A thermodynamic study of gaseous BaSiO3

Cordfunke, E.H.P.; Groen, Cornelis Petrus; Huntelaar, M.E.; Alexander, C.A.; Ogden, J.S.

doi:10.1006/jcht.1999.0635

Cited by 8 publications

(11 citation statements)

References 16 publications

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“…The multiplicity of ground state in both cases is singlet. These molecular parameters are in good agreement with the ones in reference [1]. The experimentally determined barium-oxygen distance in the gaseous molecule BaMoO 4 [15] is 0.254 nm.…”

Section: Resultssupporting

confidence: 76%

“…The thermodynamic properties measured in this study are completely different to those obtained in reference [1]. On the basis of the data obtained in [1], the BaSiO 3 is major component of the gaseous phase, but in our experiences the BaSiO 3 and BaSiO 2 partial pressures were approximately 0.1% from partial pressures of dissociation products.…”

Section: Discussioncontrasting

confidence: 66%

“…On the basis of the data obtained in [1], the BaSiO 3 is major component of the gaseous phase, but in our experiences the BaSiO 3 and BaSiO 2 partial pressures were approximately 0.1% from partial pressures of dissociation products. The authors of reference [1] also did not mention any interactions between the sample and cell.…”

Section: Discussionmentioning

confidence: 88%

“…The changes in the composition of the condensed phase during vaporization of the sample studied in [1] could have influenced the accuracy of their results. The ratio of the partial pressures of SiO and BaO increased during the experiment.…”

Section: Discussionmentioning

confidence: 97%

“…Currently, there is one study of the high temperature behavior of the barium silicate system available in the literature [1]. The authors report that BaSiO 3 evaporated congruently with only minor decomposition to the constituent oxides BaO and SiO 2 .…”

Section: Introductionmentioning

confidence: 97%

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Thermodynamic properties of the gaseous barium silicates BaSiO2 and BaSiO3

Лопатин

Шугуров

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et al. 2006

The Journal of Chemical Thermodynamics

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Section: Resultssupporting

confidence: 76%

Section: Discussioncontrasting

confidence: 66%

Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Thermodynamic properties of the gaseous barium silicates BaSiO2 and BaSiO3

Лопатин

Шугуров

Stolyarova

et al. 2006

The Journal of Chemical Thermodynamics

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10.1007/s10634-008-1002-5

2000

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The key factor in the thermal stability of a salt in vapor is the difference in the acid-base properties of the oxides forming the salt [1]. Calcium oxide is a typical cation-forming oxide and is thermally stable in a wide temperature range. Now, over fifteen gaseous calcium salts are known for which the standard enthalpies of formation have been determined.Vaporization of SiO 2 was studied in detail in [2]. Silica converts to vapor on heating under weak reducing conditions in the presence of molybdenum to give SiO, Si 2 O 2 , SiO 2 , and oxygen. Silicon oxides SiO and SiO 2 exhibit acid properties and act as anion-forming oxides. The existence of gaseous lithium [3], calcium [4], strontium [5], and barium [6-8] silicates has been reported.As has been repeatedly demonstrated, the enthalpies of atomization of gaseous salts in isocationic series of gaseous salts of oxygen-containing acids are a linear function of the enthalpy of atomization of anion-forming oxides [1]. The dependence can be represented by the equation (1) where M and X are cation-and anion-forming elements, respectively; O is oxygen; m and n stand for the number of atoms in a molecule; and k and b are the constants of proportionality.Only one gaseous calcium silicate CaSiO 3 has been identified in the vapor over the system at T = 33 K in [4], whereas, in the vapor over the SrO-SiO 2 and BaO-SiO 2 systems, two silicates-SrSiO 2 and SrSiO 3 and BaSiO 2 and BaSiO 3 , respectively-have been identified [5][6][7][8]. It is also noteworthy that the enthalpy of atomization of CaSiO 3 calculated from the data in [4] does not correlate with the results of determination of the thermodynamic characteristics of gaseous calcium salts summarized in [1], which can indicate that the data in [4] are incorrect.In the present work, the CaO-SiO 2 system was studied by high-temperature mass spectrometry on an MS-1301 mass spectrometer at an ionizing electron energy of 25 eV. Effusion cells made of tungsten were heated by electron impact. Temperatures in the range 1600-2200 K were measured by an EOP-66 optical pyrometer with an accuracy of ± 5 K. The equipment was preliminarily calibrated against the vapor pressure of CaF 2 [9]. ions have been identified in the vapor over the CaO-SiO 2 system at 2170-2240 K. Measurements of the appearance energies of ions in the mass spectrum of vapor and comparison of our results with available data [5][6][7]10] showed that the vapor contains calcium, silicon, and tungsten oxides; atomic calcium; oxygen; and calcium tungstates and silicates CaSiO 2 and CaSiO 3 .To determine the standard enthalpies of formation of gaseous calcium silicates, we measured the equilibrium constants of the gas-phase reactions CaO + SiO = CaSiO 2 ,CaO + SiO 2 = CaSiO 3 ,and calculated the enthalpies of these reactions by the equation (4) where ∆ r H 0 (0) and ∆ r Φ 0 ( T ) are the changes in the enthalpy and reduced Gibbs energy of a reaction at temperatures 0 and T , respectively, and K p is the equilibrium constant of a reaction. The partial pressures of the...

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