Magnetic and Crystallographic Characteristics of Praseodymium Hydrides

The susceptibilities (χ) and lattice parameters are reported for a series of praseodymium hydrides represented by the formula PrH_x in which x varies from 0.99 to 2.57. _χ was measured from 4° to 300° and at field strengths up to 21 kOe. The samples are two‐phase for $\text{x\hspace{0.17em}≤\hspace{0.17em}1.85.}$ Curie–Weiss behavior is observed for all samples above 100°K with slopes in fairly good agreement with that expected for an assemblage of free tripositive ions. Deviations occur below 100°K. These are two kinds—negative for $\text{x\hspace{0.17em}<\hspace{0.17em}2.1,}$ and positive for $\text{x\hspace{0.17em}>\hspace{0.17em}2.1.}$ The deviations in the first case are small and appear to result from the crystal‐field interaction. The positive deviations are ascribed to a change of valence for Pr from 3 + to 4 +. Magnetic, electrical, and crystallographic evidence is in accord with this postulate. There is no indication of magnetic ordering in the hydrides at 4.2°K.