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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ho3(CoGe2)2 by Materials Project

Ho3(CoGe2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 12-coordinate geometry to four equivalent Co and eight Ge atoms. There are a spread of Ho–Co bond distances ranging from 2.86–3.20 Å. There are a spread of Ho–Ge bond distances ranging from 2.95–3.24 Å. In the second Ho site, Ho is bonded in a 6-coordinate geometry to eight Ge atoms. There are a spread of Ho–Ge bond distances ranging from 2.96–3.32 Å. Co is bonded in a 4-coordinate geometry to four equivalent Ho and four Ge atoms. There are a spread of Co–Ge bond distances ranging from 2.34–2.43 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 10-coordinate geometry to six Ho, three equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.96 Å. In the second Ge site, Ge is bonded in a 6-coordinate geometry to six Ho, one Co, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.71 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3(Si3Pd10)2 by Materials Project

Ho3(Pd10Si3)2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a distorted tetrahedral geometry to four equivalent Pd atoms. All Ho–Pd bond lengths are 2.83 Å. In the second Ho site, Ho is bonded in a cuboctahedral geometry to twelve equivalent Pd atoms. All Ho–Pd bond lengths are 3.00 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded to one Ho and three equivalent Si atoms to form a mixture of corner and edge-sharing PdHoSi3 tetrahedra. All Pd–Si bond lengths are 2.48 Å. In the second Pd site, Pd is bonded in a 2-coordinate geometry to one Ho and two equivalent Si atoms. Both Pd–Si bond lengths are 2.43 Å. Si is bonded in a 8-coordinate geometry to eight Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3(In2Co)2 by Materials Project

Ho3(CoIn2)2 crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. Ho is bonded in a 10-coordinate geometry to three Co and seven In atoms. There are two shorter (2.73 Å) and one longer (3.08 Å) Ho–Co bond lengths. There are a spread of Ho–In bond distances ranging from 3.04–3.47 Å. There are two inequivalent Co sites. In the first Co site, Co is bonded in a 6-coordinate geometry to six equivalent Ho and three equivalent In atoms. All Co–In bond lengths are 3.21 Å. In the second Co site, Co is bonded in a 9-coordinate geometry to three equivalent Ho and six equivalent In atoms. All Co–In bond lengths are 2.83 Å. There are two inequivalent In sites. In the first In site, In is bonded in a trigonal planar geometry to three equivalent Ho and six equivalent In atoms. All In–In bond lengths are 3.30 Å. In the second In site, In is bonded in a 11-coordinate geometry to six equivalent Ho, three Co, and two equivalent In atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3(P3Pd10)2 by Materials Project

Ho3(Pd10P3)2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded to sixteen Pd atoms to form distorted HoPd16 tetrahedra that share edges with six equivalent HoPd16 tetrahedra and faces with four equivalent HoP6Pd12 cuboctahedra. There are four shorter (2.84 Å) and twelve longer (3.35 Å) Ho–Pd bond lengths. In the second Ho site, Ho is bonded to twelve equivalent Pd and six equivalent P atoms to form distorted face-sharing HoP6Pd12 cuboctahedra. All Ho–Pd bond lengths are 2.99 Å. All Ho–P bond lengths are 3.24 Å. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 4-coordinate geometry to one Ho, six equivalent Pd, and three equivalent P atoms. All Pd–Pd bond lengths are 3.04 Å. All Pd–P bond lengths are 2.49 Å. In the second Pd site, Pd is bonded in a 6-coordinate geometry to three Ho, nine Pd, and two equivalent P atoms. There are one shorter (2.69 Å) and four longer (2.99 Å) Pd–Pd bond lengths. Both Pd–P bond lengths are 2.40 Å. P is bonded in a 9-coordinate geometry to one Ho and eight Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho5(SiB4)2 by Materials Project

Ho5Si2B8 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 12-coordinate geometry to nine B and three equivalent Si atoms. There are a spread of Ho–B bond distances ranging from 2.62–2.95 Å. There are one shorter (3.04 Å) and two longer (3.11 Å) Ho–Si bond lengths. In the second Ho site, Ho is bonded to two equivalent B and four equivalent Si atoms to form corner-sharing HoSi4B2 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Ho–B bond lengths are 2.71 Å. All Ho–Si bond lengths are 2.89 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four equivalent Ho and five B atoms. There are a spread of B–B bond distances ranging from 1.75–1.83 Å. In the second B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. The B–B bond length is 1.83 Å. In the third B site, B is bonded in a 9-coordinate geometry to five Ho and four equivalent B atoms. Si is bonded in a 9-coordinate geometry to eight Ho and one Si atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho3(AlNi3)2 by Materials Project

