A new discovery answers an old question

Jan 30, 2012
A new discovery answers an old question
Diffraction intensity contrast maps for Fe0.94O measured at 24.7 GPa. From Yang Ding et al., Appl. Phys.Lett. 100, 041903 (2012).

(PhysOrg.com) -- The transition-metal monoxide FeO is an archetypal example of a Mott insulator—a material that should conduct electricity under conventional band theories but becomes an insulator when measured, especially at low temperatures—and a major iron-bearing component of the Earth’s interior. Understanding the high-pressure behavior of this material is important for both solid-state physics and Earth science. But despite considerable study over the past 30 years, the origin of the well-known high-pressure-induced cubic-rhombohedral ferroic transition in FeO, which is a distortion of the original cubic structure to that of as rhomboid shape, has been not well understood.

Now the first imaging of non-reflection domain wall structures forming in the ferroic transition of the ferrous oxide Fe0.94O has been reported by researchers from the U.S. Department of Energy Office of Science’s Advanced Photon Source (APS) and the High Pressure Synergetic Consortium (HPSynC). The team carried out the study at the 2-ID-D x-ray beamline at the APS, applying a pressure of approximately 250,000 atm in a pressure vessel called a diamond anvil cell, and imaging the material’s crystalline structure using the new high-pressure nanodiffraction imaging technique developed by these researchers.

The team’s results revealed a non-reflection type of domain wall structure forming due to the so-called “cubic-rhombohedral transition,” where the crystal structure of the material changes from cubic to rhomboidal. This discovery suggests the cubic-rhomboid transition could be associated with defects in the material and is unlikely to be caused by ferroelasticity, in which a material may develop a spontaneous strain, as predicated by previous research.

The surprising impact of defects on structural stability discovered by this study not only brings with it a new understanding of the origin of the cubic-rhomboid transition, but also underscores the need for a greater understanding of how defects in a material influences electronic and thermoelastic properties at high pressure, which has almost never been taken into consideration in previous high-pressure studies of .

In addition, this study demonstrates the power of the new nanodiffraction imaging technique for investigation of pressure-induced phase transitions, which has emerged as a very active area in condensed matter physics, but until now has lacked suitable in situ techniques for probing the nanoscopic origins of the transitions.

Explore further: Asteroid impacts on Earth make structurally bizarre diamonds

More information: Zhonghou Cai, et al. “Nanoscale diffraction imaging of the high-pressure transition in Fe1-xO,” Appl. Phys.Lett. 100, 041903 (2012). DOI: 10.1063/1.3679117

Related Stories

Simple lithium good for many surprises

Jan 14, 2011

(PhysOrg.com) -- At first glance, lithium should be a simple atomic system. It is the lightest solid element and with just three electrons, it should exhibit simple, crystalline structures. However, an international ...

How diamonds emerge from graphite

Sep 21, 2011

Scientists have used a new method to precisely simulate the phase transition from graphite to diamond for the first time. Instead of happening concerted, all at once, the conversion evidently takes place in ...

A new kind of metal in the deep Earth

Dec 19, 2011

(PhysOrg.com) -- The crushing pressures and intense temperatures in Earth's deep interior squeeze atoms and electrons so closely together that they interact very differently. With depth materials change. New ...

Micro-explosion reveals new super-dense aluminium

Aug 24, 2011

(PhysOrg.com) -- Although materials scientists have theorized for years that a form of super-dense aluminum exists under the extreme pressures found inside a planet’s core, no one had ever actually seen ...

Recommended for you

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

jimbo92107
not rated yet Jan 30, 2012
"In addition, this study demonstrates the power of the new nanodiffraction imaging technique for investigation of pressure-induced phase transitions..."

Why don't you do a story on this new nanodiffraction technique? It sounds more interesting than squashed Iron Monoxide.
rwinners
not rated yet Jan 30, 2012
Ah, a challenge to the community!

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.