Yale scientists confirm how crystals form
A team of researchers at Yale University is the first to devise a way to predict the microstructure of crystals as they form in materials, according to a report in the September issue of Applied Physics Letters.
Although there are theoretical models that predict grain size and ways to monitor the growth of individual crystals, this new method makes it possible to estimate grain size and therefore the properties of materials that are dependant on microstructure.
Researchers in many fields including materials science, geology, physical chemistry and biochemistry will now be able to tailor material properties that are sensitive to microstructure.
According to senior author Ainissa G. Ramirez, assistant professor of mechanical engineering, the Yale team monitored real-time images taken at two-second intervals while they heated crystallizing samples of nickel-titanium within a transmission electron microscope.
They directly determined the rate of crystal assembly (nucleation), and the rate that the crystals grew, by measuring the number of crystals and their change in size with time. Their results agree with the conventional Johnson-Mehl-Avrami-Kolmogorov method which only gives an overall crystallization rate, with the nucleation and growth rates coupled.
The novel contribution of this work is that the nucleation and growth rates are measured independently during crystallization and can be used to infer the grain size after crystallization is complete.
"We used the mathematics of crystallization in a new way," said Ramirez. "We found that our measured grain sizes and the mathematical predictions agreed over a broad range of temperatures. This method allows researchers to now explore the connection between structure and properties of different materials."
Janet Rettig Emanuel | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...