  The complex metal oxides Mn2ASbO6 (A=In, Sc) with a corundum-related
structure A3BO6 have been prepared as polycrystalline powders by a solid state
reaction route. The crystal structure and magnetic properties have been
investigated using a combination of X-ray and neutron powder diffraction,
electron microscopy, calorimetric and magnetic measurements. At room
temperature these compounds adopt a trigonal structure, space group R-3 with a
= 8.9313(1) {\AA}, c = 10.7071(2) {\AA} (for In) and a = 8.8836(1) {\AA}, c =
10.6168(2) {\AA} (for Sc) which persists down to 1.6 K. The Mn and A cations
were found to be randomly distributed over the A-sites. The overall behavior of
the magnetization of Mn2InSbO6 and Mn2ScSbO6 is quite similar. In spite of the
relatively large amount of Mn ions on the A-site, only short-ranged magnetism
is observed. Neutron diffraction patterns of Mn2InSbO6 showed no evidence of a
long-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic
peak was observed at low temperatures. The factors governing the observed
structural and magnetic properties of Mn2ASbO6 are discussed and compared with
those of other Mn-containing complex metal oxides with a corundum-related
structure. The influence of the A-cation sublattice on magnetic properties is
also considered.
