Synthesis and Formation Process of LaxY1-xBa2Cu3Oy Powder by Aqueous Chelate-Mix Technique

LaxY1-xBa2Cu3Oy powders were synthesized by the aqueous chelate-mix technique using ethylenediamine-tetraacetic acid (EDTA), nitrilo-tri-acetic acid (NTA) and imino-di-acetic acid (IDA) as chelating agents. The intermediate products obtained in each formation process were investigated by thermogravimetry, X-ray diffraction technique and infrared spectroscopy. It was found that the formation of the 123 phase from precursor-gel proceeds in the following four steps; (1) decomposition of ammonium acetate and Cu-EDTA and formation of metal-copper at 120-220°C, (2) decomposition of carboxyl group of chelate at 340-410°C, (3) combustion of the residual organics and formation of BaCO3 and other oxides at 410-480°C, and (4) decomposition BaCO3 and formation of 123 phase around 800°C.