Tuesday, December 21, 2010

New State of Matter Seen in Clay - ScienceNOW

New State of Matter Seen in Clay - ScienceNOW: In the latest research, carried out over 7 years, physicist Barbara Ruzicka of the University of Rome "La Sapienza" and colleagues have shown how an existing material—the synthetic clay Laponite, which is used as a thickener in many household products—can form a stable gel. The researchers suspended Laponite in water and used the powerful x-ray beams of ESRF to study how the structure of the suspension changes over time and how this evolution depends on the amount of clay present.

At concentrations of up to 1% Laponite by weight, the initial fluid transformed into a gel after a few months, the researchers found. Then about 3 years later, it separated into two phases: one clay-rich and the other clay-poor. However, no such phase separation occurred at concentrations above 1%. Unlike at the lower concentrations, at which the arrangement of the clay particles was continually in flux, at concentrations above 1% the structure eventually stopped changing, indicating that the particles had locked into a stable structure: the equilibrium gel.

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