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Abstract:
We synthesized a high-quality sample of the boride Eu4Pd29+xB8 (x =
0.76) and studied its structural and physical properties. Its tetragonal
structure was solved by direct methods and confirmed to belong to the
Eu4Pd29B8 type. All studied physical properties indicate a valence
fluctuating Eu state, with a valence decreasing continuously from about
2.9 at 5 K to 2.7 at 300 K. Maxima in the T dependence of the
susceptibility and thermopower at around 135 K and 120 K, respectively,
indicate a valence fluctuation energy scale on the order of 300 K.
Analysis of the magnetic susceptibility evidences some inconsistencies
when using the ionic interconfigurational fluctuation (ICF) model, thus
suggesting a stronger relevance of hybridization between 4f and valence
electrons compared to standard valence-fluctuating Eu systems.