Synthesis, Mo-valence state, thermal stability and thermoelectric properties of SrMoO{sub 3-x}N{sub x} (x>1) oxynitride perovskites

Journal Article · Mon Oct 15 04:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.06.035· OSTI ID:21049494

Logvinovich, D ^[1]; Aguiar, R ^[2]; Robert, R; Trottmann, M ^[1]; Ebbinghaus, S G; Reller, A ^[2]

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1. Empa, Swiss Federal Laboratories for Materials Testing and Research, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf (Switzerland)
2. Universitaet Augsburg, Festkoerperchemie, Institut fuer Physik, Universitaetsstrasse 1, D-86159 Augsburg (Germany)

Oxynitrides of the general composition SrMoO{sub 3-x}N{sub x} (x>1) were synthesized by thermal ammonolysis of crystalline SrMoO{sub 4}. According to neutron and X-ray diffraction experiments, the materials crystallize in the cubic perovskite structure (space group Pm3-bar m). X-ray absorption spectroscopy (XAS) shows evidence of local distortions of the Mo(O,N){sub 6} octahedra. The oxidation states of Mo determined by X-ray absorption near edge structure (XANES) spectroscopy are slightly lower than that calculated from the oxygen/nitrogen(O/N) content. The disagreement arises from the higher covalence of the Mo-N bonding when compared to the Mo-O bonding ('chemical shift'). The electrical transport properties of the samples are strongly different from SrMoO{sub 3}. It was found that the conductivity of the samples decreases with increasing nitrogen content. The Seebeck coefficient values are up to three times higher than those of SrMoO{sub 3}. - Graphical abstract: Oxynitrides of the general composition SrMoO{sub 3-x}N{sub x} (x>1) were synthesized by thermal ammonolysis of SrMoO{sub 4}. X-ray and neutron diffraction detect no deviation from the cubic symmetry for the samples. X-ray absorption spectroscopy shows evidence of local distortions of Mo(O,N){sub 6} octahedra. The resistivity values of the samples are higher and the Seebeck coefficient values are lower than those of SrMoO{sub 3}. Rietveld refinement plot of the ND data for SrMoO{sub 1.95}N{sub 1.05}. Space group: Pm3-bar m, a=3.9835(1) A, wR{sub p}=6.78, R{sub p}=5.20, {chi}{sup 2}=1.36.

• OSTI ID: 21049494
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 10 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION
ABSORPTION SPECTROSCOPY
AMMONOLYSIS
CHEMICAL SHIFT
CUBIC LATTICES
MOLYBDATES
NEUTRON DIFFRACTION
NITRIDES
NITROGEN
OXYGEN
OXYGEN COMPOUNDS
PEROVSKITE
SPACE GROUPS
STABILITY
SYNTHESIS
THERMOELECTRIC PROPERTIES
VALENCE
X RADIATION
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY