GROWTH OF SINGLE-CRYSTALS IN THE SYSTEMS WITH R-RH-B AND R-RH-B-C (R = RARE-EARTH ELEMENT) FROM MOLTEN COPPER FLUX

A slow cooling method using molten copper as a flux mas applied for cr ystal growth in the systems R-Rh-B and R-Rh-B-C (R = rare earth elemen t). Ternary borides: Single crystals of RRh3B2 (R = Gd, Dy, Er, Tm, Yb , and Lu), RRh4B4 (R = Sm, Dg, Er, and Tm), and RRh3B (R = Sm, Gd, Er, and Tm) were successfully obtained. Crystals of ErRh3B2 are hexagonal rectangulars belonging to the monoclinic system a = 0.5355(1) nm, b = 0.9282(1) nm, c = 0.3102(1) nm, and beta = 90.89(3)degrees. A super l attice appears along both, the a and the c axes with the periods of 3a and 6c, respectively. Single crystals of ErRh4B4 were obtained as rec tangulars with a primitive tetragonal structure: a = 0.5292(4) nm and c = 0.7379(3) nm. Single crystals of ErRh3B were extracted as cubes. E rRh3B is cubic with a = 0.41466(1) nm. PrRh4.8B2 crystallized as hexag onal plates. This new compound is orthorhombic: a = 0.9697(4) nm, b = 0.5577(2) nm, and c = 2.564(3) nm. Quaternary borocarbides: Single cry stals of the new tetragonal compounds of RRh2B2C have been obtained fo r R = Er and Gd as thin plates. Lattice parameters of e.g., ErRh2B2C, are a = 0.36848(2) nm and c = 1.05520(3)nm. (C) 1997 Academic Press.