We spend much of our time looking at materials and seeing how they work, particularly grain boundaries in semiconductors and ceramics, Pennycook says. Impurities in these structures can change totally the way these materials behave. These grain boundaries are interfaces between similar materials. Other interfaces occur where materials have been deposited on other materials to obtain certain properties. Much of superconducting and semiconductor materials research hinges on how successfully these boundaries are structured.
Grain boundaries are a mystery.
It s usually because of impurities in the materials they can be anything really that affect the strength of an alloy or the electrical barrier in a ceramic. They can completely change the property of the material. You need tremendous sensitivity so see these. Knowing where the impurities occur can show how a boundary is constructed, which can show why it behaves the way it does. We often dope a material with impurities to study these effects.