The mechanism of hydrogen release from solid state ammonia borane (AB) has been investigated via in situ 11B and 11B{1H} MAS-NMR techniques external fields 7.1 T 18.8 at a decomposition temperature 88 °C, well below the reported melting point. AB is described by an induction, nucleation growth mechanistic pathway. During induction period, little released AB; however, new species identified as mobile phase observed NMR spectra. Subsequent to reaction times when initially being released, three...

The iron(III)-substituted tungstogermanate [Fe6(OH)3(A-alpha-GeWO34(OH)3)2]11- (1) has been synthesized and characterized by IR, elemental analysis, SQUID magnetometry, electron paramagnetic resonance (EPR), electrochemistry. Single-crystal X-ray analysis was carried out on Cs4Na7[Fe6(OH)3(A-alpha-GeW9O34(OH)3)2] x 30H2O, which crystallizes in the monoclinic system, space group C2/m, with a = 36.981(4) A, b 16.5759(15) c 16.0678(15) beta 95.311(3) degrees, Z 4. Polyanion 1 consists of two...

Coherent carbon cryogel−ammonia borane (C−AB) nanocomposites were synthesized, and improved H2 storage properties are reported. Porous cryogels impregnated with AB in tetrahydrofuran solution at 25 °C under argon; 30% of the cryogel pore volume was filled to produce a 24 wt % C−AB nanocomposite. Nitrogen sorption isotherms, X-ray diffraction, differential scanning calorimetry, thermal/thermal gravimetric analyses, mass spectrometry, 11B NMR used characterize coherent nanocomposites. Findings...

The novel dimeric germanotungstates [M4(H2O)2(GeW9O34)2]12- (M = Mn2+, Cu2+, Zn2+, Cd2+) have been synthesized and characterized by IR spectroscopy, elemental analysis, magnetic measurements, 183W-NMR spectroscopy. X-ray single-crystal analyses were carried out on Na12[Mn4(H2O)2(GeW9O34)2]·38H2O (Na12-1), which crystallizes in the monoclinic system, space group P21/n, with a 13.0419(8) Å, b 17.8422(10) c 21.1626(12) β 93.3120(10)°, Z 2; Na11Cs2[Cu4(H2O)2(GeW9O34)2]Cl·31H2O (Na11Cs-2)...

The novel heteropolyanion [Cu(4)K(2)(H(2)O)(8)(alpha-AsW(9)O(33))(2)](8)(-) (1) has been synthesized and characterized by IR spectroscopy, elemental analysis, magnetic studies. Single-crystal X-ray analysis was carried out on [K(7)Na[Cu(4)K(2)(H(2)O)(6)(alpha-AsW(9)O(33))(2)].5.5H(2)O](n)(K(7)Na-1), which crystallizes in the tetragonal system, space group P42(1)m, with a = 16.705(4) A, b c 13.956(5) Z 2. Interaction of lacunary [alpha-AsW(9)O(33)](9)(-) Cu(2+) ions neutral, aqueous medium...

The 15-cobalt-substituted polyoxotungstate [Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}](5-) (1) has been characterized by single-crystal XRD, elemental analysis, IR, electrochemistry, magnetic measurements, and EPR. Single-crystal X-ray analysis was carried out on Na(5)[Co(6)(H(2)O)(30){Co(9)Cl(2)(OH)(3)(H(2)O)(9)(beta-SiW(8)O(31))(3)}].37H(2)O, which crystallizes in the hexagonal system, space group P6(3)/m, with a = 19.8754(17) A, b c 22.344(4) alpha= 90 degrees,...

Aluminium hydride has been synthesized electrochemically, providing a synthetic route which closes reversible cycle for regeneration of the material and bypasses expensive thermodynamic costs have precluded AlH3 from being considered as H2storage material.

We report pulsed field magnetization and ESR experiments on a {Cu3} nanomagnet, where antiferromagnetically coupled Cu(2+) (S = 1/2) ions form slightly distorted triangle. The remarkable feature is the observation of half step magnetization, hysteresis loops, an asymmetric between positive negative in fast sweeping external field. This attributed to adiabatic change magnetization. energy levels determined by unveil that different mixing nature spin chirality total S 1/2 Kramers doublet...

Single crystals of semiconductor-grade lithium indium selenide (LiInSe2) were grown using the vertical Bridgman method. The orthorhombic structure materials was verified powder x-ray diffraction. room temperature band gap crystal found to be 2.85 eV optical absorption measurements. Resistivity LiInSe2, obtained current-voltage measurements, has semiconducting nature (decreases with increasing temperature) and is in order 1010 Ω·cm. Photoconductivity measurement showed photocurrent peak at...

