ankur26888
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Using high-powered lasers, scientists at Lawrence Livermore National Laboratory and collaborators discovered that molten magnesium silicate undergoes a phase change in the liquid state, abruptly transforming to a more dense liquid with increasing pressure. The research provides insight into planet formation. Just as graphite can transform into diamond under
high pressure, liquid magmas may similarly undergo
major transformations at the pressures and
temperatures that exist deep inside Earth-like
planets. Using high-powered lasers, scientists at Lawrence Livermore National Laboratory and collaborators
discovered that molten magnesium silicate
undergoes a phase change in the liquid state,
abruptly transforming to a more dense liquid with
increasing pressure. The research provides insight
into planet formation. "Phase changes between different types of melts
have not been taken into account in planetary
evolution models," said lead scientist Dylan
Spaulding, a UC Berkeley graduate student who
conducted most of his thesis work at the
Laboratory's Jupiter Laser Facility. "But they could have played an important role during Earth's
formation and may indicate that extra-solar 'Super-
Earth' planets are structured differently from Earth." Melts play a key role in planetary evolution. The
team said that pressure-induced liquid-liquid phase
separation in silicate magmas may represent an
important mechanism for global-scale chemical
differentiation and also may influence the thermal
transport and convective processes that govern the formation of a mantle and core early in planetary
history. Liquid-liquid phase separation is similar to the difference between oil and vinegar – they want
to separate because they have different densities. In
the new research, however, the researchers noticed
a sudden change between liquid states of silicate magma that displayed different physical properties even though they both have the same composition
when high pressure and temperatures were
applied. The team used LLNL's Janus laser and OMEGA at the
University of Rochester to conduct the experiments
to achieve the extreme temperatures and pressures
that exist in the interiors of exoplanets -- those
objects outside our solar system. In each experiment, a powerful laser pulse
generated a shock wave while it traveled through
the sample. By looking for changes in the velocity of
the shock and the temperature of the sample, the
team was able to identify discontinuities that
signaled a phase change in the material. "In this case, the decay in shock-velocity and
thermal emission both reverse themselves during
the same brief time interval," Spaulding said. The team concluded that a liquid-liquid phase
transition in a silicate composition similar to what
would be found in terrestrial planetary mantles
could help explain the thermal-chemical evolution
of exoplanet interiors.
Http://pda.physorg.com/news/2012-02-planets-solar.html
high pressure, liquid magmas may similarly undergo
major transformations at the pressures and
temperatures that exist deep inside Earth-like
planets. Using high-powered lasers, scientists at Lawrence Livermore National Laboratory and collaborators
discovered that molten magnesium silicate
undergoes a phase change in the liquid state,
abruptly transforming to a more dense liquid with
increasing pressure. The research provides insight
into planet formation. "Phase changes between different types of melts
have not been taken into account in planetary
evolution models," said lead scientist Dylan
Spaulding, a UC Berkeley graduate student who
conducted most of his thesis work at the
Laboratory's Jupiter Laser Facility. "But they could have played an important role during Earth's
formation and may indicate that extra-solar 'Super-
Earth' planets are structured differently from Earth." Melts play a key role in planetary evolution. The
team said that pressure-induced liquid-liquid phase
separation in silicate magmas may represent an
important mechanism for global-scale chemical
differentiation and also may influence the thermal
transport and convective processes that govern the formation of a mantle and core early in planetary
history. Liquid-liquid phase separation is similar to the difference between oil and vinegar – they want
to separate because they have different densities. In
the new research, however, the researchers noticed
a sudden change between liquid states of silicate magma that displayed different physical properties even though they both have the same composition
when high pressure and temperatures were
applied. The team used LLNL's Janus laser and OMEGA at the
University of Rochester to conduct the experiments
to achieve the extreme temperatures and pressures
that exist in the interiors of exoplanets -- those
objects outside our solar system. In each experiment, a powerful laser pulse
generated a shock wave while it traveled through
the sample. By looking for changes in the velocity of
the shock and the temperature of the sample, the
team was able to identify discontinuities that
signaled a phase change in the material. "In this case, the decay in shock-velocity and
thermal emission both reverse themselves during
the same brief time interval," Spaulding said. The team concluded that a liquid-liquid phase
transition in a silicate composition similar to what
would be found in terrestrial planetary mantles
could help explain the thermal-chemical evolution
of exoplanet interiors.
Http://pda.physorg.com/news/2012-02-planets-solar.html
