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Published February 1982 | public
Journal Article

Orientation and Motion of Water Molecules in Cordierite: A Proton Nuclear Magnetic Resonance Study

Abstract

Conventional and solid state proton nuclear magnetic resonance (NMR) techniques have been used to examine water molecules in the channels of a single crystal of cordierite, (Mg, Fe)_2Al_4Si_5O_(18), as a function of temperature, magnetic field, and orientation. Only one type of water was found rather than water in two distinct rigid orientations which were indicated by earlier infrared spectral studies. However, the measured dipolar splittings indicate that this water is in rapid motion. Shifts in the dipolar doublet due to Fe^(2+) impurities indicate that the water molecules are not moving among adjacent channel sites along a channel cavity. A two-site hopping model is proposed involving the major residence time spent with the hydrogen-hydrogen vector parallel to the channels, a minor residence time spent with the hydrogen-hydrogen vector perpendicular to the channels, and a short time (<1 μs) in transit. This model fits both the present NMR data and previously reported infrared absorption data and is compared to previously reported neutron diffraction data.

Additional Information

© 1982 Springer-Verlag. Received December 5, 1980. This work was supported by National Science Foundation grants DMR-7721394 and EAR 77-23147. We thank Dr. Sunney Chan (Caltech) for helpful discussion.

Additional details

Created:
August 22, 2023
Modified:
October 26, 2023