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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Four homochiral coordination polymers contain N-acetyl-L-tyrosine and different N-donor ligand: Influence of metal cations, ancillary ligands and coordination modes

Using the chiral ligand N-acetyl-L-tyrosine (Hacty) and maintaining identical reaction conditions, Zn(II), Co(II), and Cd(II) salts provided four novel homochiral coordination polymers ([Zn(acty)(bipy){sub 2}(H{sub 2}O){sub 2}]·NO{sub 3}·2H{sub 2}O){sub n}1, ([Co(acty)(bipy){sub 2}(H{sub 2}O){sub 2}]·NO{sub 3}·2H{sub 2}O){sub n}2, ([Cd(acty){sub 2}(bipy)H{sub 2}O]·H{sub 2}O){sub n}3, and ([Cd(acty)(bpe){sub 2}(Ac)]·6H{sub 2}O){sub n}4 (bipy=4,4′-bipyridine; bpe=1,2-di(4-pyridyl)ethane) in the presence of ancillary ligands. Compounds 1 and 2 are isostructural 1D chain structures. The neighboring chains are further linked into a 3D supramolecular structure via π⋯π stacking and hydrogen bond interactions. Compound 3 shows a 2D network and 4 generates 1D infinite chains along the c-axis. Compounds 3 and 4 are further connected into 3D supramolecular network by hydrogen bond interactions. More importantly, coordination in acyl oxygen atoms and ancillary ligands (bpe) as monodentate decorating ligands in 4 are rarely reported. Ancillary ligands and metal cations significantly influence the structure of the complexes. The photoluminescence properties of 1, 3, and 4 were studied at room temperature. Circular dichroism (CD) of the complexes have been investigated. - Graphical abstract: Four new homochiral coordination polymers were prepared and structurally characterized, which investigate the influence of the ancillary ligands and metal ions on the design and synthesis of coordination polymers. Display Omitted - Highlights: • It is rarely reported that the chiral coordination polymers prepared with N-acetyl-L-tyrosine ligands. • The alkalescent acetyl oxygen atom is difficult to participate in coordination but it is happened in the N-acetyl-L-tyrosine ligands. • The ancillary ligands (4,4′-bipy and bpe) are present in an unusual coordination modes, monodentate decorating ligands in 1, 2 and 4. • Structure comparative analyses results indicate that the secondary ligands and metal ions influence the fabrication of these inorganic–organic arrangements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

New iodocuprates(I) with N-heterocyclic molecules as the cations

Under the hydrothermal conditions, the reactions between CuI, KI and bp/bpp (bp=4,4′-bipiperidine, bpp=1,3-bis(4-piperidyl)propane) in an acidic alcohol solution produced three new organically templated iodocuprates(I) as [H{sub 2}bp]{sub 2}[Cu{sub 2}I{sub 6}] 1, [tmbp][Cu{sub 2}I{sub 4}] 2 and [tmbpp] 2 [Cu{sub 4}I{sub 8}]·2H{sub 2}O 3 (tmbp{sup 2+}=N,N,N′,N′-tetramethyl-4,4′-bipiperidinium; tmbpp{sup 2+}=N,N,N′,N′-tetramethyl-1,3-bis(4-piperidyl)propane dication). X-ray analysis revealed that (i) tmbp{sup 2+} and tmbpp{sup 2+} in compounds 2 and 3 originated from the complete N-alklation of bp/bpp with CH{sub 3}OH; (ii) templated by H{sub 2}bp{sup 2+}, the inorganic anion [Cu{sub 2}I{sub 6}]{sup 2−} of 1 possesses a dinuclear structure, whereas templated by tmbp{sup 2+}, the inorganic anion [Cu{sub 2}I{sub 4}]{sup 2−} of 2 exhibits a one-dimensional (1D) chain structure; (iii) templated by tmbpp{sup 2+}, the inorganic anion [Cu{sub 4}I{sub 8}]{sup 4−} of 3 shows a cubane-like structure modified by four terminal I{sup −} ions. The photoluminescence analysis indicates that compounds 1 and 2 emit blue light, while compound 3 emits green light. - Graphical abstract: By employing hydrothermal in situ N-alkylation of bp/bpp with CH{sub 3}OH, three new organically templated iodocuprates(I) were obtained. Display Omitted - Highlights: • Three new organically templated iodocuprates(I) were reported. • Cations tmbp{sup 2+} and tmbpp{sup 2+} originated from in situ alkylation of bp/bpp with CH{sub 3}OH. • H{sup +} and I{sup −} play a key role in alkylation of bp/bpp with CH{sub 3}OH. • Photoluminescence emission for iodocuprates(I) is related to Cu···Cu interaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Cation substitution in β-tricalcium phosphate investigated using multi-nuclear, solid-state NMR

