Diluted ferromagnetic semiconductors(DMSs)that combine the properties of semiconductors with ferromagnetism have potential application in spin-sensitive electronic(spintronic)devices.The search for DMS materials exploded after the observation of ferromagnetic ordering in Ⅲ-Ⅴ(Ga,Mn)As films.Recently,a series of DMS compounds isostructural to iron-based superconductors have been reported.Among them,the highest Curie temperature TC of 230 K has been achieved in(Ba,K)(Zn,Mn)2As2.However,most DMSs,including(Ga,Mn)As,are p-type,i.e.,the carriers that mediate the ferromagnetism are holes.For practical applications,DMSs with n-type carriers are also advantageous.Very recently,a new DMS Ba(Zn,Co)2As2 with n-type carriers has been synthesized.Here we summarize the recent progress on this research stream.We will show that the homogeneous ferromagnetism in these bulk form DMSs has been confirmed by microscopic techniques,i.e.,nuclear magnetic resonance(NMR)and muon spin rotation(μSR).