Penternary Wurtzitic Nitrides LiZnGeGaN: Powder Synthesis, Crystal Structure, and Potentiality as a Solar-Active Photocatalyst.

We developed a new penternary wurtzitic nitride system LiZnGeGaN (0 ≤ ≤ 1) by hybridizing LiGeN and ZnGeGaN. Fairly stoichiometric fine powder samples were synthesized by the reduction-nitridation process at 900 °C. While the end member LiGeN possessed a relatively large band gap of 4.

Hidden chemical order in disordered BaNbMoO revealed by resonant X-ray diffraction and solid-state NMR.

The chemical order and disorder of solids have a decisive influence on the material properties. There are numerous materials exhibiting chemical order/disorder of atoms with similar X-ray atomic scattering factors and similar neutron scattering lengths. It is difficult to investigate such order/disorder hidden in the data obtained from conventional diffraction methods.

Disposable Nitric Oxide Generator Based on a Structurally Deformed Nitrite-Type Layered Double Hydroxide.

The inhalation of nitric oxide (NO), which acts as a selective vasodilator of pulmonary blood vessels, is an established medical treatment. However, its wide adoption has been limited by the lack of a convenient delivery technique of this unstable gas. Here we report that a solid mixture of FeSO·7HO and a layered double hydroxide (LDH) containing nitrite (NO) in the interlayer spaces (NLDH) stably generates NO at a therapeutic level (∼40 ppm over 12 h from freshly mixed solids; ∼80 ppm for 5-10 h from premixed solids) under air flow (0.

Separated quadrupole and shift interactions of H NMR spectra in paramagnetic solids by asymmetric pulse sequences.

Separated pure-quadrupole (PQ) and -shift (PS) spectra of H nuclear magnetic resonance (NMR) of paramagnetic solids are obtained and correlated by simple pulse sequences that can acquire the full magnetization under ideal conditions. Two-dimensional NMR signals obtained using an asymmetric π-pulse-inserted quadrupole-echo (APIQE) sequence yielded separated spectra through the skew operation of an affine transform (AT) before a Fourier transform. Modified APIQE sequences that acquire whole echo signals were fabricated, and separated PQ and PS spectra were obtained by applying a combination of AT, such as rotation and skew operations, to the signal data.

Quaternary Wurtzitic Nitrides (1 - )ZnGeN-2GaN ( = 0.02, 0.05): Disorder-Induced Band-Gap Narrowing and Potentiality as a Solar-Active Photocatalyst.

We examined the ZnGeN-GaN solid-solution system (ZnGeGaN) in the unexplored compositional region of < 0.10 to reveal the transitional structural and optical properties caused by the introduction of Ga. Fairly stoichiometric fine powder specimens with compositions of = 0.

Why Do Carbonate Anions Have Extremely High Stability in the Interlayer Space of Layered Double Hydroxides? Case Study of Layered Double Hydroxide Consisting of Mg and Al (Mg/Al = 2).

Layered double hydroxides (LDHs) are promising compounds in a wide range of fields. However, exchange of CO anions with other anions is necessary, because the CO anions are strongly affixed in the LDH interlayer space. To elucidate the reason for the extremely high stability of CO anions intercalated in LDHs, we investigated in detail the chemical states of CO anions and hydrated water molecules in the LDH interlayer space by synchrotron radiation X-ray diffraction, solid-state NMR spectroscopy, and Raman spectroscopy.

Constancy of the quadrupolar interaction product in nanocrystalline gallium nitride revealed by Ga MAS NMR shift distribution.

The question of whether the broad Ga nuclear magnetic resonance (NMR) signal of hexagonal gallium nitride (h-GaN) at 530-330 ppm is related to the Knight shift (caused by the presence of carriers in semiconductors) is the subject of intense debate. The intensity increase observed for the narrower Ga magic angle spinning (MAS) NMR signals above 1050 °C suggests that the broader signals do not reflect the decomposition of h-GaN. Herein, we utilized Ga multi-quantum (MQ) MAS NMR spectroscopy to reveal that the quadrupolar interaction products for the broad signal of nanocrystalline h-GaN are almost constant in the entire shift range that we investigated, equaling 1.

Investigation of the effects of sintering and indium-doping of zinc oxide using Zn magic angle spinning NMR analysis.

