Influence of Disordering upon Concentrated Kondo Effect for Pd7Ce Alloys

The changes in electrical resistivity and valence of Ce for Pd7Ce alloy were measured as a function of quenching temperature in order to clarify the effect of order-disorder on the physical properties related with 4f electrons. The absolute value of resistivity increases with quenching temperatures, and the temperature coefficient is different between the specimens quenched from higher and lower temperatures than Tc. The anomalies in resistivity can be explained in terms of an effect of 4f electrons in Ce, or “concentrated Kondo effect”. The valence of Ce was measures by L3-XANES using synchrotron radiation. The Ce valence changes insignificantly with quenching temperature. The results for resistivity and Ce valence suggest that the spacial distribution of the valence is wide in the alloy with a low degree of order， and the wide distribution causes the remarkable increase in resistivity and the small change in the averaged valence of Ce