TRANSPORT-PROPERTIES OF (U1-XNPX)RU2SI2 ALLOYS

Synthesis and resistivity measurements on URu2Si2-NpRu2Si2 solid solut ions are reported. U1-xNpxRu2Si2 systems, with x = 0.01, 0.1, 0.3, 0.5 , 0.7 and 0.9, crystallize in the tetragonal ThCr2Si2-type structure. Resistivity measurements indicate a marked variation of the transport properties with regard to the Np substitution. For low Np dilution (le ss than or equal to 0.1) considerable changes are observed from the x= 0 Cr-like anomaly and a Kondo-like minimum appears below 10 K. In the systems for 0.3 less than or equal to x less than or equal to 0.7, an increase of T-N is clearly seen and the Cr-like anomaly destroyed in f avor of a strong increase of the resistivity suggesting a gap opening. At higher Np-concentration the resistivity is very similar to the pur e Np compounds but a large increase in the pure Np-compound 6 K anomal y is observed. (C) 1997 Elsevier Science S.A.