Specific heat of mixed-valence intermetallic system Yb1-xCexInCu4

The YbInCu4 exhibits a first-order phase transition associated with a transformation of the valence state of the Yb ion. The effect of alloying on the valence transition in Yb1-xCexInCu4 ( 0 <= x <= 0.2) has been investigated by specific heat C measurements in the range 5-300 K. The C vs. T dependence in YbInCu4 reveals sharp peak at TV 39 K. This peak shifts to higher temperatures with x and its shape gradually transforms to that of continuous phase transition. The specific heat measurements have also been made for nonmagnetic isomorphous compound YInCu. The comparison of YInCu4 data with those of Yb1-xCexInCu4 allows an estimate of the value of entropy Delta S released at the phase transition. The Sommerfeld coefficient values in the Yb1-xCexInCu4 family of compounds were found increasing with Ce concentration. (c) 2007 Elsevier B. V. All rights reserved.