Molar heat capacity and thermodynamic functions of the type II antiferromagnet MnO

The thermodynamics of formation, molar heat capacity, and thermodynamic functions ofZrTiO4(cr)

“…(5,(19)(20)(21) The sample mass was 15.7585 g. Helium gas at a pressure of 4.80 kPa at T = 295.15 K was used inside the sealed calorimeter to facilitate thermal equilibration. Temperatures were measured by using a Rosemont 25 capsule thermometer calibrated on the ITS-90 temperature scale.…”

Gibbs Energy of Formation of MnO: Measurement and Assessment

“…To assess the best value for the entropy of MnO, an assessment of the available heat capacity data is required. (a) Recalculated from their emfs using more recent data on the reference electrodes Basic and Applied Research: Section I by Millar [12] is slightly lower than those of Todd and Bonnickson [13] and Shapiro et al [14] The transition from antiferromagnetic to paramagnetic state occurs at Neel temperature T N = 117.7 K. [9] Millar [12] measured the heat capacity of MnO in the temperature range from 70 to 300 K. To calculate the entropy at 298.15 K, a large extrapolation to 0 K is required. Data above the transition were used to determine the Debye and Einstein coefficients.…”

Molar heat capacities and thermodynamic functions of CaHf Ti2O7( cr ) and CaZr0.26Hf0.74Ti2O7( cr)

“…The deviations from the orthogonal polynomial fits are generally within ±1 per cent below T = 30 K with a maximum deviation of 3 per cent, but improve to ±0.15 per cent from T = 50 K to T = 400 K with a maximum deviation of 0.2 per cent for just a few points. Deviations of the fit with equation (4) are comparable above T = 150 K. Parameters obtained for the best fit to equation (4) 7 were calculated by numerical integration of the smoothed heat capacity curve and are also given in tables 4 and 5. Two crystallographic studies on zirconolite (12,17) have established the TABLE 4.…”

“…(4,7,14,15) The mass of the CaHfTi 2 O 7 sample was 9.6612 g, corrected for the CaTiO 3 impurity, and the mass of the CaZr 0.26 Hf 0.74 Ti 2 O 7 sample was 11.0367 g, also corrected for the CaTiO 3 impurity. Temperatures were measured with a Rosemont 25 capsule thermometer calibrated on the ITS-90 temperature scale.…”

“…Based on a six-parameter fitting equation, (4,(7)(8)(9) the heat capacities and thermodynamic functions have been extrapolated to T = 1500 K. The formation energetics will be reported separately. (10) The results show that the predicted entropy at T = 298.15 K for the solid solution is higher than the measured value by 0.9 per cent, and the zero-point entropy of the mixture makes a substantial stabilization contribution, implying the zero-point entropy for other mixtures in the plutonium disposition program could also have large stabilizing effects.…”