Manufacture of ultrafine BiPbSrCaCuO powder by an in situ nanometre reaction process

A new method has been developed for the manufacture of the bismuth-based superconductor precursor powder BiPbSrCaCuO for fabrication of high-J_c Ag/Bi(2223) tape. The new method consists of two main stages. First, nanoparticles with specific stoichiometry are prepared in a low-surface-tension liquid medium based on a coprecipitation reaction and in situ dispersed in the medium to obtain a suspension. Second, the suspension is in situ transformed into ultrafine oxide particles (∼200 nm) by heat treatment where each nanoparticle reacts on a nanometre scale (nanometre reaction) with the least possibility of contact and agglomeration. The new method has brought about a new process termed an in situ nanometre reaction process (INRP). The new process can be used to manufacture finer BiPbSrCaCuO particles with a lower carbon content in a shorter time than the traditional coprecipitation process (TCP) because the agglomeration processes from filtration through drying to calcination are omitted.