Infrared studies of Bi2Sr2Ca1-xYxCu2O8+δ and correlation between Cu-O distance derived from X-ray and IR

Abstract Absorption spectra of well-characterized Bi 2 Sr 2 Ca 1- x Y x Cu 2 O 8+δ ceramic samples have been studied in the middle and far infrared region. Assignment of different vibrational frequencies have been revisited in the framework of Y substitution in the Ca site which creates screening and a shift of different vibrations apart from the metal-to-insulator transition. The estimated values of the Cu-O distance (and thus the a parameter of the unit cell) from the Cu-O stretching vibration frequency and from X-ray diffraction data have been compared.