Crystal structure and properties of Nd4Co3O10+delta and Nd4Ni3O10-delta

The crystal structures of Nd4M3O10 (M = Co, Ni) correspond to the n = 3 mem bers of the Ruddlesden-Popper series of A(n+1)B(n)O(3n+1). Rietveld-type an alyses of high-resolution powder synchrotron X-ray and ponder neutron diffr action (PND) data of Nd4Co3O10+delta and Nd4Ni3O10-delta reveal their cryst al structures to be slightly monoclinically distorted. The symmetry lowerin g to space group P2(1)/a is caused by tilting of the MO6 octahedra within t he (NdMO3)(3) layers. Long apical M-O distances are observed in the octahed ra pointing toward the NdO layers. Magnetic susceptibility data for Nd4Co3O 10.00 indicate long-range antiferromagnetic ordering below 15 K. The ordere d moment is too low to be detected by PND at 8 K. Above 60 K, two nearly Cu rie-Weiss paramagnetic regions are observed: 60-560 K and 650-920 K. Therma l analysis data for Nd4Co3O10+delta in atmospheres of oxygen and nitrogen s hows a complex behavior, with respect to both possible phase transitions an d redox properties. (C) 2000 Academic Press.