CRYSTAL-STRUCTURE OF U2GA5-XCU12

Single crystals of new pseudo-ternary compounds with compositions rang ing from U2Ga9Cu8 to U2Ga5Cu12 were prepared. The crystal structure of U2Ga5-xCu12 was determined by the single crystal X-ray diffraction me thod. In the refinement performed for 765 independent reflections and 23 variable parameters, the residual value R = 4.96% has been reached for the crystal structure of rhombohedral Th2Zn17-type. Position 6(c) can prove to be occupied with the occupancy factor of 0.67, while for the other positions ordered substitutions are supposed to occur.