Thermodynamic parameters of vaporization of EuBr2

Abstract

The vaporization process of europium dibromide was studied using high temperature mass spec trometry. It was ascertained that saturated vapor in temperature range of 1049-1261 K was represented mainly by EuBr 2 molecules; the fraction of dimer molecules Eu 2 Br 4 was less than 1%. Heat capacities of solid and liquid europium dibromide, as well as the melting enthalpy were measured by means of differential scan ning calorimetry in temperature range 300-1100 K; using these data thermodynamic functions for EuBr 2 in condensed state were calculated. For all experimental data, including the literature data, thermodynamic characteristics of the vaporization of europium dibromide were determined using a unified set of thermody namic functions according to the methods of the second and third laws of thermodynamics. The value of Δ s H°(298.15 K) = 354 ± 5 kJ/mol was recommended for the reaction of sublimation of EuBr 2 (cr.) = EuBr 2 .

Atomization Energies of LnX Molecules (Ln = Sm, Eu, and Yb; X = Cl, Br, and I)

“…In both cases the comparative method was applied but based on different data. In ref the functions of EuCl, EuCl 2 , and EuBr 2 were used as a comparison, whereas in this work those of LnX (Ln = Eu and Yb; X = F and Cl) and YbBr were employed. In our opinion, the latter approach is more reliable since it considers simple diatomic molecules only, whereas the uncertainties reported in ref were apparently underestimated.…”

Formation energies of molecules and anions of europium bromides

“…The measured equilibrium constants (I) are pre sented in Table 1. Thermodynamic functions (G°(T) -H°(298.15 K))/T, which are needed to calculate Δ r (I) ( Table 1), were taken from [12] for Ba and Eu atoms and BaBr molecules, while they were esti mated for EuBr molecules using the comparative method in [13] and from the data in [14] for EuCl, EuCl 2 , and EuBr 2 [15] molecules. The dissociation energy D 298 (EuBr) = 346 ± 11 kJ/mol was estimated using the obtained formation enthalpy of EuBr (Table 2).…”

Determination of the Work Function for Europium Dibromide by Knudsen Effusion Mass Spectrometry

“…On heating EuBr 2 to temperatures of (1049 to 1301) K, the major identified vapor species in the EI and TE regimes were the molecule EuBr 2 and the negative ion EuBr 3 – . The EI mass spectra, their interpretation, and the determination of the EuBr 2 pressure have been reported by us elsewhere . Figure shows the temperature dependence of the pressure p (EuBr 2 ).…”

“…From these data, the sublimation enthalpy Δ s H °(EuBr 2 , 298.15 K) = 354 ± 5 kJ·mol –1 was obtained by the techniques of the second and third laws of thermodynamics. Details are given in ref . Figure shows the temperature dependence of the product I (EuBr 3 – ) T 1/2 , where I is the ion current.…”

“…Additionally, the following reference data for Δ f H °(298.15 K) in kJ·mol –1 were used: 178.2 ± 3.0 for Eu, 111.86 ± 0.12 for Br, and −219.04 ± 0.23 for Br – . The data were reduced to a temperature of 1264 K using the enthalpy increments of the reaction participants. ,, …”