Crystal structure - Thermal neutron scattering techniques and profile refinement analyses are being utilized to investigate crystal and magnetic structures, composition, dynamics and crystal chemical properties. This research is being carried out in collaboration with a number of industrial and university experts and researchers at National Laboratories. The properties of impurities which form during processing of superconductors, or which are intentionally added to modify the properties, are also investigated. Measurements performed include AC and DC magnetization as a function of temperature and applied magnetic field, hysteresis loops, flux penetration and viscosity, critical fields, and critical temperatures. Microstructural studies are performed using scanning and transmission electron microscopy.
Emphasis is on high temperature superconducting materials.
It will also improve the ability of manufacturers to characterize and control the characteristics and quality of material they produce, will increase critical current densities by improvements in flux pinning, and provide better control over the flux pinning properties of materials for shielding and levitation bearings. It was found that the low temperature spin-Peierls transition of the pure material was modified by the Sn doping. Sr 4-x Ca x PtO 6 were measured. This information was used to help determine phase relationships in this system. Phase diagrams determined at NIST are being used by industry to fabricate improved high temperature superconducting materials.