CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF COR(BO2)(5) (R-Y, GD) AND NIR(BO2)(5) (R-ND, GD)

Single crystals of the title berates were grown from mixtures of R(2)O(3), NiO or Co3O4 and a large excess of B2O3. Single-crystal X-ray diffraction showed them to be monoclinic, centrosymmetric space group P2(1)/n (No. 14), Z=4, with cell parameters (in angstroms) a=8.494(2) and 8.560(4), b=7.574(2) and 7.578(2), c=9.364(6) and 9.370(2), and beta=94.03(3)degrees and 93.35(3)degrees for Co berates and R=Y and Gd respectively; the parameters were a=8.617(2) and 8.514(6), b=7.565(3) and 7.554(3), c=9.472(2) and 9.4329(6), and beta=93.46(1)degrees and 93.81(2)degrees for Ni berates and R=Nd and Gd respectively. The crystals studied by X-ray diffraction were analyzed using energy-dispersive X-ray spectroscopy. Magnetic measurements were taken from 300 to 4 K for the four borates.