X-RAY SINGLE-CRYSTAL REFINEMENTS ON SOME CEFESI-TYPE RTX COMPOUNDS (R=RE ELEMENTS T=MN, FE, CO, RU X=SI, GE) - EVOLUTION OF THE CHEMICAL-BONDS

The crystallographic data of CeFeSi-type RTX compounds have been refin ed from single crystal X-ray data. The results show that the atomic co ordinates vary with the size of the rare earth element in order to kee p optimum values for the T-X and R-X distances on one hand, and with t he nature of the transition metal as a function of the relative T-R af finity on the other hand. These behaviours are compared with those obs erved in the closely related ThCr2Si2-type RT2X2 compounds. Attempts t o correlate these results with the magnetic behaviours observed in the RTX and RT2X2 series are made. (C) 1998 Elsevier Science S.A.