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• W2214397128 abstract "The goal of this dissertation is to employ computational methods to gain greater insights into the energetics and defect interactions of complex oxides that are relevant for today's energy challenges. To achieve this goal, the development of novel computational methodologies are required to handle complex systems, including systems containing nearly 650 ions and systems with tens of thousands of possible atomic configurations. The systems that are investigated in this dissertation are aliovalently doped lanthanum orthophosphate (LaPO4) due to its potential application as a proton conducting electrolyte for intermediate temperature fuel cells, and aliovalently doped uranium dioxide (UO2) due to its importance in nuclear fuel performance and disposal.First we undertake density-functional-theory (DFT) calculations on the relative energetics of pyrophosphate defects and protons in LaPO4, including their binding with divalent dopant cations. In particular, for supercell calculations with 1.85 mol% Sr doping, we investigate the dopant-binding energies for pyrophosphate defects to be 0.37 eV, which is comparable to the value of 0.34 eV calculated for proton-dopant binding energies in the same system. These results establish that dopant-defect interactions further stabilize proton incorporation, with the hydration enthalpies when the dopants are nearest and furthest from the protons and pyrophosphate defects being -1.66 eV and -1.37 eV, respectively. Even though our calculations show that dopant binding enhances the enthalpic favorability of proton incorporation, they also suggest that such binding is likely to substantially lower the kinetic rate of hydrolysis of pyrophosphate defects.We then shift our focus to solid solutions of fluorite-structured UO2 with trivalent rare earth fission product cations (M3+=Y, La) using a combination of ionic pair potential and DFT based methods. Calculated enthalpies of formation with respect to constituent oxides show higher energetic stability for La solid solutions than for Y. Additionally, calculations performed for different atomic configurations show a preference for reduced (increased) oxygen vacancy coordination around La (Y) dopants. The current results are shown to be qualitatively consistent with related calculations and calorimetric measurements of heats of formation in other trivalent doped fluorite oxides, which show a tendency for increasingstability and increasing preference for higher oxygen coordination with increasing size of the trivalent impurity. We expand this investigation by considering a series of trivalent rare earth fission product cations, specifically, Y3+ (1.02 A, Shannon radius with eightfold coordination), Dy3+ (1.03 A), Gd3+ (1.05 A), Eu3+ (1.07 A), Sm3+ (1.08 A), Pm3+ (1.09 A), Nd3+ (1.11 A), Pr3+ (1.13 A), Ce3+ (1.14 A) and La3+ (1.16 A). Compounds with ionic radius of the M3+ species smaller or larger than 1.09 A are found to have energetically preferred defect ordering arrangements. Systems with preferred defect ordering arrangements are suggestive of defect clustering in short range ordered solid solutions, which is expected to limit oxygen ion mobility and therefore the rate of oxidation of spent nuclear fuel.Finally, the energetics of rare earth substituted (M3+= La, Y, and Nd) UO2 solid solutions are investigated by employing a combination of calorimetric measurements and DFT based computations. The calorimetric studies are performed by Lei Zhang and Professor Alexandra Navrotsky at the University of Calfornia, Davis, as part of a joint computational/experimental collaborative effort supported through the Materials Science of Actinides Energy Frontier Research Center. Calculated and measured formation enthalpies agree within 10 kJ/mol for stoichiometric oxygen/metal compositions. To better understand the factors governing the stability and defect binding in rare earth substituted urania solid solutions, systematic trends in the energetics are investigated based on the present results and previous computational and experimental thermochemical studies of rare earth substituted fluorite oxides. A consistent trend towards increased energetic stability with larger size mismatch between the smaller host tetravalent cation and the larger rare earthtrivalent cation is found for both actinide and non-actinide fluorite oxide systems where aliovalent substitution of M cations is compensated by oxygen vacancies. However, the large exothermic oxidation enthalpy in the UO2 based systems favors compositions with higher oxygen-to-metal ratios where charge compensation occurs through the formation of uranium cations with higher oxidation states." @default.
• W2214397128 created "2016-06-24" @default.
• W2214397128 creator A5053250901 @default.
• W2214397128 date "2015-01-01" @default.
• W2214397128 modified "2023-09-24" @default.
• W2214397128 title "Energetics and Defect Interactions of Complex Oxides for Energy Applications" @default.
• W2214397128 cites W1520027199 @default.
• W2214397128 cites W1581176928 @default.
