Crystallographic and physical properties of RE2-xNi21B6 (RE = Er, Yb and Lu)

Crystallographic and physical properties of cubic Er2-xNi21B6, Yb2-xNi21B6 and Lu2-xNi21B6 have been studied. Their crystal structures have been established from single-crystal and powder X-ray diffraction data (space group Fm (3) over barm, Cr23C6 type of structure): Er2-xNi21B6, a = 10.6520(2) angstrom, R-F = 0.041, R-W = 0.044 (for x=0.18); Yb2-xNi21B6, a=10.6412(2)angstrom, R-F=0.021, R-W=0.022 (for x=0.14); a=10.6243(2)angstrom, R-F = 0.023, R-W = 0.025 (for x = 0.30); Lu2-xNi21B6, a = 10.6269(2)angstrom, R-F = 0.023, R-W = 0.023 (for x = 0.35). Small homogeneity ranges extend from x = 0.1-0.9 for Er2-xNi21B6 and from x = 0.1-0.3 for Yb2-xNi21B6. No homogeneity range was found for Lu2-xN21B6 (x=0.35). Magnetization measurements for Yb-2 -xNi(21)B(6) and Er2-xNi21B6 reveal the 4 integral(13)(Yb3+) and 4 integral(11)(Er3+) electronic state and no magnetic ordering above 1.8 K. RE2-xNi21B6 compounds show metallic behavior in electrical conductivity. (c) 2008 Elsevier Masson SAS. All rights reserved.