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Optical, electrical, and EPR studies of polycrystalline Al:Cr:ZnSe gain elements

Transition metal-doped II-VI (TM:II-VI) chalcogenides are well-known laser materials for optically pumped middle-infrared lasers. Cr:ZnSe is a key representative of this class of transition metal doped II-VI gain media and is arguably considered the material of choice for optically pumped middle-infrared lasers. In addition to effective mid-IR lasing under optical excitation, these crystals, being wide-band semiconductors, hold the potential for direct electrical excitation. One way to form n-type conductivity in ZnSe crystals is by annealing them in a melt of Zn-Al alloy. However, this annealing of Cr:ZnSe crystals results in their purification and transfer of chromium to the melt of Zn-Al alloy. In this article, we report on optimizing the doping technique for providing n-type conductivity in Al:Cr:ZnSe crystals while preserving the chromium concentration. Al:Cr:ZnSe samples with resistivities ranging from 10.8 to 992 Ω-cm were fabricated. While the 2 + valence state of Cr is typically dominant in Cr:ZnSe, both Cr 2+ and Cr + were detected in Al:Cr:ZnSe samples. The maximum level of Cr + concentration was measured to be 4 × 10 18 cm -3 .

36 MATERIALS SCIENCE↗

Achieving strong and stable nanocrystalline Al alloys through compositional design

Abstract Al alloys often suffer from low mechanical strength and lack high-temperature microstructural and mechanical robustness. A series of binary and ternary nanocrystalline (NC) Al transition metal alloys with supersaturated solid solution and columnar nanograins have been recently developed by using magnetron sputtering, manifesting a new realm of mechanical properties and thermal stability. Distinct solutes cause evident differences in the phase transformations and efficiencies for grain refinement and crystalline-to-amorphous transition. Certain sputtered Al-TM alloys have shown room-temperature mechanical strengths greater than 2 GPa and outstanding thermal stability up to 400 °C. In addition, the NC Al alloys show mechanical anisotropy and tension–compression asymmetry, revealed by micromechanical tests. Through the process encapsulating various compositionally distinct systems, we attempt to illuminate the solute effects on grain refinement and properties and more importantly, tentatively unravel the design criteria for high-strength and yet thermally stable NC Al alloys. Graphic Abstract

36 MATERIALS SCIENCE↗

Al-Ce Alloy-Based Compact Heat Exchanger for Refrigerant Charge Reduction and Unprecedented Durability

• Oak Ridge National Laboratory and Eck Industries produced and characterized durable and corrosion resistant Al-Ce-Mg alloy-based heat exchanger. • Eck Industries successfully casted Al-Ce-Mg heat exchanger. • ORNL characterized reaction bonding between Al-2Ce-6Mg alloy and stainless-steel tube in a heat exchanger header. • Metallurgical bonds were achieved between stainless steel tubes and Al-Ce-Mg alloy cast headers. • ORNL performed corrosion testing on Al-Ce-Mg alloy/stainless steel tube reactive bond interface. • In most cases no significant changes to the reactive bond morphology or compositional distribution were observed in the samples after exposure to acid for 267h acid.

36 MATERIALS SCIENCE↗

Tritium Trapping Thermodynamics by Point Defects at Interfacial Fe-Al Phases of the Aluminide Coating

Density functional theory (DFT) simulations have been carried out to evaluate the potential for tritium trapping by metal vacancies in four phases (i.e., (Fe, Cr, Ni), AlFe 3 , NiAl, and AlFe) identified near the interface between the Al coating and 316 stainless steel (316 SS) cladding. In addition, an ab initio thermodynamics approach has been employed to predict the temperature and T 2 -partial pressure dependence on the thermodynamics of tritiated defects. Key results in this work suggest that metal vacancies in the four phases have the potential to favorably trap tritium species. This thermodynamic trend can be correlated to the high energy cost of having an interstitial tritium in the lattice, which has been calculated to be at least 0.48 eV. By combining the results of this study with previous theoretical works investigating tritium behavior in other Fe-Al phases identified in the aluminide coating, suggest that metal vacancies are generally able to trap tritium in various Fe-Al aluminide phases. Especially, it was found that Al vacancies are the most efficient to trap tritium, followed by Fe vacancies, then Ni and Cr vacancies. Strong interactions between tritium and the metal vacancies are occurring by the formation of Fe—T bonds. The formation of Cr—T, Ni—T, or Al—T bonds are found less energetically favorable than Fe—T bonds.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Thermodynamics of Tritium Trapping by Point Defects at Interfacial Cr-based Phases of the Al Coating

