Synthesis, structure and magnetic susceptibility of the oxynitride spinel Mn{sub 2}(MnTa{sub 3})N{sub 6-{delta}}O{sub 2+{delta}}, 0 {le} {delta} {le} 1

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1995.1245· OSTI ID:171914

Grins, J; Kaell, P O; Svensson, G ^[1]

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1. Stockholm Univ. (Sweden)

The oxynitride spinel Mn{sub 2}(MnTa{sub 3})N{sub 6-{delta}}O{sub 2+{delta}} with 0 {le} {delta} {le} 1, has been synthesized at 1175 K by ammonolysis of a mixture of a Ta-containing xerogel and Mn(OAc){sub 2} {center_dot} 4H{sub 2}O. The N content was determined by combustion analysis and thermogravimetric oxidation, yielding a composition confined between Mn{sub 2}(MnTa{sub 3})N{sub 6}O{sub 2} ({delta} = 0) and Mn{sub 2}(MnTa{sub 3})N{sub 5}O{sub 3} ({delta} = 1). The structure is cubic, with space group Fd3m and a = 8.8353(3) {angstrom}. It was refined using the Rietveld technique temperature and 15 K, to R{sub F} = 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 {theta}{sub a} = -250(20) K and {mu}{sub eff} = 5.7(2) Bohr magnetrons 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) {angstrom} and tentative composition Mn{sub 0.8}Ta{sub 0.2}(O,N) was observed in preparations at 1175 K. A hexagonal Mn{sub 4}Ta{sub 2}(O,N){sub x} phase with cell dimensions a = 5.3024(4) {angstrom}, c = 14.493(2) {angstrom} was obtained at 973 K.

• OSTI ID: 171914
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 117; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMMONOLYSIS
CHEMICAL COMPOSITION
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
CUBIC LATTICES
MAGNETIC SUSCEPTIBILITY
MANGANESE NITRIDES
MANGANESE OXIDES
SPINELS
STOICHIOMETRY
TANTALUM NITRIDES
TANTALUM OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
THERMAL GRAVIMETRIC ANALYSIS