Understanding tungsten migration blazes trail for nano electronic device development

September 15, 2011, Pacific Northwest National Laboratory

Trios of tungsten atoms are greatly influenced in their migration across the wilds of a tiny particle by the shape of the particle, according to a team of experts, including Pacific Northwest National Laboratory's Dr. Fei Gao. The U.S. and China team performed complex computational simulations to determine the energetics involved in the tungsten cluster migration. They found that the 3 to 4 adatom, or surface atom, clusters prefer to form close-packed islands. The reorientation is the dominant migration mechanism for the dimer, while the net migration of lager clusters can be accomplished by the dimer shearing, concerted motion and rotation mechanisms.

The research was highlighted on the cover of the European Physical Journal B in March 2011 along with the peer-reviewed article: "Tungsten Clusters Migration on Nanoparticles: A Dimer Method Study."

The demand for miniaturization of electronic devices will benefit from a more in-depth understanding of nanostructured materials. has unique properties such as high density, hardness, melting temperature, elasticity and conductivity, along with low thermal expansion. These unique properties and nanometer-sized particles can be used to store and arrange electrons for use by semiconductors, providing engineers with a material of lower resistance and improved conductivity.

Using supercomputers in the Environmental Molecular Sciences Laboratory, the research team performed the calculations necessary to search for possible transition states and migration paths for tungsten clusters on tungsten nanoparticles, and corresponding migration energies for the possible migration paths of these clusters.

Tungsten clusters with up to four adatoms are found to prefer 2D-compact structures with relatively low binding energies. The team determined that the effect of interface and vertex regions on the migration behavior of the clusters is significantly strong compared to the nanoparticle size.

Migration mechanisms are very different when the clusters are located at the center of the nanoparticle and near the interface or vertex areas. Near the interfaces and vertex areas the substrate atoms tend to participate in the migration processes of the clusters, and can join the adatoms to form a larger cluster or lead to the dissociation of a cluster via the exchange mechanism, which results in the adatom crossing the facets.

The calculated energy barriers for the trimers suggest that the concerted is more probable than the successive jumping of a single adatom in the clusters.

The multi-scale computational method, ranging from ab initio calculation to long time dynamics method, will be further employed to study structural evolution of nanometer-sized metal clusters with increasing size and phase transformation of these metal clusters. These studies will provide significant insights into nanoscale catalysts, sensors and electrochromic applications such as smart glass where light or heat transmission properties of the glass are changed by applying voltage.

Explore further: Uniform tungsten trimers stand and deliver

More information: Chen D, et al. 2011. "Tungsten Cluster Migration on Nanoparticles: Minimum Energy Pathway and Migration Mechanism." The European Physical Journal B 80(1):31-40.

Related Stories

Uniform tungsten trimers stand and deliver

September 18, 2006

Like tiny nano-soldiers on parade, the cyclic tungsten trioxide clusters line up molecule-by-molecule on the titanium dioxide platform. One tungsten atom from each cluster is raised slightly, holding forth the potential to ...

Large or small, platinum clusters provide new insights

April 28, 2011

Using Environmental Molecular Sciences Laboratory's high-performance supercomputing capabilities, scientists helped resolve longstanding controversies about the effect of platinum cluster size on some emissions-reducing reactions ...

Scientists Find New Way to Produce Hydrogen

January 22, 2009

Scientists at Penn State University and the Virginia Commonwealth University have discovered a way to produce hydrogen by exposing selected clusters of aluminum atoms to water. The findings are important because they demonstrate ...

Cluster collisions switch on radio halos

August 30, 2010

(PhysOrg.com) -- This is a composite image of the northern part of the galaxy cluster Abell 1758, located about 3.2 billion light years from Earth, showing the effects of a collision between two smaller galaxy clusters.

Recommended for you

New technology for diagnosing immunity to Ebola

January 15, 2018

A promising new approach to detect immunity to Ebola virus infection has been developed by researchers from i-sense in a collaboration between UCL and Imperial College London.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.