The substitution of aluminium, gallium and sodium cations into β-tricalcium phosphate (β-TCP; Ca{sub 3}(PO{sub 4}){sub 2}) has been investigated, and the Ca sites involved successfully determined, using a combination of 1D {sup 31}P, {sup 27}Al, {sup 71}Ga, {sup 23}Na and {sup 43}Ca (natural abundance) NMR and 2D {sup 27}Al({sup 31}P), {sup 71}Ga({sup 31}P) and {sup 23}Na({sup 31}P) rotary-resonance-recoupled heteronuclear multiple-quantum correlation (R{sup 3}-HMQC) NMR. Over the compositional range studied, substitution of Ca{sup 2+} by Al{sup 3+} or Ga{sup 3+} was observed only on the Ca(5) site, whilst substitution by Na{sup +} was confined to the Ca(4) site. Some AlPO{sub 4} or GaPO{sub 4} second phase was observed at the highest doping levels in the Al{sup 3+} and Ga{sup 3+} substituted samples. - Graphical abstract: 2D contour plots with skyline projections showing recoupling of {sup 27}Al, {sup 71}Ga and {sup 23}Na to different {sup 31}P sites. - Highlights: • β-Ca{sub 3}(PO{sub 4}){sub 2} has been prepared pure and also with Al{sup 3+}, Ga{sup 3+} and Na{sup +} substituents. • Multi-nuclear 1D NMR and heteronuclear X({sup 31}P) recoupling have been used. • Models for substitution correctly predict site preference and occupancy. • Progressive changes in {sup 31}P spectra have been explained. • Al{sup 3+} and Ga{sup 3+} substitute onto the Ca(5) site, and Na{sup +} onto the Ca(4) site.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Cationic disorder and Mn{sup 3+}/Mn{sup 4+} charge ordering in the B′ and B″ sites of Ca{sub 3}Mn{sub 2}NbO{sub 9} perovskite: a comparison with Ca{sub 3}Mn{sub 2}WO{sub 9}

We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca{sub 3}Mn{sup 3+}{sub 2}WO{sub 9} and Ca{sub 3}Mn{sup 3+/4+}{sub 2}NbO{sub 9} were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P2{sub 1}/n); Ca{sub 3}Mn{sub 2}WO{sub 9} presents a long-range ordering over the B sites, whereas Ca{sub 3}Mn{sub 2}NbO{sub 9} is strongly disordered. By “in-situ” NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈Mn–O〉) for Ca{sub 3}Mn{sub 2}NbO{sub 9}, driven by a charge ordering effect between Mn{sup 3+} and Mn{sup 4+} atoms, related to the anomaly observed in the transport measurements at T≈160 K. Both materials present a magnetic order below T{sub C}=30 K and 40 K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime. - Graphical abstract: Comparison between the octahedron size and the magnetic behaviour for Ca{sub 3}Mn{sub 2}NbO{sub 9} in the temperature region where the charge and magnetic order occur. Display Omitted - Highlights: • Two novel Mn-containing double perovskites were obtained by solid-state reactions. • Both double perovskites are monoclinic (P2{sub 1}/n) determined by XRPD and NPD. • Ca{sub 3}Mn{sub 2}WO{sub 9} contains Mn{sup 3+} while Ca{sub 3}Mn{sub 2}NbO{sub 9} includes mixed-valence cations Mn{sup 3+}/Mn{sup 4+}. • Ca{sub 3}Mn{sub 2}NbO{sub 9} presents a charge-ordering effect between Mn{sup 3+} and Mn{sup 4+} evidenced by NPD. • The magnetic and transport studies evidenced the charge ordering in Ca{sub 3}Mn{sub 2}NbO{sub 9}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Syntheses, structures, molecular and cationic recognitions and catalytic properties of two lanthanide coordination polymers based on a flexible tricarboxylate

