RESUMEN
Numerical calculations of parameters of an electrical power network where an HTS fuse is used as a fault current limiting device have been done. The calculations were performed for networks containing different types of HTS cables as well. The design of HTS fuse was developed based on the numerical calculation for the network-rated parameters considering the special types 2G HTS tape characteristics. The distinctive feature of these tapes is the minimal thickness (about 30 µm) of the substrate at the critical current 450-600 A. The tests were performed at a voltage of 1 kV and demonstrated the ability of circuit breaking at fault currents about 3-4 kA. A comparison of experimental results with the calculations allows us to conclude that the HTS fuse of this design can operate as a fault current limiting device in electrical power networks at various rated voltage levels.
RESUMEN
The unique family of coordination polymers [Ln4(OH)2(piv)10(H2O)2]∞ of 11 lanthanides (Ln = La-Er) has been prepared by a simple solution method based on controlled hydrolysis. The ribbon-like polymeric structure consisting of connected tetranuclear clusters and supported by pivalate ligands and a framework of H-bonds has been revealed by single-crystal X-ray diffraction. While the compounds demonstrate similar PXRD patterns and unit cell parameters, the joint single-crystal XRD and pair distribution function data suggest the significant local structure change along the lanthanide series. The compounds exist as two packing polymorphs (α and ß) with similar ribbon geometry, but different supramolecular arrangement of the ribbons. Dehydration of either polymorph does not disturb the tetranuclear core but leads to a translational symmetry loss along the ribbon and a transformation of the 3D-ordered crystal into a 2D-ordered mesostructure. Rehydration of the mesostructure leads to the ß polymorph (except La and Ce), allowing the deliberate switching between the polymorphs via dehydration-rehydration evidenced by means of powder X-ray diffraction, pair distribution function analysis, and density functional theory calculations. Ab initio calculations reveal significant magnetic anisotropy of Ln3+ ions with ferro- and antiferromagnetic interactions within tetranuclear [Ln4(OH)2(piv)10(H2O)2] species. Magnetic susceptibility measurements demonstrated antiferromagnetic coupling, slow magnetic relaxation for Dy, Ho, and Er complexes, and field-induced single-chain magnetism for the Dy compound.
RESUMEN
The microstructure of GdBa2Cu3O7-δ based on superconducting tapes with BaSnO3 and BaZrO3 artificial pinning centers formed by high-rate pulse laser deposition in SuperOx Japan was studied by scanning/transmission electron microscopy. The artificial pinning centers have adopted columnar morphology with average diameter of about 8 nm (BaSnO3-doped sample) and 6.5 nm (BaZrO3-doped sample) and density of 500 µm-2 for the both samples. The average length of the BaSnO3 nanocolumns is about two times higher than the BaZrO3 nanocolumns. The angular dependences of critical current in magnetic field up to 1 Tesla at 77 and 65 K have been obtained. The critical current and its anisotropy depend on artificial pinning centers presence and their type. The angular dependence of resistivity in the field up to 9 Tesla was also studied and discussed.
