Phase formation, structural and microstructural characterization of novel oxynitride-perovskites synthesized by thermal ammonolysis of (Ca,Ba)MoO{sub 4} and (Ca,Ba)MoO{sub 3}

Journal Article · Mon Sep 15 00:00:00 EDT 2008 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.05.012· OSTI ID:21128438

Logvinovich, D; Aguirre, M H ^[1]; Hejtmanek, J ^[2]; Aguiar, R; Ebbinghaus, S G; Reller, A ^[3]

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1. Solid State Chemistry and Catalysis, Empa, Ueberlandstr. 129, CH-8600 Duebendorf (Switzerland)
2. Institute of Physics, ASCR, Cukrovarnicka 10, CZ-15263, Prague 6 (Czech Republic)
3. Lehrstuhl fuer Festkoerperchemie, Institut fuer Physik, Universitaet Augsburg, Universitaetsstrasse 1, D-86159, Augsburg (Germany)

Reactions of AMoO{sub 4} and AMoO{sub 3} (A=Ca{sup 2+}, Ba{sup 2+}) with ammonia were investigated at 873 K<T<1123 K with the particular intention to synthesize novel oxynitride-perovskites of the general composition AMo(O,N){sub 3} and to study their crystal structure. CaMo(O,N){sub 3} and BaMo(O,N){sub 3} were prepared by thermal ammonolysis of the corresponding CaMoO{sub 3} and BaMoO{sub 3} precursors at T=898 and 998 K, respectively. The structural parameters of the oxynitrides were obtained from Rietveld refinements of X-ray and neutron powder diffraction data. CaMo(O,N){sub 3} crystallizes in the GdFeO{sub 3} distorted perovskite structure with orthorhombic space group Pbnm and a=5.5029(1) A, b=5.5546(1) A, c=7.8248(1) A as determined by X-ray powder diffraction. Its O/N content refined from the neutron diffraction data corresponds to the composition CaMoO{sub 1.7(1)}N{sub 1.3(1)}. BaMo(O,N){sub 3} crystallizes in the cubic perovskite structure with space group Pm3-bar m and a=4.0657(1) A as determined by X-ray powder diffraction. Transmission electron microscopy reveals a complex microstructure for both CaMoO{sub 3} and CaMoO{sub 1.7(1)}N{sub 1.3(1)} represented by twin domains of different orientation. - Graphical abstract: Reactions of AMoO{sub 4} and AMoO{sub 3} (A=Ca{sup 2+}, Ba{sup 2+}) oxides with ammonia have been studied at T=873-1123 K. Orthorhombic CaMoO{sub 1.7(1)}N{sub 1.3(1)} (Pbnm) and cubic BaMo(O,N){sub 3} (Pm3-bar m) were prepared by thermal ammonolysis of the corresponding CaMoO{sub 3} and BaMoO{sub 3} precursors at T=898 and 998 K, respectively. Display Omitted.

• OSTI ID: 21128438
• Journal Information: Journal of Solid State Chemistry, Vol. 181, Issue 9; Other Information: DOI: 10.1016/j.jssc.2008.05.012; PII: S0022-4596(08)00232-6; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIA
AMMONOLYSIS
BARIUM COMPOUNDS
BARIUM IONS
CALCIUM COMPOUNDS
CALCIUM IONS
CUBIC LATTICES
MICROSTRUCTURE
MOLYBDATES
NEUTRON DIFFRACTION
NITRIDES
ORTHORHOMBIC LATTICES
PEROVSKITE
SPACE GROUPS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION