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Yu M Matskevich - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic stability and Hydration Enthalpy of strontium cerate doped with yttrium
Thermochimica Acta, 2006Co-Authors: N I Matskevich, Th Wolf, Yu G Stenin, Yu M MatskevichAbstract:Abstract The standard molar Enthalpy of formation of SrY 0.05 Ce 0.95 O 2.975 has been derived by combining the Enthalpy of solution in 1 M HCl + 0.1 KI with auxiliary literature data, Δ f H ° (SrY 0.05 Ce 0.95 O 2.975 , s, 298.15 K) = −1720.4 ± 3.4 kJ/mol. The formation Enthalpy of SrY 0.05 Ce 0.95 O 2.975 from the mixture of binary oxides is Δ ox H ° (298.15 K) = −45.9 ± 3.4 kJ/mol and the Enthalpy of reaction of SrY 0.05 Ce 0.95 O 2.975 with water forming Sr(OH) 2 , CeO 2 , and Y 2 O 3 is Δ r H ° (298.15 K) = −85.5 ± 3.4 kJ/mol. Our data and the entropies of different substances show that SrY 0.05 Ce 0.95 O 2.975 is thermodynamically stable with respect to a mixture of SrO, Y 2 O 3 , CeO 2 and that the reaction of SrY 0.05 Ce 0.95 O 2.975 with water is thermodynamically favourable.
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the thermodynamic stability and Hydration Enthalpy of strontium cerate doped by yttrium
arXiv: Materials Science, 2005Co-Authors: N I Matskevich, Th Wolf, Yu M MatskevichAbstract:The standard molar Enthalpy of formation of SrY0.05Ce0.95O2.975 has been derived by combining the Enthalpy of solution of this compound in 1 M HCl + 0.1 KI obtained by us and auxiliary literature data. The following value has been derived: DfH (SrY0.05Ce0.95O2.975, s, 298.15 K) = -1720.4 (3.4) kJ/mol. The obtained value has been used to obtain the formation Enthalpy of SrY0.05Ce0.95O2.975 from the mixture of binary oxides (DoxH (298.15 K) = -45.9 (3.4) kJ/mol) and formation Enthalpy of reaction of SrY0.05Ce0.95O2.975 with water forming Sr(OH)2, CeO2, Y2O3 (DrH (298.15 K) = -85.5 (3.4) kJ/mol). Data obtained by solution calorimetry and additional information on the entropies of different substances have shown that SrY0.05Ce0.95O2.975 is thermodynamically stable with respect to a mixture of SrO, Y2O3, CeO2 and that the reaction of SrY0.05Ce0.95O2.975 with water is thermodynamically favourable.
Reidar Haugsrud - One of the best experts on this subject based on the ideXlab platform.
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Structure, Hydration, and proton conductivity in 50% La and Nd doped CeO2 – La2Ce2O7 and Nd2Ce2O7 – and their solid solutions
Solid State Ionics, 2020Co-Authors: Liv-elisif Kalland, Reidar Haugsrud, Tor S. Bjørheim, Andreas Løken, Truls NorbyAbstract:Abstract We have measured water uptake and Hydration Enthalpy in 50% La and Nd doped CeO2, also to be taken as compositions in the series La2−xNdxCe2O7 (x = 0.0, 0.5, 1.0 and 2.0) using combined thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC. The TG-DSC data unambiguously yield standard molar Hydration enthalpies of ~−74 kJ/mol independent of water uptake. The interpretation of the TG results, however, does not fit a classical model of Hydration of all oxygen vacancies. Instead, the Hydration appears to be limited to a small fraction of the free vacancies. Hydration further decreases as the Nd content (x) and long-range order increases and regions of disorder decrease. We propose a new model explaining why Hydration occurs only in a small fraction of the nominally free vacancies: The higher basicity of La/Nd compared to Ce promotes protonation at oxide ion sites with high coordination to La/Nd, and the observed water uptake and modelling suggests that mainly oxide ions fully coordinated to 4 La/Nd neighbours become protonated. The statistical variation of coordination around oxygen sites in a disordered fluorite oxide creates a limited number of such oxide ions sites which results in limited Hydration. The model matches well the experimental results and DFT calculations of proton trapping at the fully La-coordinated sites for 50% La-doped CeO2, and also rationalizes conductivity data.
