X-Ray single-crystal investigation of rare earth osmium silicides

The crystal structure of the Nd2Os3Si5 compound was refined from single-crystal X-ray diffraction (P4/mnc space group, a=10.762(5) A, c=5.796(2) A) down to R=0.0662 for 393 reflections with F0>4σ(F0). This compound belongs to a partly disordered U2Mn3Si5 type structure: the Si2 site has been refined with a split position x,y,z (16i) instead of x,x+1/2,1/4 (8g), and for an occupancy of 50%. X-Ray single-crystal investigations of the PrOs2Si2 and Ce(Ru0.6Os0.4)2Si2 compounds were also performed for the first time. Both compounds crystallize in the CeGa2Al2 structure type, I4/mmm space group, with a=4.1678(4) A, c=9.901(1) A, R=0.0433 and a=4.173(1) A, c=9.797(3) A, R=0.0393, respectively