STRUCTURAL AND TRANSPORT-PROPERTIES OF SOME UTX COMPOUNDS WHERE T=FE,CO, NI AND X=SI, GE

The ternary intermetallic compounds with general formula UTX (T=Fe, Co , Ni; X= Si, Ge) were analyzed by X-ray methods and some of their phys ical properties examined. All the studied phases belong to the well kn own TiNiSi-type structure. The compound UFeGe shows a phase transition at 500 K; at room temperature it crystallizes in a new monoclinic str ucture with a=6.986, b=4.308, c=6.992 Angstrom, beta=93.71 degrees in the space group P2(1)/m; above 500 K it changes into the orthorhombic TiNiSi-type. Electrical resistivity measurements were carried out in t he range 1.5-300 K for all samples, and up to 600 K for UFeGe. Anomali es in the resistivity behaviour were detected for UNiSi, UFeGe, UCoGe and UNiGe at 19, 80, 46 and 41 K respectively and ascribed to magnetic transitions.