Indium-doped zinc oxide, a potential alternative material to indium tin oxide, was analyzed in powder form via Zn magic angle spinning nuclear magnetic resonance (MAS NMR). The Zn MAS NMR results show that the line shapes of zinc oxide were broadened by sintering, which was also observed for indium-doped zinc oxide, in which the broadening also depended on the sintering time. Furthermore, the line shapes of indium-doped zinc oxide were significantly broader than those of the corresponding zinc oxide, and were independent of the degree of indium doping.

Ce-Doped LaSiAlNO, a Rare Highly Efficient Blue-Emitting Phosphor at Short Wavelength toward High Color Rendering White LED Application.

Phase pure nondoped and Ce doped LaSiAlNO (Al containing La N-phase) samples have been obtained by solid-state reaction synthesis for the first time. 1% Ce-doped LaSiAlNO phosphor displays a broad excitation band ranging from UV to 410 nm, with a maximum at 355 nm. UV light excitation results in a narrow Ce 5d-4f emission band (fwhm = 68 nm) centered at 418 nm.

Na-α'-GeGaON Solid Solution Analogous to α'-SiAlON: Synthesis, Crystal Structure, and Potentiality as a Photocatalyst.

We demonstrated, for the first time, formation of the Na-α'-GeGaON (NamGe12-(m+n)Gam+nOnN16-n) solid solution, an analogue of the well-established α'-SiAlON system. We successfully synthesized single-phase powder samples by reduction-nitridation of Na2CO3-GeO2-Ga2O3, in the solubility range of m ≈ 0.8-1.

Manipulation of shell morphology of silicate spheres from structural evolution in a purely inorganic system.

We have investigated the structural transformation of solid silica spheres into various more complex spherical structures including flower-like, thick or thin nanosheet-shelled and porous shelled spheres. In the absence of organic additives, sodium salts contained in this inorganic reaction system apparently direct the silica dissolution and regrowth of dissolved silicate at the nanometer-scale, leading to the formation of a nanosheet network rather than solid aggregates. Subsequent removal of the salts by simple water washing results in voids in the siloxane network and a significant availability of surface silanol groups so that the resulting nanosheets and spheres composed of them possess large surface areas, pore volumes, and morphological flexibility, which can be varied by an applied stimulus.

Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g.

Electron localization of polyoxomolybdates with ε-Keggin structure studied by solid-state 95Mo NMR and DFT calculation.

We report electron localization of polyoxomolybdates with ε-Keggin structure investigated by solid-state (95)Mo NMR and DFT calculation. The polyoxomolybdates studied are the basic ε-Keggin crystals of [Me3NH]6[H2Mo12O28(OH)12{MoO3}4] · 2H2O (1), the crystals suggested to have a disordered {ε-Mo12} core of [PMo12O36(OH)4{La(H2O)2.75Cl1.

Dynamic breathing of CO2 by hydrotalcite.

The carbon cycle of carbonate solids (e.g., limestone) involves weathering and metamorphic events, which usually occur over millions of years.

Naked-eye discrimination of methanol from ethanol using composite film of oxoporphyrinogen and layered double hydroxide.

Methanol is a highly toxic substance, but it is unfortunately very difficult to differentiate from other alcohols (especially ethanol) without performing chemical analyses. Here we report that a composite film prepared from oxoporphyrinogen (OxP) and a layered double hydroxide (LDH) undergoes a visible color change (from magenta to purple) when exposed to methanol, a change that does not occur upon exposure to ethanol. Interestingly, methanol-induced color variation of the OxP-LDH composite film is retained even after removal of methanol under reduced pressure, a condition that does not occur in the case of conventional solvatochromic dyes.

Hydrogen-bond-driven 'homogeneous intercalation' for rapid, reversible, and ultra-precise actuation of layered clay nanosheets.

The use of hydrogen bonds permits a fluidic motion of differently sized alcohol molecules across the interlayer gap in LDH, which enables rapid and reversible tuning of interlayer spacing of the LDH at sub-Ångström precision by changing the mole ratio of the different alcohols.

Molecular dynamics of a polyaniline/β-cyclodextrin complex investigated by 13C solid-state NMR.

