LOW-TEMPERATURE SPECIFIC-HEATS OF CERIUM AND PRASEODYMIUM TRIHYDRIDES - 2ND-ORDER PHASE-TRANSITIONS AND CRYSTAL-FIELD SPLITTING EFFECTS

The low temperature specific heats of cerium and praseodymium trihydrides, CeH2,70 and PrH2,65 are measured in the temperature range from 2 to 260 K. Two λ‐type specific heat anomalies are found for both hydrides at 235 and 253 K, respectively. These anomalies are most probable due to temperature‐dependent metal‐to‐semiconductor transitions. Additional, a λ‐type specific heat anomaly due to a magnetic transition is found for CeH2,70 at (2.70 ± 0.05) K. Schottky specific heat analysis is consistent with the existence of a singlet crystal field ground state for Pr3+ ion and this fact explains the absence of magnetic ordering in praseodymium trihydride. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA