Crystal structure and magnetic properties of the DyCuxGa4−x−δ compounds with BaAl4-type derivatives

• A series of Dy-Cu-Ga alloys containing 20–22 at. % Dy was studied.
• Four individual DyCuxGa4–x–δ compounds were identified.
• Electronic structure of the compounds was characterised by XPS analysis.
• Effective magnetic moments of Dy ions were determined.
• Values of magnetic moments are related to the crystal and electronic structures.

The DyCuxGa4−x−δ alloys (x = 1.2–0.05) have been studied by the X-ray single-crystal and powder diffraction methods as well as by the magnetometric and XPS techniques. Four individual closely related compounds identified here were shown to be the derivatives of BaAl4-type structure (tetragonal or orthorhombically distorted) with the increased multiplicity of their a and b sublattice constants, namely, I-DyCu1.25−1.12Ga2.67−2.80 (1 × 1), II-DyCu1.07Ga2.74 (3 × 3), III-DyCu0.92−0.76Ga2.84−3.00 (3 × 3) and IV-DyCu0.63−0.06Ga3.00−3.57 (9 × 9). All alloys studied are paramagnets at (300–650) K temperature range. The effective paramagnetic moment per Dy atom was found to exceed the value for the Dy3+ ion (10.65 μB). Besides, it increases up to 11.2 μB with Ga content increasing. Magnetic properties of these alloys are discussed based upon crystal and electronic structure changes.

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