Infrared Absorption of Phase Separated La_0.67-xPr_xCa_0.33MnO₃

Infrared absorption spectra of La_0.67-xPr_xCa_0.33MnO₃ (x=0, 0.18 and 0.36) are experimentally studied in the temperature range 20--300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn--O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.