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Published November 16, 2006 | public
Journal Article

Phonons and Thermodynamics of Unmixed and Disordered Li_(0.6)FePO_4

Abstract

The lithium-storage material Li_(0.6)FePO_4 was studied by inelastic neutron scattering and differential scanning calorimetry. Li_(0.6)FePO_4 undergoes a transformation from a two-phase mixture (heterosite and triphylite) to a disordered solid-solution at 200 °C. Phonon densities of states (DOS) obtained from the inelastic neutron scattering were similar for the two-phase sample measured at 180 °C and the disordered sample measured at 220 °C. The vibrational entropy of transformation is 1.8 ±0.9 J/(K mol), which is smaller than the configurational entropy difference of approximately 3.1 J/(K mol). The measured enthalpy of the disordering transition was estimated as 2.5 kJ/mol. The phonon data show a small change in lattice dynamics upon disordering.

Additional Information

© 2006 American Chemical Society. Received: June 20, 2006; In Final Form: September 7, 2006. Publication Date (Web): October 13, 2006. The authors thank Dr. Khalil Amine, Dr. Ilias Belharouak, and Argonne National Laboratory for providing the LiFePO_4 material. This work was supported by the Department of Energy through the Basic Energy Sciences Grants DE-FG03-00ER15035 and BES-MS, W-31-109-ENG-38, and by the National Sciences and Engineering Research Council of Canada through a Discovery grant.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023