Thermodynamics Research Center, ThermoML : Journal of Chemical Thermodynamics

An experimental calorimetric and a DFT + U study of the thermodynamic properties of Cs4[(UO2)4(WO5)(W2O8)O2] and Cs4[(UO2)7(WO5)3O3]

Lelet, Maxim I., Yakun'kova, Maria L., Kowalski, Piotr M., Suleimanov, Evgeny V., Geiger, Charles A., Alekseev, Evgeny V.
J. Chem. Thermodyn. 2019, 139, 105873
ABSTRACT
A calorimetric and thermodynamic investigation of two alkali-metal uranyl tungstates, Cs4UO24WO5W2O8O2(cr) and Cs4[UO27WO53O3](cr), was undertaken. Both phases were synthesized by solid-state sintering of a mixture of cesium nitrate, tungsten (VI) oxide and gamma-uranium (VI) oxide at high temperature. The synthetic products were characterized by X-ray powder diffraction and X-ray fluorescence methods. The enthalpies of formation of both phases were determined using HF-solution calorimetry giving deltafHmoT=298.15K,Cs4UO24WO5W2O8O2,cr=-9239+-17kJ*mol-1 anddeltafHmoT=298.15K,Cs4UO27WO53O3,cr=-13008+-23kJ*mol-1. The low-temperature heat capacity, Cp,mo, was measured using adiabatic calorimetry from T = 5 K to 324 K for Cs4UO24WO5W2O8O2cr and from T = 5 K to 325 K for Cs4UO27WO53O3cr. Using these Cp,moT data, the third law entropy at T = 298.15 K, Smo, is calculated as (931 +- 4) J*K-1*mol-1 for Cs4UO24WO5W2O8O2cr and (1262 +- 8) J*K-1*mol-1 for Cs4UO27WO53O3cr. These new experimental results, together with literature data, are used to calculate the Gibbs energy of formation, deltafGmo, for both phases giving: deltafGmoT=298.15K,Cs4UO24WO5W2O8O2,cr=-8623+-18kJ*mol-1 and deltafGmoT=298.15K,Cs4UO27WO53O3,cr=-12171+-24kJ*mol-1. Smoothed Cp,moT values between 0 K and 320 K are presented, along with values for Smo and the functions HmoT-Hmo0 and GmoT-Hmo0, for both phases. Based on these data, the enthalpy of the intercalation reaction Cs4UO24WO5W2O8O2cr+3UO3cr,gamma-greater thanCs4UO27WO53O3cr at 298 K was determined as -98+-29kJ*mol-1. A value of -90.3kJ*mol-1 at 0 K was obtained from DFT + U calculations. The results show the potential of using DFT + U simulations to understand solid-state reactions involving crystalline phases having 5d- and 5f-elements.
Compounds
# Formula Name
1 W tungsten
2 Cs cesium
3 U uranium
4 O2 oxygen
5 Cs4O23U4W3 cesium tungsten uranium oxide (Cs4W3U4O23)
6 Cs4O32U7W3 cesium tungsten uranium oxide (Cs4W3U7O32)
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 5
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 5
  • Molar enthalpy, kJ/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 5
  • Molar entropy, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 5
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 184
  • POMD
  • 6
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 6
  • Molar enthalpy, kJ/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 6
  • Molar entropy, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 39
  • POMD
  • 6
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 176
  • RXND
  • 1
  • 2
  • 3
  • 5
  • 4
  • Molar enthalpy of reaction, kJ/mol
  • Solution calorimetry
  • 1
  • RXND
  • 1
  • 2
  • 3
  • 6
  • 4
  • Molar enthalpy of reaction, kJ/mol
  • Solution calorimetry
  • 1