Gaseous phase above Ru–O system: A thermodynamic data assessment

Abstract

The present study is a critical assessment of thermochemical data for gaseous ruthenium oxides based on available experimental data. A full critical analysis and a reinterpretation of data are presented with a proposition for new accurate standard formation enthalpies values: Δ f H°2 98 (RuO 4 , g) = -197.6 ± 5.5 kJ mol -1 , Δ f H°2 98 (RuO 3 , g) = -53.0 ± 10 kJ mol -1 , Δ f H°2 98 (RuO 2 , g,) =158 ± 20 kJ mol -1 and Δ f H°2 98 (RuO, g) = 301 ± 28 kJ mol -1 .

Coordination Inversion of the Tetrahedrally Coordinated Ru4f Surface Complex on RuO2(100) and Its Decisive Role in the Anodic Corrosion Process

“…To estimate the entropy of dissolved RuO 4 , we assume that the ratio of S normalR normalu normalO 4 , normala normalq / S normalR normalu normalO 4 , normalg is similar to that of S normalH 2 normalO , normall / S normalH 2 normalO , normalg , that is, S normalR normalu normalO 4 , normala normalq / S normalR normalu normalO 4 , normalg ≈ S normalH 2 normalO , normall / S normalH 2 normalO , normalg . With S normalR normalu normalO 4 , normalg = 280.8 J/(K mol), we obtain S...…”

“…To estimate the entropy of dissolved RuO 4 , we assume that the ratio of / is similar to that of / , that is, / / . With 280.8 J/(K mol), we obtain ≈ 104.55 J/(K·mol). This assumption influences the equilibrium potential of corrosion but has no consequence for the free energies of corrosion intermediates because RuO 4,aq is only formed in the final dissolution step.…”

Thermodynamic assessment of RuO4 oxide

“…During the condensation process, oxygen is removed by pumping. Other gaseous oxides such as RuO 3 (g) are probably in very small amounts in the initial vapor phase -see previous analysis by Nuta et al [15] on the gas phase in the Ru-O binary system -and their condensation in the deposit may form an orange RuO 4 (s) oxide with excess O 2 (g) rather than the RuO 2 (s) -RuO 4 (s) diphase that quickly turns grey or black.…”

“…In previous studies -(i) we proposed new thermodynamic data for RuO 2 (s) [14] i.e. heat capacity, entropy and enthalpy of formation, -(ii) we revised the standard formation enthalpies as well as the entropies of RuO 4 (g), RuO 3 (g), RuO 2 (g) and RuO(g) [15] and compared them with calculations from the SSUB database [16] and with the ab-initio data given by Miradji [17]. The low temperature region of the Ru-O phase diagram is not accurate and some data are missing.…”

Chemical equilibrium calculations for bulk silicate earth material at high temperatures

“…The second factor is their high affinity for oxygen, i.e., the formation of well-known oxide gases such as Re2O7 (rhenium heptoxide), RuO4 (ruthenium tetroxide), and OsO4 (osmium tetroxide) and solid oxides such as ReO2, RuO2, and OsO2 (Pownceby andO'Neill 1994, O'Neill andNell 1997). Mass spectrometric and other experimental studies show Re, Ru, and Os form monoxide, dioxide, and trioxide gases (e.g., Hildenbrand and Lau 1992, Nuta et al 2021, Skinner and Searcy 1973, Watson et al 1991). This complicates their chemistry at the high fO2 of the BSE melt -vapor system at 10 -6 to 10 2 bar total pressure and leads to consideration of multiple oxide gases and solids in the condensation calculations.…”