Magnetic and electrical properties of (PrxLa1-x)Ru4P12

In order to study the metal-insulator (MI) transition (T-MI similar to 60 K ) and the inter-site effects in PrRu4P12, we have performed the measurement s of the magnetic susceptibility, magnetization and electrical resistivity for the dilute system (PrxLa1-xRu4P12 prepared at high temperatures and hig h pressures. It is found that the semiconductor-like behavior is suppressed and T-MI shifts to lower temperature with increasing La concentration. The MI transition disappears For x < 0.8. The experiments for La-rich compound (x = 0.10) are well explained by the isolate Pr3+ (4f(2)) ion with a Gamma (1) (singlet) or a Gamma(3) (non-Kramers doublet) as the crystalline-electr ical-field ground state. On the Ether hand, the inter-site interactions bet ween the Pr3+ ions seem to be a considerable effect in Pr-rich compounds, T his effect could be related to the MI transition. (C) 2000 Elsevier Science B.V. All rights reserved.