There’s a fair bit in the physics magazines at the moment on superconductivity. http://Physicsworld.com has some interesting articles, for example this one by Ted Forgan and an interview with Frank Wilczek.
Superconductivity has its hundreth birthday this year. In 1911, in Leiden, Netherlands, Heike Onnes and Gilles Holst discovered that mercury lost its electrical resistance at 4.2 K. This followed Onnes earlier development of a technique to liquify helium; he was honoured for this development with the 1913 Nobel Prize for Physics.
Since then, researchers have been interested in both how to use superconductors (e.g. how they interact with magnetic fields, as exemplified by the classroom levitation experiment), just why superconductors superconduct (from which we have learnt a lot about electrons and quantum mechanics) and how to make superconductors that are superconductive at higher temperatures. Room temperature superconductors would be an astonishing breakthrough, opening up vast possibilities, but they still remain a dream at the moment.
Experimentally, the stride forward that made superconductivity more than just a quirky bit of physics was the 1986-87 work in ceramics. A variety of compounds containing yttrium, barium, copper and oxygen (known as YBCO) are superconducting at temperatures above the boiling point of nitrogen (77 K). Liquid nitrogen is easy and cheap to get hold of, and so these superconductors are easily studied. Unfortunately, however, since then the record temperature has only inched upwards (standing at 138 K for atmospheric pressure, and that record has stood since1993) and it looks as if another quantum leap is required to get to room temperature.
But there are options other than YBCO that have been studied recently. There are plenty of researchers working on superconductors, for example in New Zealand we have a well respected. group at IRL, led by Buckley and Tallon. People have looked at organic materials and very recently iron compounds. Just perhaps, someday soon, someone will hit on something that pushes the superconducting temperature up another 100 Kelvin or so. That would really be Nobel Prize stuff.
Simon Arnold says:
Worth a couple of other comments about the NZ angle.
The first high temperature superconductor to be turned into long length conductors (BSCCO) was patented by the team at DSIR/IRL and licensing this to American Superconductors (AMSC) gave NZ access to HTS wire. This helped build the commercial capability to use HTS in high field magnets. This capability was the basis for establishing HTS-110 Ltd in 2004.
While most manufacturers have moved to YBCO for wire because of its potential to be cheaper, BSCCO still remains the mainstay for commercial activity (Sumitomo EI is now the main supplier). IRL however continues to work with AMSC (alongside US National Labs) on improving the performance of its YBCO wire.
HTS-110 started manufacturing HTS coils and is today entering the market with HTS NMR.
Looking ahead to application in power systems equipment NZ has developed a high current, low AC loss Roebel winding cable. This is being manufactured by General Cable Superconductors in NZ.
The other technology required for power systems is a robust low cost cryocooler, and again NZ has developed a product targeted at this market.
In each case (magnets, NMR, Roebel cable and robust cryocoolers) NZ has a lead on the rest of the world. It is in these applications up the value chain where by far the bulk of NZ’s R&D investment has been going (not as might be thought into researching the material).
The most recent public investment is going into a four year program to demonstrate HTS Roebel cable in a 1MVA transformer (this will be deployed in Vector’s network) and in developing an orthopedic MRI for use outside the highly controlled environments demanded by the existing low temperature superconductor MRIs.
Marcus Wilson says:
Thanks for that Simon – it’s nice to get some fill-in on the NZ details. Nice also to be re-assured that NZ is a world-leader in things other than dairy.