Low Temperature Heat Capacity Study of FePO₄ and Fe₃(P₂O₇)₂
The heat capacities of FePO4 and Fe3(P 2O7)2 have been measured using a Quantum Design Physical Property Measurement System (PPMS) over the temperature range from (2 to 300) K. The phase transition due to the Fe3+ magnetic ordering in FePO4 has been determined to occur at T = 25.0 K, which agrees well with magnetic measurements reported in the literature. For Fe3(P 2O7)2, a Schottky anomaly and a four-peak phase transition have been found below 50 K. The thermodynamic functions, magnetic heat capacities, and magnetic entropies of these two compounds have been calculated based on curve fitting of the experimental heat capacity values. The standard molar entropy at T = 298.15 K has been obtained to be (122.21 ± 1.34) J · K-1 · mol-1 and (384.12 ± 4.23) J · K-1 · mol-1 for FePO4 and Fe3(P2O7)2, respectively. All rights reserved.
Q. Shi et al., "Low Temperature Heat Capacity Study of FePO₄ and Fe₃(P₂O₇)₂," Journal of Chemical Thermodynamics, Elsevier, Jan 2013.
The definitive version is available at http://dx.doi.org/10.1016/j.jct.2013.02.017
Materials Science and Engineering
Article - Journal
© 2013 Elsevier, All rights reserved.