Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Al-O”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Crystal Structure of an Anisotropic Pyrope Garnet That Contains Two Cubic Phases

The crystal structure of two different samples of pyrope garnet, ideally Mg 3 Al 2 Si 3 O 12 , from South Africa was refined using the Rietveld method, space group Ia3¯d, and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Sample 1 from Wesselton Mine is a single cubic phase and is optically isotropic. Electron-probe microanalysis (EPMA) provided an average composition {Mg 2.30 Fe 2+ 0.26 Ca 0.42 Mn 2+ 0.02 } Σ3 [Al 1.53 Fe 3+ 0.06 Cr 3+ 0.40 Ti 4+ 0.01 Fe 2+ 0.01 ] Σ2 Si 3 O 12 , which contains a significant amount of Cr cations. The unit-cell parameter (Å) and bond distances (Å) are a = 11.56197(1) Å, average = 2.2985, Al-O = 1.9101(4), and Si-O = 1.6343(3) Å. Sample 2 from De Beers Diamond Mine has an average composition {Mg 2.33 Fe 2+ 0.33 Ca 0.33 Mn 2+ 0.01 } Σ3 [Al 1.73 Fe 3+ 0.12 Cr 3+ 0.06 Ti 4+ 0.05 Fe 2+ 0.05 ] Σ2 Si 3 O 12 and is a fine-scale intergrowth of two cubic phases. The weight percentage, unit-cell parameter (Å), and bond distances (Å) for phase 2a are 62.2(1)%, a = 11.56185(1) Å, average = 2.3006, Al-O = 1.9080(4), Si-O = 1.6334(4) Å. The corresponding values for phase 2b are 37.8(1)%, a = 11.53896(1) Å, average = 2.2954, Al-O = 1.9020(6), Si-O = 1.6334(6) Å. The two cubic phases in sample 2 cause the crystal to be optically anisotropic because of strain induce birefringence. The unit-cell parameter and bond distances for sample 1 are similar to those in phase 2a.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fast oxygen redox enabled by flexible Al–O bonds in P2-type layered oxides for sodium batteries

Sodium-ion batteries (SIBs) exhibit significant potential for large-scale energy storage systems due to the abundance and low cost of sodium resources. Triggering lattice oxygen redox (LOR) in P2-type transition metal oxides is considered a promising approach to enhance energy density in SIB cathodes, providing high operating potential and substantial capacity. However, irreversible phase transitions associated with LOR, particularly from prisms (P-type stacking) to octahedrons (O-type stacking), lead to severe structural distortions and sluggish Na + diffusion kinetics. In this work, an Al-substitution strategy is proposed to suppress the formation of O-type stacking and instead promote the formation of a beneficial Z phase. Furthermore, the flexible Al-O bonds accommodate asymmetric variations in their occupied states during the sodiation process, mitigating local structural distortions through Al-O bond contraction. Stabilization of the local structure ensures the maintenance of a robust Na + diffusion pathway. As a result, the Al-substituted cathode achieves a low Na + diffusion barrier of 0.47 eV and delivers a capacity of 86 mAh/g even at a high current density of 1 A/g within 1.5–4.5 V, maintaining 62.5% capacity retention over 100 cycles.

36 MATERIALS SCIENCE↗
DOE OSTI2022

In-situ radiation response of additively manufactured modified Inconel 718 alloys

Here in this study, a novel alloy of modified Inconel 718 produced by laser powder bed fusion is studied before and after in-situ Kr irradiation up to 3 dpa at 200 and 450 °C. Before irradiation, the microstructure consists of dislocation cells having a misorientation angle less than 5° and with an average size of ~500 nm. There are also second phase particles of MC type carbides, Laves phase and oxides such as Y-O, Y-(Ti)-Al-O. While the microstructure consists of stacking fault tetrahedra, faulted and perfect loops after irradiation at 200 °C, dislocation loops are the primary defects at 450 °C. With increasing dose, the size of the defects remains similar at 200 °C while it increases at 450 °C. This has been attributed to the existence of vacancy type defects at 200 °C and the different defect transport mechanisms at different temperatures. Moreover, matrix and second phase particle compositions seem to be similar after irradiation. The sink strengths of the structures have been calculated and superior radiation resistance of this alloy has been attributed to the existence of fine cell boundaries stabilized by the second phase particles produced by additive manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Mechanisms of dissolution from gibbsite step edges elucidated by ab initio molecular dynamics with enhanced sampling

