{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/28683"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/28683","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"An x-ray study of the structure of K1-xRbxCy","abstract":"The mixed layered compounds K1-xRbxC8 and K1-xRbxC24 represent quasi two-dimensional alloys interleaved by graphite hexagonal planes. We report extensive x-ray scattering investigations of the structural aspects of these compounds. In stage 1 K1-xRbxC8, we find that the interlayer separation exhibits a slight deviation from linearity, independent of the graphite material used (pyrolytic graphite or single crystals), with a maximum deviation centered at x=2/3. In the plane, the mixed alkali layers form a (2x2)R0° superstructure with complete site disorder among the K and Rb metal atoms. Extensive low temperature investigations have not revealed any tendency of the mixed layer to either super-order or phase separate. The stacking sequence is independent of alloy composition and is identical to the stacking sequence in KC8 as well as in RbC8. The carbon-carbon bond length appears not to change with alloy composition. By comparing the diffusion constants from a macroscopic diffusion experiment with self diffusion constants obtained from quasi-elastic neutron scattering data, we found that the substitutional intercalation process must be drastically hindered by a barrier at the perimeter of the sample. The stage 2 K1-xRbxC24 (x-0.52,0.80) compounds were synthesized for the first time. Below the ordering temperature (Tu-149 and 159K, respectively) peaks corresponding to a discommensuration domain structure are observed, which correspond to the compositional average of the unmixed compounds. By taking single crystal Laue photographs, we have determined the position and orientation of the peaks near the origin. We propose a simple physical model to interpret the x-ray data. Below a second transition temperature TL~ lOOK, the domain structure becomes unstable against a composition modulation.","abstract_html":"The mixed layered compounds K1-xRbxC8 and K1-xRbxC24 represent quasi two-dimensional alloys interleaved by graphite hexagonal planes. We report extensive x-ray scattering investigations of the structural aspects of these compounds. In stage 1 K1-xRbxC8, we find that the interlayer separation exhibits a slight deviation from linearity, independent of the graphite material used (pyrolytic graphite or single crystals), with a maximum deviation centered at x=2/3. In the plane, the mixed alkali layers form a (2x2)R0° superstructure with complete site disorder among the K and Rb metal atoms. Extensive low temperature investigations have not revealed any tendency of the mixed layer to either super-order or phase separate. The stacking sequence is independent of alloy composition and is identical to the stacking sequence in KC8 as well as in RbC8. The carbon-carbon bond length appears not to change with alloy composition. By comparing the diffusion constants from a macroscopic diffusion experiment with self diffusion constants obtained from quasi-elastic neutron scattering data, we found that the substitutional intercalation process must be drastically hindered by a barrier at the perimeter of the sample. The stage 2 K1-xRbxC24 (x-0.52,0.80) compounds were synthesized for the first time. Below the ordering temperature (Tu-149 and 159K, respectively) peaks corresponding to a discommensuration domain structure are observed, which correspond to the compositional average of the unmixed compounds. By taking single crystal Laue photographs, we have determined the position and orientation of the peaks near the origin. We propose a simple physical model to interpret the x-ray data. Below a second transition temperature TL~ lOOK, the domain structure becomes unstable against a composition modulation.","abstract_has_math":false,"creators":["Chow, Paul C."],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Zabel, Hartmut"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-01-23T18:20:10Z","date_published":"2012-01-23T18:20:10Z","updated_at":"2026-07-22T22:25:27Z","subjects":["x-ray","quasi two-dimensional alloy"],"languages":["en"],"rights":["1988 Paul C. Chow"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/28683","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Zabel, Hartmut"]},{"key":"dc:creator","label":"Author","values":["Chow, Paul C."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-01-23T18:20:10Z","10000-01-01","1988"]},{"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":["x-ray","quasi two-dimensional alloy"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["1988 Paul C. 