Structural and Magnetic Properties of the $PrNi_{1-x}Cu_{x}Al$ Series

Polycrystalline samples of $PrNi_{1-x}Cu_{x}Al$ series were studied by X-ray diffraction, magnetization and specific heat. The hexagonal ZrNiAl-type structure is preserved in the whole series. Compounds with x up to 0.4 order antiferromagnetically with the Néel temperatures between 3 and 5 K. The rest of the compounds (x = 0.5-0.9) exhibits a transition into a spin glass state below the freezing temperatures around 4 K. The analysis of the specific heat data reveals a quasi-doublet ground state well separated from higher crystal field levels in the whole series.