  We report two solid solutions based on magnetic ion doping of the double
perovskite oxide Sr2GaSbO6: Sr2Ga1-xCrxSbO6 (0.1 < x < 0.4) and Sr2Ga1-xFexSbO6
(0.1 < x < 0.4). All compositions crystallize in the same space group (I4/m) as
their undoped parent phase Sr2GaSbO6, with the trivalent magnetic cations Cr3+
or Fe3+ partially substituting for non-magnetic Ga3+ in one of the B-cation
sites. The Cr- and Fe-doped phases display dominant antiferromagnetic coupling
among the dopant magnetic moments, and exhibit decreasing band gaps with
increasing substitution level.
