Structural and magnetic study of Yb3+ in the perovskites Sr2YbMO6 (M = Nb, Ta, Sb)

Coomer, Fiona C. and Campbell, John and Giordano, Nico and Collins, Oonagh M. and Cussen, Edmund J. (2015) Structural and magnetic study of Yb3+ in the perovskites Sr2YbMO6 (M = Nb, Ta, Sb). Journal of Solid State Chemistry, 221. pp. 411-417. ISSN 0022-4596

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    Abstract

    The compounds Sr2YbNbO6, Sr2YbTaO6 and Sr2YbSbO6 have been prepared using solid state methods by heating pelleted reagents in air at temperatures up to 1400°C. Rietveld refinement against room temperature neutron powder diffraction data show that all three compounds crystallise with a cationordered variant of the perovskite structure in the P21/n space group. Complete cation ordering occurs between M5+ and Yb3+ over two octahedrally-coordinated sites in the structure and all compounds are stoichiometric in oxygen. The Sb-O bond lengths are similar to related perovskite compounds but differ slightly from those indicated by bond valence sums. Magnetic susceptibility data resemble Curie-Weiss paramagnetic behaviour, but can be better understood as arising from the effect of the octahedral crystal field on the 2F5/2 ground state of Yb3+ leading to a temperature dependent magnetic moment on this ion below 100 K.