Scientists are just beginning to discover and investigate materials that can change from insulators to conductors at room temperature under an applied voltage. There are only a few known examples, but their potential for use in new technologies – as futuristic as the “invisibility cloak” donned by Harry Potter in the book series by the same name – is very exciting.
At NSLS, researchers have studied a new addition to this elite group – nanowires made of vanadium oxide bronze – and measured drastic, never-before-seen transitions from insulator to conductor. Their work also hints at what happens at the atomic-level. This is a crucial step toward developing possible applications, which include a type of computer memory known as a memristor, now in development at some companies; new varieties of electrochromic coatings, thin films that reversibly change color in response to an applied voltage; and transistors.
Here, researchers from the University of Buffalo used several x-ray and microscopy methods to study the nanowires, some to characterize the wires after synthesis and others to “see” what happened when the wires were pressed into pellets and subjected to an electric field. Together, the techniques yield a detailed picture of the wires’ atomic and electronic structures before and after the transition.
The wires are made of the elements vanadium, oxygen, and lead (in the form of positive ions). The group created them using a synthesis method that yields very high-quality samples. This is an important achievement in and of itself, as the inability to create samples with structures that are nearly defect-free has previously been a roadblock to studying these materials, as too many imperfections stifle the phenomenon.
Read more at: Phys.org