The Department of Energy's Oak Ridge National Laboratory has published a paper in the April 15, 2004 issue of Nature that could change the way advanced ceramic materials are developed. The paper includes atom-scale images that could hold the key to predicting and modelling the properties of advanced ceramics.
The work, by ORNL researchers Stephen Pennycook of the Condensed Matter Sciences Division, Gayle Painter and Paul Becher of the Metals and Ceramics Division and visiting researcher Naoya Shibata, shows world-record 0.7 angstrom resolution images of the location of atoms within a silicon nitride ceramic.
The images are proof that their theoretical predictions have been correct with the atoms residing almost exactly in their expected positions.
The images were made with ORNL's 300-kilovolt Z-contrast scanning transmission electron microscope (STEM) and enhanced using aberration correction, a technique that uses computers to correct errors caused by imperfections in the electron lenses.
Researchers are looking at ways to make the strong and lightweight silicon nitride less brittle and therefore more suited for applications that require strong, heat-resistant and light-weight components.
It can be toughened with whisker-like grains that act similarly to concrete reinforcing rods. Doping agents like lanthanum oxide are used to grow the whiskers but this changes other properties in the material. The ability to predict and manipulate the structure of these materials at the atomic level will aid researchers in developing the ceramic materials with the most desirable properties.