Structure and magnetic properties of RE2Cu 2Cd

Abstract

The ternary intermetallic compounds RE 2Cu 2Cd ( 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 Gd 2Cu 2Cd was refined from single crystal X-ray diffractometer data: Mo 2FeB 2 type, space group P4/ mbm, a=756.2(3), c=380.2(3) pm, w R2=0.0455, 321 F 2 values, 12 variables. The structures are 1:1 intergrowth variants of slightly distorted CsCl and AlB 2 related slabs of compositions RECd and RECu 2. The copper and cadmium atoms build up two-dimensional [Cu 2Cd] networks (257 pm Cu–Cu and 301 pm Cu–Cd in Gd 2Cu 2Cd) which are bonded to the rare earth atoms via short RE–Cu contacts (290 pm in Gd 2Cu 2Cd). Temperature dependent susceptibility measurements of RE 2Cu 2Cd with RE=Gd, Tb, Dy, and Tm show experimental magnetic moments which are close to the free RE 3+ 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. Dy 2Cu 2Cd shows a spin reorientation at T N=16.9(1) K.