Department of Science, Technology and Engineering

Permanent URI for this collectionhttp://erepository.kibu.ac.ke/handle/123456789/113

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Browsing Department of Science, Technology and Engineering by Subject "Entropy"

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    Effect of duo fermion spin on the specific heat and entropy of a mixture of helium isotopes
    (Journal of Multidisciplinary Engineering Science and Technology (, 2018-10-01) Lusamamba, Simon Mwatulo; Sakwa, Thomas W.; Odhiambo, Jared Oloo
    Spin normally determines the character, rate of collision and subsequently the properties of ultracold systems. This study investigated the effect of double spin degeneracy on the thermodynamic properties of Helium-3 and Helium-4 isotopes specifically the specific heat and entropy of a grand canonical ensemble. The approach used was statistical in nature where permutation and exclusion was done on fermions and bosons. From thermodynamics, the expression of partition function which was used to derive other expressions of specific heat and entropy as temperature dependence. Specific heat and entropy were found to increase with temperature. The kink in specific heat at a temperature of 35K implied that there was a phase transition.
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    Specific heat and entropy of a three electron model in bismuth based cuprate superconductor
    (Science Publishing Group : World Journal of applied physics, 2018-06-11) Odhiambo, Jared Oloo; Makokha, John Wanjala
    A theoretical study considering Bi2201, Bi2212 and Bi2223 bismuth based cuprates whose critical Temperatures (TC) are 20K, 95K and 110K with one, two and three CuO2 planes respectively; based on a three electron model in Bismuth based cuprates oxide shows that there is a direct correlation between energy of interaction and the number of CuO2 planes at the TC. The specific heat for a mole of Bismuth based cuprates at TC was found to be 7.471×10-24JK-1 regardless of the number of CuO2 planes; though the specific heat per unit mass, Sommerfeld coefficient as well as entropy per unit mass decreased with an increase in the number of CuO2 planes.The entropy of a mole of Bismuth based cuprates at TC was found to be 5.603×10-24JK-1 irrespective of the TC or mass. The peak Sommerfeld coefficient temperature was noted to occur at the ratio T/TC=0.66 in the bismuth based cuprates.
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    Thermodynamic properties of yttrium based cuprate due to electron-cooper pair interaction using BVT
    (Open Access Library Journal, 2018-10-15) Mukubwa, Abel Wanjala; Odhiambo, Jared Oloo; Makokha, John Wanjala
    Since the discovery of high temperature superconductivity (HTSC), there have been varied results concerning the high pairing energy in the unconventional superconductivity. In an attempt to unearth the mechanism behind the high pairing energy, we study a model in which an excited electron interacts with a Cooper pair. The interaction was studied earlier on using second quantization which depended on a wave function. We now use Bogoliubov- Valatini transformation (BVT) that is independent of the wave function to study the thermodynamic properties due to the interaction between an electron and a Cooper pair in a Yttrium based cuprate. The interaction energy increases with temperature and at T = 93 K ; we record the interaction energy of 2.173 meV and the specific heat of 4.669 J∙mol−1∙K−1. The entropy of this system is found to be 5.11 mJ∙g−1∙K−1. The Sommerfeld’s coefficient is maximum at T = 2/3 Tc where γ = 62.4 mJ ⋅mol−1 ⋅K−2 . It has also been observed, for the first time, that the thermodynamic quantities of YBCO123 are constant when temperature varies between 0 K and 18 K. Above 18 K, the thermodynamic quantities rise sharply. This observation has been attributed to the pairing of electrons in the singlet-s and singlet-p states.