A radiation defect in pyromorphite and vanadinite
Vassilikou-Dova, Aglaia B.; Lehmann, Gerhard
published: Mar 8, 1990
manuscript accepted: Oct 2, 1989
manuscript received: Dec 27, 1988
ArtNo. ESP147050201010, Price: 29.00 €
Abstract In a green pyromorphite from Pr̂ibram (Bohemia, Czechoslovakia) and red vanadinites from Globe (Arizona, U.S.A.) and Mibladen (Morocco), electron centres with fairly large deviations of g factors from the free electron value, as well as a septet hyperfine structure, were observed and analyzed by EPR. The latter can only arise from two at least approximately equivalent Cl nuclei, thus showing that the centres are localized on Pbπ sites of monoclinic site symmetry. They have an axial symmetry in pyromorphite and a triclinic one in vanadinite. The higher symmetry in pyromorphite may arise from a dynamic Jahn-Teller effect, whereas the lower one in vanadinite most likely is caused by substitution of an adjacent PbI by trivalent impurities. These centres are tentatively assigned to Pb+, although no hyperfine satellites due to 207Pb could be detected.