Code: WOD	Time Slot/Poster Number: 4:00-4:25	Session: Solids III Inorganics & Small Molecules
Ab initio simulation of spin dynamics in solids
Jean-Nicolas Dumez1; Mark C. Butler2; Elodie Salager1; Bénédicte Elena1; Lyndon Emsley1
1ENS Lyon, Lyon, France; 2University of California, Berkeley, California
Abstract
We introduce a method of simulating large, densely coupled spin systems in a reduced Liouville space. Using this approach we are able to simulate the medium-term coherent dynamics of a powder sample under MAS for a crystalline lattice of over 200 protons. This constitutes an order-of-magnitude increase in the number of spins for which such dynamics have been simulated, and suggests that the structure and dynamics of solids may be probed by directly studying the dependence of experimental observables on coherent interactions involving many spins. We show that ab initio simulations in reduced spin spaces can quantitatively reproduce experimental proton spin diffusion curves. We also present results for calculations of other observables of interest in solid-state MAS NMR, including spectra.

Code: WOD	Time Slot/Poster Number: 4:25-4:40	Session: Solids III Inorganics & Small Molecules
Solid State NMR Studies of Defect Structures and Mobility in Doped Perovskites
Frederic Blanc1; Lucienne Buannic1; Derek S. Middlemiss1; Chris J. Pickard2; Zhehong Gan3; Clare P. Grey1, 4
1Dept. of Chemistry, State University of New York, Stony Brook, NY; 2Dept. of Physics/Astronomy, Univ. College London, London, UK; 3National High Field Magnetic Laboratory, Tallahassee, FL; 4Dept. of Chemistry, University of Cambridge, Cambridge, UK
Abstract
We have used multinuclear (17O, 25Mg, 71Ga, 89Y and 119Sn) solid state NMR to investigate the ionic mobility and defect chemistry of two types of doped perovskites materials (Sr and Mg-doped lanthanum gallate LaGaO3 and Y doped barium stannate BaSnO3). 17O MAS spectra including variable temperature experiments revealed the different 17O sites and 17O motion mechanism while the NMR of the metal cations themselves (Mg2+, Ga3+, Y3+ and Sn4+) allowed us to locate the defect via a coordination number – isotropic chemical shift correlation.

Code: WOD	Time Slot/Poster Number: 4:40-5:05	Session: Solids III Inorganics & Small Molecules
Prediction of NMR J-coupling in solid materials
Jonathan Yates
University of Oxford, Oxford, United Kingdom
Abstract
In recent years, bond correlation experiments, in particular, those employing spin-echo magic angle spinning techniques, have resulted in accurate measurements of J-coupling in both inorganic and organic solids. Motivated by these advances we have developed a first principles method to calculate J-coupling in solid-state systems. As well as assisting with experiment design and interpretation, the calculations provide a direct insight into how J is mediated. We have applied calculations, in combination with experimental work undertaken by several groups, to a range of solid-state systems. Examples include both organic and inorganic crystals (ordered and disordered), and couplings which involve a range of nuclei and  bond types (regular, hydrogen bonds, and also non-bonding interactions).

Code: WOD	Time Slot/Poster Number: 5:05-5:20	Session: Solids III Inorganics & Small Molecules
Q(n)-Species Distribution in K20 • 2 SiO2 Glass by 29Si Magic Angle Flipping NMR
Michael C. Davis1; Derrick C. Kaseman1; Sahar M. Parvani1; Kevin J. Sanders1; Philip J. Grandinetti1; Pierre Florian2; Dominique Massiot2
1The Ohio State University, Columbus, OH; 2CNRS and Universite d Orleans, Orleans Cedex 2, France
Abstract
Two-dimensional magic angle flipping (MAF) NMR was employed to measure the Q(n) distribution in a 29Si enriched potassium disilicate glass (K2O • 2 SiO2). Relative concentrations of [Q(4)] = 7.23 +/- 0.339 %, [Q(3)] =82.97 +/- 0.118 %, [Q(2)] = 9.80 +/- 0.660 % were obtained. Using the thermodynamic model for Q(n) disproportionation, an equilibrium constant k3 = 0.01029 +/- 0.00084 was calculated, indicating a close to binary distribution of Q(n) species. Trends in nuclear shielding anisotropy for Q(2) and Q(3) indicate that as the field strength of the modifying cation increases the silicon-non-bridging oxygen bond length increases, causing the nucleus to become more deshielded.

Code: WOD	Time Slot/Poster Number: 5:20-5:45	Session: Solids III Inorganics & Small Molecules
Hydrogen storage systems studied by NMR
Mark Conradi
Washington Univ., St. Louis, MO
Abstract
Mark S. Conradi1, Tim M. Ivancic1, David T. Shane1, Robert L. Corey2, Robert C. Bowman, Jr.3 1. Washington University, Dept. of Physics, Saint Louis, MO 63130 2. South Dakota School of Mines and Technology, 501 West Saint Joseph Street, Rapid City, SD 57701 3. RCB Hydrides LLC, 117 Miami Avenue, Franklin, Ohio 45005 Solid-state materials are a possible solution to the problem of dense hydrogen fuel storage for automobiles, trucks and buses. To obtain adequate vehicle range, attention has focused on hydrides of lightweight metal atoms, such as Li, B, Na, Mg and Al. The resulting hydrides are ionic or ionic-covalent as in NaAlH4 and LiBH4. While the mass fractions of reversible hydrogen can be impressive (13.8% for LiBH4), the reaction kinetics are very slow, in part due to slow hydrogen diffusion. We report NMR measurements of line narrowing, T1D, and T1ρ on these systems to better understand the atomic mobilities. Bulk MgH2, an archetypal ionic hydride, has a H jump rate of only 400 s-1 at 400 °C, as measured by T1D. Ball-milled MgH2 and NaMgH3 reveal mobile fractions already at 125°C.The mobile H atoms appear to be associated with disorder near the grain boundaries. Nanoscaffolds offer a solution to grain growth during dehydriding- rehydriding cycles, serving as structure directing agents. In LiBH4, where the H resonance narrows at 180 °C in bulk, a substantial fraction of narrowed H signal is evident at room temperature for aerogel nanoscaffolded material. LiBH4 doped with C60 forms a polymer scaffold. In NaAlH4, we have used in situ 27Al NMR to detect a new, mobile species. The species occurs during dehydriding and rehydriding conditions and is distinct from the well-known reaction products (Al metal, Na3AlH6). A method to recover the new material at ambient conditions will allow other techniques to identify it.