Noninteger Ce valency in Ce2Ni22C2.75

It has been claimed earlier (J Alloys Comp. 186, 223 (1992)) that Ce2Ni22C2 .75 is ferromagnetic at room temperature. In this paper it is shown, with m agnetic susceptibility and electrical resistivity measurements, that no fer romagnetic order exists in our Ce2Ni22C2.75 sample down to 1.7 K. Moreover, the temperature dependencies of both magnetic susceptibility and electrica l resistivity agree well with the existing theoretical models for intermedi ate valence fluctuating compounds. This agreement together with X-ray absor ption spectroscopy data obtained at two fixed temperatures, 10 and 300 K, c learly give evidence for a nonintegral valence state of Ce in Ce2Ni22C2.75. (C) 2001 Academic Press.