Polymer-metal chelate precursor reduced its firing temperature and time for preparing yttrium barium cuprate powder

Bulk YBa₂Cu₃O _x was prepared by a polymer chelate precursor method using poly(N,Ndicarboxymethyl)allylamine] as a chelating polymer of which molecular weights were 3 × 10⁴ (PDAA-L) and 3 × 10⁵ (PDAA-H), respectively. X-ray diffraction (XRD) analysis of the precursor from PDAA-H shows that YBa₂Cu₃O _x (Y123) phase appeared after being calcined at 750 °C for 5 h and the mixture was completely converted to tetragonal Y123 phase after being calcined at 800 °C for 5 h. The phase evolution of the precursor from PDAA-H during isothermal experiment at 800 °C showed that pure tetragonal Y123 was produced even after the polymer chelate precursor was heated for 2 h in air, although a very small amount of BaCO₃ was recognized. This BaCO₃ phase was hardly recognized after 4 h calcination. The precursor prepared from PDAA-L was fully converted to pure tetragonal Y123 after 3 h calcining at 800 °C. On the other hand, the sample prepared from metal nitrate solution without PDAA was not fully transferred to Y123 phase after heating at 800 °C for 10 h. Large amounts of Y₂O₃, BaCO₃ and CuO were observed. These results indicated that the greater homogeneity in the polymer chelate precursor leads to reduced firing times and temperature compared with the metal nitrate precursor.