How crystal becomes a conductor

Feb 05, 2008

Squeeze a crystal of manganese oxide hard enough, and it changes from an electrical insulator to a conductive metal. In a report published online this week by the journal Nature Materials, researchers use computational modeling to show why this happens.

The results represent an advance in computer modeling of these materials and could shed light on the behavior of similar minerals deep in the Earth, said Warren Pickett, professor of physics at UC Davis and an author on the study.

Manganese oxide is magnetic but does not conduct electricity under normal conditions because of strong interactions between the electrons surrounding atoms in the crystal, Pickett said. But under pressures of about a million atmospheres (one megabar), manganese oxide transitions to a metallic state.

Pickett and colleagues Richard Scalettar at UC Davis, Jan Kunes at the University of Augsburg, Germany, Alexey Lukoyanov at the Ural State Technical University, Russia, and Vladimir Anisimov at the Institute of Metal Physics in Yekaterinburg, Russia, built and ran computational models of manganese oxide.

Using the model, the researchers were able to test different explanations for the transition and identify the microscopic mechanism responsible. They found that when the atoms are forced together under high pressure, the magnetic properties of the manganese atoms become unstable and collapse, freeing the electrons to move through the crystal.

Manganese oxide has similar properties to iron oxide and silicates (silicon oxides), which make up a major part of the Earth's crust and mantle. Understanding how these materials behave under enormous pressures deep underground could help geologists understand the Earth's interior, Pickett said.

Source: University of California - Davis

Explore further: Atomic trigger shatters mystery of how glass deforms

add to favorites email to friend print save as pdf

Related Stories

Size matters in crucial redox reactions

Oct 12, 2010

(PhysOrg.com) -- Particle size has a far more dramatic impact on chemical reactivity than previously thought, according to new research from UC Davis. The results have implications for understanding a wide range of vital ...

Recommended for you

Cold Atom Laboratory creates atomic dance

5 hours ago

Like dancers in a chorus line, atoms' movements become synchronized when lowered to extremely cold temperatures. To study this bizarre phenomenon, called a Bose-Einstein condensate, researchers need to cool ...

Wild molecular interactions in a new hydrogen mixture

11 hours ago

Hydrogen—the most abundant element in the cosmos—responds to extremes of pressure and temperature differently. Under ambient conditions hydrogen is a gaseous two-atom molecule. As confinement pressure ...

Scientists create possible precursor to life

12 hours ago

How did life originate? And can scientists create life? These questions not only occupy the minds of scientists interested in the origin of life, but also researchers working with technology of the future. ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

out7x
1 / 5 (1) Feb 07, 2008
What is the conductivity differences of MnO2, Fe2O3, and silicates at one megabar? What are the implications of the magnetohydrodynamics?