Long-wavelength optical phonons of CdxZn1-xSb mixed crystals

Far-infrared reflectivity and Raman scattering have been studied in CdxZn1-xSb (x=0, 0.12, 0.92, 1) single crystals at 300 K. The composition dependence of 12 IR active phonons (out of 15 predicted by symmetry) and 16 Raman active phonons (out of 24) has been surveyed. This dependence corresponds generally to 'one-mode' behaviour, with the exclusion of extra high-frequency peaks at x=0.92 that may be ascribed to 'two-mode' type. For CdSb, some new phonon peaks are found. For ZnSb, the new data confirm the results obtained recently by the magnetophonon resonance method.