Synthesis of porous high-temperature superconductors via a melamine formaldehyde sacrificial template.

Nanostructured high-temperature superconductors YBa 2 Cu 3 O 6+ δ and Bi 2 Sr 2 CaCu 2 O 8+ δ were synthesised using a melamine formaldehyde sponge as a sacrificial template, via three solution-based approaches. In the case of YBa 2 Cu 3 O 6+ δ , a modified Pechini method produced a material with a superconducting transition at 92 K and a specific surface area of 4.22 m 2 g -1 . Further analysis with Hg porosimetry determined that the sponge exhibited a porosity of 82%. In the case of Bi 2 Sr 2 CaCu 2 O 8+ δ , this method produced a material that exhibited superconductivity at 86 K with a specific surface area of 9.62 m 2 g -1 . Hg-porosimetry determined that the BSCCO sponge exhibited a porosity of 78%.