New ternary aluminides Ce0.67Pd2Al5, Ce1.33Pd3Al8, and Ce1.74Pd5.29Al11.71

Abstract

Polycrystalline samples of novel compounds Ce 0.67 Pd 2 Al 5 , Ce 1.33 Pd 3 Al 8 , and Ce 1.74 Pd 5.29 Al 11.71 were prepared by arc-melting. The crystal structure of the latter compound was determined from the single-crystal X-ray diffraction data to be a disordered variant of the hexagonal Th 2 Ni 17 type [ P 6 3 / mmc , a = 9.1961(5) Å, c = 8.8861(5) Å]. The crystal structures of the other aluminides were examined by powder X-ray diffraction and found to be isotypic with Sc 0.67 Fe 2 Si 5 [ P 6 3 / mmc , a = 4.3385(5) Å, c = 16.5255(15) Å] and Gd 1.33 Pt 3 Al 8 [ R 3 ¯ m , a = 4.37960(10) Å, c = 39.1683(9) Å], respectively. Based on the thermodynamic and electrical resistivity data measured down to 0.4 K in external magnetic fields up to 9 T, the new materials were characterized as metallic Curie-Weiss paramagnets due to fairly stable trivalent Ce ions. In Ce 1.33 Pd 3 Al 8 , an antiferromagnetic ordering was established below T N = 2.3 K, while no long-range magnetic order was found in the other compounds. All three phases exhibit electrical conductivity that is governed by the interplay of Kondo and crystalline electric field interactions, and significantly affected by structural disorder inherent to their crystal lattices. • Novel compounds Ce 0.67 Pd 2 Al 5 , Ce 1.33 Pd 3 Al 8 , and Ce 1.74 Pd 5.29 Al 11.71 were synthesized. • They form with Sc 0.67 Fe 2 Si 5 , Gd 1.33 Pt 3 Al 8 , and Th 2 Ni 17 structure types, respectively. • Electrical transport is strongly affected by structural disorder and Kondo effect.. • They are Curie-Weiss paramagnets; Ce 1.33 Pd 3 Al 8 orders antiferromagnetically at 2.3 K.