XPS and XRD studies of early stages of crystallisation process in (Bi–Pb)4Sr3Ca3Cu4Ox glass–ceramics

✍ Scribed by M. Gazda; A. Winiarski

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 523 KB
• Volume: 432
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2005.07.007

✦ Synopsis

Bi 0.8 Pb 0.2 ) 4 Sr 3 Ca 3 Cu 4 O x glass was obtained by a standard technique of quenching melted substrates. As a result of annealing at 850 °C the glass crystallised, forming glass-ceramic material. The transformation of the material was studied by X-ray diffraction and X-ray photoelectron spectroscopy.

On the basis of the experimental results a consistent picture of the initial stage of the crystallisation of (Bi 0.8 Pb 0.2 ) 4 Sr 3 Ca 3 Cu 4 O x glass at 850 °C has been proposed. Superconducting phases e.g. (Bi,Pb) 2 Sr 2 Cu 1 O x , (Bi,Pb) 2 Sr 2 CaCu 2 O x and other oxides like Ca 2 PbO 4 , CuO and CaO were detected. At 850 °C, the 2212 phase forms rapidly. On the other hand, the 2201 phase crystallisation occurs mainly at temperatures below 840 °C, that is, during heating and cooling stages of annealing. To obtain glass-ceramic material containing mainly 2212 phase, both heating and cooling of the glass should be performed as quickly as possible.

Oxygen is incorporated by Ca 2 PbO 4 on the surface and by the 2212 and 2201 phases mostly inside the material. The Ca 2 PbO 4 phase, present on the surface only, does not enhance oxygen diffusion towards the interior part of material.