STRUCTURAL-PROPERTIES OF THE THMN12-TYPE NONSTOICHIOMETRIC SOLID-SOLUTIONS IN THE FE-CD-MO SYSTEM

Several compositions of the Fe-Gd-Mo system for which the ThMn12-type structure (space group I4/mmm) was formed have been investigated by X- ray diffraction followed by Rietveld refinement. In addition to previo us studies, we have found that the ThMn12-type phase can be represente d in the ternary system as a two-dimensional field with the general fo rmula Gd1+nFe12-x-vMox square(v) (where square denotes a vacancy), rat her than as a line. As it follows from the Rietveld refinement, that t he Mo atoms occupy only the 8(i)-sites, whereas the vacancies are dist ributed over the 8(f) and 8(j) positions. The Gd atoms were found on t he 2(a)- and 8(i)-sites. The interatomic distances and atomic coordina tes were found to vary with composition. (C) 1998 Elsevier Science S.A .