Density functional theory (DFT) simulations have been carried out to evaluate the potential for tritium trapping by metal vacancies in four phases Cr-containing phases (i.e., Cr3Si, Al0.3Cr0.7, Al8Cr5-HT, and Al8Cr5) identified near the interface between the Al coating and 316 stainless steel (316 SS) cladding. In addition, an ab initio thermodynamics approach has been employed to predict the temperature and T2-partial pressure dependence on the thermodynamics of singly tritiated defects. Key results in this work suggest that metal vacancies in the four phases have the potential to favorably trap tritium species, especially Si vacancies in Cr3Si phase. This overall thermodynamic trend can be correlated to the energy cost of having an interstitial tritium in the lattice, which has been calculated to range from 0.17 eV in Al8Cr5-HT to 0.89 eV in Cr3Si. A comparison of the results from this study with previous theoretical works investigating tritium behavior in other Fe-Al phases identified in the aluminide coating, suggests that metal vacancies are generally able to trap tritium in various Fe-Al aluminide phases. Especially, it was found that Si and Al vacancies would be the most efficient to trap for tritium, followed by Cr vacancies, then Fe and Ni vacancies. In the four Cr-based material phases investigated in this work, it is interesting to note that, in the absences of Fe or Ni species, strong interactions between tritium and the metal vacancies are always occurring by the formation of preferential Cr—T bonds (i.e., no Si—T or Al—T bonds were formed).

Sassi, Michel J.↗

Assessing Strain Rate Sensitivity of Nanotwinned Al–Zr Alloys through Nanoindentation

Nanotwinned metals have exhibited many enhanced physical and mechanical properties. Twin boundaries have recently been introduced into sputtered Al alloys in spite of their high stacking fault energy. These twinned Al alloys possess unique microstructures composed of vertically aligned Σ3(112) incoherent twin boundaries (ITBs) and have demonstrated remarkable mechanical strengths and thermal stability. However, their strain rate sensitivity has not been fully assessed. A modified nanoindentation method has been employed here to accurately determine the strain rate sensitivity of nanotwinned Al–Zr alloys. The hardness of these alloys reaches 4.2 GPa while simultaneously exhibiting an improved strain rate sensitivity. The nanotwinned Al–Zr alloys have shown grain size-dependent strain rate sensitivity, consistent with previous findings in the literature. This work provides insight into a previously unstudied aspect of nanotwinned Al alloys.

36 MATERIALS SCIENCE↗

Low-Temperature Crystal Structure and Mean-Field Modeling of Er x Dy 1- x Al 2 Intermetallics

Low-temperature crystal structure of the Er x Dy 1-x Al 2 alloys with x = 0.45, 0.67, 0.90 was examined using temperature-dependent powder X-ray diffraction. The Er-rich sample, Er 0.9 Dy 0.1 Al 2 , exhibits a rhombohedral distortion associated with the magnetic ordering that occurs around 20 K. The rhombohedral distortion is suppressed in Er 0.67 Dy 0.33 Al 2 , while a weak low-temperature tetragonal distortion is observed in Er 0.45 Dy 0.55 Al 2 . The mean-field theory supports the correlation between the type of structural distortion and the variable easy magnetization axis in Er x Dy 1-x Al 2 intermetallics.

36 MATERIALS SCIENCE↗

Effect of Cr and Al on Elastic Constants of FeCrAl Alloys Investigated by Molecular Dynamics Method

The FeCrAl alloy system is recognized as one of the candidate materials for accident-tolerant fuel (ATF) cladding in the nuclear power industry due to its high oxidation resistance under irradiation and high-temperature environments. The concentrations of Cr and Al have a significant effect on elastic properties of the FeCrAl alloy. In this work, elastic constants C 11 , C 12 , C 44 , bulk modulus and shear modulus of FeCrAl alloy were calculated with molecular dynamics methods. We explored compositions with 1–15 wt.% Cr and 1–5 wt.% Al at temperatures from 0 K to 750 K. The results show that the concentrations of Al and Cr have different effects on the elastic constants. When the concentration of Al was fixed, a decrease in bulk modulus and shear modulus with increasing Cr content was observed, consistent with previous experimental results. The dependence of elastic constants on temperature was also the same as in the experiments. Investigations into elastic properties of defect-containing alloys have shown that vacancies, voids, interstitials and Cr-rich precipitations have different effects on elastic properties of FeCrAl alloys. Investigations of elastic properties of defect-containing alloys have shown that vacancies, void, interstitials and Cr-rich precipitations have different effects on elastic properties of FeCrAl alloys. Therefore, the present results indicate that both the Cr and Al concentrations and radiation defects should be considered to develop and apply the FeCrAl alloy in ATF design.

36 MATERIALS SCIENCE↗

Manufacturing Bulk Nanocrystalline Al-3Mg Components Using Cryomilling and Spark Plasma Sintering

In the current study, pure aluminum (Al) powders were cryomilled with and without 3 wt.% pure magnesium (Mg) dopant for varying durations followed by spark plasma sintering (SPS) of powders to prepare bulk components with superior mechanical properties. The crystallite sizes were determined for powders and the bulk components by analyzing the X-ray diffraction (XRD) spectrum. The calculations indicated a reduction in crystallite size with the increase in the cryomilling duration. The results also showed a more significant decrease in the crystallite sizes for Al-3Mg samples than that of pure Al. The changes in the surface morphology of powders were characterized using scanning electron microscopy (SEM). The elemental mapping analysis at nanoscale was carried out using Energy-dispersive X-ray spectroscopy (EDX) in Scanning transmission electron microscopy (STEM). The mechanical properties of the bulk components were assessed using a Vickers Microhardness tester. The test results demonstrated an improvement in the hardness of Mg-doped components. Higher hardness values were also reported with an increase in the cryomilling duration. This article discusses the mechanisms for the reduction in crystallite size for pure Al and Al-3Mg and its subsequent impact on improving mechanical properties.

