Thermodynamics of gaseous barium cerate studied by Knudsen effusion mass spectrometry

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

log p ((),, {CeO}_{2}, Pa) = - ((), 25919 \pm 1730) / normalT + ((), 11.80 \pm 0.84)

log p ((),, CeO, Pa) = - ((), 28119 \pm 1658) / normalT + ((), 12.20 \pm 0.81)

and the formation enthalpy of CeO 2 (gas) at 298 K was determined to be −563 ± 33 kJ/mol.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic properties of gaseous cerium molybdates and tungstates studied by Knudsen effusion mass spectrometry

Шугуров

Panin

Лопатин

2018

“…Oxyacid salts can be thought of as products of the reaction between acidic and basic oxides. It has been established that the CeO and CeO 2 molecules are the significant vapor species in equilibrium with solid cerium dioxide . To synthesize gaseous cerium molybdates and tungstates, CeO 2 was evaporated from molybdenum or tungsten effusion cells.…”

Section: Resultsmentioning

confidence: 99%

“…30,31 Reasonable data agreement was obtained when the value σ(VO 2 )/σ(VO) = 1.14 (Mann 3 , additivity rule) was replaced by the factor 0.33. 12,13 Earlier, 15 we found that in the isocation series of gaseous oxyacid salts the atomization enthalpy of gaseous salts was linearly dependent on the atomization enthalpy of the gaseous anion-forming oxides, with the actual dependence being represented by Equation 23: This dependence for the cerium isocation series is depicted in Table 3.…”

mentioning

confidence: 84%

Evaluation of relative electron ionization cross‐sections for some oxides and oxyacid salts

Лопатин

Шугуров

Panin

et al. 2017

Self Cite

The enthalpies of formation of gaseous cerium molybdates and tungstates were evaluated by measurements of the reaction enthalpies for several independent reactions. The best agreement was obtained with the data from the analysis of experimentally determined relative ionization cross-sections, and using ionization cross-sections of polyatomic molecules recommended by Drowart et al. The widely used additivity method, in spite of the additional corrections introduced, gives the worst convergence of the values under consideration.

Thermodynamics of gaseous strontium and calcium cerates studied by Knudsen effusion mass spectrometry and estimation of relative electron ionization cross‐section for CeO₂(g)

Shugurov,

Lopatin,

Zhinkina

et al. 2024

RationaleCeria‐based systems are of great interest because of their unique properties. Such systems may be used as anode materials for SOFCs or in oxygen sensors. The exploitation of these materials often requires high temperatures. In such conditions, the partial or complete evaporation of materials is possible. Therefore, knowledge of the values of partial pressures and thermodynamic properties is essential to predict and/or prevent possible consequences and accidents.MethodsKnudsen effusion mass spectrometry was used to determine partial pressures of vapor species over the SrO–CeO2 and CaO‐CeO2 systems. Measurements of partial pressures were performed with a MS‐1301 mass spectrometer. Vaporization was carried out using molybdenum or tungsten effusion cells. A theoretical study of gaseous strontium and calcium cerates was performed by several quantum chemical methods: density functional theory (DFT) M06, DFT PBE0, and MP2.ResultsThe minimum value of relative electron ionization cross‐section for CeO2 was estimated. In the temperature range of 2218–2249 K above the SrO‐CeO2 system and of 2128–2208 K above the CaO‐CeO2 system, gaseous M, MO, MO, CeO2, O, O2 and MCeO3 (M = Sr, Ca) were found. Energetically favorable structures of gaseous SrCeO3 and CaCeO3 were found, and vibrational frequencies were evaluated in the “rigid rotor‐harmonic oscillator” approximation. On the basis of the equilibrium constants of gaseous reaction MO + CeO2 = MCeO3, the standard formation enthalpy of gaseous SrCeO3 (−913 ± 26 kJ/mol) and of gaseous CaCeO3 (−917 ± 26 kJ/mol) at 298 K were determined.ConclusionsThe estimated value of relative electron ionization cross‐section for CeO2 is in agreement with the general rule applicable for dioxides. The stability of SrCeO3 and CaCeO3 gaseous species was confirmed by KEMS. Gas‐phase reactions involving gaseous SrO (CaO) and CeO2 with gaseous SrCeO3(CaCeO3) were studied. Enthalpy of formation reaction of gaseous SrCeO3(CaCeO3) from gaseous SrO (CaO) were evaluated theoretically, and the obtained value is in agreement with the experimental one.