Preparation and Characterization of Large-Quantity Bi-2223 Precursor Powder by Oxalate Coprecipitation

We report on the study of (Bi,Pb)₂Sr₂Ca₂Cu₃O_x(Bi-2223) precursor powder prepared by oxalate coprecipitation, which mainly focus on the process parameters and heat treatment for large-quantity preparation. Three kilograms of powder with a high homogeneity and an ideal composition can be prepared in one batch by controlling the pH value (2.9) and the aging time (2 days) of mixed solutions. Meanwhile, the powder has a particle size of less than 3 μm and a narrow size distribution. The different phase composition and Bi-2212 structure can be obtained with different heat treatment temperatures and atmospheres. To illuminate the properties of the precursor powder, a 19-filament tape was fabricated using a precursor powder calcined at 800 °C/20 h and 820 °C/20 h in air. A superconducting transition temperature T_c of up to 110 K was obtained using a thermomechanical treatment based on two heat treatments and one intermediate rolling. Our results show that it can be applied in a large-quantity preparation of Bi-2223 precursor powder.