Ho3(Ni3Al)2 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Ho is bonded in a 12-coordinate geometry to eight equivalent Ni and four equivalent Al atoms. There are four shorter (2.77 Å) and four longer (3.00 Å) Ho–Ni bond lengths. All Ho–Al bond lengths are 3.16 Å. Ni is bonded in a 12-coordinate geometry to four equivalent Ho, four equivalent Ni, and two equivalent Al atoms. All Ni–Ni bond lengths are 2.56 Å. Both Ni–Al bond lengths are 2.46 Å. Al is bonded in a distorted hexagonal planar geometry to six equivalent Ho and six equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Spin-orbital order and excitons in magnetoresistive HoBi

The magnetism of the rocksalt fcc rare-earth monopnictide HoBi, a candidate topological material with extreme magnetoresistance, is investigated. From the Ho 3+ non-Kramers J=8 spin-orbital multiplet, the cubic crystal electric field yields six nearly degenerate low-energy levels. These constitute an anisotropic magnetic moment with a Jahn-Teller-like coupling to the lattice. In the cubic phase for T>T N =5.72(1)K, the paramagnetic neutron scattering is centered at k=($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) and was fit to dominant antiferromagnetic interactions between Ho spins separated by {100} and ferromagnetic interactions between spins displaced by {$\frac{1}{2}$ $\frac{1}{2}$ 0}. For T < T N , a type-II AFM long-range order with k=($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) develops along with a tetragonal lattice distortion. While neutron diffraction from a multidomain sample cannot unambiguously determine the spin orientation within a domain, the bulk magnetization, structural distortion, and our measurements of the magnetic excitations all show the easy axis coincides with the tetragonal axis. Finally, the weakly dispersive excitons for T < T N can be accounted for by a spin Hamiltonian that includes the crystal electric field and exchange interactions within the random phase approximation.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Kinetically Controlled Linker Binding in Rare Earth-2,5-Dihydroxyterepthalic Acid Metal–Organic Frameworks and Its Predicted Effects on Acid Gas Adsorption

In the pursuit of highly stable and selective metal–organic frameworks (MOFs) for the adsorption of caustic acid gas species, an entire series of rare earth MOFs have been explored. Each of the MOFs in this series (RE-DOBDC; RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; DOBDC = 2,5-dihydroxyterepthalic acid) was synthesized in the tetragonal space group I4/m. Crystallized MOF samples, specifically Eu-DOBDC, were seen to have a combination of monodentate and bidentate binding when synthesized under typical reaction conditions, resulting in a contortion of the structure. However, extended crystallization times determined that this binding is kinetically controlled and that the monodentate binding option was crystallographically eliminated by extended reaction times at higher temperatures. Furthermore, this series allows for the direct study of the effect of the metal center on the structure of the of the MOF; herein, the lanthanide metal ionic radii contraction across the periodic table results in a reduction of the MOF pore size and lattice parameters. Scanning electron microscopy–energy-dispersive spectroscopy was used to investigate the stages of crystal growth for these RE-DOBDC MOFs. All MOFs, except Er-DOBDC had a minimum of two stages of growth. These analogues were demonstrated by analysis of neutron diffraction (PND) to exhibit a cooperative rotational distortion of the secondary building unit, resulting in two crystallographically distinct linker sublattices. Computational modeling efforts were used to show distinct differences on acid gas (NO 2 and SO 2 ) binding energies for RE-DOBDC MOFs when comparing the monodentate/bidentate combined linker with the bidentate-only linker crystal structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Engineered disorder in CO 2 photocatalysis

Light harvesting, separation of charge carriers, and surface reactions are three fundamental steps that are essential for an efficient photocatalyst. Here we show that these steps in the TiO 2 can be boosted simultaneously by disorder engineering. A solid-state reduction reaction between sodium and TiO 2 forms a core-shell c-TiO 2 @a-TiO 2-x (OH) y heterostructure, comprised of HO-Ti-[O]-Ti surface frustrated Lewis pairs (SFLPs) embedded in an amorphous shell surrounding a crystalline core, which enables a new genre of chemical reactivity. Specifically, these SFLPs heterolytically dissociate dihydrogen at room temperature to form charge-balancing protonated hydroxyl groups and hydrides at unsaturated titanium surface sites, which display high reactivity towards CO 2 reduction. This crystalline-amorphous heterostructure also boosts light absorption, charge carrier separation and transfer to SFLPs, while prolonged carrier lifetimes and photothermal heat generation further enhance reactivity. The collective results of this study motivate a general approach for catalytically generating sustainable chemicals and fuels through engineered disorder in heterogeneous CO 2 photocatalysts.

