NEW TBFESI2-TYPE AND U3NI4SI4-TYPE STRUCTURE COMPOUNDS OBTAINED IN R-T-T'-X SYSTEMS (R = RARE-EARTH ELEMENTS T = MN, CO, RU, RH T' = NI, CU, PD, PT X = SI, GE)

Investigations in R-T-T'-X systems (R=rare earths; T=Mn-Co; T'=Ni, Cu, Pd, Pt; X=Si, Ge) lead to the stabilization of new pseudo-ternary RT( T'X-0.5(1.5)) and R3T2T'X-2(4) compounds with TbFeSi2- and U3Ni4Si4-ty pe structures, respectively. These structures are characterized by a s tacking of RT2X2 (BaAl4-type) and RT'X (AlB2-type) layers. Therefore, the new alloys may be considered as members of a structural series of compounds with general formula Rn+1T2T'X-n(2+n) (n=1, 2). The stabiliz ation of these compounds through strong T'X interlayer bonds is discus sed. Correlations with the ThCr2Si2-CaBe2Ge2 dimorphism are underlined . (C) 1998 Elsevier Science S.A.