Structure and stability of Ba-Cu-Ge type-I clathrates Academic Article uri icon


  • We have prepared samples of nominal type Ba8CuxGe46-x by induction melting and solid state reaction. Analysis shows that these materials form type-I clathrates, with a copper content between x = 4.9 and 5.3, nearly independent of the starting composition. We used x-ray powder diffraction and single-crystal electron diffraction to confirm the cubic type-I clathrate structure, while electron microprobe measurements confirmed the stability of the x 5 composition. This result differs from the corresponding Ag and Au clathrates and was not known previously due perhaps to the similar Cu and Ge form factors in x-ray diffraction. The observed composition adheres very tightly to a valence-counting scheme, in agreement with a Zintl-type stability mechanism. This implies a gap in the electronic density of states, also in contrast to the metallic behaviour of the Au and Ag analogues. Magnetization measurements showed a large diamagnetic response in the Ba-Cu-Ge clathrate. This behaviour is consistent with semiconducting or semimetallic behaviour and is similar to that of a number of intermetallic semiconductors.

published proceedings


author list (cited authors)

  • Li, Y., Chi, J., Gou, W. P., Khandekar, S., & Ross, J. H.

citation count

  • 31

complete list of authors

  • Li, Y||Chi, J||Gou, WP||Khandekar, S||Ross, JH

publication date

  • August 2003