{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/25282"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/25282","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Study of tunneling impurities in alkali halides at low temperatures","abstract":"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.","abstract_html":"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 &gt; 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 &lt; 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.","abstract_has_math":false,"creators":["Dobbs, James Norris"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Anderson, A.C."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-06-06T14:44:30Z","date_published":"2011-06-06T14:44:30Z","updated_at":"2026-07-22T22:25:24Z","subjects":["tunneling impurities","alkali halides","specific heat","thermal expansion","Schottky anomaly"],"languages":["en"],"rights":["Copyright 1985 James Norris Dobbs"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["842396"],"render_values":[{"text":"842396","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/25282","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Anderson, A.C."]},{"key":"dc:creator","label":"Author","values":["Dobbs, James Norris"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-06-06T14:44:30Z","10000-01-01","1985"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["tunneling impurities","alkali halides","specific heat","thermal expansion","Schottky anomaly"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1985 James Norris Dobbs"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["842396","http://hdl.handle.net/2142/25282"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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"]},{"key":"dc:title","label":"Title","values":["Study of tunneling impurities in alkali halides at low temperatures"]}]}],"canonical_facts":{"dc:contributor":["Anderson, A.C."],"dc:creator":["Dobbs, James Norris"],"dc:date":["2011-06-06T14:44:30Z","10000-01-01","1985"],"dc:description":["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"],"dc:identifier":["842396","http://hdl.handle.net/2142/25282"],"dc:language":["en"],"dc:rights":["Copyright 1985 James Norris Dobbs"],"dc:subject":["tunneling impurities","alkali halides","specific heat","thermal expansion","Schottky anomaly"],"dc:title":["Study of tunneling impurities in alkali halides at low temperatures"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:24Z"}