Magnetic Characteristics of Compounds of Cerium and Praseodymium with Va Elements

Abstract

The magnetic behavior of CeP, CeAs, CeSb, PrP, PrAs, and PrSb has been investigated over the temperature range extending from 4° to 300°K. Curie—Weiss behavior is observed for all compounds in the upper portion of the temperature range studied with effective moments in fair agreement with those expected for the free tripositive ions. The cerium compounds have Néel points at temperatures ranging from 8° to 25°K. The praseodymium compounds give no evidence of magnetic ordering. At low temperatures they exhibit the Van Vleck temperature‐independent paramagnetism. This is attributed to the influence of the crystal field in splitting the ninefold degenerate ground state of the free Pr³⁺ ion. The susceptibility—temperature behavior of PrSb can be accounted for in terms of a single parameter from which an over‐all crystal field splitting of 157 cm⁻¹ is deduced. Similar attempts for PrP and PrAs were unsuccessful, presumably because of the increased importance of nonlinear shielding effects in these materials. The results for CeP and CeAs indicate partial quadrivalency of Ce in these compounds. Results for CeSb are very complex; indications are that this compound orders in several stages.