The stacks of hexagonal nanoplates around a central rod correspond
to a more advanced stage of growth. Structural and cathodoluminescence
characterization of the samples shows that Mn ions are
incorporated into the structures, as well as the formation of a spinel
phase in some areas. The amount of Mn ranges between 1 and
6 at.% and does not depend on the initial MnCO3 content of the
samples