Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Low temperature heat capacity Study of Fe(PO3)3 and Fe2P2O7

Shi, Q.[Quan], Zhang, L.[Liying], Schlesinger, M. E.[Mark E.], Boerio-Goates, J.[Juliana], Woodfield, B. F.[Brian F.]
J. Chem. Thermodyn. 2013, 61, 51-57
ABSTRACT
The heat capacities of two iron phosphates, Fe(PO3)3 and Fe2P2O7, have been measured over the temperature range from (2 to 300) K using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS). A phase transition related to magnetic ordering has been found in the heat capacity at T = 8.76 K for Fe(PO3)3 and T = 18.96 K for Fe2P2O7, which are comparable with literature values from magnetic measurements. By fitting the experimental heat capacity values, the thermodynamic functions, magnetic heat capacities, and magnetic entropies have been determined. Additionally, theoretical fits at low temperatures suggest that Fe2P2O7 has an anisotropic antiferromagnetic contribution to the heat capacity and a large linear term likely caused by oxygen vacancies. Further data fitting in a series over widened temperature regions found that this linear term exists only below 15 K and disappears gradually from (15 to 17) K.
Compounds
# Formula Name
1 FeO9P3 iron(III) metaphosphate
2 Fe2O7P2 iron(II) pyrophosphate
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
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Gas
  • Quantum Design PPMS relaxation calorimeter
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Gas
  • Quantum Design PPMS relaxation calorimeter
  • 1
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 57
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 81
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 9
  • POMD
  • 1
  • Molar entropy, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 8
  • POMD
  • 1
  • Molar enthalpy, kJ/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 8
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 51
  • POMD
  • 1
  • Molar entropy, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 50
  • POMD
  • 1
  • Molar enthalpy, kJ/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 50
  • POMD
  • 2
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Gas
  • Quantum Design PPMS relaxation calorimeter
  • 1
  • POMD
  • 2
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Gas
  • Quantum Design PPMS relaxation calorimeter
  • 1
  • POMD
  • 2
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 51
  • POMD
  • 2
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 114
  • POMD
  • 2
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 19
  • POMD
  • 2
  • Molar entropy, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 18
  • POMD
  • 2
  • Molar enthalpy, kJ/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • Quantum Design PPMS relaxation calorimeter
  • 18
  • POMD
  • 2
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 41
  • POMD
  • 2
  • Molar entropy, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 40
  • POMD
  • 2
  • Molar enthalpy, kJ/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • Quantum Design PPMS relaxation calorimeter
  • 40