Synthesizing metallic to superconducting ceramic nanoparticles using optimized microemulsion systems.

摘要

A microemulsion system with cetyltrimethylammonium bromide (CTAB) as surfactant, 1-butanol as cosurfactant and n-octane as the oil phase was optimized to produce nanoparticles. Based on the results of conductivity and droplet size, oil/surfactant weight ratio of 1.5 was chosen to perform the study due to its higher solubilization and droplet stability. Nanoparticles of monometallic Fe, bimetallic Fe/Ni, oxide Y2O3, complex oxide Y 2BaCuO5 (Y211) and YBa2Cu3O7-x (Y123) have been successfully synthesized using the water-in-oil microemulsion method.; The size of amorphous Fe, Fe/Ni nanoparticles were about 10 nm and 5 nm respectively. The reduction rate of trichloroethylene (TCE, a model contaminant) by the Fe produced from the microemulsion system was the highest compared to the solution product and the commercial product. In the case of Fe/Ni nanoparticles, the initial degradation rate is four times faster than for Fe nanoparticles.; Nanocrystalline Y2O3 particles were flake shaped with dimension in the range of 16--30 nm. Y2BaCuO5 and YBa2Cu3O7-x nanoparticles (∼110 nm) produced using the microemulsion method had lower processing temperature than other processing methods due to their smaller particle size. As the reaction time was shortened, the Y211 particle size reduced from larger than 100 nm to the 30--100 nm range. Superconductivity of Y123 nanoparticles was verified using magnetic measurements and the critical transition temperature was 91 K.; In the melt-textured Y123 disk, a single domain with a maximum trapped field of 0.14 T was successfully fabricated with the addition of 30% Y211 nanoparticles produced by the microemulsion method. The JC and size distribution of Y211 grain in the Y123 matrix were slightly better than in conventional samples.