Boron-induced valence change of cerium in CePd3

Abstract

It is found that boron can be added to Ce${\mathrm{Pd}}_{3}$ to form compounds having the formula $\mathrm{Ce}{\mathrm{Pd}}_{3}{\mathrm{B}}_{x}$ where $x$ typically lies between 0 and 1. Addition of boron causes an expansion in cell volume without a change in the structure. The increase in cell volume as a function of boron concentration is much larger in $\mathrm{Ce}{\mathrm{Pd}}_{3}{\mathrm{B}}_{x}$ compounds compared with that in $\mathrm{La}{\mathrm{Pd}}_{3}{\mathrm{B}}_{x}$ or $\mathrm{Gd}{\mathrm{Pd}}_{3}{\mathrm{B}}_{x}$ compounds. While Ce${\mathrm{Pd}}_{3}$ is a well-known mixed-valent system, susceptibility and lattice-parameter measurements show that the addition of boron to Ce${\mathrm{Pd}}_{3}$ causes a change in the valence state of cerium from a mixed-valent to an almost trivalent state. The change is striking in going from Ce${\mathrm{Pd}}_{3}$ to Ce${\mathrm{Pd}}_{3}$${\mathrm{B}}_{0.12}$.