Superconducting-Normal Phase Transition In (Ba1-Xkx)Bio3,X=0.40, 0.47

Specific-heat measurements on (Ba1-xKx)BiO3, x = 0.40 and 0.47, 0.7 less than or equal to T less than or equal to 35 K, 0 less than or equal to H less than or equal to 9 T, have determined the coefficient (gamma) of the normal-state conduction electron specific heat, and shown well-defined specific-heat anomalies at T-c that are consistent with the value of gamma and BCS expressions. These results contradict the suggestion in a recent Letter that gamma is several orders of magnitude greater than these experimental values and that the absence of a correspondingly large specific-heat anomaly constitutes evidence that the transition is an Ehrenfest fourth-order transition.