Structure and magnetic properties of RE2Cu2Cd

摘要

The ternary intermetallic compounds RE2Cu2Cd (RE = Y, Sm, Gd-Tm, Lu) were synthesized by induction-melting of the elements in sealed tantalum tubes. The samples were characterized by X-ray powder diffraction. The structure of Gd2Cu2Cd was refined from single crystal X-ray diffractometer data: Mo2FeB2 type, space group P4/mbm, a = 756.2(3), c = 380.2(3) pm, wR2 = 0.0455, 321 F-2 values, 12 variables. The structures are 1:1 intergrowth variants of slightly distorted CsCl and AlB2 related slabs of compositions RECd and RECu2. The copper and cadmium atoms build up two-dimensional [Cu2Cd] networks (257 pm Cu-Cu and 301 pm Cu-Cd in Gd2Cu2Cd) which are bonded to the rare earth atoms via short RE-Cu contacts (290 pm in Gd2Cu2Cd). Temperature dependent susceptibility measurements of RE2Cu2Cd with RE = Gd, Tb, Dy, and Tm show experimental magnetic moments which are close to the free RE3+ ion values. The four compounds show ferromagnetic ordering at T-C = 116.7(2), 86.2(3). 48.4(1), and 14.5(1) K, respectively, as confirmed by heat capacity measurements. Dy2Cu2Cd shows a spin reorientation at T-N = 16.9(1) K. (C) 2008 Elsevier Inc. All rights reserved.