STRUCTURE AND PROPERTIES OF THE NICKEL(III) OXIDE FAMILY - LNSR(5)NI(3)O(11) (LN=Y, DY, HO, ER, AND TM)

Tetragonal K2NiF4 type phases LnSr(5)Ni(3)O(11) have been prepared for Ln = Dy, Ho, Er, and Tm. They are isostructural with previously repor ted YSr5Ni3O11. Thermogravimetric analysis indicates that these phases are stoichiometric nickel(III) oxides. Rietveld refinement using X-ra y and neutron powder diffraction data confirms that the Ln(3+) and Sr2 + ions are disordered over the same lattice sites. Local structural fe atures were investigated for YSr5Ni3O11 using Sr and Y K edge EXAFS, a nd the total oxygen coordination number about the Y site, 7.7(3), was found to be lower than that of the Sr site, 8.6(3). Magnetic susceptib ility data for these LnSr(5)Ni(3)O(11) phases show Curie-Weiss paramag netic behavior between 6 and 300 K.