Cation distribution in bismuth-doped M-type barium hexaferrite P. Winotai a , S. Thongmee a , I.M. Tang b,c, * a Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand b Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand c Institute of Science and Technology for Research and Development, Mahidol University, Nakorn Pathom 71730, Thailand (Communicated by C.N.R. Rao) (Received 5 January 2000; accepted 27 January 2000) Abstract Mo ¨ssbauer studies were conducted on Bi-doped barium ferrites BaFe 12–x Bi x O 19 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.6) with special attention paid to the behavior of the line widths in the Mo ¨ssbauer sextets. Assuming that the broadening of the line widths in the various sextets is due to increases in the fluctuations in the hyperfine field (acting on a Fe ion in given site) caused by the introduction of the Bi ions into the neighboring Fe sites, the observed broadening of the lines belonging to the 4f vi and 4e patterns indicated that the impurity ions were entering into the 4e and 4f vi sites. The initial decrease in M s would arise if the Bi ions first substituted in the 4f vi and then into the 4e sites as more Bi is added. © 2000 Elsevier Science Ltd. All rights reserved. Keywords: A. Ceramics; A. Magnetic materials; C. Mo ¨ssbauer spectroscopy 1. Introduction M-type barium hexaferrites (BaF) have been around for a long time. Interests in them have continued because new applications have been found for them. Their fabrication often requires the use of high sintering temperatures. Heating at too high of a temperature can, however, lead to destruction of the crystalline structure, while heating at too low of a * Corresponding author. E-mail address: scimt@mahidol.ac.th (I.M. Tang). Pergamon Materials Research Bulletin 35 (2000) 1747–1753 0025-5408/00/$ – see front matter © 2000 Elsevier Science Ltd. All rights reserved. PII: S0025-5408(00)00382-2