Reversible nanoscale switching of polytwin orientation in a ferroelectric thin film induced by a local electric field

The response to a local, tip-induced electric field of ferroelastic domains in thin polycrystalline lead zirconate titanate films with predominantly (110) orientation has been studied using Enhanced Piezoresponse Force Microscopy. Two types of reversible polytwin switching between well-defined orientations have been observed. When a-c domains are switched to other forms of a-c domains, the ferroelastic domain walls rotate in-plane by 109.5°, and when a-c domains are switched to c-c domains (or vice-versa), the walls rotate by 54.75°. © 2013 AIP Publishing LLC.

Design and market considerations for axial flux superconducting electric machine design

In this paper, the authors investigate a number of design and market considerations for an axial flux superconducting electric machine design that uses high temperature superconductors. The axial flux machine design is assumed to utilise high temperature superconductors in both wire (stator winding) and bulk (rotor field) forms, to operate over a temperature range of 65-77 K, and to have a power output in the range from 10s of kW up to 1 MW (typical for axial flux machines), with approximately 2-3 T as the peak trapped field in the bulk superconductors. The authors firstly investigate the applicability of this type of machine as a generator in small- and medium-sized wind turbines, including the current and forecasted market and pricing for conventional turbines. Next, a study is also carried out on the machine's applicability as an in-wheel hub motor for electric vehicles. Some recommendations for future applications are made based on the outcome of these two studies. Finally, the cost of YBCO-based superconducting (2G HTS) wire is analysed with respect to competing wire technologies and compared with current conventional material costs and current wire costs for both 1G and 2G HTS are still too great to be economically feasible for such superconducting devices.