Solution-sol-gel-SHS process of quickly synthesizing bismuth-based superconductor precursor powder

A new process (solution-sol-gel-SHS, SSGS) based on the combination of the advantages of solution-sol-gel (SSG) process and solution self-propagating high-temperature synthesis (SHS) process has been developed to synthesize bismuth-based superconductor precursor powder. The new process consists of two main steps: (i) SSG process is used to prepare homogeneous wet gel; (ii) solution SHS process is carried out to transit wet gel to soft-agglomerated ultrafine (∼ 0.3 μm) precursor powder with low carbon content (<400×10^-6). The new process has overcome many serious shortcomings of traditional SSG-processed powder such as hard agglomerate, coarse particles and high carbon content, and also greatly shortened the powder preparation period. The powder can be sintered into 110K 2223 superconductor with excellent quality in a short time. The process parameters to obtain homogeneous wet gel are optimized and SSG transition mechanism is also discussed.