NMR study of internal motions in certain iron group fluosilicates

Rangarajan, G and Ramakrishna, J (1969) NMR study of internal motions in certain iron group fluosilicates. In: Journal of Chemical Physics, 51 (12). pp. 5290-5294.

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Abstract

NMR study of ferrous fluosilicate hexahydrate indicated the presence of motion of both proton and fluorine nuclei. Only a single narrow line was observed for protons for any arbitrary orientation of a single crystal with respect to the applied magnetic field. This can be interpreted in terms of a phase-correlated flip motion of the interproton vectors between two disordered orientations or in terms of a hindered rotation of the Fe(H2O) 6 octahedron about the fourfold axes, together with the flip motion. The fluorine second moment indicated that the SiF6 octahedron also is undergoing reorientation. The temperature variation of the powder linewidth showed a transition around 195°K and led to rather low values for the potential barriers hindering the motions. No significant temperature variation of the linewidth was observed for hexahydrated cobalt fluosilicate in the temperature range between 90°K and room temperature. Similar observations in a powder sample of tetrahydrated copper fluosilicate also showed the presence of internal motions. The linewidth transition in this case took place at about 220°K and was found to be rather abrupt. The potential barrier for the motion was found to be relatively high.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
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:	05 May 2010 04:31
Last Modified:	19 Sep 2010 06:01
URI:	http://eprints.iisc.ac.in/id/eprint/27521

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