MSGID: 1:317/3 64080f69   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    New 'camera' with shutter speed oftrillionth of a second sees through   
   dynamic disorder of atoms    
      
     Date:   
         March 7, 2023   
     Source:   
         Columbia University School of Engineering and Applied Science   
     Summary:   
         Researchers have developed a new 'camera' that sees the local   
         disorder in materials. Its key feature is a variable shutter speed:   
         because the disordered atomic clusters are moving, when the team   
         used a slow shutter, the dynamic disorder blurred out, but when they   
         used a fast shutter, they could see it. The method uses neutrons   
         to measure atomic positions with a shutter speed of around one   
         picosecond, a trillion times faster than normal camera shutters.   
      
      
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   FULL STORY   
   ==========================================================================   
   Researchers have developed a new "camera" that sees the local disorder   
   in materials. Its key feature is a variable shutter speed: because the   
   disordered atomic clusters are moving, when the team used a slow shutter,   
   the dynamic disorder blurred out, but when they used a fast shutter,   
   they could see it. The method uses neutrons to measure atomic positions   
   with a shutter speed of around one picosecond, a trillion times faster   
   than normal camera shutters.   
      
      
   ==========================================================================   
   Researchers are coming to understand that the best performing materials   
   in sustainable energy applications, such as converting sunlight or waste   
   heat to electricity, often use collective fluctuations of clusters of   
   atoms within a much larger structure. This process is often referred to as   
   "dynamic disorder."  Dynamic disorder Understanding dynamic disorder in   
   materials could lead to more energy-efficient thermoelectric devices, such   
   as solid-state refrigerators and heat pumps, and also to better recovery   
   of useful energy from waste heat, such as car exhausts and power station   
   exhausts, by converting it directly to electricity. A thermoelectric   
   device was able to take heat from radioactive plutonium and convert it   
   to electricity to power the Mars Rover when there was not enough sunlight.   
      
   When materials function inside an operating device, they can behave as if   
   they are alive and dancing -- parts of the material respond and change   
   in amazing and unexpected ways. This dynamic disorder is difficult to   
   study because the clusters are not only so small and disordered, but   
   they also fluctuate in time.   
      
   In addition, there is "boring" non-fluctuating disorder in materials that   
   researchers aren't interested in because the disorder doesn't improve   
   properties. Until now, it has been impossible to see the relevant dynamic   
   disorder from the background of less relevant static disorder.   
      
   New "camera" has incredibly fast shutter speed of around 1 picosecond   
   Researchers at Columbia Engineering and Universite' de Bourgogne   
   report that they have developed a new kind of "camera" that can see the   
   local disorder. Its key feature is a variable shutter speed: because   
   the disordered atomic clusters are moving, when the team used a slow   
   shutter, the dynamic disorder blurred out, but when they used a fast   
   shutter, they could see it. The new method, which they call variable   
   shutter PDF or vsPDF (for atomic pair distribution function), doesn't   
   work like a conventional camera -- it uses neutrons from a source at   
   the U.S. Department of Energy'sOak Ridge National Laboratory (ORNL) to   
   measure atomic positions with a shutter speed of around one picosecond,   
   or a million million (a trillion) times faster than normal camera   
   shutters. The study was published February 20, 2023, by Nature Materials.   
      
   "It's only with this new vsPDF tool that we can really see this side   
   of materials," said Simon Billinge, professor of materials science and   
   applied physics and applied mathematics. "It gives us a whole new way   
   to untangle the complexities of what is going on in complex materials,   
   hidden effects that can supercharge their properties. With this technique,   
   we'll be able to watch a material and see which atoms are in the dance and   
   which are sitting it out."  New theory on stabilizing local fluctuations   
   and converting waste heat to electricity The vsPDF tool enabled the   
   researchers to find atomic symmetries being broken in GeTe, an important   
   material for thermoelectricity that converts waste heat to electricity   
   (or electricity into cooling). They hadn't previously been able to see the   
   displacements, or to show the dynamic fluctuations and how quickly they   
   fluctuated. As a result of the insights from vsPDF, the team developed a   
   new theory that shows just how such local fluctuations can form in GeTe   
   and related materials. Such a mechanistic understanding of the dance will   
   help researchers to look for new materials with these effects and to apply   
   external forces to influence the effect, leading to even better materials.   
      
   Research team Billlinge's co-lead on this work with Simon Kimber,   
   who was at the University of Bourgogne in France at the time of   
   the study. Billinge and Kimber worked with colleagues at ORNL and the   
   Argonne National Laboratory (ANL), also funded by the DOE. The Inelastic   
   neutron scattering measurements for the vsPDF camera were made at ORNL;   
   the theory was done at ANL.   
      
   Next steps Billinge is now working on making his technique easier to use   
   for the research community and applying it to other systems with dynamic   
   disorder. At the moment, the technique is not turn-key, but with further   
   development, it should become a much more standard measurement that could   
   be used on many material systems where atomic dynamics are important,   
   from watching lithium moving around in battery electrodes to studying   
   dynamic processes during water- splitting with sunlight.   
      
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   ==========================================================================   
   Story Source: Materials provided by   
   Columbia_University_School_of_Engineering_and_Applied Science. Original   
   written by Holly Evarts. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Simon A. J. Kimber, Jiayong Zhang, Charles H. Liang, Gian   
      G. Guzma'n-   
         Verri, Peter B. Littlewood, Yongqiang Cheng, Douglas L. Abernathy,   
         Jessica M. Hudspeth, Zhong-Zhen Luo, Mercouri G. Kanatzidis, Tapan   
         Chatterji, Anibal J. Ramirez-Cuesta, Simon J. L. Billinge. Dynamic   
         crystallography reveals spontaneous anisotropy in cubic GeTe. Nature   
         Materials, 2023; 22 (3): 311 DOI: 10.1038/s41563-023-01483-7   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/03/230307174315.htm   
      
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