Making Sense of Melting
may be yielding to scientific investigation. Researchers have a pretty good handle on how freezing occurs.
may be yielding to scientific
investigation. Researchers have a pretty good handle on how freezing
occurs. Melting, on the other hand, has proved far trickier to discern.
But new findings are chipping away at the problem. In the current issue
of Science, researchers report having observed premelting within
a crystal for the first time. Previously, this stage had been seen only
on crystal surfaces. Premelting, it appears, starts at defects in the
crystalline structure, such as the cracks and grain boundaries among
the otherwise orderly atoms. The image above shows a cross section of a
crystal, with the circles representing spherical particles. The colors
indicate the frequency of particle vibrational fluctuations as the
crystal was heated. Premelting manifested as an increased movement
along the defects in the crystal, and subsequently spread into the more
ordered areas.
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