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Electrical conductivity and TG-DSC study of Hydration of Sc-doped CaSnO3 and CaZrO3
Solid State Ionics, 2014Co-Authors: Andreas Løken, Christian Kjolseth, Reidar HaugsrudAbstract:Abstract Correlations linking Hydration thermodynamics to materials parameters can be of vital importance for further development of proton conducting oxides. However, the currently proposed correlations are troubled by scattering limiting their predictive power. As such, the present contribution has investigated Sc-doped CaSnO 3 and CaZrO 3 in an attempt to further elucidate the trends in the thermodynamics of Hydration for perovskites. Conductivity and impedance spectroscopy on 5 and 10% Sc-doped CaSnO 3 demonstrated that it is primarily an oxygen ion conductor with a small protonic contribution at lower temperatures (below 500 °C) under wet conditions. Simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC, was applied to measure the standard molar Hydration Enthalpy of CaSn 1− x Sc x O 3− δ and CaZr 1− x Sc x O 3− δ ( x = 0.05, 0.10, 0.15 and 0.20) as a function of the Sc concentration. The Hydration Enthalpy becomes increasingly negative with increasing Sc substitution, which is discussed on the basis of changes in electronegativity, basicity and tolerance factor.
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Conductivity and Hydration trends in disordered fluorite and pyrochlore oxides: A study on lanthanum cerate–zirconate based compounds
Solid State Ionics, 2012Co-Authors: Vasileios Besikiotis, Truls Norby, Sandrine Ricote, Molly Hjorth Jensen, Reidar HaugsrudAbstract:Abstract In the present contribution we discuss the influence of order/disorder on the concentration and mobility of ionic charge carriers in undoped and acceptor (calcium) doped fluorite and pyrochlore structured lanthanum cerate–zirconate solid solutions: (La1 − yCay)2(Ce1 − xZrx)2O7 − δ (y = 0, 0.02, 0.10; x = 0, 0.50, 0.75). Characterization of the electrical conductivity as a function of temperature and oxygen partial pressure revealed contribution from electronic carriers in reducing atmosphere, but otherwise these materials are ionic conductors. Oxide ion conductivity dominates at high temperatures while protons become more dominating as charge carrier at temperatures below typically 500 °C under wet conditions. The Hydration enthalpies were determined by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). The contribution from ionic conductivity increases and the Hydration Enthalpy becomes more exothermic with higher cerium content, i.e. with more disordered materials. The proton conductivity decreases upon acceptor substitution of La3 + with Ca2 + which is attributed to trapping of the charge carriers by the effectively negative acceptor.
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Hydration thermodynamics of pyrochlore structured oxides from TG and first principles calculations.
Dalton Transactions, 2012Co-Authors: Tor S. Bjørheim, Vasileios Besikiotis, Reidar HaugsrudAbstract:In this contribution we investigate trends in the defect chemistry and Hydration thermodynamics of rare-earth pyrochlore structured oxides, RE2X2O7 (RE = La–Lu and X = Ti, Sn, Zr and Ce). First principles density functional theory (DFT) calculations have been performed to elucidate trends in the general defect chemistry and Hydration Enthalpy for the above-mentioned series. Further, to justify the use of such theoretical methods, the Hydration properties of selected compositions were studied by means of thermogravimetric measurements. Both DFT calculations and TG measurements indicate that the Hydration Enthalpy becomes less exothermic with decreasing radii of RE ions within the RE2X2O7 series (X = Ti, Sn, Zr and Ce), while it is less dependent on the X site ion. The observed Hydration trends are discussed in connection with trends in the stability of both protons and oxygen vacancies and changes in the electronic density of states and bonding environment through the series. Finally, the findings are discussed with respect to existing correlations for other binary and ternary oxides.
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determination of the Enthalpy of Hydration of oxygen vacancies in y doped bazro3 and baceo3 by tg dsc
Solid State Ionics, 2010Co-Authors: Christian Kjolseth, Linyung Wang, Reidar Haugsrud, Truls NorbyAbstract:Abstract Simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC, have been applied for the first time to measure directly the standard molar Enthalpy changes of a defect chemical reaction, here the Hydration of oxygen vacancies in two proton conducting perovskite oxides, BaZr 0.9 Y 0.1 O 3 − δ (BZY10) and BaCe 0.9 Y 0.1 O 3 − δ (BCY10). The measurements were done isothermally by parallel recording of the weight and heat exchanges associated with step changes in the water vapour pressure. The obtained molar Hydration Enthalpy of BZY10 was investigated at 300–900 °C and was found constant at − 81 ± 4 kJ mol − 1 (per mole of H 2 O) over this range. The molar Hydration Enthalpy of BCY10 was investigated at 600 °C and found to be − 170 ± 6 kJ mol − 1 . Both values are in good agreement with the majority of literature data for the two materials obtained more indirectly by equilibrium methods.
