柠檬酸溶胶凝胶法合成YBa_2Cu_3O_(7-δ)

采用溶胶 凝胶法制备了均匀的YBa2Cu3O7-δ超导细粉·讨论了凝胶的形成过程·配合剂柠檬酸与金属离子结合形成了可溶性的大分子化合物,除水后缩聚反应形成的聚合物长大为小粒子簇,相互连结成连续的三维网络·柠檬酸盐溶液的pH值控制在6 4～6 7之间可防止白色Ba(NO3)2沉淀·溶剂挥发温度宜控制在300℃,使凝胶的形成和自燃过程能在相同温度条件下连续进行·合成YBa2Cu3O7-δ的温度大约在880℃左右,其粉末粒度大约在0 2～1μm之间·

Synthesis of YBa2Cu3O7-δ superconducting powder through sol-gel process

Homogeneous YBa2Cu3O7-δ powder was prepared through sol-gel process. The citric acid was used as complexing agent to form macromolecule compound with Y³⁺, Ba²⁺ and Cu²⁺ ions. After dehydration the compound grew into small particle clusters which bonded together to form continuous three-dimension net. The pH value of citrate solution should be controlled in a range from 6.4 to 6.7 to prevent from forming Ba(NO3)2 sediment and ensure the quality of gel. It' s preferable to control the evaporating temperature at 300°C so as to form gel in shortened time continuously along with its spontaneous combustion process at the same temperature. Thus the process is simplified. The temperature required for synthesizing YBa2Cu3O7-δ powder is about 880°C, at which the particle size is about 0.2-1 μm.