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

Effective point-charge analysis of crystal fields: Application to rare-earth pyrochlores and tripod kagome magnets 𝑅 ⁢3⁢ Mg⁢ 2 ⁢Sb⁢ 3⁢ O⁢ 14

An indispensable step to understand collective magnetic phenomena in rare-earth compounds is the determination of spatially anisotropic single-ion properties resulting from spin-orbit coupling and crystal field (CF). The CF Hamiltonian has a discrete energy spectrum—accessible to spectroscopic probes such as neutron scattering—controlled by a number of independent parameters reflecting the point symmetry of the magnetic sites. Determining these parameters in low-symmetry systems is often challenging. Here, we describe a general method to analyze CF excitation spectra using adjustable effective point-charges. We benchmark our method to existing neutron-scattering measurements on pyrochlore rare-earth oxides and obtain a universal point-charge model that describes a large family of related materials. We adapt this model to the newly discovered tripod kagome magnets (𝑅 3 ⁢Mg 2 ⁢Sb 3 ⁢O 14 , 𝑅 = Tb, Ho, Er, Yb) for which we report broadband inelastic neutron-scattering spectra. Analysis of these data using adjustable point-charges yields the CF wave functions for each compound. From this, we calculate thermomagnetic properties that accurately reflect our measurements on powder samples and predict the effective gyromagnetic tensor for pseudospin degrees of freedom—a crucial step to understand the exotic collective properties of these kagome magnets at low temperature. We present further applications of our method to other tripod kagome materials and triangular rare-earth compounds 𝑅⁢MgGaO 4 (𝑅 =Yb, Tm). Overall, this study establishes a widely applicable methodology to predict CF and single-ion properties of rare-earth compounds based on interpretable and adjustable models of effective point charges.

Crystal-field theory↗
DOE OSTI2023

Optimal coupling of Ho W 10 molecular magnets to superconducting circuits near spin clock transitions

A central goal in quantum technologies is to maximize GT 2 , where G stands for the coupling of a qubit to control and readout signals and T 2 is the qubit’s coherence time. Furthermore, this is challenging, as increasing G (e.g., by coupling the qubit more strongly to external stimuli) often leads to deleterious effects on T 2 . Here, we study the coupling of pure and magnetically diluted crystals of Ho W 10 magnetic clusters to microwave superconducting coplanar waveguides. Absorption lines give a broadband picture of the magnetic energy level scheme and, in particular, confirm the existence of level anticrossings at equidistant magnetic fields determined by the combination of crystal field and hyperfine interactions. Such “spin clock transitions” are known to shield the electronic spins against magnetic field fluctuations. The analysis of the microwave transmission shows that the spin-photon coupling also becomes maximum at these transitions. The results show that engineering spin-clock states of molecular systems offers a promising strategy to combine sizable spin-photon interactions with a sufficient isolation from unwanted magnetic noise sources.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Highly permeable polyethersulfone substrates with bicontinuous structure for composite membranes in CO 2 /N 2 separation

Substrate morphology has a significant effect on the CO 2 transport performance of a thin-film composite (TFC) membrane. In this study, a new mixed solvent comprising 2-pyrrolidone (2-PD) and 2-methoxyethanol (2-ME) was used to prepare polyethersulfone (PES) substrates with bicontinuous structure by water vapor-induced phase separation, followed by immersion in water as nonsolvent. Here, compared with the commonly used solvent, N-methyl-2-pyrrolidone (NMP), the 2-PD/2-ME mixed solvent is more hydrophilic and can decrease the thermodynamic stability of the casting solution significantly. As a result, the phase separation was induced via the spinodal decomposition mechanism. The open morphology bestowed the optimized substrate with a very high CO 2 permeance of 133,226 ± 3,870 GPU (1 GPU = 10 –6 cm 3 (STP) s –1 cm –2 cmHg –1 = 3.3464 × 10 -9 kg-mol s –1 m –2 Pa –1 ), which was 5 times more permeable than the baseline substrate synthesized with NMP. By using this new substrate, the prepared TFC membrane containing amines showed an increased CO 2 permeance of 908 ± 8 GPU at 57°C, which was 48 GPU higher than that with the baseline substrate. Meanwhile, the CO 2 /N 2 selectivity was retained at 162 ± 4 at 57°C. In addition, the good scalability of the new PES substrate was demonstrated by roll-to-roll fabrication of a 50' long scale-up PES substrate with a width of 21".

