Theoretical investigation of thermochemical properties of cesium borates species

Revaporization Behavior of Cesium and Iodine Compounds from Their Deposits in the Steam–Boron Atmosphere

“…In the former case, generation of gaseous iodine was considered as the reaction between CsI deposits and boron, which also produced a low volatile cesium borate compound, while the latter might have resulted from the reaction of CsI deposits with the stainless steel that produced gaseous iodine and cesium chromate. At the given temperature (850–750 K), the expected cesium borates and cesium chromate are in the condensed phase, ,− and hence, their existence as condensate on the stainless steel surface would corroborate the revaporization mechanism (i.e., secondary gaseous iodine generation). Also, at the revaporization phase in TeRRa-RBS-1 (steam–boron effect), it has been confirmed that the iodine aerosol transited to the colder region as CsI with the given molar ratio equal to 1.…”

High‐temperature mass spectrometric study of vaporization and thermodynamics of the Cs2O‐B2O3 system: Review and experimental investigation

“…The slope coefficients of the temperature dependences of the CsBO 2 partial vapor pressures over CsBO 2 (Tables S1 and S2, supporting information) can be converted into the enthalpy of the cesium metaborate sublimation reaction in the form of the monomer (Equation ) at the middle temperature of the corresponding experiment. For comparison, it is desirable to calculate the CsBO 2 sublimation enthalpies obtained in the experiments of the present study at a temperature of 298.15 K. The thermodynamic properties of the condensed cesium metaborate were taken from the study by Cordfunke et al, 50 and the heat capacities of gaseous CsBO 2 were from Vandeputte et al 19 These reference data on the thermodynamic functions of condensed and gaseous CsBO 2 allowed the sublimation enthalpy of cesium metaborate to be recalculated to a temperature of 298 K. This procedure, which is known as calculation according to the Second Law of thermodynamics, 15,45 yielded the value of 274 ± 4 kJ/mol for sublimation from the platinum cell and 248 ± 11 kJ/mol for sublimation from the molybdenum cell at 298.15 K. The data do not contradict each other significantly if we take into consideration the uncertainty of the experimental studies. A Third Law calculation led to a value of 327 ± 17 kJ/mol for the cesium metaborate sublimation enthalpy.…”

“…The enthalpy of the cesium metaborate sublimation reaction in the dimeric form (Equation ) was obtained on the basis of the slope coefficient in Equation and was 303 ± 37 kJ/mol at 878 K. Calculation of the sublimation enthalpy of cesium borate in the form of the dimer at 298.15 K was carried out using the temperature dependences of the Cs 2 BO 2 + ion current intensities from Table S2 (supporting information), the enthalpy increments of solid CsBO 2 from Cordfunke et al, 50 and the Cs 2 B 2 O 4 heat capacities from Vandeputte et al 19 This led to a value of 305 ± 13 kJ/mol for the sublimation enthalpy of cesium borate in the form of the dimer at a temperature of 298.15 K.…”

“…The structure of CsBO 2 , including a point group, internuclear distances, and bond angles, was investigated experimentally by gas‐phase electron diffraction 17 . Later, equilibrium geometries and thermodynamic functions, such as standard enthalpies of formation, standard absolute entropies, and heat capacities in the temperature range 300–1500 K, were calculated for a number of cesium borates, including CsBO 2 , by the quantum chemical approaches of density functional theory and coupled cluster theory 19 …”