It is also a likely component in the Earth's mantle, and it plays an important role in the life cycle. But at high pressure, carbon dioxide can transform to a solid.
The commonly known solid-state form of carbon dioxide is the so called "dry ice", which is a molecular crystal and has many important applications, e.g. food producation and storage, artificial fog in theatre and artificial rainfall, etc.
Even more interesting, as the pressure increases and temperature varies, the intra- and inter-molecular interactions of carbon dioxide change dramatically and this results in different crystal structures in polymeric dense phases with interesting physical properties, such as "super-hardness". Thus carbon dioxide has become an extremely hot topic in science in the last decade.
Recently, a collaborative study between the research groups in Canada, Germany, Slovakia, Italy and USA achieved progress on this highly interested compound. Using a novel computer-based simulation method called metadynamics combined with accurate quantum mechanical calculations, they found that a molecular solid called CO2-II transfers to a layered polymeric structure at a pressure of 60 GPa (1 GPa is approximately 10000 atmospheres) and temperature at 600 Kelvin.
Based on the good agreement between their calculated Raman spectra and X-ray diffraction patterns and the previous experimental values, a new interpretation of a previous experimental result is given. A recently identified dense phase VI found in experiment, assumed to be disordered stishovite-like structure, is instead interpreted as the result of an incomplete transformation from the molecular phase into a final layered polymeric structure.
In addition, a new ?-cristobalite-like CO2 as found in silicon dioxide, is predicted to be formed from CO2-III via an intermediate structure at 80 GPa and temperature lower than room temperature. Defects in the crystals increase with temperature and CO2 transforms to an amorphous form when temperature is higher than room temperature, consistent with previous experiments.
These results obtained from fully dynamical simulations reveal hitherto unknown microscopic transformation mechanisms, and illustrate the transformation from a molecular solid characterized by only intra-molecular bonding to a polymerized structure. The transformation takes place at pressures within the range found in the Earth's mantle, where a significant amount of oxidized carbon is thought to be present, either in the form of carbonates or as a fluid. The large and abrupt changes in the bonding properties of CO2 reported here hint to possible discontinuities in the carbon chemistry of the mantle. Their article by Dr. Jian Sun et al. is soon to be (has been) published in the prestigious journal - Proceedings of the National Academy of Sciences USA.
Jian Sun, Dennis D. Klug, Roman Martonak, Javier Antonio Montoya, Mal-Soon Lee, Sandro Scandolo and Erio Tosatti: High-pressure polymeric phases of carbon dioxide. In: PNAS early edition, http://www.pnas.org_cgi_doi_10.1073_pnas.0812624106
Dr. Jian Sun, Lehrstuhl für Theoretische Chemie der Ruhr-Universität Bochum, D-44780 Bochum, Tel. +49 (0)234 32 22121, E-Mail: firstname.lastname@example.org
Dr. Josef König | idw
Further reports about: > CO2 > CO2-II transfers > Earth's mantle > GPa > Sun > artificial fog > artificial rainfall > carbon dioxide > computer-based simulation method > dry ice > earth's atmosphere > intra- and inter-molecular interactions > metadynamics > molecular crystal > polymeric materials > quantum mechanical calculations > room temperature > stishovite-like structure > super-hardness
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy