Thermodynamic assessment of RuO4 oxide

International audience ; RuO4 oxide appears much less stable than RuO2 (s) in the Ru-O binary system with a melting point close to room temperature and a certain propensity to vaporize or decompose at low temperatures. Ab initio simulations in the framework of density functional theory (DFT) on RuO4 (s) are performed to analyze the cubic and monoclinic structures and to evaluate the heat capacities at low temperatures. Then, a critical evaluation of thermodynamic data from calorimetry and vapor pressure determinations-was carried out coupled with ab-initio calculations to propose new thermodynamic data: the entropy, S° (RuO4, s, cubic, 298K) = 132.7 J•K-1 mol-1 and formation enthalpy, D f H° (RuO 4 , s, cubic, 298K) =-252.4 +/- 5.5 kJ mol-1 .