Preparation of GdBa2Cu3O6+x (GdBCO) precursor powder by spray-drying a nitrate solution containing PEG

Abstract

Several precursor powders, obtained after precipitation from metal nitrate solution containing polyethylene glycol (PEG) (inside a Pyrex glass reactor or by spray-drying), and their thermal evolution to GdBCO were analyzed by thermogravimetry (TG), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The amount of PEG had a crucial role in the BaCO3 content of the 'Kjeldahl precursors' but a minor effect on the degree of transformation to GdBCO at 900ºC, which did not reach completion after 1 h. In contrast, a low-PEG spray-dried powder led to almost 100% GdBCO in only 5 min. The high degree of cation dispersion reached by spray-drying and the coexistence with a liquid phase can explain this short reaction time. The spray-dried powder compares favorably with the mechanical mix of metal oxides and Ba carbonate that is commonly used as precursor powder for the synthesis following a solid-state reaction