U Engineering to Work with Versatile Test Reactor

Engineers from the University of Utah’s Department of Materials Science and Engineering are working with a large team of researchers to prepare experiments for the U.S. Department of Energy’s upcoming Versatile Test Reactor to test various molten salt reactor technologies.

These experiments are part of just one research project that will take advantage of the VTR, which is designed to test fuels, materials and sensors for power reactors. While the VTR is going through a federal approval process and has not yet been built, projects such as the one the U’s MSE department is working on are already underway.

The Idaho National Laboratory has published a new story about what the U’s experiment will be about, which involves the MSE chair, Michael Simpson, and involves irradiating molten salt to see how it would change.

Click here to read the INL story.

Dr. Bedrov and SMRC discover new liquid phase

Research activities in the MRSEC Soft Materials Research Center (SMRC) that includes molecular simulation group of Prof. Bedrov have discovered an elusive phase of matter, first proposed more than 100 years ago and sought after ever since. The “ferroelectric nematic” phase of liquid crystal has been described in recent study published in the Proceedings of the National Academy of Sciences (PNAS 2020 117, 14021-14031; https://doi.org/10.1073/pnas.2002290117). The discovery opens a door to a new universe of materials.

Nematic liquid crystals have been a hot topic in materials research since the 1970s. These materials exhibit a curious mix of fluid- and solid-like behaviors, which allow them to control light and have been extensively used in liquid crystal displays (LCDs) in many laptops, TVs and cellphones. The nematic liquid crystals like dropping a handful of pins on a table. The pins in this case are rod-shaped molecules that are “polar”—with heads that carry, say, a positive charge and tails that are negatively charged. In a traditional nematic liquid crystal, half of the pins point up and the other half point down, with the direction chosen at random. A ferroelectric nematic liquid crystal phase, however, patches or “domains” form in the sample in which the molecules all point in the same direction, either up or down, and therefore creating a material with polar ordering.

Debye and Born first suggested in the 1910s that, if you designed a liquid crystal correctly, its molecules could spontaneously fall into a polar ordered state. In the decades since, however, scientists struggled to find a liquid crystal phase that behaved in the same way. That is, until MRSEC researchers began examining RM734, an organic molecule created by a group of British scientists several years ago. That same British group, plus a second team of Slovenian scientists, reported that RM734 exhibited a conventional nematic liquid crystal phase at higher temperatures. At lower temperatures, another unusual phase appeared. When the MRSEC team tried to observe that strange phase under the microscope they noticed something new. Under a weak electric field, this phase of RM734 was 100 to 1,000 times more responsive to electric fields than the usual nematic liquid crystals and the molecules are nearly all pointing in the same direction.

However, experimentally it is hard to zoom down to molecular scale and understand why and how these RM734 molecules were achieving such collective behavior. This is where atomistic molecular dynamics simulations conducted by Dengpan Dong and Xiaoyu Wei from Prof. Bedrov group allowed to gain atomic scale understanding. First, the simulations were able to confirm that aligning all RM734 molecules in the same direction is energetically more favorable than to have conventional random alignment of molecular dipoles. Second, detail analysis of structural and orientational correlations obtained from simulations identified key groups and intermolecular interactions that stabilize the ferroelectric nematic phase. Using these tools Bedrov’s group currently explores other chemical structures that can lead to a similar behavior.

Discovery of this new liquid crystal material starts a new chapter in condensed-matter physics and could open up a wealth of technological innovations—from new types of display screens to reimagined computer memory. Within couple days of publication, the manuscript got a world-wide attention and was picked up by more than 25 news outlets around the world.

Ebrahiminia awarded second place at the Lithium Ion Batteries Symposium

The 236th Electrochemical Society meeting was held in Atlanta during the week of October 13-17, 2019. Mahsa Ebrahiminia, an MSE Ph.D. student from Dr. Dmitry Bedrov group, presented her latest work on transport and mechanical properties of model solid electrolyte interphases (SEI) that she studied using atomistic molecular dynamics simulations and was awarded the second place at the Lithium Ion Batteries Symposium.

SEI is one of the key components in the Li-ion batteries that, on the one hand, protects electrolytes from electrochemical decomposition and suppresses the growth of Li dendrites, but on the other hand, creates additional resistance for Li-ion transport between electrodes. Mahsa’s simulations provide a molecular scale insight into mechanisms of Li-ion transport and structure-property relationships that hard to obtain from experiments but are badly needed in order to design new materials for next generation of batteries.

Congratulations Mahsa!

Dr. Sparks to speak at TEDxSalt Lake City

The University of Utah Department of Materials Science and Engineering is proud to announce that associate professor Taylor Sparks has been chosen to be a speaker at this year’s TEDxSaltLakeCity event on Sept. 21 at Kingsbury Hall on the university campus in Salt Lake City.

Sparks, whose research is focused on new materials for energy applications such as batteries, thermoelectrics, thermal barrier coatings and more, will be speaking on materials informatics, the process of using big data and machine learning to help researchers solve materials science challenges. The talk, titled “Striking a New Balance in Materials Discovery,” will dive into about how scientists can leverage information stored in materials data and compare that to how they traditionally discover new materials, which can largely be from trial-and-error.

TEDxSaltLake City describes itself as the “Wasatch Front’s leading platform for citizens to present and explore their ideas, stories, and creative solutions.” This year’s lineup will include 14 speakers and six musical acts.