POWDER NEUTRON AND X-RAY-DIFFRACTION STUDY OF LA4CO3O10.00

The crystal structure of stoichiometric La4Co3O10.00 is of the Ruddles den-Popper type and contains slabs of triple perovskite-type layers se parated by rock salt layers, the composition corresponding to n = 3 in the A(n+1)B(n)O(3n+1) series. On heating, the slightly orthorhombical ly deformed structure converts into a tetragonal one at around 840 K. Antiferromagnetic ordering occurs below T-N approximate to 10 K. Cryst al structure data from powder neutron diffraction are presented. Sligh t line broadening of some X-ray reflections and a few, weak additional neutron reflections indicates that the true symmetry is lower than Fm mm.