Computer Simulations Indicate Calcium Carbonate Has a Dense Liquid Phase
Research could help scientists predict how carbon is stored underground
Artistic rendition of liquid-liquid separation in a supersaturated calcium carbonate solution. New research suggests that a dense liquid phase (shown in red in the background and in full atomistic detail based on computer simulations in the foreground) forms at the onset of calcium carbonate crystallization. (Credit: Berkeley Lab). Enlarge Image.
Results: Led by Pacific Northwest National Laboratory's Dr. James De Yoreo when he was at Lawrence Berkeley National Laboratory, computer simulations could help scientists make sense of a recently observed and puzzling wrinkle in important natural processes. It turns out that calcium carbonate -- a huge player in the planet's carbon cycle -- may momentarily exist in liquid form as it crystallizes from solution. The team's work appears in the August 23 issue of Science.
Why It Matters: The existence of a dense liquid phase could influence the response of Earth's oceans to rising atmospheric carbon dioxide levels, and help scientists predict the extent to which geological formations can act as carbon storage reservoirs, among other examples. The research may also reconcile confounding experimental observations. For more than a century, scientists believed that crystals nucleate from solution by overcoming an energy barrier. But recent studies of calcium carbonate revealed the presence of nanosized clusters which, under certain conditions, appear to circumvent the barrier by following an alternative aggregation-based crystallization pathway.
"Because nucleation is ubiquitous in both natural and synthetic systems, those findings have forced diverse scientific communities to reevaluate their longstanding view of this process," says the study's co-corresponding author De Yoreo.
Sponsor: Center for Nanoscale Control of
Geologic CO2, an Energy Frontier Research Center at Lawrence
Berkeley National Laboratory
User Facilities: Molecular Foundry and National Energy Research Scientific Computing Center
Research Area: Subsurface Science
Reference: Wallace AF, LO Hedges, AF Fernandez-Martinez, P Raiteri, S Whitelam, GA Waychunas, JD Gale, JF Banfield, and JJ De Yoreo. 2013. "Microscopic Evidence for Liquid-Liquid Separation in Supersaturated CaCO3 Solutions." Science 341(6148):885-889. DOI: 10.1126/science.1230915