Nb2O2F3: A reduced niobium (III/IV) oxyfluoride with a complex structural, magnetic, and electronic phase transition

T. Thao Tran, Melissa Gooch, Bernd Lorenz, Alexander P. Litvinchuk, Maurice G. Sorolla, Jakoah Brgoch, Paul C.W. Chu, Arnold M. Guloy

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21 Citations (Scopus)

Abstract

A new niobium oxyfluoride, Nb2O2F3, synthesized through the reaction of Nb, SnO, and SnF2 in Sn flux, within welded Nb containers, crystallizes in a monoclinic structure (space group: I2/a; a = 5.7048(1)Å, b = 5.1610(1)Å, c = 12.2285(2)Å, β = 95.751(1)°). It features [Nb2X10] units (X = O, F), with short (2.5739(1) Å) Nb-Nb bonds, that are linked through shared O/F vertices to form a 3D structure configurationally isotypic to ζ-Nb2O5. Nb2O2F3 undergoes a structural transition at ∼90 K to a triclinic structure (space group: P1¯; a = 5.1791(5)Å, b = 5.7043(6)Å, c = 6.8911(7)Å, α = 108.669(3)°, β = 109.922(2)°, γ = 90.332(3)°). The transition is described as a disproportionation or charge ordering of [Nb2]7+ dimers: (2[Nb2]7+ → [Nb2]6+ + [Nb2]8+), resulting in doubly (2.5000(9) Å) and singly bonded (2.6560(9) Å) Nb2 dimers. The structural transition is accompanied by an unusual field-independent "spin-gap-like" magnetic transition.

Original languageEnglish
Pages (from-to)636-639
Number of pages4
JournalJournal of the American Chemical Society
Volume137
Issue number2
DOIs
Publication statusPublished - 2015 Jan 21

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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