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Anderson, A.C. Dobbs, James Norris 2011-06-06T14:44:30Z 2011-06-06T14:44:30Z 10000-01-01 1985 The impurity tunneling systems of Li+ in KCl and CN-in KBr have been studied by means of specific heat (C) and thermal expansion (a) measurements obtained at temperatures T between 0.09 K and 10 K. For the Li+ defects, a peak occurs in the thermal expansion near 1 K which is qualitatively similar to the Schottky anomaly observed in the specific heat. For T > 0.6 K, the GrUneisen parameter, r, 3a/C, is isotropic and tt equal to +150±15 independent of temperature and lithium isotope. At lower temperatures, r becomes temperature dependent and anisotropic with respect to crystal orientation, probably because of interactions between Li+ sites. All measurements were for Li+ concentrations < 200 ppm. The KBr:CN system has been studied for CN-concentrations ranging from 0.034% to 50%. At the lowest concentration, the thermal expansion consists of a positive peak near 1 K (r ~ +50) and a negative peak near 0.2 K (r ~ -100). As the CN-concentration is increased, the thermal expansion becomes smaller in magnitude and in temperature dependence as the orientational glass phase develops. At 50% concentration, the thermal expansion (with r ~ +1) is similar to that of many amorphous solids. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-06T14:44:30Z No. of bitstreams: 1 1985_dobbs.pdf: 3824609 bytes, checksum: bebac3b725dbc3db3f19ef76da45e0fc (MD5) Made available in DSpace on 2011-06-06T14:44:30Z (GMT). No. of bitstreams: 1 1985_dobbs.pdf: 3824609 bytes, checksum: bebac3b725dbc3db3f19ef76da45e0fc (MD5) Previous issue date: 1985 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-06-06T14:44:30Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:11:26-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 842396 http://hdl.handle.net/2142/25282 en Copyright 1985 James Norris Dobbs tunneling impurities alkali halides specific heat thermal expansion Schottky anomaly Study of tunneling impurities in alkali halides at low temperatures Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.