N I Matskevich - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic stability and Hydration Enthalpy of strontium cerate doped with yttrium
Thermochimica Acta, 2006Co-Authors: N I Matskevich, Th Wolf, Yu G Stenin, Yu M MatskevichAbstract:Abstract The standard molar Enthalpy of formation of SrY 0.05 Ce 0.95 O 2.975 has been derived by combining the Enthalpy of solution in 1 M HCl + 0.1 KI with auxiliary literature data, Δ f H ° (SrY 0.05 Ce 0.95 O 2.975 , s, 298.15 K) = −1720.4 ± 3.4 kJ/mol. The formation Enthalpy of SrY 0.05 Ce 0.95 O 2.975 from the mixture of binary oxides is Δ ox H ° (298.15 K) = −45.9 ± 3.4 kJ/mol and the Enthalpy of reaction of SrY 0.05 Ce 0.95 O 2.975 with water forming Sr(OH) 2 , CeO 2 , and Y 2 O 3 is Δ r H ° (298.15 K) = −85.5 ± 3.4 kJ/mol. Our data and the entropies of different substances show that SrY 0.05 Ce 0.95 O 2.975 is thermodynamically stable with respect to a mixture of SrO, Y 2 O 3 , CeO 2 and that the reaction of SrY 0.05 Ce 0.95 O 2.975 with water is thermodynamically favourable.
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short communication thermodynamic stability and Hydration Enthalpy of strontium cerate doped with yttrium
2006Co-Authors: N I Matskevich, G SteninAbstract:The standard molar Enthalpy of formation of SrY0.05Ce0.95O2.975 has been derived by combining the Enthalpy of solution in 1 M HCl + 0.1 KI with auxiliary literature data, � fH ◦ (SrY0.05Ce0.95O2.975, s, 298.15 K) = −1720.4 ± 3.4 kJ/mol. The formation Enthalpy of SrY0.05Ce0.95O2.975 from the
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the thermodynamic stability and Hydration Enthalpy of strontium cerate doped by yttrium
arXiv: Materials Science, 2005Co-Authors: N I Matskevich, Th Wolf, Yu M MatskevichAbstract:The standard molar Enthalpy of formation of SrY0.05Ce0.95O2.975 has been derived by combining the Enthalpy of solution of this compound in 1 M HCl + 0.1 KI obtained by us and auxiliary literature data. The following value has been derived: DfH (SrY0.05Ce0.95O2.975, s, 298.15 K) = -1720.4 (3.4) kJ/mol. The obtained value has been used to obtain the formation Enthalpy of SrY0.05Ce0.95O2.975 from the mixture of binary oxides (DoxH (298.15 K) = -45.9 (3.4) kJ/mol) and formation Enthalpy of reaction of SrY0.05Ce0.95O2.975 with water forming Sr(OH)2, CeO2, Y2O3 (DrH (298.15 K) = -85.5 (3.4) kJ/mol). Data obtained by solution calorimetry and additional information on the entropies of different substances have shown that SrY0.05Ce0.95O2.975 is thermodynamically stable with respect to a mixture of SrO, Y2O3, CeO2 and that the reaction of SrY0.05Ce0.95O2.975 with water is thermodynamically favourable.
Truls Norby - One of the best experts on this subject based on the ideXlab platform.
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Structure, Hydration, and proton conductivity in 50% La and Nd doped CeO2 – La2Ce2O7 and Nd2Ce2O7 – and their solid solutions
Solid State Ionics, 2020Co-Authors: Liv-elisif Kalland, Reidar Haugsrud, Tor S. Bjørheim, Andreas Løken, Truls NorbyAbstract:Abstract We have measured water uptake and Hydration Enthalpy in 50% La and Nd doped CeO2, also to be taken as compositions in the series La2−xNdxCe2O7 (x = 0.0, 0.5, 1.0 and 2.0) using combined thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC. The TG-DSC data unambiguously yield standard molar Hydration enthalpies of ~−74 kJ/mol independent of water uptake. The interpretation of the TG results, however, does not fit a classical model of Hydration of all oxygen vacancies. Instead, the Hydration appears to be limited to a small fraction of the free vacancies. Hydration further decreases as the Nd content (x) and long-range order increases and regions of disorder decrease. We propose a new model explaining why Hydration occurs only in a small fraction of the nominally free vacancies: The higher basicity of La/Nd compared to Ce promotes protonation at oxide ion sites with high coordination to La/Nd, and the observed water uptake and modelling suggests that mainly oxide ions fully coordinated to 4 La/Nd neighbours become protonated. The statistical variation of coordination around oxygen sites in a disordered fluorite oxide creates a limited number of such oxide ions sites which results in limited Hydration. The model matches well the experimental results and DFT calculations of proton trapping at the fully La-coordinated sites for 50% La-doped CeO2, and also rationalizes conductivity data.
