Profile analysis of neutron diffuse scattering from faulted magnetic crystals in heavy-light rare earth alloys

The intensity equation for x-ray diffraction from a one dimensionally disordered crystal developed by Kakinoki and Komura has been extensively adapted for studies of elastic magnetic diffuse scattering of neutrons from faulted crystals between the Sm-type and the hcp structures in Tb-light rare earth alloys. A simple extension of the arrangements of the magnetic moments in the Sm-type o up up (chh)-o down down (chh) and the hcp up up up (hhh)- up up up (hhh) structures to the faulted structures, o up up (chh)-up up up (hhh) and up up up (hhh)-o down down (chh) with the stacking fault parameters α and β, respectively are proposed, where h and c denote hexagonal and cubic close packed layers, respectively. The experimental magnetic diffuse scattering profiles of neutrons from the various stages of faulted crystals of Tbsub(0.798)-Prsub(0.202) and Tbsub(0.803)-Prsub(0.197) between the Sm-type and the hcp structures have been well reproduced by the profile analysis method. The refined stacking fault parameters are α = 0.14 (1), β = 0.27 (3) and α = 0.36 (1), β = 0.78 (1) for the Tbsub(0.798)-Prsub(0.202) and the martensitically transformed Tbsub(0.803)-Prsub(0.197) crystals, respectively. (author)