Raman scattering study of the lattice dynamics of β-Zn4−xCdxSb3
Résumé
Micro-Raman scattering experiments have been performed on the ternary solid solution in the Zn4Sb3–Cd4Sb3 system. Ten samples were studied; their compositions go from Zn4Sb3 to Zn3.1Cd0.9Sb3. The homogeneity of these samples was checked by X-ray diffraction and electron microprobe analysis. The corresponding lattice parameters were calculated and their concentration dependence exhibits a small negative deviation from Vegard's law between end members of the Zn4Sb3–Cd4Sb3 system. Three peaks and one shoulder are easily observable in the Raman spectrum of β-Zn4Sb3. These peaks are still present when the zinc atoms are substituted by cadmium ones. As the intensities of the Raman lines were observed to be very sensitive to the direction of the microcrystallites, only the change of the position could be discussed. From these experiments, we can suggest that the peak at about 155 cm−1 should imply essentially Sb–Sb bondings while the peaks at about 172 cm−1 and 320 cm−1 must also imply Cd–Sb and Zn–Sb bondings.