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Conductivity and Hydration trends in disordered fluorite and pyrochlore oxides: A study on lanthanum cerate–zirconate based compounds
Solid State Ionics, 2012Co-Authors: Vasileios Besikiotis, Truls Norby, Sandrine Ricote, Molly Hjorth Jensen, Reidar HaugsrudAbstract:Abstract In the present contribution we discuss the influence of order/disorder on the concentration and mobility of ionic charge carriers in undoped and acceptor (calcium) doped fluorite and pyrochlore structured lanthanum cerate–zirconate solid solutions: (La1 − yCay)2(Ce1 − xZrx)2O7 − δ (y = 0, 0.02, 0.10; x = 0, 0.50, 0.75). Characterization of the electrical conductivity as a function of temperature and oxygen partial pressure revealed contribution from electronic carriers in reducing atmosphere, but otherwise these materials are ionic conductors. Oxide ion conductivity dominates at high temperatures while protons become more dominating as charge carrier at temperatures below typically 500 °C under wet conditions. The Hydration enthalpies were determined by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). The contribution from ionic conductivity increases and the Hydration Enthalpy becomes more exothermic with higher cerium content, i.e. with more disordered materials. The proton conductivity decreases upon acceptor substitution of La3 + with Ca2 + which is attributed to trapping of the charge carriers by the effectively negative acceptor.
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determination of the Enthalpy of Hydration of oxygen vacancies in y doped bazro3 and baceo3 by tg dsc
Solid State Ionics, 2010Co-Authors: Christian Kjolseth, Linyung Wang, Reidar Haugsrud, Truls NorbyAbstract:Abstract Simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC, have been applied for the first time to measure directly the standard molar Enthalpy changes of a defect chemical reaction, here the Hydration of oxygen vacancies in two proton conducting perovskite oxides, BaZr 0.9 Y 0.1 O 3 − δ (BZY10) and BaCe 0.9 Y 0.1 O 3 − δ (BCY10). The measurements were done isothermally by parallel recording of the weight and heat exchanges associated with step changes in the water vapour pressure. The obtained molar Hydration Enthalpy of BZY10 was investigated at 300–900 °C and was found constant at − 81 ± 4 kJ mol − 1 (per mole of H 2 O) over this range. The molar Hydration Enthalpy of BCY10 was investigated at 600 °C and found to be − 170 ± 6 kJ mol − 1 . Both values are in good agreement with the majority of literature data for the two materials obtained more indirectly by equilibrium methods.
Christian Kjolseth - One of the best experts on this subject based on the ideXlab platform.
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Electrical conductivity and TG-DSC study of Hydration of Sc-doped CaSnO3 and CaZrO3
Solid State Ionics, 2014Co-Authors: Andreas Løken, Christian Kjolseth, Reidar HaugsrudAbstract:Abstract Correlations linking Hydration thermodynamics to materials parameters can be of vital importance for further development of proton conducting oxides. However, the currently proposed correlations are troubled by scattering limiting their predictive power. As such, the present contribution has investigated Sc-doped CaSnO 3 and CaZrO 3 in an attempt to further elucidate the trends in the thermodynamics of Hydration for perovskites. Conductivity and impedance spectroscopy on 5 and 10% Sc-doped CaSnO 3 demonstrated that it is primarily an oxygen ion conductor with a small protonic contribution at lower temperatures (below 500 °C) under wet conditions. Simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC, was applied to measure the standard molar Hydration Enthalpy of CaSn 1− x Sc x O 3− δ and CaZr 1− x Sc x O 3− δ ( x = 0.05, 0.10, 0.15 and 0.20) as a function of the Sc concentration. The Hydration Enthalpy becomes increasingly negative with increasing Sc substitution, which is discussed on the basis of changes in electronegativity, basicity and tolerance factor.
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determination of the Enthalpy of Hydration of oxygen vacancies in y doped bazro3 and baceo3 by tg dsc
Solid State Ionics, 2010Co-Authors: Christian Kjolseth, Linyung Wang, Reidar Haugsrud, Truls NorbyAbstract:Abstract Simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC, have been applied for the first time to measure directly the standard molar Enthalpy changes of a defect chemical reaction, here the Hydration of oxygen vacancies in two proton conducting perovskite oxides, BaZr 0.9 Y 0.1 O 3 − δ (BZY10) and BaCe 0.9 Y 0.1 O 3 − δ (BCY10). The measurements were done isothermally by parallel recording of the weight and heat exchanges associated with step changes in the water vapour pressure. The obtained molar Hydration Enthalpy of BZY10 was investigated at 300–900 °C and was found constant at − 81 ± 4 kJ mol − 1 (per mole of H 2 O) over this range. The molar Hydration Enthalpy of BCY10 was investigated at 600 °C and found to be − 170 ± 6 kJ mol − 1 . Both values are in good agreement with the majority of literature data for the two materials obtained more indirectly by equilibrium methods.
