EPR observations of anomalous triplet states in Ba1-xKxBiO3 and BaPbyBi1-yO3

Electron paramagnetic resonance (EPR) spectra of samples of the systems Ba1 -xKxBiO3 and BaPbyBi1-yO3 are investigated over wide ranges of composition and temperature. Two main lines in the EPR spectrum with factors g(1) appro ximate to 2.1 and g(2) approximate to 4.2 are found for all compositions. I t is shown that the observed EPR line with g(2) approximate to 4.2 is due t o oxygen ions. This probably indicates the presence of oxygen ions with dif ferent effective charges, i.e., the existence of charge density waves in th e oxygen-ion sublattice in addition to charge density waves in the bismuth sublattice. (C) 1999 American Institute of Physics. [S1063-7761(99)01204-4] .