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The stacking sequence is independent of alloy composition and is identical to the stacking sequence in KC8 as well as in RbC8. The carbon-carbon bond length appears not to change with alloy composition. By comparing the diffusion constants from a macroscopic diffusion experiment with self diffusion constants obtained from quasi-elastic neutron scattering data, we found that the substitutional intercalation process must be drastically hindered by a barrier at the perimeter of the sample. The stage 2 K1-xRbxC24 (x-0.52,0.80) compounds were synthesized for the first time. Below the ordering temperature (Tu-149 and 159K, respectively) peaks corresponding to a discommensuration domain structure are observed, which correspond to the compositional average of the unmixed compounds. By taking single crystal Laue photographs, we have determined the position and orientation of the peaks near the origin. We propose a simple physical model to interpret the x-ray data. Below a second transition temperature TL~ lOOK, the domain structure becomes unstable against a composition modulation.","Submitted by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:20:10Z No. of bitstreams: 1 1988_chow.pdf: 3807254 bytes, checksum: 2ca8ba098f7ce389691ba50ccd0b0271 (MD5)","Made available in DSpace on 2012-01-23T18:20:10Z (GMT). No. of bitstreams: 1 1988_chow.pdf: 3807254 bytes, checksum: 2ca8ba098f7ce389691ba50ccd0b0271 (MD5) Previous issue date: 1988","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:20:10Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:10:27-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation","dissertation","U of I Only"]},{"key":"dc:title","label":"Title","values":["An x-ray study of the structure of K1-xRbxCy"]}]}],"canonical_facts":{"dc:contributor":["Zabel, Hartmut"],"dc:creator":["Chow, Paul C."],"dc:date":["2012-01-23T18:20:10Z","10000-01-01","1988"],"dc:description":["The mixed layered compounds K1-xRbxC8 and K1-xRbxC24 represent quasi two-dimensional alloys interleaved by graphite hexagonal planes. We report extensive x-ray scattering investigations of the structural aspects of these compounds. In stage 1 K1-xRbxC8, we find that the interlayer separation exhibits a slight deviation from linearity, independent of the graphite material used (pyrolytic graphite or single crystals), with a maximum deviation centered at x=2/3. In the plane, the mixed alkali layers form a (2x2)R0° superstructure with complete site disorder among the K and Rb metal atoms. Extensive low temperature investigations have not revealed any tendency of the mixed layer to either super-order or phase separate. The stacking sequence is independent of alloy composition and is identical to the stacking sequence in KC8 as well as in RbC8. The carbon-carbon bond length appears not to change with alloy composition. By comparing the diffusion constants from a macroscopic diffusion experiment with self diffusion constants obtained from quasi-elastic neutron scattering data, we found that the substitutional intercalation process must be drastically hindered by a barrier at the perimeter of the sample. The stage 2 K1-xRbxC24 (x-0.52,0.80) compounds were synthesized for the first time. Below the ordering temperature (Tu-149 and 159K, respectively) peaks corresponding to a discommensuration domain structure are observed, which correspond to the compositional average of the unmixed compounds. By taking single crystal Laue photographs, we have determined the position and orientation of the peaks near the origin. We propose a simple physical model to interpret the x-ray data. Below a second transition temperature TL~ lOOK, the domain structure becomes unstable against a composition modulation.","Submitted by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:20:10Z No. of bitstreams: 1 1988_chow.pdf: 3807254 bytes, checksum: 2ca8ba098f7ce389691ba50ccd0b0271 (MD5)","Made available in DSpace on 2012-01-23T18:20:10Z (GMT). No. of bitstreams: 1 1988_chow.pdf: 3807254 bytes, checksum: 2ca8ba098f7ce389691ba50ccd0b0271 (MD5) Previous issue date: 1988","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:20:10Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:10:27-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation","dissertation","U of I Only"],"dc:identifier":["http://hdl.handle.net/2142/28683"],"dc:language":["en"],"dc:rights":["1988 Paul C. Chow"],"dc:subject":["x-ray","quasi two-dimensional alloy"],"dc:title":["An x-ray study of the structure of K1-xRbxCy"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:27Z"}