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Sb bonding in GeSbTe compounds by NMR Measurements

Published online by Cambridge University Press:  01 February 2011

David Bobela  and
P. Craig Taylor
David Bobela
Affiliation:
dbobela@gmail.com, University of Utah, Dept of Physics, 115 S 1400 E, Salt Lake City, UT, 84112, United States
P. Craig Taylor
Affiliation:
pctaylor@mines.edu, Colorado School of Mines, Dept of Physics, Golden, CO, 84112, United States
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Abstract

We have measured the 121Sb NMR spectra, which are highly sensitive to the electric field gradients at the nuclear site, for crystalline Sb2Te3, Ge1Sb2Te4, Ge2Sb2Te4, and Ge2Sb2Te5. Estimates of the coupling constants, which are a measure of the field gradient, based on these spectra compare well with compounds containing Sb sites that are approximately 6-fold coordinated. The coupling constants of amorphous phase counterparts are roughly an order of magnitude larger and compare favorably with compounds where the Sb sites are 3-fold coordinated. We argue that the difference in the coupling constants arises primarily from a change in the local coordination, as opposed to the slight differences in the Sb-Te bond lengths and bond angles. The NMR data agree best with a structural model of amorphous phase based upon the “8-N” rule.

Keywords

phase transformationSbnuclear magnetic resonance (NMR)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1072: Symposium G – Phase-Change Materials for Reconfigurable Electronics and Memory Applications , 2008 , 1072-G02-06
Copyright
Copyright © Materials Research Society 2008

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