Browsing by Author "Makhokha, John"

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    DFT calculations of elastic, electronic and thermal properties of TiB2Mo
    (Oxford Open Materials Science, 2022-02-02) Wafula, Job; Manyali, George; Makhokha, John
    Ceramics are materials with good mechanical properties; however, low fracture toughness, intrinsic brittleness and poor resistance against oxidation at high temperatures are challenges limiting their applications. TiB2Mo is a ceramic material whose all elastic properties have not been calculated. In this study, we investigated the elastic, electronic and thermal properties of TiB2Mo structure using first principles calculations. All first principles calculations were based on the density functional theory as implemented in Quantum ESPRESSO code with the help of Thermo-pw as a post-processing code. Obtained lattice parameters of TiB2Mo structure were in good agreement with other previous theoretical studies. TiB2Mo structure was found to be mechanically and dynamically stable at ground state conditions. The results also show that TiB2Mo is brittle, anisotropic and metallic in nature. Based on the calculated Vicker’s hardness Hv, we noted that TiB2Mo is classified as a hard material with fracture toughness of above 7MPam0:5; therefore, it is a promising ultra-high temperature ceramic.
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    The Specific Heat Of Boson-Fermion Pair Condensate In Optimally-Doped Cuprates
    (Journal of Multidisciplinary Engineering Science and Technology, 2021-12-12) Mukubwa, Abel; Makhokha, John; Masinde, Fred
    Recent studies have shown that the interaction between a finite momentum Cooperpair boson and a fermion supports superconductivity in cuprates. Specifically, the occurrence of a superconducting energy gap in cuprates is defined by the collective excitation of boson-fermion pair condensates (BFPC) above the ground state. The ground state energy of BFPC in these materials show dependence on single-fermion spins. We study the specific heat of a BFPC in high temperature cuprates based on the ground state energy which represents the total internal energy of the system. The model results are in close proximity with the empirical findings. For instance, the specific heat of the model in Y123 is determined as 𝟏𝟏𝟖. 𝟗 𝐉𝐦𝐨𝐥−𝟏𝐊−𝟏, which close to the measured value of 𝟏𝟐𝟕. 𝟖 𝐉𝐦𝐨𝐥−𝟏𝐊−𝟏.