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dc.contributor.authorJalili, Helia.en_US
dc.date.accessioned2009-06-29T14:36:53Z
dc.date.available2009-06-29T14:36:53Z
dc.date.issued2005-06-29T14:36:53Z
dc.identifier.urihttp://hdl.handle.net/10464/1647
dc.description.abstractPolycrysttdline samples of NaiCoOa were prepared using the "Rapid heat-up" method. One set of samples was annealed in flowing O2, while the other set in flowing Argon. X-Ray diffraction measurements indicated a stable phase of Nao.7Co02 mixed with C03O4 for all the samples even though they differed in concentration of Na. Argon annealed samples were insulators, whereas the ones annealed in O2 were metallic. Most of the measurements were performed on the sample Nao.7Co02, because it is the host compound for the superconductor sample Nao.35Co02-H20. Magnetization measurement showed that the magnetic moment decreased with increasing sodium concentration. This is due to the existence of C03O4 in samples with Na^ 0.7. As sodium concentration decreases, the magnetic moment increases due to the increasing concentration of C03O4 and its large magnetic moment. Magnetization measurements showed that the magnetic moment of Nao.7Co02 is field-dependent in low fields eind field-independent in fields higher than 100 G. Resistivity changes with temperature (dp/dT) increased with increasing Na concentration. Also resistivity measurements were performed under different hydrostatic pressures on Nao.7Co02. Two transitions were observed; one at a temperature Ti ~20 K and the other at T2 ^280 K, the transition at Ti has a magnetic origin and the one at T2 is a structiural transition. It was noticed that pressure aJfects resistivity of the sample. At higher pressures resistivity changes faster with temperature. Magnetoresistance measurement showed a small change in the resistivity, especially at lower temperatures. A novel layered superconductor Nao.35Co02H20 was prepared using de-intercalation of Na from the host compound Nao.7Co02. FVom the temperature dependence of the magnetization, the superconducting transition temperature and lower critictil field have been estimated as Tc=4.12 K and Hci=66 G, respectively.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectSodium cobalt oxideen_US
dc.subjectSodium cobalt oxideen_US
dc.subjectSuperconductors.en_US
dc.subjectThermoelectric materials.en_US
dc.titleProperties of NaxCoO2 /en_US
dc.typeElectronic Thesis or Dissertationen
dc.degree.nameM.Sc. Physicsen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Physicsen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US
refterms.dateFOA2021-08-07T01:59:12Z


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