ABSTRACT

The low temperature heat capacities of Fe3PO7 and Fe4(P2O7)3 have been measured using a Quantum Design Physical Property Measurement System (PPMS) over the temperature range from (2 to 300)K. Phase transitions due to Fe3+ magnetic ordering have been determined in the heat capacities at temperatures of (164.5 and 47.6)K for Fe3PO7 and Fe4(P2O7)3, respectively, which agrees well with the magnetic measurements reported in the literature. Also,another small transition occurring at around 27 K for Fe4(P2O7)3 has been found for the first time.The thermodynamic functions and magnetic heat capacities have been calculated based on the curving fitting of the experimental heat capacity values. Using the fitted heat capacity results, the standard molar entropies have been calculated to be (219.73 +-2.42) J.K-1.mol-1 and (561.03 +-6.17) J.K-1.mol-1 for Fe3PO7 and Fe4(P2O7)3, respectively. The calculated magnetic entropy of Fe3PO7 using the magnetic heat capacity suggests that the five 3d-electrons in the Fe3+ are in the t2g orbital with a low spin state according to crystal field theory.

Compounds

#	Formula	Name
1	Fe3O7P	iron oxide phosphate (Fe2O3.FePO4)
2	Fe4O21P6	iron(III) diphosphate

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	relaxation calorimetry - Quantum Design PPMS	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2			Crystal 2 Crystal 1 Gas	relaxation calorimetry - Quantum Design PPMS	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	66
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	72
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	43
POMD	1	Molar entropy, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	42
POMD	1	Molar enthalpy, kJ/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	42
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	17
POMD	1	Molar entropy, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	16
POMD	1	Molar enthalpy, kJ/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	16
POMD	2	Triple point temperature, K ; Crystal 2			Crystal 2 Crystal 1 Gas	relaxation calorimetry - Quantum Design PPMS	1
POMD	2	Triple point temperature, K ; Crystal 3			Crystal 3 Crystal 2 Gas	relaxation calorimetry - Quantum Design PPMS	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 3			Crystal 3 Crystal 2 Gas	relaxation calorimetry - Quantum Design PPMS	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2			Crystal 2 Crystal 1 Gas	relaxation calorimetry - Quantum Design PPMS	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 3	Temperature, K; Crystal 3	Pressure, kPa; Crystal 3	Crystal 3	relaxation calorimetry - Quantum Design PPMS	52
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	72
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	88
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 3	Temperature, K; Crystal 3	Pressure, kPa; Crystal 3	Crystal 3	relaxation calorimetry - Quantum Design PPMS	22
POMD	2	Molar entropy, J/K/mol ; Crystal 3	Temperature, K; Crystal 3	Pressure, kPa; Crystal 3	Crystal 3	relaxation calorimetry - Quantum Design PPMS	21
POMD	2	Molar enthalpy, kJ/mol ; Crystal 3	Temperature, K; Crystal 3	Pressure, kPa; Crystal 3	Crystal 3	relaxation calorimetry - Quantum Design PPMS	21
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	6
POMD	2	Molar entropy, J/K/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	4
POMD	2	Molar enthalpy, kJ/mol ; Crystal 2	Temperature, K; Crystal 2	Pressure, kPa; Crystal 2	Crystal 2	relaxation calorimetry - Quantum Design PPMS	4
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	34
POMD	2	Molar entropy, J/K/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	33
POMD	2	Molar enthalpy, kJ/mol ; Crystal 1	Temperature, K; Crystal 1	Pressure, kPa; Crystal 1	Crystal 1	relaxation calorimetry - Quantum Design PPMS	33

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Low temperature heat capacity study of Fe3PO7 and Fe4(P2O7)3

Shi, Q.[Quan], Zhang, L.[Liying], Schlesinger, M. E.[Mark E.], Boerio-Goates, J.[Juliana], Woodfield, B. F.[Brian F.]

ABSTRACT