Two lanthanide coordination polymers, namely, ([La(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (La-TTTA) and [Nd(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (Nd-TTTA) have been hydrothermally synthesized through the reaction of lanthanide ions (La{sup 3+} and Nd{sup 3+}) with the flexible tripodal ligand 2,2′,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid (H{sub 3}TTTA). La-TTTA and Nd-TTTA are isostructural and both show three dimensional structures. La-TTTA and Nd-TTTA show good recognition of amine molecules via quenching the luminescent intensities in amines emulsions. They can also recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions with the quenching the peak around 361 nm when the compounds immersed in ionic solutions. The two compounds act as efficient Lewis acid catalysts for the cyanosilylation of benzaldehyde and derivatives in high yields shortly due to the strong Lewis acidity and the possible open sites of the lanthanide ions. - Graphical abstract: We have synthesized two isostructural 3D compounds based on H{sub 3}TTTA. They are chemical sensor of amine solvents and cations. They have higher yields and TOFs to catalyze cyanosilylation reactions. - Highlights: • The compounds show recognition of amine molecules via quenching luminescent intensities. • The compounds recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions via quenching the peak around 361 nm. • They act as efficient Lewis acid catalysts for the cyanosilylation reactions in high yields.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Gas sorption and transition-metal cation separation with a thienothiophene based zirconium metal–organic framework

The modulated synthesis of the thienothiophene based zirconium metal–organic framework (MOF) material having formula [Zr{sub 6}O{sub 4}(OH){sub 4}(DMTDC){sub 6}]·4.8DMF·10H{sub 2}O (1) (H{sub 2}DMTDC=3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid; DMF=N,N'-dimethylformamide) was carried out by heating a mixture of ZrCl{sub 4}, H{sub 2}DMTDC linker and benzoic acid (used as a modulator) with a molar ratio of 1:1:30 in DMF at 150 °C for 24 h. Systematic investigations have been performed in order to realize the effect of ZrCl{sub 4}/benzoic acid molar ratio on the crystallinity of the material. The activation (i.e., the removal of the guest solvent molecules from the pores) of as-synthesized compound was achieved by stirring it with methanol and subsequently heating under vacuum. A combination of X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric (TG) and elemental analysis was used to examine the phase purity of the as-synthesized and thermally activated 1. The material displays high thermal stability up to 310 °C in an air atmosphere. As revealed from the XRD measurements, the compound retains its crystallinity when treated with water, acetic acid and 1 M HCl solutions. The N{sub 2} and CO{sub 2} sorption analyses suggest that the material possesses remarkably high microporosity (S{sub BET}=1236 m{sup 2} g{sup −1}; CO{sub 2} uptake=3.5 mmol g{sup −1} at 1 bar and 0 °C). The compound also shows selective adsorption behavior for Cu{sup 2+} over Co{sup 2+} and Ni{sup 2+} ions. - Graphical abstract: Selective transition-metal cation adsorption by a thienothiophene based zirconium metal–organic framework material. - Highlights: • The modulated synthesis of a thienothiophene based Zr(IV) MOF has been described. • Effect of metal salt/modulator ratio on the crystallinity was thoroughly studied. • The compound showed high thermal and physiochemical stability. • N{sub 2} and CO{sub 2} sorption experiments revealed significantly high microporosity. • The material showed high adsorption selectivity for Cu{sup 2+} over Co{sup 2+} and Ni{sup 2+} ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Structural, vibrational and morphological properties of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations

