Physicists at the Georgia Institute of Technology have made two important findings regarding gold on the nanoscale whose structure can be changed and the properties can be different from the bulk form.
The two findings are published in the journal of Physical Review Letters, according to a press release by the university on Monday.
In the first study, researchers found that applying an electrical field on a surface-supported gold nanocluster changes its structure from a three-dimensional one to a planar flat structure. Turning off the applied field or reversing it's direction results in reverting the structure back to the pyramidalone.
The researchers also discovered that the chemical activity of the adsorbed gold nanocluster varied significantly under the influence of the applied field, enhancing the low-temperature catalytic oxidation of CO to carbon dioxide.
In another paper, they discovered that gold on the nanoscale can be made magnetic through oxygenation of gold nanowires. They also found that up to a certain length, oxygenated gold nanowires behave as a conducting metal, but beyond that, they become insulators. This marks the first time on the nanoscale that such a metal-to-insulation transition has been found on the nanoscale.
Both findings are important predictions that could some day be implemented as control parameters governing the chemical and physical material properties employed in nanotechnology.
The researchers focused their investigations on gold nanostructures because of the well known chemical inertness of gold in the bulk form, allowing one to maintain samples with minimal influence on the environment.
"However, we again find that small is different," said Uzi Landman, lead researcher of the studies, repeating a phrase that he coined and has used often for close to two decades.
"On the nanoscale, even gold becomes a potent catalyst, exhibiting new and surprising, chemical, mechanical, electrical and magnetic behavior, which could not have been extrapolated or predicted on the basis of our knowledge about this substance in the bulk form. Some of these systems may find technological uses in nanocatalysis and as chemical and electrical sensors," Landman added.
Source:Xinhua
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