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Single crystals of the ternary rare earth copper arsenides LnCu1+δAs2 (Ln=Nd, Sm, Ho, and Yb) have been prepared by reaction of the elements in a LiCl/KCl flux at 850 °C during 7 days. HoCuAs2 and YbCuAs2 crystallize in the HfCuSi2 type, whereas NdCu1.06(1)As2 and SmCu1.05(1)As2 are stuffed variants of this structure type. All four compounds crystallize in space group P4/nmm (No. 129) with Z=2; the lattice parameters are a=3.979(1) A, c=10.016(2) A for NdCu1.06As2; a=3.994(1) A, c=9.994(2) A for SmCu1.05As2; a=3.868(1) A, c=9.804(1) A for HoCuAs2; and a=3.842(1) A, c=9.743(2) A for YbCuAs2. As further examples, the known structures of CeCu1.11(1)As2 (P4/nmm, a=4.028(1) A, c=10.059(2) A, stuffed variant of the HfCuSi2 type) and LaCu1.25(1)As2 (I4/mmm, a=4.096(1) A, c=20.224(4) A, Z=4, stuffed variant of the SrZnBi2 type) have been confirmed [J. Solid State Chem. 147 (1999) 140]. |
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