BI-209 NQR POWDER SPECTRA INFLUENCED BY LOCAL AND APPLIED MAGNETIC-FIELDS

Several experimental techniques have shown evidence for the existence of internal magnetic fields of the order of 200 G in alpha-Bi2O3[1]. T he asymmetrical Bi-209 NQR lineshapes in Bi3O4 Br also point to a sour ce of poorly resolved splitting present in this compound. In order to obtain further insight into the origin of the local magnetic fields in these compounds the Bi-209 NQR lineshapes of polycrystalline alpha-Bi 2O3 and Bi3O4Br were recorded in weak (below 500 G) static magnetic fi elds. A calculation of the expected powder lineshapes in alpha-Bi2O3 u nder the influence of the internal and applied magnetic fields up to 1 kG was made. The results of the computer simulation are compared with the lineshapes recorded. From the Bi-209 lineshapes observed in the e xperiment, the local magnetic field at one of the two Bi-sites in Bi3O 4Br was estimated.