@article { ISI:000253339800027,
	title = {Sn-119 magic angle spinning NMR of nanocrystalline SnO2},
	journal = {Journal of Nanoscience and Nanotechnology},
	volume = {8},
	number = {1},
	year = {2008},
	month = {JAN},
	pages = {321-328},
	publisher = {AMER SCIENTIFIC PUBLISHERS},
	address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA},
	abstract = {<p>Nanocrystalline SnO2 samples of different grain sizes, prepared by inert gas condensation technique (IGCT) and chemical precipitation method and conforming to the tetragonal phase, have been studied by variable speed (3-10 kHz) Sn-119 MAS NMR at 11.74 Tesla field. Sn-119 solid-state NMR results show that the IGCT prepared samples have good crystallinity and phase purity compared to the samples prepared by the chemical method. The determination of Sn-119 chemical shielding parameters (delta(iso), Delta delta and eta) from slow MAS spectra shows that the Sn-119 isotropic chemical shift (delta(iso)) is strongly influenced at smaller grain sizes, attributable to the change in the O2- local symmetry for the surface Sn-119 ions at smaller grain sizes. The observed line widths in MAS spectra are significantly larger than the life-time broadening due to spin-lattice (T-1) and spin-spin (T,) relaxation. The Sn-119 MAS NMR spectra are thus inhomogeneously broadened by a distribution of isotropic chemical shifts, the line broadening increasing with decrease in grain size.</p>},
	keywords = {Hydrolysis, IGCT, MAS NMR, nanocrystalline SnO2},
	issn = {1533-4880},
	doi = {10.1166/jnn.2008.015},
	author = {Sabarinathan, V. and Chandran, C. Vinod and Ramasamy, S. and Ganapathy, Subramanian}
}
@article { ISI:000274270100005,
	title = {Perturbations to Al-27 electric field gradients in nanocrystalline alpha-Al2O3 studied by high-resolution solid-state NMR},
	journal = {Journal of Physical Chemistry B},
	volume = {114},
	number = {5},
	year = {2010},
	month = {FEB},
	pages = {1775-1781},
	publisher = {AMER CHEMICAL SOC},
	address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
	abstract = {<p>Al-27 solid-state NMR has been employed to study the perturbations to Al-27 electric field gradients for the aluminum environments in nanocrystalline alpha-alumina. Triple quantum magic angle spinning experiments show that the octahedral aluminum coordination remains unchanged down to 12 nm, although severe perturbations to Al-27 electric field gradients are noticed at 28 nm and below. 3Q-MAS and SATRAS experimental data of nano alpha-alumina have been analyzed through extensive spectral simulations to probe Al-27 electric field gradients of aluminum in the grains and grain boundaries. While the aluminum in the grains has a unique field gradient tensor, the same octahedrally coordinated aluminum environments in the grain boundaries suffer a distribution of electric field gradients. This is evidenced by data analysis of both 3Q-MAS and SATRAS spectra. By invoking the Gaussian isotropic model, in which the (C-Q, eta(Q)) parameter space is discretely sampled by the Czjzek distribution, we have been able to analyze the Al-27 SATRAS spectra of nanocrystalline alpha-alumina samples having grain sizes of 52, 28, 20, and 12 nm. Good agreement between experimental and simulated spectra has led to the quantitative determination of grain and grain boundary components in these materials.</p>},
	issn = {1520-6106},
	doi = {10.1021/jp907469n},
	author = {Sabarinathan, V. and Ramasamy, S. and Ganapathy, Subramanian}
}
