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

• Cation-ordered perovskites are studied using neutron diffraction and magnetometry.
• Yb3+ cations form a pseudo face centred cubic lattice in a distorted structure.
• Sb5+ cation is slightly overbonded as observed in related perovskites.
• Crystal field splitting of 4f13 Yb3+ giving a temperature dependent moment.
• Magnetic susceptibility reproduces theoretical predictions below 100 K.

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 cation-ordered 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.

The magnetic susceptibility of the face-centred cubic Yb3+ lattice is dominated by the temperature dependent single-ion moment below 100 K.Figure optionsDownload as PowerPoint slide