Surface reactions underpin our collective understanding of mineral dissolution. This impacts a range of predictive geochemical models (for weathering, the fate and transport of metals) as well as industrial utilization of minerals. Yet atomistic details are rarely known due to the complex mineral/fluid interfacial environment. There is significant need to understand the mechanistic details of dissolution reactions and how they depend on surface morphology and solution conditions. This work utilizes surface pit models in conjunction with changes to solution composition that mimic pH to explore surface detachment of aluminate from gibbsite, which is a primary source of Al in soils and within the industrial processing of aluminum. Ab initio molecular dynamics simulations with enhanced sampling has been used to explore the detailed process of the detachment, the results of which indicate two potential pathways that are differentiated based upon the extent of water hydration. Here, the heights of the energy barriers depend upon the local morphology which influence the number of bridges (quasi-)simultaneously broken (1 or 2) or the Al-O coordination of the neighboring aluminum atoms (5 or 6) at the armchair edge. pH effects are significant, with a nearly 50% reduction in barrier height under alkaline conditions that are relevant to geothermal fluids and Al extraction from minerals.

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

Elimination of oxygen sensitivity in α-titanium by substitutional alloying with Al

Individually, increasing the concentration of either oxygen or aluminum has a deleterious effect on the ductility of titanium alloys. For example, extremely small amounts of interstitial oxygen can severely deteriorate the tensile ductility of titanium, particularly at cryogenic temperatures. Likewise, substitutional aluminum will decrease the ductility of titanium at low-oxygen concentrations. Here, we demonstrate that, counter-intuitively, significant additions of both Al and O substantially improves both strength and ductility, with a 6-fold increase in ductility for a Ti-6Al-0.3 O alloy as compared to a Ti-0.3 O alloy. The Al and O solutes act together to increase and sustain a high strain-hardening rate by modifying the planar slip that predominates into a delocalized, three-dimensional dislocation pattern. Furthermore, the mechanism can be attributed to decreasing stacking fault energy by Al, modification of the “shuffle” mechanism of oxygen-dislocation interaction by the repulsive Al-O interaction in Ti, and micro-segregation of Al and O by the same cause.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Electronegative metal dopants improve switching variability in Al 2 ⁢O 3 resistive switching devices

Resistive random-access memories are promising for nonvolatile memory and brain-inspired computing applications. High variability and low yield of these devices are key drawbacks hindering reliable training of physical neural networks. In this paper, we show that doping an oxide electrolyte, Al 2 ⁢O 3 , with electronegative metals makes resistive switching significantly more reproducible, surpassing the reproducibility requirements for obtaining reliable hardware neuromorphic circuits. Based on density functional theory calculations, the underlying mechanism is hypothesized to be the ease of creating oxygen vacancies in the vicinity of electronegative dopants due to the capture of the associated electrons by dopant midgap states and the weakening of Al-O bonds. These oxygen vacancies and vacancy clusters also bind significantly to the dopant, thereby serving as preferential sites and building blocks in the formation of conducting paths. Throughout this work, we validate this theory experimentally by implanting different dopants over a range of electronegativities in devices made of multiple alternating layers of Al 2 ⁢O 3 and WN and find superior repeatability and yield with highly electronegative metals, Au, Pt, and Pd. These devices also exhibit a gradual SET transition, enabling multibit switching that is desirable for analog computing.