In coarse-grained MgH2, the diffusive motion of hydrogen remains too slow (<105 hops s−1) to narrow H NMR line up 400 °C. Slow-motion dipolar relaxation time T1D measurements reveal motion, with hopping rate ωH from 0.1 430 s−1over range 260 °C, first direct measurement in MgH2. The data are described by an activation energy 1.72 eV (166 kJ/mol) and attempt frequency 2.5 × 1015 s−1. ball-milled MgH2 0.5 mol % added Nb2O5 catalyst, line-narrowing is evident already at 50 shape shows distinct...

The structural behavior of 11B-, 2H-enriched ammonia borane, ND311BD3, over the temperature range from 15 to 340 K was investigated using a combination neutron powder diffraction and ab initio molecular dynamics simulations. In low orthorhombic phase, progressive displacement borane group under amine observed leading alignment B−N bond near parallel c-axis. tetragonal phase transition at 225 is marked by dramatic change in both group. resulting hydrogen disorder problematic extract metrics...

We report high resolution 15N NMR probing of the solid−solid phase transition 15N-labeled ammonia borane (NH3BH3) at 225 K. Both isotropic chemical shift (δiso) and spin−lattice relaxation rate (T1-1) exhibited strong anomalies around The analysis T1-1 using Bloembergen, Purcell, Pound model showed that motional correlation time, τ, increased from about 1 to 100 ps corresponding Arrhenius activation energy 6 14.5 kJ/mol on going through toward lower temperatures. temperature dependence δiso...

Abstract Magnetic susceptibility and high‐frequency EPR spectroscopy investigations were carried out on the isostructural family of tricopper( II )‐substituted, sandwich‐type polyoxotungstates [Cu 3 (H 2 O) (α‐AsW 9 O 33 ) ] 12− ( 1 ), (α‐SbW (α‐SeW 10− (α‐TeW 4 with intention examining possible influence diamagnetic heteroatoms X (X = As III , Sb Se IV Te magnetic exchange properties three Cu 2+ ions in central belt. data indicate a single antiferromagnetic spin constant J for triangular...

The activation energies for rotations in low-temperature orthorhombic ammonia borane were analyzed and characterized terms of electronic structure theory. perdeuterated (11)B-enriched borane, (11)BD(3)ND(3), sample was synthesized, the refined from neutron powder diffraction data at 175 K. This temperature has been chosen as median range previously reported nuclear magnetic resonance spectroscopy measurements these rotations. A representative molecular cluster model assembled geometry,...

6LiInSe2 is a promising thermal neutron semiconductor detector material. The performance of the affected by carrier mobility-lifetime products. Therefore, defects that function as recombination centers need to be identified. In this letter, characterization defect levels in photo-induced current transient spectroscopy (PICTS) and photoluminescence reported. PICTS measurements revealed electron-related located at 0.22, 0.36, 0.55 eV hole-related 0.19, 0.30, 0.73 eV. Free exciton...

A hand-held device for laser-induced breakdown spectroscopy has been investigated the determination of uranyl fluoride surface contamination. This research demonstrates ability to successfully detect uranium on surfaces when using a low resolving power (λ/Δλ=4000) spectrograph, with 5 mJ energy per 1 ns pulsed laser radiation, available as commercially packaged system. Sand/uranyl mixtures are prepared simulate residue likely encountered during decontamination efforts at facilities that...

Oxidation of Os(2)(hpp)(4)Cl(2), 1 (hpp = the anion 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine), with (FeCp(2))PF(6) produces air-stable [Os(2)(hpp)(4)Cl(2)]PF(6), 2. This is first structurally confirmed metal-metal bonded paddlewheel compound having an M(2)(7+) core. The Os-Os distances for two crystalline forms, 2.2acetone and 2.hexane, are 2.3309(4) 2.3290(6) A, respectively. EPR, (1)H NMR, magnetization data indicate that 2 has unpaired electron exceptionally low g value 0.791...

Hydrogen and 23Na NMR were performed to 400 °C on NaMgH3 powder produced by reactive ball-milling of NaH MgH2. The H resonance shows narrowing already at 100 as a narrow line superimposed the broad, rigid-lattice signal. With increasing temperature, fraction spins in component grows smoothly, approaching 100% near 275 °C. This heterogeneous suggests wide distribution motion rates. After annealing °C, intensity temperatures below 200 was substantially reduced both relaxation rates 1/T1...

Incoherent inelastic neutron scattering is used to probe the effects of dihydrogen bonding on vibrational dynamics in molecular crystal ammonia borane. The thermal energy loss spectra B11 enriched borane isotopomers (B11H3NH3, B11D3NH3, and B11H3ND3) are presented compared power spectrum calculated using ab initio dynamics. A harmonic analysis NH3BH3 clusters was also explored check for consistency with experiment spectrum. measured computed compare extremely well (50–500 cm−1). Some...