POSSIBLE STRUCTURAL PHASE TRANSITION OF SINGLE PHASE (Bi, Pb)2Sr2Ca2Cu3O10+y SUPERCONDUCTING CERAMIC: AN INFRARED STUDY

The infrared spectra of single phase (Bi, Pb)2Sr2Ca2Cu3O10+y polycrystalline samp were studied over a temperature range of 300–120 K. Three vibrational modes were found at ambient temperature. A new band appears at 900 cm−1 near 200 K and experi evidence proved that the appearance of the new band is actually through an isothermal-like process, indicating a structural phase transition taking place. Unstable fluctuations were also observed between 200 and 140 K. This phenomenon is consistent with our previously reported ultrasonic, specific heat and lattice constants anomalies of the same sample. A possible mechanism of this phase transition is also discussed.