Layered double hydroxides are anionic clays with formula [M{sup II}{sub 1−x} M{sup III}{sub x}(OH){sub 2}]{sup q+}[A{sup n−}]{sub q/n}·mH{sub 2}O, finding possible uses as catalyst support, adsorbents and so on. In this paper, we address the phase formation of layered double hydroxides containing Ni{sup 2+}, Zn{sup 2+}, Al{sup 3+} and Zr{sup 4+} cations, namely, NiZn-Al, NiZn-AlZr and NiZn-Zr compositions obtained by the coprecipitation method. Such systems were characterized by X-ray diffraction, confirming the phase formation for NiZn-Al and NiZn-AlZr samples. Infrared and Raman spectroscopies elucidated the anion and water molecules occurrence in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and specific surface area. The isotherm shapes were Type IV, according to the IUPAC, and represent a mesoporous structure. A morphological study was performed by means of scanning and transmission electron microscopies, and particle size values of 120, 131 and 235 nm for NiZn-Al, NiZn-AlZr and NiZn-Zr, respectively, were determined. Thermogravimetric analysis of the decomposition of the systems revealed that their complete disintegration occurred at ~ 450 °C and resulted in mixed oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Manipulating the morphology and textural property of γ-AlOOH by modulating the alkyl chain length of cation in ionic liquid

Graphical abstract: - Highlights: • γ-AlOOH was the only product in all experiments. • Different morphology of γ-AlOOH was obtained according to the alkyl chain length. • The textural property of γ-AlOOH was changed according to the alkyl chain length. • The possible formation mechanisms for hollow sphere and microflower were proposed. - Abstract: We demonstrated that the morphology and textural property of γ-AlOOH can be tuned by modulating the alkyl chain length of cation in [C{sub n}mim]{sup +}Cl{sup −} (n = 4, 8, 16). Using the short alkyl chain length-based [C{sub 4}mim]{sup +}Cl{sup −} as the structure-directed reagent, the morphology of γ-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of γ-AlOOH increased with the increase of [C{sub 4}mim]{sup +}Cl{sup −} dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C{sub 8}mim]{sup +}Cl{sup −} and [C{sub 16}mim]{sup +}Cl{sup −}, the morphologies of γ-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of γ-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of γ-AlOOH have been proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Cation distribution in Ni–Cu–Zn nanoferrites from {sup 57}Fe in-field Mössbauer spectra

Highlights: • Occupancy of copper ions at about 20% towards tetrahedral sites. • Distribution is proposed on the basis of % of Fe ions at both A and B sites. • Distribution is checked by estimating the theoretical lattice constant values. - Abstract: The nanoparticles of Ni{sub 1−x}Cu{sub x}Zn{sub 0.35}Fe{sub 2}O{sub 4} were synthesized by sol–gel method using polyvinyl alcohol as a chelating agent. X-ray diffraction patterns of all the samples confirmed the single phase spinel structure. The site occupancy of copper in the nanosized nickel–zinc ferrite spinels was investigated with the help of in-field Mössbauer spectroscopy. Cation distribution for the whole series of compositions was proposed by considering the amounts of iron ions present at both tetrahedral and octahedral interstitial sites in the spinel lattice. Confirmation of the proposed distributions was done by estimating quantitatively the lattice parameters for these compositions and comparing their values with those of the experimentally observed ones.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Effects of cation compositions on the electronic properties and optical dispersion of indium zinc tin oxide thin films by electron spectroscopy

