Heat Capacity and Thermodynamic Properties of Synthetic Magnetite (Fe3O4) from 300 to 1050 K. Ferrimagnetic Transition and Zero-Point Entropy Entity Journal Article uri icon

DCO ID 11121/1840-7517-2475-9035-CC

year of publication

  • 1974

abstract

  • The heat capacity of synthetic Fe3O4 has been measured in the range 300 to 1050 K. The 
    λ-type transition, related to the change from ferri- to paramagnetism in the compound, is 
    delineated and a maximum heat capacity of about 340 J K-1 mol-1 is observed at 848.5 K. 
    Values of various thermodynamic functions have been derived; Cp(1000 K), {Hº(1000 K) 
    -H°(298.15 K) }, and {Sº(1000 K) - Sº(298.15 K)} are 212.4 J K-1 mol-1 , 149.80 kJ 
    mol-1 , and 246.2 J K-1 mol-1 , respectively. The non-cooperative heat capacity has been 
    estimated and the excess thermodynamic properties have been evaluated. Combination of 
    available data for the reaction: 3Fe(s)+4H2O(g) = Fe3O4(s)+4H2(g), indicates that 
    zero-point entropy of about 4 J K-1 mol-1  might be present in Fe3O4. This is in agreement 
    with theoretical predictions of 3.4 J K-1 mol-1

publication date

  • 1974

volume

  • 6