Metallic conductivity and a Ca substitution study of NaRh2O4 comprising a double chain system

摘要

The metallic compound NaRh2O4 forms a full range solid solution to theinsulating phase CaRh2O4. At a Na concentration of 0.25 moles per formula unit,we found an unexpected contribution to the specific heat at low temperature [K.Yamaura et al. Chem. Mater. 17 (2005) 359]. To address this issue, specificheat and ac and dc magnetic susceptibilities were additionally measured under avariety of conditions for the Na0.25 sample. A new set of data clearly indicatethe additional specific heat is magnetic in origin; however, the magneticentropy is fairly small (~1 % of Schottky term for a simple splitting doublet),and there is no other evidence to suggest that a magnetic phase transition isresponsible for the anomalous specific heat.