Mixed-valent, heavy-fermion, and Kondo behavior in (Ce, Th)Pd3 and related Ce systems

Lattice constant, x-ray absorption, dc resistivity, specific heat, and magnetic susceptibility of the (Ce,Th)Pd3 system were measured. CePd3 is a strongly mixed valent material. The results of this thesis show that the valence of Ce is driven towards 3+ by Th substitution. Heavy-fermion behavior was observed in samples near the trivalent state. A striking similarity was observed between the non-lattice system (Ce,Th)Pd3 and the lattice system Ce(Pd,Ag)3. Both systems have similar temperature dependence of thermodynamic properties, if one compares samples with the same Ce valence. The maximum magnetic resistivity, the linear coefficient of specific heat and the magnetic susceptibility of both systems qualitatively agree with theoretical predictions of existing models. The results of this study clearly indicate that one can produce a heavy-fermion material in both lattice and non-lattice systems by decreasing the valence of Ge, via alloying, to the trivalent state. The data strongly suggest that the heavy-fermion state is the n/sub f/ → or T/sub K/ → 0 limit of the mixed-valence phenomenon