Highlights: • REELS analysis can provide optical dispersion and electronic properties of oxide materials. • The band gap varied with In/Zn/Sn compositions and increased after annealing. • The optical properties were examined using REELS in conjunction with the Tougaard–Yubero model. • The dispersion parameters were determined by a single-oscillator Wemple–DiDomenico model. • The Zn and Sn contents play a crucial role in determining the single-oscillator constant and dispersion energy of IZTO thin films. - Abstract: The electronic properties and optical dispersion of indium zinc tin oxide (IZTO) films with different cation compositions were investigated by reflection electron energy loss spectroscopy (REELS). The REELS spectra of IZTO films revealed that the band gap varied with different Sn/Zn ratios and In content. The optical properties were examined with REELS data using Tougaard–Yubero model and the results were compared with the envelope of the transmission spectra obtained using a UV-spectrometer. The dispersion behavior of the refractive index from REELS results was studied in terms of the single-oscillator Wemple–DiDomenico model. The results showed that the different compositions of In/Zn/Sn caused a change in the dispersion parameters of IZTO thin films in contrast to the static values of refractive indices and dielectric constant which remained the same. Our work demonstrated that REELS is an efficient tool to study the optical properties of a material by obtaining the optical parameters.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Preparation and optical properties of Bi2FeVMoO10 nanoparticles structurally derived from cation-substitutions in Scheelite-type BiVO4

Highlights: • Bi{sub 2}FeVMoO{sub 10} with Scheelite structure was synthesized by co-precipitation. • The structural Rietveld refinement was finished. • The nanoparticles (50–80 nm) show high absorption in UV-vis region (E{sub g} = 2.07 eV). • Photocatalysis of Bi{sub 2}FeVMoO{sub 10} was markedly enhanced than BiVO{sub 4} and Bi{sub 2}Mo{sub 3}O{sub 12}. • The mechanism of this photocatalysis system was proposed. - Abstract: Bi{sub 2}FeVMoO{sub 10} [(Bi{sub 0.8}Fe{sub 0.4})(Mo{sub 0.4}V{sub 0.4})O{sub 4}] was prepared via facile co-precipitation route. It has a tetragonal Scheelite structure derived by cation substitutions in monoclinic BiVO{sub 4}. Rietveld refinements of Bi{sub 2}FeVMoO{sub 10} were performed in body-centered tetragonal Scheelite. The morphological property was tested via SEM, EDX, and TEM measurements. The optical property was measured by UV-vis absorption spectrum. Bi{sub 2}FeVMoO{sub 10} shows a narrower band gap of 2.07 eV than the monoclinic BiVO{sub 4} and α-Bi{sub 2}Mo{sub 3}O{sub 12}. The photo-degradation experiments of Rhodamine-B (RhB) dye solutions were conducted. Bi{sub 2}FeVMoO{sub 10} nanoparticles have more efficient photocatalytic ability on RhB degradation than that of BiVO{sub 4} and α-Bi{sub 2}Mo{sub 3}O{sub 12}. The results were discussed on the Scheelite structure characteristics such as complicated optical absorption centers, loose space in the lattice because of the vacancies, large dispersion in the CB and VB electronic components and the Fe{sup 3+}/Fe{sup 2+} redox couples. This multicomponent Scheelite oxide could have potential applications in environment protection.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2015

Electrochemically influenced cation inter-diffusion and Co 3 O 4 formation on La 0.6 Sr 0.4 CoO 3 infiltrated into SOFC cathodes

Nanosized LSC electrocatalyst was infiltrated into a porous scaffold cathode composed of Sm 2 O 3 -doped CeO 2 (SDC) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) in a commercial button solid oxide fuel cell (SOFC). To understand the stability of cathodes infiltrated with LSC, the infiltrated composite cells were subjected to both electrochemical operating and thermal aging states at 750 °C for 1500 h. Nanostructure and local chemistry evolution of La 0.6 Sr 0.4 CoO 3 (LSC) infiltrated cathodes upon operation and aging were investigated by transmission electron microscopy. After operation, the LSC remained a cubic perovskite, and the crystal grains exhibit comparable size to as-infiltrated LSC grains. Inter-diffusion of Fe from the LSCF to a Fe-incorporated LSC layer developed on the LSCF backbone. However, only sharp interfaces were observed between LSC and SDC backbone in the as-infiltrated cathode and such interfaces remain after operation. The infiltrated LSC on the SDC backbone also retains granular particle morphology. Furthermore, newly grown Co 3 O 4 nanocrystals were found in the operated cathode. After thermal aging, on the other hand, cation inter-diffusion across the interfaces of the infiltrate particles and the cathode backbones is less than that from the operated cells. Lastly, the following hypothesis is proposed: Co 3 O 4 forms on LSC arising from local charge balancing between cobalt and oxygen vacancies.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Two-Dimensional and Three-Dimensional Tetrel-Arsenide Frameworks Templated by Li and Cs Cations

