Abstract
The RECU2Si2(RE=Rare Earth) series shows pronounced anomalies of the lattice parameters. In those stable valent compounds with 4f orbital angular momentumL≠0 thec/a ratio shows an anomalous temperature dependence due to crystal field effects. The compounds with unstable valence (RE=Ce, Eu, Yb) show less or no such effects but on the other hand show anomalies of the volume which are temperature dependent. Using these volume anomalies of the unstable valent systems and the measured bulk moduli of the reference compounds we have extracted the valence as function of temperature.
Between 4K and 300K the valences of CeCu2Si2 and YbCu2Si2 change by only a few percent towards 3, while it changes for EuCu2Si2 by ca. 20% towards 2. A critical discussion of these valences will be given.
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Neumann, G., Langen, J., Zahel, H. et al. Temperature and pressure dependence of lattice parameters of the XCu2Si2 compounds (X=Ce, Eu, Yb, La, Gd, Lu, Ca, Th). Z. Physik B - Condensed Matter 59, 133–141 (1985). https://doi.org/10.1007/BF01725529
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DOI: https://doi.org/10.1007/BF01725529