Hot videos; superconductor waves; driverless cars/crop dusting.
The University of Minnesota has recorded videos that show how heat travels through materials, a move that could give researchers insight into the behavior of atoms and other structures.
It could also pave the way towards the development of more efficient materials for use in electronics and other applications.
In the lab, researchers used FEI’s transmission electron microscope (TEM). FEI’s TEM, dubbed Tecnai, is capable of examining materials at the atomic and molecular level at femtosecond speeds. A femtosecond is one millionth of a billionth of a second.
In this work, researchers used a brief laser pulse to excite electrons. Then, they heated up crystalline semiconducting materials of tungsten diselenide and germanium. Researchers captured videos of the interaction, which was a billion times slower than the normal speed. They imaged the sub-picosecond nucleation and the launch of wavefronts at step edges. They mapped the oscillations of energy or phonons.
A video can be seen here. All told, the videos show waves of energy moving at about 6 nanometers. “In many applications, scientists and engineers want to understand thermal-energy motion, control it, collect it, and precisely guide it to do useful work or very quickly move it away from sensitive components,” said David Flannigan, an assistant professor of chemical engineering and materials science at the University of Minnesota, on the university’s Web site.
“Because the lengths and times are so small and so fast, it has been very difficult to understand in detail how this occurs in materials that have imperfections, as essentially all materials do. Literally watching this process happen would go a very long way in building our understanding, and now we can do just that,” he said.
Superconductors are devices that have zero electrical resistance, making them attractive for a range of applications. For example, superconductors could enable electricity to travel from power plants to houses with zero loss. The devices could be used in high-speed trains and cell-phone towers.
The problem? Superconductors must be cooled down to temperatures at or near absolute zero on the Kelvin scale to work. This, in turn, limits their applications. Absolute zero equates to −273.15° on the Celsius scale and −459.67° on the Fahrenheit scale.
Hoping to solve some of the issues, Binghamton University and others provided new insights into superconductors. In the lab, researchers studied cuprate superconductors. These are compounds, such as copper and oxygen, that super-conduct at relatively high temperatures. This is below 90-150 Kelvin.
Researchers used a scanning tunneling microscope (STM) with a superconducting tip. Researchers put the tip close to a sample. They applied a voltage between them. The goal was to obtain a current.
All told, researchers were able to look at the superconductivity at the atomic scale. They observed that superconductivity can have waves in itself. “This is a better and different way of looking at these cuprate materials than has previously been possible,” said Michael Lawler, a theoretical physicist at Binghamton University, on the university’s Web site. “Before now, what we’ve known is that there are lots of waves present in these materials. You can think of the charge changing in a wavelike pattern, where the wave is 4 atoms across.
“I’m excited about seeing this wave that we can now probe directly,” Lawler said. “We can find out if there are materials where this dramatic wave happens. They would be different kinds of superconductors than we typically study.”
Driverless cars/crop dusting
The U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) has announced up to $60 million in funding for two new programs.
The first program, NEXT-Generation Energy Technologies for Connected and Automated on-Road vehicles (NEXTCAR), seeks to develop new technologies that decrease energy consumption of future vehicles through the use of connectivity and automation.
The NEXTCAR program is providing up to $30 million in funding to create new control technologies that reduce the energy consumption of future vehicles by using connectivity and vehicle automation. The program seeks transformative technological solutions that will enable at least a 20% reduction in the energy consumption of future Connected and Automated Vehicles (CAVs), compared to vehicles without these technologies.
The second program, Rhizosphere Observations Optimizing Terrestrial Sequestration (ROOTS), seeks to improve crop breeding for root and soil function to allow for greater carbon storage in plants.