Thermodynamic studies of CaLaFe11O19(s)

Abstract Thermodynamic studies on CaLaFe 11 O 19 (s) were carried out using Knudsen effusion mass spectrometry and calorimetry, viz. differential scanning calorimetry and high temperature oxide melt solution calorimetry. Standard molar Gibbs free energy of formation (Δ f G 0 m ), enthalpy of formation and heat capacity ( C 0 p , m ) of the compound were calculated as a function of temperature for the first time. C 0 p , m (CaLaFe 11 O 19 ) was determined and used for second law analysis, from which enthalpy and entropy of formation of the compound were calculated and the respective values are: Δ f H 0 m (298.15 K)/kJ mol −1 =−6057(±8) and S 0 m (298.15 K)/J K −1  mol −1 =427(±5). Δ f H 0 m (298.15 K)/kJ mol −1 : −6055(±6) was also calculated using oxide melt solution calorimetry, which is in close agreement with the second law value. A heat capacity anomaly was also observed at T =684 K. A table of thermodynamic data from 298.15 K to 1000 K for CaLaFe 11 O 19 (s) was also constructed to represent an optimized set of data.