2-Pyrrolidone↗
NASA NTRS1998

HO:LULF and HO:LULF Laser Materials

A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

Barnes, Norman P.↗
DOE OSTI2025

The power of lanthanides: same composition, but different lanthanides leading to different interesting materials properties, from magnetocalorics to molecular magnets and phosphors

Commonly accepted design concepts for ionic liquids (ILs) state that the constituting ions must be large and carry low, well-dispersed charges. A series of ILs based of pentadeca charged ILs with pentanuclear linear {Ln 5 } units ([Ln 5 (C 2 H 5 -C 3 H 3 N 2 -CH 2 COO) 16 (H 2 O) 8 ](Tf 2 N) 15 (C 3 H 3 N 2 = imidazolium moiety, Tf 2 N = bis(trifluoromethanesulfonyl)amide) with Ln = Er, Ho, Tm) demonstrates that these criteria are not absolute. Highly charged ions can also support IL formation, provided they are sufficiently large. Expanding the series of these unconventional, record pentadeca charged with new lanthanide representatives, led to the discovery of additional unprecedented properties for ILs: The Gd compound exhibits a strong magnetocaloric effect (MCE) in the liquid state with a maximum magnetic entropy change of −ΔS M = −11 J⋅kg −1 ⋅K −1 at 2 K for Δμ 0 H = 7 T. Albeit the Dy representative shows slow magnetic relaxation, the relaxation times are not favorable for practical application as a molecular magnet. Lastly, for both the Gd and the Y compound, phosphorescence in the seconds time scale is observed, which is, to the best of our knowledge, the longest ever reported for an IL.

