pd–In bond distances ranging from 2.72–2.80 Å. There are four inequivalent In sites. In the first In site, In is bonded in a 3-coordinate geometry to three equivalent Ce and three equivalent Pd atoms. In the second In site, In is bonded in a 4-coordinate geometry to one Ce and four Pd atoms. In the third In site, In is bonded in a 4-coordinate geometry to three equivalent Ce and four Pd atoms. In the fourth In site, In is bonded in a 3-coordinate geometry to three equivalent Ce and three equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(IO3)2 by Materials Project

Ce(O3I)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ce–O bond distances ranging from 2.09–2.64 Å. There are six inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to two equivalent Ce and one I atom. The O–I bond length is 1.90 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Ce and one I atom. The O–I bond length is 1.83 Å. In the third O site, O is bonded in a 1-coordinate geometry to one Ce and one I atom. The O–I bond length is 1.87 Å. In the fourth O site, O is bonded in a distorted trigonal planar geometry to one Ce and two I atoms. There are one shorter (1.87 Å) and one longer (2.64 Å) O–I bond lengths. In the fifth O site, O is bonded in a water-like geometry to two equivalent Ce atoms. In the sixth O site, O is bonded in a distorted trigonal planar geometry to one Ce and two I atoms. There are one shorter (1.93 Å) and one longer (2.51 Å) O–I bond lengths. There are two inequivalent I sites. In the first I site, I is bonded in a 3-coordinate geometry to four O atoms. In the second I site, I is bonded in a 2-coordinate geometry to three O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(SO6)2 by Materials Project

Ce(SO6)2 crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two Ce(SO6)2 sheets oriented in the (0, 0, 1) direction. Ce is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ce–O bond distances ranging from 2.12–2.48 Å. S is bonded in a tetrahedral geometry to four O atoms. There is three shorter (1.48 Å) and one longer (1.50 Å) S–O bond length. There are seven inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Ce and one S atom. In the third O site, O is bonded in a single-bond geometry to one Ce atom. In the fourth O site, O is bonded in a single-bond geometry to one Ce atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Ce and one S atom. In the sixth O site, O is bonded in a single-bond geometry to one Ce atom. In the seventh O site, O is bonded in a single-bond geometry to one S atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Al5Fe)2 by Materials Project

Al10Fe2Ce crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ce is bonded in a 8-coordinate geometry to four equivalent Fe and sixteen Al atoms. All Ce–Fe bond lengths are 3.41 Å. There are a spread of Ce–Al bond distances ranging from 3.12–3.62 Å. Fe is bonded in a 10-coordinate geometry to two equivalent Ce and ten Al atoms. There are a spread of Fe–Al bond distances ranging from 2.52–2.71 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.61–2.82 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to one Ce, two equivalent Fe, and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.67–3.02 Å. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.57–2.75 Å. In the fourth Al site, Al is bonded in a 2-coordinate geometry to one Ce, two equivalent Fe, and eight Al atoms. There are one shorter (2.70 Å) and two longer (2.78 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Fe, and eight Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Ce IV 70 Oxosulfate Rings, Frameworks, Supramolecular Assembly, and Redox Activity**

Abstract 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. 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. This study opens the door to mixed‐metal, highly porous framework catalysts, and new clusters for metal‐organic framework design

Colliard, Ian↗
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↗
DOE OSTI2020

Thallium-based scintillators for high-resolution gamma-ray spectroscopy: Ce 3+ - doped Tl 2 LaCl 5 and Tl 2 LaBr 5

In this paper we report on the crystallographic and scintillation properties of Tl 2 LaCl 5 :Ce 3 + and Tl 2 LaBr 5 :Ce 3 + , two novel thallium-containing high-resolution scintillators for gamma-ray spectroscopy. Crystals of Tl 2 LaCl 5 :Ce 3 + and Tl 2 LaBr 5 :Ce 3 + were grown by the Vertical Bridgman method up to 1-inch diameter and 1-inch long. Single crystals of Tl 2 LaCl 5 :Ce 3 + and Tl 2 LaBr 5 :Ce 3 + belong to the orthorhombic system with space group 62 and have a density of 5.16 and 5.98 g/cm 3 , respectively. The scintillators show high light yields of up to 68,000 photons/MeV, excellent gamma-ray energy resolution of ≤ 3% at 662 keV, a fast scintillation decay, and a proportional response over a wide range of energies from 32 keV up to 1275 keV. Density Functional Theory calculations show that the Ce 3 + energy levels are inside the bandgap despite the smaller bandgap of Tl 2 LaCl 5 and Tl 2 LaBr 5 compared to K 2 LaCl 5 and K 2 LaBr 5 . Finally, a systematic Ce 3 + concentration study was performed for Tl 2 LaCl 5 :Ce 3 + and trends observed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
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(SnPd)2 by Materials Project

Ce(PdSn)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 Sn atoms. There are four shorter (3.46 Å) and four longer (3.54 Å) Ce–Pd bond lengths. There are four shorter (3.49 Å) and four longer (3.56 Å) Ce–Sn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Sn atoms. All Pd–Sn bond lengths are 2.67 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.60 Å) and four longer (2.68 Å) Pd–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Ce and four equivalent Pd atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Pd atoms.

36 MATERIALS SCIENCE↗