Synthesis, structural characterisation and magnetic properties of Gd14W4O33-xNy(0<=x<=17+/-2, 0<=y<=9+/-2), a new fluorite-related oxynitride
1996 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, Vol. 240, no 1-2, 60-69 p.Article in journal (Refereed) Published
A series of crystalline Gd-W oxides, with Gd:W ratios spanning the values 0.1-3.5, has been prepared and treated with a flow of NH3(g) in the temperature range 700-1100 degrees C. Besides the previously reported formation of GdWO3N and Gd2WO3N2, the following new results were obtained: (i) cubic Gd0.1WO3 upon ammonolysis forms an (oxy)nitride Gd0.1W(O,N)(y) with an f.c.c. lattice; (ii) the previously described Gd2WO3N2 exhibits a solid solubility range Gd3-xW1+x(O,N)(y) with, approximately, 0 less than or equal to x less than or equal to 1; (iii) ammonolysis of Gd14W4O33 yields an oxynitride, the composition of which varies with the synthesis temperature according to Gd14W4O33-xNy(O less than or equal to x less than or equal to 17+/-2, 0 less than or equal to y less than or equal to 9+/-2). All strong diffraction lines, including those of the pure oxide (x = y = 0), can be indexed with a body-centred monoclinic unit cell derived from that of fluorite. For Gd14W4O33 the cell 3 parameters are a = 5.3592(11), b = 3.7295(7), c = 3.8636(8) Angstrom, beta = 92.170(2)degrees and V = 77.17 Angstrom(3). However, strong superstructure reflections in the electron diffraction patterns indicate that the true unit cell is considerably larger. A partial structure determination of Gd14W4O33-xNy has been carried out by the Rietveld method. Magnetic susceptibility measurements in the temperature interval 15-300 K show a Curie-Weiss law behaviour for Gd14W4O33-xNy, with mu(eff) = 8.08+/-0.06 Bohr magntons per Gd3+ and theta = -12.4+/-1.1 K for all compositions.
Place, publisher, year, edition, pages
1996. Vol. 240, no 1-2, 60-69 p.
Gd-W oxynitrides, ammonolysis, Rietveld refinement, electron diffraction, magnetic susceptibility
Research subject Materials Chemistry
IdentifiersURN: urn:nbn:se:su:diva-43896DOI: 10.1016/0925-8388(96)02325-0OAI: oai:DiVA.org:su-43896DiVA: diva2:371122