An electron paramagnetic resonance study was made of the mechanism of defect production by electron irradiation in barium hollandite. Three paramagnetic defects were observed, regardless of the irradiation conditions. A hole center (H center) was attributed to a superoxide ion, O2-, which originated from hole-trapping by interstitial O produced by electron irradiation. An electron center (E1 center) was attributed to a Ti3+ ion adjacent to the resultant O vacancy. Another electron center (E2 center) was attributed to a Ti3+ ion in a cation site adjacent to an extra Ba2+ ion in a neighboring tunnel; originating from Ba displacement by elastic collisions. A comparison was made of the effects of external irradiation by electrons and that resulting from the β-decay of Cs. It was concluded that the latter would be dominated by E1 and H centers, rather than E2 centers.

Paramagnetic Defects Induced by Electron Irradiation in Barium Hollandite Ceramics for Caesium Storage. V.Aubin-Chevaldonnet, D.Gourier, D.Caurant, S.Esnouf, T.Charpentier, J.M.Costantini: Journal of Physics - Condensed Matter, 2006, 18, 4007-27