The molecular dynamics of a polyaniline/β-cyclodextrin inclusion complex (PANI/β-CD IC) and its relation with optical properties were investigated using high-resolution solid-state (13)C nuclear magnetic resonance (NMR) and optical absorption spectroscopies. UV-vis measurements revealed a π-π* absorption peak of a PANI film that had a 10 nm blue-shift by inclusion of β-CD, indicating that π-conjugation of PANI was shortened in the IC. Temperature dependent analysis of (13)C NMR spectra and spin-lattice relaxation times (T(1C)) revealed that the inclusion induced acceleration of the twisting motion of the PANI chain.

Molecular dynamics of regioregular poly(3-hexylthiophene) investigated by NMR relaxation and an interpretation of temperature dependent optical absorption.

The molecular structure and dynamics of regioregulated poly(3-hexylthiophene) (P3HT) were investigated using high-resolution solid-state (13)C nuclear magnetic resonance (NMR) and optical absorption spectroscopies. A crystal (C)-plastic crystal (PC) transition induced by the molecular motion of the aliphatic side group was observed for P3HT in the temperature dependence analysis of (13)C NMR spectra and spin-lattice relaxation time (T(1C)). The aliphatic side group motion in the crystalline state weakened intermolecular pi-pi interaction, resulting in the blue shift of the characteristic absorption of the interchain exciton.

Improvement of 1H-2H cross polarization under magic-angle spinning by using amplitude/frequency modulation.

In 1H-2H cross polarization (CP) under magic-angle spinning (MAS), it has been pointed out that modulation of a H2 resonance frequency caused by MAS acts as adiabatic frequency sweep and efficient CP over the broad H2 powder pattern can be achieved. The adiabaticity, however, does not hold when the MAS frequency becomes faster, leading to insufficient CP enhancement. In this work, it is demonstrated that by applying amplitude/frequency modulation for H2 irradiation during CP, CP efficiency at faster MAS can be improved appreciably.

Intra- and intermolecular effects on 1H chemical shifts in a silk model Peptide determined by high-field solid state 1H NMR and empirical calculations.

A combination of solid state 1H NMR chemical shift measurements and empirical chemical shift calculations has been used to interpret 1H solid state chemical shifts of a model peptide (Ala-Gly)15 for the crystalline domain of Bombyx mori silk fibroin in silk I and silk II structures, including a treatment of both intra- and intermolecular arrangements. Silk I and silk II are the structures of silk fibroin before and after spinning, respectively. Two peaks with equal intensity were observed for the amide protons of (AG)15 in silk I, whereas only one broad peak was observed for silk II, reflecting a difference of 1.

B nuclear magnetic resonance in boron-doped diamond.

This review summarizes recent results obtained by B solid-state nuclear magnetic resonance (NMR) on boron-doped diamond, grown by the high-pressure high-temperature (HPHT) or chemical vapor deposition techniques. Simple single-pulse experiments as well as advanced two-dimensional NMR experiments were applied to the boron sites in diamond. It is shown that magic-angle spinning at magnetic fields above 10 T is suitable for observation of high-resolution B spectra of boron-doped diamond.

Conformational and microstructural characteristics of poly(L-lactide) during glass transition and physical aging.

The glass transition and physical aging processes of poly(L-lactide) (PLLA) were studied by variable-temperature Fourier transform infrared (FTIR) spectroscopy and (13)C solid-state NMR spectroscopy. The glass transition temperature (T(g)) of PLLA can be well determined from the temperature-dependent FTIR intensity. Nearby T(g), a distinct change in the slope of spectral intensity versus temperature plot is detected.

High field 17O solid-state NMR study of alanine tripeptides.

(17)O chemical shifts of Ala-Ala-Ala, with parallel and anti-parallel beta-sheet structures, are observed using a 930-MHz high-resolution solid-state NMR spectrometer. Ala-Ala-Ala serves as a model sheet-forming peptide because it can be easily prepared as either a parallel or an anti-parallel beta-sheet structure. Spectral differences between the two samples are observed which arise from molecular packing differences between the two sheet structures.

Molecular dynamics in paramagnetic materials as studied by magic-angle spinning 2H NMR spectra.

A magic-angle spinning (MAS) 2H NMR experiment was applied to study the molecular motion in paramagnetic compounds. The temperature dependences of 2H MAS NMR spectra were measured for paramagnetic [M(H2O)6][SiF6] (M=Ni2+, Mn2+, Co2+) and diamagnetic [Zn(H2O)6][SiF6]. The paramagnetic compounds exhibited an asymmetric line shape in 2H MAS NMR spectra because of the electron-nuclear dipolar coupling.