Two new ternary tetrel pnictide phases, Li 1.08 Ge 4.92 As 7 and Cs 0.11 Zn 0.05 Si 0.95 As, have been synthesized. Both compounds crystallize in new structure types, which demonstrate the flexibility of Ge(Si)–As layers when accommodating electropositive cations of various sizes. Li 1.08 Ge 4.92 As 7 displays a Ge-As layer motif that has not been observed in ternary Ge-As systems, while Cs 0.11 Zn 0.05 Si 0.95 As exhibits a 3D framework composed of fragments of the 2D parent-phase SiAs. For Li 1.08 Ge 4.92 As 7 , a combination of computational modeling and solid-state 7 Li MAS NMR was used to establish the correct crystal structure with one mixed occupied Ge/Li site. The compositions of the phases were confirmed through energy-dispersive X-ray spectroscopy. Transport properties and UV–Vis spectroscopy reveal both reported compounds to be semiconductors. Cs 0.11 Zn 0.05 Si 0.95 As shows high thermal stability with congruent melting at 1300 K and an exceptionally low thermal conductivity of 0.5 W m –1 K –1 at 300 K. Temperature-dependent Li-ion hopping dynamics in Li 1.08 Ge 4.92 As 7 was characterized using 7 Li solid-state NMR.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Intrinsic Role of Cationic Substitution in Tuning Li/Ni Mixing in High-Ni Layered Oxides

Nickel-rich transition metal (TM) layered oxides, particularly those ones with high Ni content, attract world-wide interest for potential use as high-capacity cathodes in next-generation Li-ion batteries. However, as Ni loading increases, Li and Ni sitting at octahedra tend to mix, resulting in reduced electrochemical activity, which has been one major obstacle to their practical applications. We investigate the kinetic and thermodynamic aspects of Li/Ni mixing in LiNi 0.7 MnxCo 0.3-x O 2 (0≤x≤0.3) as they are being synthesized, through a multimodal approach for quantitative determination of structural ordering and com-parison to ab initio calculations. Results from this study elucidate the role of Mn/Co substitution at Ni sites in tuning Li/Ni ordering, intrinsically through local magnetic interaction. Specifically, Co substitution facilitates Li/Ni ordering by relieving the intra-plane magnetic frustration and reducing the inter-plane super-exchange (SE) interaction; in contrast, Mn exacerbates mag-netic frustration, strengthens SE, thereby aggravating Li/Ni mixing. These findings highlight the interplay between local magnetic interactions and cationic ordering, which has yet to be fully investigated for the needs of designing high-Ni layered cathodes and, broadly, TM-based oxides for various applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Kinetics and Energetics of Electron Transfer to Dimer Radical Cations

In this work, spectra of the dimer cations naphthalene (Nap 2 •+ ) and ethene (Ethene 2 •+ ) were measured in liquid dichloromethane (DCM). The spectra peak at very different energies, 1.2 and 3.3 eV. In DCM dimerization stabilizes Nap 2 •+ by Δ$G_\text{d}°$(Nap 2 •+ ) = -218 meV relative to the monomer Nap •+ as determined from the dimerization equilibrium constant. Both dimers can transfer a positive charge to hole acceptor molecules, but for both the rate constants rise more gradually with reaction energetics than do many charge transfer reactions previously studied. A striking observation finds that the rate constant for hole transfer from the Nap 2 •+ dimer to phenanthrene is smaller by two decades than that from biphenyl•+ monomer to Nap, although both reactions have the same –Δ$\textit{G}°$=0.05 eV. A plausible interpretation for these observations is the presence of an energy of reorganization, λ(M 2 ), for the dimer that involves movement apart of the two partners in the dimer. While the dimerization equilibrium cannot be measured for Ethene 2 •+ the charge transfer data imply that both Δ$G_\text{d}°$(Ethene 2 •+ ) and λ(Ethene 2 •+ ), are considerably larger, perhaps by factors of 2-4 than for Nap 2 •+ .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Effects of γ-Irradiation, Cation Size, and Salt Concentration on the Aggregation of Boehmite Nanoplatelets

