1. a Czechoslovak Academy of Sciences, Institute of Physical Metallurgy , Zizkova 22, ČS-61662 Brno, ČSFR
2. b Laboratory of Nuclear Chemistry, Eőtvős University , P.O. Box 32, H-1518, Budapest, Hungary
3. c Central Institute of Solid State Physics and Materials Science , Helmholtzstraße 20, O-8027 Dresden, F.R. of Germany