UPd3 under High Pressure - Lattice Properties.

The 5f electronic states in UPd 3 have a localized 5f 2 ground state. Our study examining the behavior of the UPd 3 crystal lattice under pressure up to 53 GPa does not reveal any volume anomaly, which could be associatedwith a delocalization of the 5f electronic states, in the entire pressure range. We thus find a disagreement with calculations based on the self-interaction corrected local spin-density approximation, which predict a transition around the pressure of 25 GPa. A bulk modulus of B 0 = 175(4) GPa with B' 0 = 5.0(4) was determined.