Data are presented showing that the addition of B to ${\mathrm{URh}}_3$, which is well known to be a compound having itinerant f electrons, results in a localization of those f electrons and a narrowing of the 5f band. Band-structure calculations carried out for ${\mathrm{URh}}_3$ and ${\mathrm{URh}}_3$B show that the band narrowing occurs due to a dehybridization between U f electrons and Rh d electrons as boron is added to the system. The nature of the band narrowing relative to this dehybridization is clarified. Comparison of heat-capacity data with the band-structure results shows that the band narrowing causes an increase both in the f-electron density of states at the Fermi energy and in the f-electron mass enhancement. However, the latter is still smaller than that seen in classic mixed-valence systems, such as ${\mathrm{CeSn}}_3$, or in heavy-fermion systems, such as ${\mathrm{UPt}}_3$.

• Received 12 December 1988

DOI:https://doi.org/10.1103/PhysRevB.39.5640