36 MATERIALS SCIENCE↗
DOE OSTI2022

On the Nature of Extra-Framework Aluminum Species and Improved Catalytic Properties in Steamed Zeolites

Steamed zeolites exhibit improved catalytic properties for hydrocarbon activation (alkane cracking and dehydrogenation). The nature of this practically important phenomenon has remained a mystery for the last six decades and was suggested to be related to the increased strength of zeolitic Bronsted acid sites after dealumination. We now utilize state-of-the-art infrared spectroscopy measurements and prove that during steaming, aluminum oxide clusters evolve (due to hydrolysis of Al out of framework positions with the following clustering) in the zeolitic micropores with properties very similar to (nano) facets of hydroxylated transition alumina surfaces. The Bronsted acidity of the zeolite does not increase and the total number of Bronsted acid sites decreases during steaming. O 5 Al(VI)-OH surface sites of alumina clusters dehydroxylate at elevated temperatures to form penta-coordinate Al 1 O 5 sites that are capable of initiating alkane cracking by breaking the first C-H bond very effectively with much lower barriers (at lower temperatures) than for protolytic C-H bond activation, with the following reaction steps catalyzed by nearby zeolitic Bronsted acid sites. This explains the underlying mechanism behind the improved alkane cracking and alkane dehydrogenation activity of steamed zeolites: heterolytic C-H bond breaking occurs on Al-O sites of aluminum oxide clusters confined in zeolitic pores. Our findings explain the origin of enhanced activity of steamed zeolites at the molecular level and provide the missing understanding of the nature of extra-framework Al species formed in steamed/dealuminated zeolites.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2021

DEVELOPMENT OF STABLE ANODE AND CATHODE MATERIALS FOR RECHARGEABLE BATTERIES

Batteries have been employed in a variety of applications, such as portable electronics, electric vehicles (EVs), and stationary energy storage to preserve energy from other renewable sources (like wind or solar energy). The ultimate goal is to develop high energy density, long life span, better safety, and low cost of the batteries. However, current commercialized batteries (like lead-acid, zinc-alkaline, lithium-ion batteries (LIBs)) could not fulfill all the demands of diversified applications. LIBs predominate the market because of their high energy density. To achieve a higher capacity of the cell, high-nickel layered (Ni > 90%) cathode materials are promising candidates since they compose high specific capacity and discharge voltage. In chapter 1, an introduction to cell energy density and the development of high-nickel layered cathode materials along with associated obstacles of poor cycling stability and thermal stability have been discussed. Associated works like doping or surface coating have also been mentioned in this section. In chapter 2, Al doping in high-nickel layered cathode materials to enhance the structural and thermal stability was introduced. Uniform incorporation of Al doping is achieved by mechanical fusion and calcination processes. The Al doping not only decreased the Li/Ni mixing ratio but also enhance the thermal resistance to oxygen evolution because of strong Al-O bonding, which leads to elevated electrochemical and thermal stability. In chapter 3, TiN is implemented as a Ti dopant for high-nickel layered cathode materials to improve the electrochemical performance in the LIBs. The Ti not only diffused within the bulk structure but also formed segregation on the surface, which improved the structural stability and led to better cycling performance. Although LIBs deliver high energy density, safety concerns of flammable organic electrolytes have not been resolved yet. Therefore, the aqueous rechargeable zinc-ion batteries (ZIB) have been praised for their safe, low-cost, eco-friendly stationary energy storage, which is considered as a complementary system to LIBs. In chapter 4, the mechanism, advantages, and challenges of ZIBs would be given and the strategies for solving the zinc metal anode issues have been discussed in this section. In chapter 5, a polymer coating method was reported to facilitate Zn deposition/ stripping by coordination with Zn2+ and prevented direct contact with aqueous electrolyte to block corrosion side-reactions. With this coating, a boost in a lifetime (up to 400 hours) and lower polarization under extremely high current conditions (10 mA cm-2) have been achieved in repeated Zn deposition/ stripping cycling.

