Preparation of High‐T c Superconducting Oxides by the Amorphous Citrate Process

The high‐T c superconducting oxide Yba 2 Cu 3 O 7–y has been prepared by the amorphous citrate process. A citrate‐nitrate solution was prepared at room temperature and dehydrated at around 80°C to yield a solid precursor material. The precursor was fired to high temperature to form the desired compound. The decomposition mechanism was studied with thermogravimetric analysis and X‐ray diffraction. Intermediate products were formed during the decomposition reactions. Nearly phase‐pure Yba 2 Cu 3 O 7‐y powders were obtained by firing the precursor in air to 900°Cfor2 h. Sintered samples were typically over 90% dense and exhibited good superconducting properties.