METAL-INSULATOR-TRANSITION IN 3D TRANSITION-METAL OXIDES WITH ABO3 AND A2BO4 TYPE STRUCTURES

3d transition-metal oxides with perovskite and K2NiF4 crystal structures, (La,Sr)VO3, (La,Sr)FeO3, (La,Sr)CoO3, LaNiO3 and (La,Sr)2NiO4 systems are investigated focusing on the effect of carrier doping performed by the A-site ion substitution. Both (La,Sr)VO3 and (La,Sr)CoO3 systems show an insulator to metal transition by Sr substitution, however, the magnetic behavior differs drastically. The mid-infrared structure induced by Sr substitution is observed in the optical spectra of (La,Sr)2NiO4 system. Relation between the behavior of metal-insulator transition and the variation of the electronic and/or spin structure in these systems is discussed in comparison with the high-T(c) copper oxides.