Specific heat of the Kagome mixed compounds (Co1-xNix)3V2O8

We present high-resolution specific heat data from 2 to 3 0 K of the mixed Kagome compounds (Co1-xNix)(3)V2O8 for x = 0, 0.12, 0.2, 0.5 and 1.0. We show that the specific heat at the first-order transitions of the end compounds (x = 0 and 1), obtained using relaxation calorimetry, is up to a factor of 10 larger than that previously reported in the literature. The mixed compounds exhibit only the highest temperature transition to an presumably, incommensurate magnetic structure. A slope change of T-N versus x at x = 0.2 indicates the transition from the Ni3V2O8- to Co3V2O8-type magnetic structures. (C) 2007 Elsevier B.V. All rights reserved.