NMR investigation of certain hydrated fluorosilicates

Muthukrishnan, K and Ramakrishna, J (1973) NMR investigation of certain hydrated fluorosilicates. In: Journal of Chemical Physics, The, 59 (10). pp. 5571-5577.

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Abstract

Proton and fluorine NMR were investigated in the temperature range 90–425 °K in the hexahydrated fluorosilicates of Zn, Cu, Mn, Co, and Ni and in the tetrahydrated CuSiF6 to obtain information about the internal motions in these solids. Second moment transitions were observed at widely different temperatures for the different substances, and these are ascribed to the onset of reorientation of the M(H2O)₆²⁺ and SiF₆^2- octahedra. The correlation frequency and the potential barrier hindering the motion were calculated in all the cases. Apart from the narrowing taking place at higher temperatures, the Co salt showed a change in the line structure at 248 °K, where a phase transition was reported from magnetic susceptibility measurements. Studies on the single crystals of ZnSiF6 · 6H2O and NiSiF6 · 6H2O showed that there are three nonequivalent p-p vectors, and after the transition they all become equivalent, with the M(H2O)₆²⁺ octahedron reorienting about the fourfold axes.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics, The
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	16 Dec 2009 10:08
Last Modified:	19 Sep 2010 05:50
URI:	http://eprints.iisc.ac.in/id/eprint/24568

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