Heat capacity and thermodynamic properties of LaFeO3 and LaCoO3 from T = 13 K to T = 1000 K

The heat capacities of LaFeO3 and LaCoO3 have been determined by adiabatic calorimetry from T = (13 to 900) K, and from T = (13 to 1000) K, respectively. Both compounds undergo electronic transitions; LaFeO, a magnetic order-disorder (AF to para) transition at T approximate to 735 K; LaCoO3 a continuous low to intermediate to high-spin transition which gives rise to heat capacity maxima at T approximate to 60 K, and at T approximate to 530 K. Energetic aspects of the transitions are discussed. The thermodynamic properties have been evaluated, and the values of the molar heat capacities, entropies, and enthalpies for LaFeO3 and LaCoO3 at T = (298.15, 900, 298.15, and 1000) K, respectively, are: [GRAPHICS] (C) 1998 Academic Press Limited.