Phase transitions in vanadium oxide nanostructures

当二氧化钒（VO2）被加热到临界温度Tc（68℃）以上时，它会从绝缘相转变为金属态。这种转变背后的精确机制仍然存在争议，主要是因为局部应变和Tc之间的耦合使得从大体积的宏观测量中推断材料的真实（微观）特性非常具有挑战性。西雅图华盛顿大学的David Cobden教授开创了一种研究这一问题的新方法，即使用比特征畴尺寸更小的VO2“纳米束”。然而，迄今为止所有的结果都是通过光学显微镜和悬浮在接触之间的纳米梁的电子测量获得的。华威大学在电子显微镜方面的专业知识，为以前所未有的细节研究绝缘相和金属相之间的领域边界提供了机会，目的是回答长期存在的问题和由Cobden教授的工作引起的新问题。一个短期的研究计划将于2011年夏天实施，这笔旅行资助将为我们未来的研究提供一个机会，使我们能够维持这种新的合作。

Vanadium dioxide, VO2, undergoes a transition from an insulating phase to a metallic state when it is heated above a critical temperature Tc of 68C. The precise mechanisms underlying this transformation remain controversial, primarly because coupling between local strain and Tc makes it very challenging to infer the true (microscopic) properties of the material from macroscopic measurements that average over a large volume.A new way to study this problem has been pioneered by Prof. David Cobden at the University of Washington in Seattle, by using VO2 'nanobeams', smaller than the characteristic domain size. However all the results to date have been obtained using optical microscopy and electrical measurements of nanobeams suspended between contacts. The expertise at Warwick, in electron microscopy, provides an opportunity to study the domain boundary between the insulating and metallic phases in unprecedented detail, with the aim of answering long-standing problems and new questions arising from Prof. Cobden's work. A short programme of research is in place for the summer of 2011, and this travel grant will provide an opportunity to develop proposals for future research, enabling us to sustain this new collaboration.