Specific heat anomaly due to valence transition in Eu(Pd1-xPtx)(2)Si-2

Specific heat was measured for Eu(Pd1-xPtx)(2)Si-2 with 0 less than or equa l to x less than or equal to 0.10, in which the Eu valence sharply varies w ith temperature. A large specific heat peak due to the valence change was o bserved in each compound. Using the specific heat of LaPd2Si2 as a normal p art, we estimated the entropy associated with valence transition. It was fo und that the entropy increases abruptly around the valence transition tempe rature and reaches a saturation value of 22-23 J/K mol at room temperature. The temperature dependence of the entropy associated with the valence tran sition was calculated in terms of the interconfigurational fluctuation (ICF ) model. We will demonstrate that the experimental results are well describ ed by the ICF model. (C) 2001 Elsevier Science Ltd. All rights reserved.