A collaboration between researchers at Northwestern University's Center for Catalysis and scientists at Oxford University has produced a new approach for understanding surfaces, particularly metal oxide surfaces, widely used in industry as supports for catalysts.
This knowledge of the surface layer of atoms is critical to understanding a material's overall properties. The findings were published online Feb. 14 by the journal Nature Materials.
Using a combination of advanced experimental tools coupled with theoretical calculations, the research team has shown how, using methods commonly taught to undergraduate chemistry students, one can understand how atoms are arranged on a material's surface. (These methods date back to the pioneering work of Linus Pauling and others to understand the chemical bond.)
"For a long time we have not understood oxide surfaces," said Laurence Marks, professor of materials science and engineering in the McCormick School of Engineering and Applied Science at Northwestern. "We only have had relatively simple models constructed from crystal planes of the bulk structure, and these have not enabled us to predict where the atoms should be on a surface.
"Now we have something that seems to work," Marks said. "It's the bond-valence-sum method, which has been used for many years to understand bulk materials. The way to understand oxide surfaces turns out to be to look at the bonding patterns and how the atoms are arranged and then to follow this method."
Marks, together with Kenneth Poeppelmeier, professor of chemistry in Northwestern's Weinberg College of Arts and Sciences, and Martin Castell, university lecturer in the department of materials at Oxford, led the research.
In the study, Northwestern graduate student James Enterkin analyzed electron diffraction patterns from a strontium titanate surface to work out the atomic structure. He combined the patterns with scanning-tunnelling microscopy images obtained by Bruce Russell at Oxford. Enterkin then combined them with density functional calculations and bond-valence sums, showing that those that had bonding similar to that found in bulk oxides were those with the lowest energy.
Writing in a "News and Views" article from the same issue of Nature Materials, Ulrike Diebold from the Institute of Applied Physics in Vienna, Austria, said, "This simple and intuitive, yet powerful concept [the bond-valence-sum method] is widely used to analyze and predict structures in inorganic chemistry. Its successful description of the surface reconstruction of SrTiO3 (110) shows that this approach could be relevant for similar phenomena in other materials."
The Nature Materials paper is titled "A homologous series of structures on the surface of SrTiO3 (110)." The authors of the paper are James A. Enterkin (first author), Arun K. Subramanian, Kenneth R. Poeppelmeier and Laurence D. Marks, from Northwestern, and Bruce C. Russell and Martin R. Castell, from Oxford.
Megan Fellman | EurekAlert!
Glass's off-kilter harmonies
18.01.2017 | University of Texas at Austin, Texas Advanced Computing Center
Explaining how 2-D materials break at the atomic level
18.01.2017 | Institute for Basic Science
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
19.01.2017 | Studies and Analyses
19.01.2017 | Physics and Astronomy
19.01.2017 | Life Sciences