Electrochemical, magnetic, and structural investigation of the Li x(MnyFe1-y)PO4 olivine phases

Atsuo Yamada, Yuki Takei, Hiroshi Koizumi, Noriyuki Sonoyama, Ryoji Kanno, Keiji Itoh, Masao Yonemura, Takashi Kamiyama

Research output: Contribution to journalArticlepeer-review

161 Citations (Scopus)


A series of synthetic heterosite-purpurite, (MyFe 1-y)PO4 (y < 0.8), with negligible disorder and impurities, was obtained by chemical oxidation of the well-crystallized isotypic tryphillite-lithiophilite series, Li(MnyFe 1-y)PO4 (ordered olivine structure, space group Pnma). Comparative magnetic and X-ray/neutron powder diffraction investigations of the two solid-solution lines were performed as a function of Mn content to increase understanding of the electrochemical activity loss of Mn3+/Mn 2+ in the Lix(MnyFe1-y)PO 4 electrode system. Introducing Mn ions into the 4c site did not cause significant change in the local geometry of M2+O6 and PO4 polyhedra, while the M3+O6 octahedra became severely distorted with an increase in the number of Jahn-Teller active Mn3+ ions. The edge-sharing geometry of M3+O6 and PO4 polyhedra fixed the shared O3′-O3′ interatomic distance, causing selective strong elongation of the M3+-O3′ distance with small shrinkage of other M3+-O1, M3+-O2, and M3+-O3 bond lengths. The overall distortion of the MO 6 octahedra with M = Mn3+ was much larger than the corresponding change in the unit-cell orthorombicity and significantly increased asymmetry in the M-O-M superexchange interaction. All samples exhibited antiferromagnetism; however, the trivalent series had more than a sevenfold larger decrease in Neel temperature TN (from ca. 130 K at y = 0 to ca. 50 K at y = 0.8) compared to the divalent series (from ca. 52 K at y = 0 to ca. 35 K at y = 1) as a function of the Mn content y.

Original languageEnglish
Pages (from-to)804-813
Number of pages10
JournalChemistry of Materials
Issue number3
Publication statusPublished - Feb 7 2006
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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