Inducing Ferrimagnetism in Insulating Hollandite Ba1.2Mn8O16.

Both Ba1.2Mn8O16 (I) and BaxCoyMn8-yO16 (II) are prepared by reaction of stoichiometric amounts of Mn2O3, Co3O4, and Ba(NO3)2 in a KCl flux (alumina crucible, 1123 k, 72 h).