Ionic Liquids↗
DOE OSTI2020

Materials Data on Ho3(NiRu2)2 by Materials Project

Ho3(Ru2Ni)2 is Hexagonal Laves-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Ho sites. In the first Ho site, Ho is bonded in a 12-coordinate geometry to eight Ru and four Ni atoms. There are a spread of Ho–Ru bond distances ranging from 3.04–3.12 Å. There are a spread of Ho–Ni bond distances ranging from 3.01–3.12 Å. In the second Ho site, Ho is bonded in a 12-coordinate geometry to seven Ru and five Ni atoms. There are a spread of Ho–Ru bond distances ranging from 3.04–3.09 Å. There are a spread of Ho–Ni bond distances ranging from 3.00–3.14 Å. In the third Ho site, Ho is bonded in a 12-coordinate geometry to nine Ru and three equivalent Ni atoms. There are a spread of Ho–Ru bond distances ranging from 3.04–3.15 Å. There are a spread of Ho–Ni bond distances ranging from 3.02–3.12 Å. There are five inequivalent Ru sites. In the first Ru site, Ru is bonded to six Ho, four Ru, and two equivalent Ni atoms to form distorted RuHo6Ni2Ru4 cuboctahedra that share corners with five NiHo6Ni2Ru4 cuboctahedra, corners with thirteen RuHo6Ni2Ru4 cuboctahedra, edges with two equivalent NiHo6Ni2Ru4 cuboctahedra, edges with four equivalent RuHo6Ni2Ru4 cuboctahedra, faces with six NiHo6Ni2Ru4 cuboctahedra, and faces with twelve RuHo6Ni3Ru3 cuboctahedra. There are a spread of Ru–Ru bond distances ranging from 2.61–2.67 Å. There are one shorter (2.62 Å) and one longer (2.63 Å) Ru–Ni bond lengths. In the second Ru site, Ru is bonded to six Ho, three Ru, and three Ni atoms to form RuHo6Ni3Ru3 cuboctahedra that share corners with six NiHo6Ni2Ru4 cuboctahedra, corners with twelve RuHo6Ni2Ru4 cuboctahedra, edges with six equivalent RuHo6Ni3Ru3 cuboctahedra, faces with nine RuHo6Ni2Ru4 cuboctahedra, and faces with nine NiHo6Ni2Ru4 cuboctahedra. There are one shorter (2.54 Å) and one longer (2.61 Å) Ru–Ru bond lengths. There are two shorter (2.62 Å) and one longer (2.66 Å) Ru–Ni bond lengths. In the third Ru site, Ru is bonded to six equivalent Ho, four Ru, and two equivalent Ni atoms to form RuHo6Ni2Ru4 cuboctahedra that share corners with four equivalent NiHo6Ru6 cuboctahedra, corners with fourteen RuHo6Ni2Ru4 cuboctahedra, edges with six equivalent RuHo6Ni2Ru4 cuboctahedra, faces with six equivalent NiHo6Ru6 cuboctahedra, and faces with twelve RuHo6Ni2Ru4 cuboctahedra. Both Ru–Ru bond lengths are 2.60 Å. Both Ru–Ni bond lengths are 2.63 Å. In the fourth Ru site, Ru is bonded to six Ho, two equivalent Ru, and four Ni atoms to form RuHo6Ni4Ru2 cuboctahedra that share corners with four equivalent NiHo6Ru6 cuboctahedra, corners with fourteen RuHo6Ni2Ru4 cuboctahedra, edges with six RuHo6Ni2Ru4 cuboctahedra, faces with eight RuHo6Ni2Ru4 cuboctahedra, and faces with ten NiHo6Ni2Ru4 cuboctahedra. There are two shorter (2.62 Å) and two longer (2.63 Å) Ru–Ni bond lengths. In the fifth Ru site, Ru is bonded to six Ho, four Ru, and two equivalent Ni atoms to form RuHo6Ni2Ru4 cuboctahedra that share corners with six NiHo6Ni2Ru4 cuboctahedra, corners with twelve RuHo6Ni2Ru4 cuboctahedra, edges with six RuHo6Ni4Ru2 cuboctahedra, faces with seven NiHo6Ni2Ru4 cuboctahedra, and faces with eleven RuHo6Ni2Ru4 cuboctahedra. There are one shorter (2.63 Å) and one longer (2.64 Å) Ru–Ni bond lengths. There are three inequivalent Ni sites. In the first Ni site, Ni is bonded to six Ho, four Ru, and two equivalent Ni atoms to form NiHo6Ni2Ru4 cuboctahedra that share corners with six NiHo6Ni2Ru4 cuboctahedra, corners with twelve RuHo6Ni2Ru4 cuboctahedra, edges with six NiHo6Ni2Ru4 cuboctahedra, faces with four equivalent NiHo6Ni2Ru4 cuboctahedra, and faces with fourteen RuHo6Ni2Ru4 cuboctahedra. Both Ni–Ni bond lengths are 2.62 Å. In the second Ni site, Ni is bonded to six Ho and six Ru atoms to form NiHo6Ru6 cuboctahedra that share corners with eight NiHo6Ni2Ru4 cuboctahedra, corners with ten RuHo6Ni2Ru4 cuboctahedra, edges with six NiHo6Ni2Ru4 cuboctahedra, a faceface with one NiHo6Ni2Ru4 cuboctahedra, and faces with seventeen RuHo6Ni2Ru4 cuboctahedra. In the third Ni site, Ni is bonded to six Ho, four Ru, and two equivalent Ni atoms to form NiHo6Ni2Ru4 cuboctahedra that share corners with eight NiHo6Ru6 cuboctahedra, corners with ten RuHo6Ni2Ru4 cuboctahedra, edges with two equivalent NiHo6Ni2Ru4 cuboctahedra, edges with four equivalent RuHo6Ni2Ru4 cuboctahedra, faces with six NiHo6Ni2Ru4 cuboctahedra, and faces with twelve RuHo6Ni3Ru3 cuboctahedra.

36 MATERIALS SCIENCE↗
NASA NTRS2005

One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser

Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality.

Yu, Jirong↗
DOE OSTI2023

Control of the Structural Charge Distribution and Hydration State upon Intercalation of CO 2 into Expansive Clay Interlayers

Numerous experimental investigations indicated that expansive clays such as montmorillonite can intercalate CO 2 preferentially into their interlayers and therefore potentially act as a material for CO 2 separation, capture, and storage. However, an understanding of the energy–structure relationship during the intercalation of CO 2 into clay interlayers remains elusive. Here, in this study, we use metadynamics molecular dynamics simulations to elucidate the energy landscape associated with CO 2 intercalation. Our free energy calculations indicate that CO 2 favorably partitions into nanoconfined water in clay interlayers from a gas phase, leading to an increase in the CO 2 /H 2 O ratio in clay interlayers as compared to that in bulk water. CO 2 molecules prefer to be located at the centers of charge-neutral hydrophobic siloxane rings, whereas interlayer spaces close to structural charges tend to avoid CO 2 intercalation. The structural charge distribution significantly affects the amount of CO 2 intercalated in the interlayers. These results provide a mechanistic understanding of CO 2 intercalation in clays for CO 2 separation, capture, and storage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