Dielectric loss anomaly of BaBiO₃

Dielectric properties of oxygen deficient BaBiO_3-δ have been analyzed, and dielectric loss anomalies at 175 and 225 K were found, which were dependent on oxygen deficiency. The activation energies corresponding to the relaxation processes of dielectric anomalies at 175 and 225 K were 0.26 and 0.50 eV, respectively. The dielectric anomaly at 175 K is believed to be caused by hole movement from an occupied Bi 6s band to hole polaron accommodating band state. Another anomaly at 225 K is believed to occur from the hopping of a hole between a Bi 6.s band and the Fermi level.