The effects of radiation on the aggregation of nanoplatelets of aluminum oxyhydroxide (boehmite) in slurries of M 1+ cation nitrates has been observed using tumbler small- and ultra-small-angle neutron scattering. Nitrate solutions of H, Li, Na, K, and Rb at concentrations of 10 -5 , 10 -3 , 10 -1 , 2, and 4 molal were compared to the results for pure H 2 O. Primary aggregates consisting of small stacks of boehmite platelets that form immediately after the boehmite is placed in water are smaller for irradiated boehmite than the pristine material. Here, the primary aggregates for irradiated boehmite also appear to have a rougher surface than those observed for unirradiated materials. Both results are possibly due to breaking of the surface OH species and a neutralization of the surface. At low salt concentrations, the pH of the irradiated boehmite slurries is lower than that of the corresponding pristine material indicating that irradiated boehmite adsorbs fewer protons or more hydroxide onto its surface than the pristine boehmite. Increasing the salt concentration decreases the pH to near neutral at 7 due to screening of the electric double layer at the solid/liquid interface. Irradiation does not seem to affect the size of secondary aggregates formed from the aggregation of primary aggregates or of the overall size of the primary aggregates.

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

Role of Polycyclic Aromatic Alkylammonium Cations in Tuning the Electronic Properties and Band Alignment of Two-Dimensional Hybrid Perovskite Semiconductors

Two-dimensional hybrid organic–inorganic perovskites (HOIPs) have recently drawn intense attention as potential photovoltaic materials. However, n = 1 two-dimensional (2D) HOIPs face the challenge of low conductivity between the inorganic layers, leading to unsatisfactory device performance. Interestingly, 2D HOIPs employing π-conjugated molecules as organic moieties show energy and charge transfers between organic and inorganic layers, indicating potentially efficient carrier transport for photovoltaic applications. Nevertheless, the development of 2D HOIP-based solar cells especially utilizing polycyclic aromatic alkylammonium as cations is in its infancy. Herein, we investigated the electronic structure and band alignment of a series of n = 1 2D Ruddlesden–Popper (RP) phase HOIPs containing different polycyclic aromatic groups and alkyl chains, based on density functional theory calculations. We find that the polycyclic aromatic group plays an important role in controlling the functionality of 2D HOIPs by directly modifying band-edge states, and the band alignment at the organic–inorganic interface can be designed to promote either exciton trapping or dissociation for light-emitting or photovoltaic applications, respectively.

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

Thermally Aged Li–Mn–O Cathode with Stabilized Hybrid Cation and Anion Redox

Though low-cost and environmentally friendly, Li–Mn–O cathodes suffer from low energy density. Although synthesized Li 4 Mn 5 O 12 -like overlithiated spinel cathode with reversible hybrid anion- and cation-redox (HACR) activities has a high initial capacity, it degrades rapidly due to oxygen loss and side-reaction-induced electrolyte decomposition. In this study, we develop a two-step heat treatment to promote local decomposition as Li 4 Mn 5 O 12 → 2LiMn 2 O 4 + Li 2 MnO 3 + 1/2 O 2 ↑, which releases near-surface reactive oxygen that is harmful to cycling stability. The produced nanocomposite delivers a high discharge capacity of 225 mAh/g and energy density of over 700 Wh/kg at active-material level at a current density of 100 mA/g between 1.8 to 4.7 V. Benefiting from suppressed oxygen loss and side reactions, 80% capacity retention is achieved after 214 cycles in half cells. With industrially acceptable electrolyte amount (6 g/Ah), full cells paired with Li 4 Ti 5 O 12 anode have a good retention over 100 cycles.

25 ENERGY STORAGE↗