Far infrared study of local impurity modes of Gd doped PbTe

Single crystal samples of lead telluride doped with Gd were grown using the Bridgman method. Far infrared reflectivity spectra in the temperature range from 10 K to 300 K were measured. The experimental diagrams were numerically analyzed using a fitting procedure based on the plasma–phonon interaction model and the optical parameters were determined, while two local modes of gadolinium were observed at about 155 cm−1 and 230 cm−1 at room temperature. The origin of these local vibrational impurity modes was discussed.