Study of the valence state of U ions in quasi-two-dimensional ternary uranium compounds.

The valence states and thermoelectric properties of two Ru-based uranium ternaries, namely U2Ru2Sn and U2RuGag, have been studied. Intermediate-valence behaviour manifests itself in broad peaks in the susceptibility, largely negative values of the paramagnetic Curie temperature, and in the occurrence of maxima in the thermoelectric power. At the same time, specific heat data show no transition at low temperatures for both studied compounds. Experimental results are fitted to equations given in the literature relevant to valence fluctuating states. The studied compounds are unique examples of such a state, found for the first time among the huge family of uranium compounds known to be magnetically ordered at low temperatures. [ABSTRACT FROM AUTHOR]