Effect of Si addition on the valence state of Ce in CePd₃

Abstract

It is observed that Si can be added to CePd₃, which has the AuCu₃ type cubic structure, to form alloys of the type CePd₃Si_x where 0 ≤ x ≤ 0.3. Addition of Si preserves the structure but results in an expansion of the cell volume. The expansion is much larger in CePd₃ than in LaPd₃ for the same silicon concentration. In CePd₃, cerium is in a mixed-valent state and its susceptibility tends to a temperature independent value at low temperature. However, as Si is added to CePd₃, the susceptibility progressively increases and shows a Curie-Weiss behavior with effective moment close to that of Ce³⁺ ions. Thus from lattice parameters and susceptibility measurements, it is inferred that Si addition causes a change in the valence of Ce in CePd₃ from mixed valent to nearly trivalent.