Preparation, structure and magnetic properties of a new nickel(III) oxide: YbSr3NiO6

Abstract

An investigation of the Yb_2–xSr_xNiO_4–δ system has shown that no phases crystallise with a K₂NiF₄ structure for reaction temperatures up to 1100 °C at 1 atm oxygen pressure, but a new phase of ideal composition YbSr₃NiO₆ is formed. Rietveld refinement using powder X-ray diffraction data shows that YbSr₃NiO₆ adopts a rhombohedral K₄PtCl₆ type structure [Rc, Z= 6, a= 9.6851 (2)Å, c= 11.0960(2)Å, R_wp= 2.8%], with a deficiency of scattering from the Yb site due to 11 % Yb vacancies or possibly cation substitutions, lodometric titrations suggest an average Ni oxidation state of 3.0+. Magnetic susceptibility data for YbSr₃NiO₆ between 5 and 300 K show Curie–Weiss behaviour at higher temperatures, characteristic of Yb³⁺ and low-spin Ni³⁺ with overall µ_eff= 4.63(1)µ_B and θ^W=–29.0(1) K. A broad susceptibility maximum at 12 K may be due to one-dimensional antiferromagnetic order.