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Simultaneous analysis of Lattice Expansion and Thermal Conductivity in Defected Oxide Ceramics

Riyad, M Faisal
http://orcid.org/0000-0001-9342-992X
http://rave.ohiolink.edu/etdc/view?acc_num=osu1492737800363063

Abstract Details

2017, Master of Science, Ohio State University, Mechanical Engineering.
Objective of this thesis is to investigate the impact of point defects on thermal conductivity and lattice expansion in uranium dioxide ceramic. Specific emphasize is on light ion irradiation induced point defects which causes the degradation of thermal conductivity of oxide ceramics. Radiation induced defects include vacancies and interstitials hosted by the anion and cation sub lattice of the structure. A crystallographic structure is assumed for each defect and is used to model defect impact on lattice parameter. In ceramic materials, thermal conductivity is governed by phonon modes determined by crystalline structure. The irradiation induced point defects limit thermal transport by acting as phonon scattering centers. The point defects scattering originates from both the mass and ionic radius mismatch between the impurity atom and the host lattice. We present a model to estimate the phonon scattering parameter for different types of point defects and implement it in classical phonon mediated thermal transport model to estimate the thermal conductivity reduction in light ion irradiated UO2. The results are compared to results of experimental measurements. Laser based modulated thermoreflectance (MTR) technique was used to measure the thermal conductivity model in ion irradiated UO2 samples. Unlike laser flash analysis, traditionally used for measuring thermal conductivity in nuclear materials, MTR method has a sensitivity to a few micron thick thin damage resulting from ion beam irradiation. In this technique, the irradiated sample, coated by a thin metallic film, is heated by a harmonically modulated laser pump and a probe beam measures the temperature induced changes in reflectivity. In this work, experimentally measured thermal wave phase profiles obtained from UO2 samples irradiated with 2.6 MeV H+ ions were analyzed using different multilayer approximations of the damaged region. An infinite damage layer approximation model that neglects undamaged layer and peak damage region characteristic to light ion irradiations is discussed. The limitation of the approach and demonstration of its applicability range was analyzed. Finally, measured conductivities of the ion irradiated samples using a thermal conductivity model for point defects was examined. Previously reported XRD measurements on same proton irradiated UO2 samples show the lattice expands linearly as a function of atomic displacements (dpa). The defect concentration can be defined as a function of dpa and the defect production rate. The estimation of defect concentration is validated by accounting their overall contribution to the change in lattice parameters and comparing them with the measured values by XRD. Finally, their overall contribution to the reduction in thermal conductivity is compared with the experimentally measured values to determine the concentration of defects in the lattice structure of UO2.
Marat Khafizov, Dr. (Advisor)
Sandip Mazumder, Dr. (Committee Member)
108 p.
Materials Science; Mechanical Engineering; Nuclear Engineering; Nuclear Physics
Lattice Expansion; Thermal Conductivity; Defected Oxide Ceramics

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Citations

  • Riyad, M. F. (2017). Simultaneous analysis of Lattice Expansion and Thermal Conductivity in Defected Oxide Ceramics [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492737800363063

    APA Style (7th edition)

  • Riyad, M Faisal . Simultaneous analysis of Lattice Expansion and Thermal Conductivity in Defected Oxide Ceramics . 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1492737800363063.

    MLA Style (8th edition)

  • Riyad, M Faisal . "Simultaneous analysis of Lattice Expansion and Thermal Conductivity in Defected Oxide Ceramics ." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492737800363063

    Chicago Manual of Style (17th edition)

osu1492737800363063
928
© 2017, some rights reserved.Creative Commons License Simultaneous analysis of Lattice Expansion and Thermal Conductivity in Defected Oxide Ceramics by M Faisal Riyad is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.