MAGNETIC-PROPERTIES OF PEROVSKITE-TYPE OXIDE BABIO3 AND OF BABI1-XMXO3 WITH M-EQUIVALENT-TO-IN,MO OR LA

The magnetic properties of BaBiO3 and the metal-substituted compounds BaBi0.5In0.5O3, BaBi0.85Mo0.15O3 and BaBi0.5La0.5O3 were measured. A c ombined behaviour of temperature-dependent Curie-like paramagnetism an d of independent diamagnetism was observed. The diamagnetic contributi on is about 8 x 10(-5) emu mol-1 almost independently of the metal imp urities. The paramagnetic contribution, on the other hand, shows marke dly different behaviours for different impurities. The number of Bohr magnetons included in a molecule is larger by one order of magnitude f or the compound with indium than for those without and with transition -metal impurities. It was concluded that the paramagnetic behaviour co mes from the holes on the Bi 6s and O 2p bonding orbits, while the dia magnetic behaviour mainly comes from the core electrons on barium or o n the other ions. A deviation from the Curie law in the low-temperatur e region was observed. In the case of BaBi0.85Mo0.15O3 and BaBi0.5La0. 5O3 the behaviour could not be explained by the simple idea of saturat ion in a field. For BaBi0.5In0.5O3 a phase-transition-like behaviour a t around 10 K was observed. It is pointed out that there is some corre lation between the number of Bohr magnetons and the number of electric current carriers.