Crystal structure of Ho6Pb2Se11 and magnetic properties of R6Pb2Se11 (RÂ =Â Y, Dy and Ho)

Single phase samples of the R6Pb2Se11 (R = Y, Dy and Ho) compounds were obtained using high temperature synthesis. Crystal structure of Ho6Pb2Se11 (Y6Pb2Se11 type, space group Cmcm, Pearson symbol oC76, lattice parameters: a = 0.40603(7) nm, b = 1.3397(3) nm, c = 3.7542(5) nm) was reinvestigated by means of X-ray single crystal diffraction and refined down to R1 = 0.0572. Magnetic properties of the R6Pb2Se11 compounds were studied in wide ranges of temperature and magnetic field. Dy6Pb2Se11 and Ho6Pb2Se11 were found to order antiferromagnetically at TN = 2.2 and 2.4 K, respectively, whereas weak diamagnetism was established for Y6Pb2Se11.