• W2214397128 cites W1596134677 @default.
• W2214397128 cites W1676180839 @default.
• W2214397128 cites W1682777897 @default.
• W2214397128 cites W1963674528 @default.
• W2214397128 cites W1964110912 @default.
• W2214397128 cites W1964846687 @default.
• W2214397128 cites W1965282282 @default.
• W2214397128 cites W1965523178 @default.
• W2214397128 cites W1966156734 @default.
• W2214397128 cites W1970127494 @default.
• W2214397128 cites W1971200136 @default.
• W2214397128 cites W1973144470 @default.
• W2214397128 cites W1973628086 @default.
• W2214397128 cites W1975821034 @default.
• W2214397128 cites W1977700257 @default.
• W2214397128 cites W1979544533 @default.
• W2214397128 cites W1981368803 @default.
• W2214397128 cites W1983196248 @default.
• W2214397128 cites W1983665455 @default.
• W2214397128 cites W1985144076 @default.
• W2214397128 cites W1985628158 @default.
• W2214397128 cites W1986706751 @default.
• W2214397128 cites W1986731219 @default.
• W2214397128 cites W1988058955 @default.
• W2214397128 cites W1988762313 @default.
• W2214397128 cites W1989203892 @default.
• W2214397128 cites W1990931910 @default.
• W2214397128 cites W1991019191 @default.
• W2214397128 cites W1991661795 @default.
• W2214397128 cites W1993608837 @default.
• W2214397128 cites W1994433158 @default.
• W2214397128 cites W1994543653 @default.
• W2214397128 cites W1996150889 @default.
• W2214397128 cites W1999873461 @default.
• W2214397128 cites W2001615266 @default.
• W2214397128 cites W2002416818 @default.
• W2214397128 cites W2005707031 @default.
• W2214397128 cites W2006704764 @default.
• W2214397128 cites W2006711619 @default.
• W2214397128 cites W2007091872 @default.
• W2214397128 cites W2007395042 @default.
• W2214397128 cites W2008423326 @default.
• W2214397128 cites W2008500997 @default.
• W2214397128 cites W2008662237 @default.
• W2214397128 cites W2011681975 @default.
• W2214397128 cites W2015534597 @default.
• W2214397128 cites W2019130299 @default.
• W2214397128 cites W2020341274 @default.
• W2214397128 cites W2021501983 @default.
• W2214397128 cites W2023109721 @default.
• W2214397128 cites W2026395415 @default.
• W2214397128 cites W2027462219 @default.
• W2214397128 cites W2027474880 @default.
• W2214397128 cites W2027977746 @default.
• W2214397128 cites W2030976617 @default.
• W2214397128 cites W2033301243 @default.
• W2214397128 cites W2034843328 @default.
• W2214397128 cites W2035263355 @default.
• W2214397128 cites W2038282514 @default.
• W2214397128 cites W2041907940 @default.
• W2214397128 cites W2042330381 @default.
• W2214397128 cites W2043033779 @default.
• W2214397128 cites W2043087385 @default.
• W2214397128 cites W2043467327 @default.
• W2214397128 cites W2045192142 @default.
• W2214397128 cites W2046914764 @default.
• W2214397128 cites W2052879266 @default.
• W2214397128 cites W2054814647 @default.
• W2214397128 cites W2056781579 @default.
• W2214397128 cites W2057502998 @default.
• W2214397128 cites W2060631563 @default.
• W2214397128 cites W2061314163 @default.
• W2214397128 cites W2069762449 @default.
• W2214397128 cites W2070767535 @default.
• W2214397128 cites W2072132749 @default.
• W2214397128 cites W2076040549 @default.
• W2214397128 cites W2076232557 @default.
• W2214397128 cites W2077773172 @default.
• W2214397128 cites W2083222334 @default.
• W2214397128 cites W2085093563 @default.
• W2214397128 cites W2085357389 @default.
• W2214397128 cites W2085509430 @default.
• W2214397128 cites W2085834325 @default.
• W2214397128 cites W2089339771 @default.
• W2214397128 cites W2090451493 @default.
• W2214397128 cites W2090976235 @default.
• W2214397128 cites W2092363334 @default.
• W2214397128 cites W2092421635 @default.
• W2214397128 cites W2099670859 @default.
• W2214397128 cites W2109597074 @default.
• W2214397128 cites W2143981217 @default.
• W2214397128 cites W2146061884 @default.

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