Concentrations of Residual Carbonate Ions in the Bi-Sr-Ca-Cu-O Glasses

It was found that the IR absorption bands appearing at 600 to 1600 cm^?1, which had been previously assigned to the fundamental vibrations of BiO₃] or BiO₆] polyhedra, are due to residual carbonate ions (CO^2?₃) dissolved in Bi-Sr-Ca-Cu-O glasses. The concentrations of the remaining CO^2?₃ in the Bi_2.2Sr₂Ca₁Cu₂O _x glasses that melted at 1100° and 1400°C are 170 × 10^?5 mol/cm³ (3.3 mol%) and 3.2 × 10^?5 mol/cm³ (0.25 mol%), respectively. The apparent activation energy for the dissociation of the carbonates was approximately 220 kJ/mol. The CO^2?₃ content in the precursor glasses did not significantly affect the superconducting properties of the resulting glass–ceramics.