Pd/Cu site interchange and non-Fermi-liquid behavior in UCu4Pd

X-ray-absorption fine-structure measurements of the local structure in UCu4Pd are described which indicate a probable lattice-disorder origin for non-Fermi-liquid behavior in this material. Short Pd-Cu distances are observed, consistent with (24 +/- 3)% of the Pd atoms occupying nominally Cu sites. A "Kondo disorder" model, based on the effect on the local Kondo temperature T-K of this interchange and some additional bond-length disorder, agrees quantitatively with previous experimental susceptibility data, and therefore also with specific heat and magnetic resonance experiments. [S0031-9007(98)07530-9].