Important Variation in Vibrational Properties of LiFePO4 and FePO4 Induced by Magnetism.
A new thermodynamically self-consistent (TSC) method, based on the quasi-harmonic approximation (QHA), is used to obtain the Debye temperatures of LiFePO4 (LFP) and FePO4 (FP) from available experimental specific heat capacities for a wide temperature range. The calculated Debye temperatures show an interesting critical and peculiar behavior so that a steep increase in the Debye temperatures is observed by increasing the temperature. This critical behavior is fitted by the critical function and the adjusted critical temperatures are very close to the magnetic phase transition temperatures in LFP and FP. Hence, the critical behavior of the Debye temperatures is correlated with the magnetic phase transitions in these compounds. Our first-principle calculations support our conjecture that the change in electronic structures, i.e. electron density of state and electron localization function, and consequently the change in thermophysical properties due to the magnetic transition may be the reason for the observation of this peculiar behavior of the Debye temperatures.
LCES Laboratory of Chemistry and Electrochemistry of Solids, Department of Chemistry, Université de Montréal, P. O. 6128, Downtown Branch, Montréal, Québec, H3C 3J7, Canada.|CRCT Center for Research in Computational Thermochemistry, Department of Chemical Eng., Polytechnique Montréal (Campus of Université de Montréal), Box 6079, Station Downtown, Montréal, Québec H3C 3A7, Canada.
Ali
A
Seifitokaldani
CRCT Center for Research in Computational Thermochemistry, Department of Chemical Eng., Polytechnique Montréal (Campus of Université de Montréal), Box 6079, Station Downtown, Montréal, Québec H3C 3A7, Canada.
Aïmen E
AE
Gheribi
CRCT Center for Research in Computational Thermochemistry, Department of Chemical Eng., Polytechnique Montréal (Campus of Université de Montréal), Box 6079, Station Downtown, Montréal, Québec H3C 3A7, Canada.
Anh Thu
AT
Phan
CRCT Center for Research in Computational Thermochemistry, Department of Chemical Eng., Polytechnique Montréal (Campus of Université de Montréal), Box 6079, Station Downtown, Montréal, Québec H3C 3A7, Canada.
Patrice
P
Chartrand
LCES Laboratory of Chemistry and Electrochemistry of Solids, Department of Chemistry, Université de Montréal, P. O. 6128, Downtown Branch, Montréal, Québec, H3C 3J7, Canada.
Mickaël
M
Dollé