a team of researchers from amber (advanced materials and bioengineering research), the science foundation ireland-funded center based at trinity college dublin, have made a breakthrough that challenges the fundamental understanding of how the building blocks of matter combine to form materials, according to a report on the amber website.
amber researchers used scanning tunneling microscopy to explore the
building blocks of copper and other materials. (amber/youtube)
the researchers, which included scientists from imperial college london and the university of pennsylvania, observed that the building blocks in copper never fit together perfectly, but are rotated, which causes misalignment and surface roughness.
the article explained, “electrical, thermal and mechanical properties are controlled by how the grains in a material are connected to each other. until now, it was thought that grains, which are made up of millions of atoms, simply pack together like blocks on a table top, with small gaps here and there.”
in reality, the nano-sized particles of copper tilt up and down, creating ridges and valleys. “this new understanding at the nanoscale will impact how these materials are designed, ultimately enabling more efficient devices, by reducing resistance to current flow and increasing battery life in hand-held devices,” the article added.
the research, which used scanning tunneling microscopy, shows that it is impossible to create perfectly flat nanoscale films of copper and other materials. this is the first time that scientists have been able to observe the 3-d structure of grain boundaries.
in the future, scientists will have a better understanding of materials and how to control the rotation of these nano-scale grains to manipulate material properties like never before.
the research was recently published in science. the abstract stated:
“we used scanning tunneling microscopy to study low-angle grain boundaries at the surface of nearly planar copper nanocrystalline (111) films. the presence of grain boundaries and their emergence at the film surface create valleys composed of dissociated edge dislocations and ridges where partial dislocations have recombined.
“geometric analysis and simulations indicated that valleys and ridges were created by an out-of-plane grain rotation driven by reduction of grain boundary energy.
“these results suggest that in general, it is impossible to form flat two-dimensional nanocrystalline films of copper and other metals exhibiting small stacking fault energies and/or large elastic anisotropy, which induce a large anisotropy in the dislocation-line energy.”
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