36 MATERIALS SCIENCE↗

Inductively Coupled Nonthermal Plasma Synthesis of Size-Controlled γ-Al 2 O 3 Nanocrystals

Gamma alumina (γ-Al 2 O 3 ) is widely used as a catalyst and catalytic support due to its high specific surface area and porosity. However, synthesis of γ-Al 2 O 3 nanocrystals is often a complicated process requiring high temperatures or additional post-synthetic steps. Here, we report a single-step synthesis of size-controlled and monodisperse, facetted γ-Al 2 O 3 nanocrystals in an inductively coupled nonthermal plasma reactor using trimethylaluminum and oxygen as precursors. Under optimized conditions, we observed phase-pure, cuboctahedral γ-Al 2 O 3 nanocrystals with defined surface facets. Nuclear magnetic resonance studies revealed that nanocrystal surfaces are populated with AlO 6 , AlO 5 and AlO 4 units with clusters of hydroxyl groups. Nanocrystal size tuning was achieved by varying the total reactor pressure yielding particles as small as 3.5 nm, below the predicted thermodynamic stability limit for γ-Al 2 O 3 .

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Influences of Mg Ions and Al Ions on Deposition Behavior of Supersaturated Silicic Acid - 20261

Silicic acid can change into various species such as deposit, colloidal, and soluble form under certain conditions: for example, gradual pH changes around geological disposal repositories. In particular, silicic acid deposits narrow groundwater flow paths, thereby restricting the flow of groundwater. Such effects may contribute to a delay in radionuclide migration. Previous studies have reported that silicic acid supersaturated in sodium and calcium ions can narrow the flow paths. This study examined the effect of magnesium (Mg) and aluminum (Al) ions on the deposition of supersaturated silicic acid on the solid phase. The deposition behavior of supersaturated silicic acid on the solid phase was investigated in a batch system while changing the initial supersaturation concentration, the coexisting ion concentration, and the amount of added solid phase. In the presence of Mg ions, silicic acid precipitation increased with increasing Mg ion concentration due to the influence of the electrolyte, and crosslinking reactions. The coexistence of Al ions significantly suppressed silicic acid deposition due to the formation of a covering on the solid surface during Al ion hydrolysis under conditions of high Al concentration (1.4 mM). On the basis of these experimental results, the apparent deposition rate constant of silicic acid was estimated to be in the range from 10{sup -11} to 10{sup -10} m/s. The Damkoehler number (the dimensionless number expressed by the ratio of the characteristic time of mass transfer and the chemical reaction constant) was sufficient to cause the clogging of the host rock by deposition. This suggests that supersaturated silicic acid deposition, regardless of the presence of Mg ions (and Al ions), contributes to improving barrier performance against radionuclide migration in the host rock. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Effect of framework Al pairing on NO storage properties of Pd-CHA passive NOx adsorbers

For this study, three Pd/H-CHA samples were prepared containing 53.0%, 10.8% and 6.5% paired Al sites at near fixed Si/Al ratio and similar Pd loading. According to H 2 temperature-programmed reduction, Pd was present almost exclusively as isolated cations in the two samples containing the higher concentrations of paired Al sites, whereas in the other sample PdO was also present. Simulated lean cold start tests on the fresh samples conducted in a microflow reactor showed that the sample containing PdO stored the lowest amount of NOx. When tested with CO/H 2 , the sample containing 53.0% paired Al sites showed significantly better storage capacity than the other samples and deactivated less rapidly upon sequential tests. Experiments using lean gasoline engine exhaust revealed similar trends. This study showed that a high concentration of paired Al sites in Pd/H-CHA is beneficial for NOx storage capacity, thermal durability, and minimizing deactivation in the presence of CO/H 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two Al(OH)3 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.98 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–1.95 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Al(PO3)3 by Materials Project

Al(PO3)3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.87–1.95 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six PO4 tetrahedra. There is one shorter (1.90 Å) and five longer (1.91 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.88–1.93 Å. There are nine 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 AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 29–34°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 32–37°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–43°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–40°. There is two shorter (1.50 Å) and two longer (1.59 Å) P–O bond length. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–37°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 31–33°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 23–37°. There are a spread of P–O bond distances ranging from 1.49–1.60 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two AlO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 32–41°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. There are twenty-seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Al3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Al3+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Al3+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-third O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.97 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.97 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 1, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–1.96 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.90–1.96 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of two Al(OH)3 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.94 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.90–1.97 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Al(HO)3 by Materials Project

Al(OH)3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one Al(OH)3 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–1.97 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.88–1.98 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Al3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Al3+ and one H1+ atom.

36 MATERIALS SCIENCE↗