We report a novel technique to grow crystals of the high‐temperature superconductor Bi2Sr2Ca2Cu3O10+x and Bi2Sr2CaCu2O8+x (2223 and 2212 BSCCO phases), both pure and Pb substituted. The technique, based on chemical transport in a thermal gradient in molten KCl, is simple and inexpensive, and yields a continuous output of crystals, with growth times of a few minutes, i.e., orders of magnitude shorter than conventional flux methods. Depending on melt aging, crystals of either the pure 2223 or the pure 2212 BSCCO phases are obtained, having zero‐resistance temperature of 105 and 90 K, respectively, and a transport critical current density of 104 A cm−2 at liquid nitrogen temperature.
Superconducting thin-films containing randomly disordered layers of and have been synthesized through a combined approach of metal-organic chemical vapour deposition (MOCVD) and thallium vapour diffusion. The BaCaCu matrices have been deposited onto yttria stabilized zirconia (YSZ) substrates using the second generation tetraglyme and tetraglyme (hfa denotes hexafluoroacetylacetonate), and the (acac denotes acetylacetonate) as volatile metal-organic precursors. BaCaCu precursor films of composition 2:2:3 were annealed in the presence of a mixture of thallium (III), barium, calcium and copper oxides at temperatures of 840 - and oxygen partial pressure varying from 0.04 - 0.5 atm. The formation of an oriented () intergrowth structure has been observed in narrow temperature and oxygen partial pressure ranges. The electrical resistivity data show which, in accordance with the scanning electron microscopy image, appears indicative of a material with weakly linked grains.
28 May 2013 in Superconductor Science and Technology
The attention of the present paper is focused on the use of an infrared imaging device to monitor the thermal response of composite materials under cyclic bending. Three types of composites are considered including an epoxy matrix reinforced with either carbon fibres (CFRP) or glass fibres (GFRP) and a hybrid composite involving glass fibres and aluminium layers (FRML). The specimen surface, under bending, displays temperature variations pursuing the load variations with cooling down under tension and warming up under compression; such temperature variations are in agreement with the bending moment. It has been observed that the amplitude of temperature variations over the specimen surface depends on the material characteristics. In particular, the presence of a defect inside the material affects the temperature distribution with deviation from the usual bending moment trend.