Crystallization of Bi2Sr2Cu1O6 and Bi2Sr2Ca1Cu2O8 phases in Bi-Sr-Ca-Cu-O glass

Crystallization of Bi4Sr3Ca3Cu4Ox glass at 472 degreesC and 800 degreesC for the different duration, studied by X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, differential scanning calorimetry, termogravimetric analysis and Fourier transform infrared spectroscopy is reported. Crystallization at the temperature 472 degreesC leads to the formation of Bi2Sr2Cu1O6 phase. This phase forms granular structure with randomly distributed grains in the glassy matrix. It was found that oxygen needed for the crystallization of the Bi2Sr2Cu1O6 phase is taken from glassy matrix and involves a change in the valency state of copper ions from Cu+1 to Cu2+ during crystallization. Annealing at 800 degreesC gives mainly Bi2Sr2Ca1Cu2O8 phase. After 200 h of heat treatment at this temperature, Bi2Sr2Cu1O6 phase, Bi2Sr2Ca2Cu3O10 phase and Cu2O was also observed.