Synthesis, structure and magnetic properties of R-W-O-N (R=Nd and Eu) oxynitrides

Journal Article · Mon Jan 15 00:00:00 EST 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.09.025· OSTI ID:21015623

Pastrana-Fabregas, R ^[1]; Isasi-Marin, J ^[1]; Cascales, C ^[2]

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1. Department of Quimica Inorganica I, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain)
2. Instituto de Ciencia de Materiales de Madrid ICMM, Consejo Superior de Investigaciones Cientificas CSIC, C/ Sor Juana Ines de la Cruz, 3. Cantoblanco, 28040 Madrid (Spain)

Neodymium and europium tungsten oxynitrides have been synthesized by the nitridation of corresponding R{sub 2}W{sub 2}O{sub 9} precursor oxides, in ammonia flow at 1173K during 24h. The obtained polycrystalline neodymium oxynitride phase, with NdWO{sub 3.05}N{sub 0.95} composition, crystallizes with the tetragonal symmetry of the scheelite-type structure, space group S.G. I4{sub 1}/a (no. 88). The analogous europium derivative, with formula EuWO{sub 1.58}N{sub 1.42}, presents the cubic perovskite-type structure, S.G. Pm3-bar m (no. 221). Unit-cell parameters, a=5.255(1)A, c=11.399(3)A, and a=3.976(3)A, have been established from Rietveld refinements of collected X-ray powder diffraction patterns for the Nd and Eu- oxynitrides, respectively. Magnetic susceptibility measurements show that NdWO{sub 3.05}N{sub 0.95} behaves as paramagnetic in a wide range of temperature T {approx}50-300K. The downwards deviation from the Curie-Weiss law below 40K reflects the splitting of the {sup 4}I{sub 9/2} ground state of Nd{sup 3+} experienced under the influence of a S{sub 4} crystal field CF potential, as the successful reproduction of the magnetic susceptibility {chi}{sup -1}{sub m} vs. T, using semi-empirical structure-derived CF parameters, indicates. EuWO{sub 1.58}N{sub 1.42} is paramagnetic down to 20K, and the measured effective magnetic moment 8.01{mu}{sub B} is indicative of the presence of Eu{sup 2+} in this oxynitride. The observed sudden jump in the magnetic susceptibility at 20K and the value of 6{mu}{sub B} for the saturation moment is attributed to the onset of ferrimagnetic interactions in which the Eu{sup 2+} and W{sup 5+} sublattices appear to be involved.

• OSTI ID: 21015623
• Journal Information: Journal of Solid State Chemistry, Vol. 180, Issue 1; Other Information: DOI: 10.1016/j.jssc.2006.09.025; PII: S0022-4596(06)00535-4; Copyright (c) 2006 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
CRYSTAL FIELD
CUBIC LATTICES
CURIE-WEISS LAW
EUROPIUM COMPOUNDS
EUROPIUM IONS
FERRIMAGNETISM
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
NEODYMIUM COMPOUNDS
NEODYMIUM IONS
NITRIDATION
NITRIDES
OXIDES
PARAMAGNETISM
PEROVSKITE
POLYCRYSTALS
SPACE GROUPS
SYNTHESIS
TEMPERATURE RANGE 1000-4000 K
TETRAGONAL LATTICES
TUNGSTEN COMPOUNDS
TUNGSTEN IONS
X-RAY DIFFRACTION