25 ENERGY STORAGE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 is Corundum structured and crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Al3+ is bonded to six equivalent O2- atoms to form a mixture of corner, edge, and face-sharing AlO6 octahedra. The corner-sharing octahedra tilt angles range from 48–60°. There is three shorter (1.87 Å) and three longer (1.99 Å) Al–O bond length. O2- is bonded to four equivalent Al3+ atoms to form a mixture of distorted corner and edge-sharing OAl4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 is Corundum-like structured and crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Al3+ is bonded to six O2- atoms to form a mixture of face, edge, and corner-sharing AlO6 octahedra. The corner-sharing octahedra tilt angles range from 51–71°. There are a spread of Al–O bond distances ranging from 1.87–2.03 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl4 tetrahedra. In the second O2- site, O2- is bonded to four equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with eight AlO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–67°. There are a spread of Al–O bond distances ranging from 1.76–1.80 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with seven AlO6 octahedra. The corner-sharing octahedra tilt angles range from 15–50°. There are a spread of Al–O bond distances ranging from 1.82–1.97 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with four equivalent AlO6 octahedra, corners with four equivalent AlO4 tetrahedra, and edges with four AlO6 octahedra. The corner-sharing octahedra tilt angles range from 13–57°. There are a spread of Al–O bond distances ranging from 1.82–2.22 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with six AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, and edges with five AlO6 octahedra. The corner-sharing octahedra tilt angles range from 13–57°. There are a spread of Al–O bond distances ranging from 1.83–2.27 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to four Al3+ atoms to form OAl4 tetrahedra that share a cornercorner with one OAl5 square pyramid, corners with two equivalent OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and an edgeedge with one OAl4 tetrahedra. In the second O2- site, O2- is bonded to four Al3+ atoms to form distorted OAl4 tetrahedra that share a cornercorner with one OAl5 square pyramid, corners with four OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and an edgeedge with one OAl4 tetrahedra. In the third O2- site, O2- is bonded to five Al3+ atoms to form distorted OAl5 square pyramids that share corners with two OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and edges with four OAl4 tetrahedra. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlO3 by Materials Project

AlO3 is alpha Rhenium trioxide-like structured and crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Al is bonded to six equivalent O atoms to form corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 9°. All Al–O bond lengths are 1.86 Å. O is bonded in a linear geometry to two equivalent Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Al2O3 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.81 Å) and two longer (1.82 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form distorted edge-sharing AlO5 square pyramids. There are a spread of Al–O bond distances ranging from 1.80–1.93 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Al3+ and one O2- atom. The O–O bond length is 1.49 Å. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 57°. There are a spread of Al–O bond distances ranging from 1.86–2.01 Å. In the second Al3+ site, Al3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Al–O bond distances ranging from 1.87–2.14 Å. In the third Al3+ site, Al3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Al–O bond distances ranging from 1.87–2.13 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 57°. There are a spread of Al–O bond distances ranging from 1.86–2.01 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted square co-planar geometry to four Al3+ atoms. In the second O2- site, O2- is bonded to four Al3+ atoms to form corner-sharing OAl4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to four Al3+ atoms. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Al3+ atoms. In the fifth O2- site, O2- is bonded to four Al3+ atoms to form corner-sharing OAl4 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to four Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with seven equivalent AlO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–63°. There is three shorter (1.77 Å) and one longer (1.81 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with seven equivalent AlO4 tetrahedra and edges with four equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–2.02 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the third O2- site, O2- is bonded to four Al3+ atoms to form a mixture of distorted edge and corner-sharing OAl4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.69–1.82 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Al3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with four equivalent AlO4 tetrahedra, an edgeedge with one AlO4 tetrahedra, and edges with two equivalent AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.82–2.02 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent AlO4 tetrahedra, corners with four equivalent AlO5 trigonal bipyramids, and an edgeedge with one AlO5 trigonal bipyramid. There are a spread of Al–O bond distances ranging from 1.76–1.79 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Al3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al2O3 by Materials Project

Al2O3 is Corundum-like structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 43°. All Al–O bond lengths are 1.93 Å. In the second Al3+ site, Al3+ is bonded to six equivalent O2- atoms to form a mixture of corner and face-sharing AlO6 octahedra. The corner-sharing octahedra tilt angles range from 43–53°. All Al–O bond lengths are 1.94 Å. In the third Al3+ site, Al3+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge, corner, and face-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There is three shorter (1.85 Å) and three longer (2.03 Å) Al–O bond length. O2- is bonded to four Al3+ atoms to form a mixture of edge and corner-sharing OAl4 trigonal pyramids.

36 MATERIALS SCIENCE↗