Synthesis, structure and magnetic susceptibility of the oxynitride spinell Mn2(MnTa3)N6-δO2+δ, 0≤δ≤1
1995 (English)In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 117, no 1, 48-54 p.Article in journal (Refereed) Published
The oxynitride spinel Mn2(MnTa3)N6-δO2+δ, with 0 ≤ δ ≤ 1, has been synthesized at 1175 K by ammonolysis of a mixture of a Ta-containing xerogel and Mn(OAc)2 · 4H2O. The N content was determined by combustion analysis and thermogravimetric oxidation, yielding a composition confined between Mn2(MnTa3)N6O2 (δ = 0) and Mn2(MnTa3)N5O3 (δ = 1). The structure is cubic, with space group Fd3m and a = 8.8353(3) Å. It was refined using the Rietveld technique and neutron powder diffraction data collected at room temperature and 15 K, to RF = 2.9 and 3.8%, respectively. The tetrahedral sites are occupied only by Mn atoms and the octahedral sites statistically by 25% Mn and 75% Ta atoms. The N and O atoms are randomly distributed over the anion sites. The magnetic susceptibility exhibits a maximum at 29 K and a Curie-Weiss behavior at higher temperatures with θa = -250(20) K and μeff = 5.7(2) Bohr magnetons per Mn atom. The neutron powder diffraction data collected at 15 K showed no evidence of magnetic ordering. A NaCl-type phase with a = 4.4382(2) Å and tentative composition Mn0.8Ta0.2(O,N) was observed in preparations at 1175 K. A hexagonal Mn4Ta2(O,N)x phase with cell dimensions a = 5.3024(4) Å, c = 14.493(2) Å was obtained at 973 K.
Place, publisher, year, edition, pages
1995. Vol. 117, no 1, 48-54 p.
IdentifiersURN: urn:nbn:se:liu:diva-60874DOI: 10.1006/jssc.1995.1245OAI: oai:DiVA.org:liu-60874DiVA: diva2:359616