A search for internal distortion in CeBi

At the IA magnetic transition (12.5 K) in CeBi a theoretical study has suggested that either the Ce or Bi sublattices should move with respect to the other. Such a distortion would give rise to extra reflections of the form 0_'0_'l+½. A search for such a reflection using a Bond X-ray diffraction technique was conducted. The 007½ line was not found and an upper limit of ~2 × 10^-4 was set for the magnitude of the expected internal distortion. This limit is valid for a surface layer whose thickness equals the penetration depth of the X-radiation which is about 0.4 × 10^-2 mm.