Materials Day poster presenters give two-minute introductions to their research during annual symposium.
Materials Day Poster Session presenters capped off the annual Materials Day Symposium with brief highlights of research ranging from solar energy and alternative fuels to spinal cord injury and neural networks for artificial intelligence.
Postdoc Grace Han, in Prof. Jeffrey Grossman’s group, Department of Materials Science and Engineering, described progress in creating materials which absorb photons from sunlight and convert them into heat energy through the charging and discharging cycle of organic photo switching molecules. “This is quite different from just heating water or concrete block by solar radiation in that we can actually store the energy and release energy by triggering,” Han said. These organic coatings can be integrated onto car windshields for deicing, fabrics for personal heating, or building materials for temperature control. Han’s poster also described a new process to harness waste heat from industrial furnaces, and store it for later release.
Janille Maragh, a graduate student in Professor Admir Masic’s lab, Department of Civil and Environmental Engineering, presented her work on sustainable construction materials. To study ancient Roman concrete from an archaeological site in Italy, she used Energy Dispersion Spectroscopy and Raman spectroscopy to map centimeter scale samples at microscopic resolution. “What we are trying to do is understand exactly what our sample is made of so can we understand this phenomenal material. … So we understand not only the bulk composition of our material but also their fracture surface.”
“Carbon monoxide is responsible for more than half of all fatal poisonings worldwide,” Vera Schroeder, a graduate student in Professor Timothy Swager’s lab, said. “Exposure to this odorless, colorless and tasteless gas is very difficult to detect for humans, which is compounded by the fact that the initial symptoms of poisoning – headache, dizziness, and confusion are non-specific.” Schroeder is developing bio-inspired carbon monoxide sensors that use a transistor-based design to activate a chemical change in iron atoms to detect carbon monoxide, even in air. “This new mode of sensor allows us to have a voltage activated, enhanced and highly specific response and we can detect carbon monoxide in air with much higher sensitivity than we detect CO2, oxygen or water,” she said.
- Repairing spinal cord damage Repairing spinal cord damage
- Making artificial axons Making artificial axons
- Fluid-solid interface on graphene Fluid-solid interface on graphene
- Organic photo switching molecules Organic photo switching molecules
- Examining hydrogen solubility Examining hydrogen solubility
Alfonso Juan Carrillo, a postdoc in the lab of Jennifer L. M. Rupp, the Thomas Lord Assistant Professor of Materials Science and Engineering, presented results of work on perovskite materials for solar-driven transformation of CO2 and water into fuels. Carillo selected the best candidate perovskite materials, synthesized these perovskites, analyzed their microstructure, and tested them in a fixed bed high-temperature reactor. “We use what are called thermochemical cycles,” Carillo said. As the perovskite absorbs oxygen, it can transform water and carbon dioxide into hydrogen and carbon monoxide.
Minghui Wang, a postdoc in Professor Karen Gleason’s lab, is creating thin-film microporous polymers for gas separation using chemical vapor deposition. Gas separation is important for industrial gas needs and carbon capture but heat-based methods are energy intensive,” he said. “One challenge is that you need to achieve both high flux and high gas selectivity for membrane materials. To do so, usually you need a rigid and microporous structure and also you need to fabricate very thin films, but to do both of them is kind of difficult. In our lab, we use chemical vapor deposition to deposit pinhole-free thin films by using this technique and using porphyrin as a monomer.” He achieved high selectivity for carbon dioxide and nitrogen separation using polymerized porphyrin on a flexible substrate.
Andrew Dane, a graduate student in Professor Karl Berggren’s group, discussed progress on improving speed and efficiency in superconducting nanowire single photon detectors. Two competing available materials tilt toward either speed or efficiency. “We changed the material deposition and made some devices and showed that we kind of combined the best of both worlds,” Dane said. “There is a quantum phase transition in the material that we’re working with and a lot of other interesting things.”
About a million Americans undergo hernia repair surgery each year and for one in four or them, hernia will re-occur. About half will experience some degree of chronic pain, said Sebastian Pattinson, a postdoc in the lab of Associate Professor of Mechanical Engineering A. John Hart. The surgical mesh used to mechanically reinforce the tissue as it heals causes many of these complications. Pattinson described a new 3D printing process that allows local customization of mechanical response in a surgical mesh and in particular allows for non-linear mechanical response in a way that mimics tissue. “We hope that these meshes will help alleviate the complications suffered by many patients all around the world,” Pattinson said.
Chemistry postdoc Zhou Lin, in Professor Troy A. Voorhis’ group, presented research on a process to double electric current in organic solar cells by splitting single excitons into pairs, a process that is called singlet fission. “We can generate two electric currents out of one high-energy photon so we can promote the efficiency of organic photovoltaics, that’s what we want,” Lin said. “Based on our electronic structure theory calculations, we are able to reproduce the experimental trend for the fission rate using three different isomers that can undergo this intramolecular singlet fission,” she said.
Yukio Cho, a graduate student in Prof. Harry L. Tuller’s lab, is working on mixed ionic and electronic conductor [MIEC] cathode materials for solid oxide fuel cells. Using electrochemical methods, Cho and colleagues synthesized n-type cathode material to improve the surface exchange. “We control the defects, control the electronic defects, and for the current result, we successfully synthesized n-type materials,” Cho said. “The expected good surface exchange capability is also confirmed through transfer diffusion measurements.”
Frank McGrogan, a graduate student in Professor Krystyn J. Van Vliet’s lab, presented his work with the Chemomechanics of Far-From-Equilibrium Interfaces [COFFEI] group on all-solid electrolytes in lithium ion battery systems. “One of the main sticking points is we have this problem of lithium metal unevenly plating the electrodes, crossing the electrolyte and shorting the cell. Our group has been treating this as a fracture issue. … We’ve demonstrated experimentally that fracture is indeed a mechanism for this lithium plating and shorting problem.”
“We’ve gone ahead and measured some mechanical properties including fracture properties of several important solid electrolytes and used these inputs in simulations to predict damage evolution,” McGrogan said. “I think that the way that our group has approached this problem and how we’re getting to the mechanism is going to change the way our field thinks about failure in all solid-state lithium ion batteries.”
Postdoc Dena Shahriari, who works with Professors Yoel Fink and Polina Anikeeva, shared an update on efforts to repair spinal cord damage by optically stimulating and guiding the growth of injured neurons. “We’re using a thermal drawing process, which is a high throughput technique which will allow us to create kilometer-long fibers in just one experiment,” Shahriari said. These highly flexible probes deliver light to the lesion of the spinal cord, and record at multiple sites of these neurons.
“For the tissue engineering part we needed to bridge the nerve gap, we needed to create porosity into these scaffolds, and for that we need to add a twist to this thermal drawing process that will allow us to not only create, but also control, porosity in that,” Shahriari said.
Gerald Wang, a graduate student in mechanical engineering under Prof. Nicolas Hadjiconstantinou, invited attendees to learn more about his poster by arranging it so that the first letters of each line spelled out “C-O-M-E.” He is exploring the fluid-solid interface atop a sheet of graphene. “It turns out when you put fluid in this environment under the right conditions, it will spontaneously arrange into a layered structure that mimics the solid below it. This layered fluid structure, practically indistinguishable from tiramisu or the layered cake of your preference, imparts upon the fluid remarkable fluid properties including enhanced heat transfer, remarkably long slip lengths and highly modified surface diffusivities very different from the bulk fluid.”
“It’s a very exciting story with some of the great actors and actresses of today including Van der Waals, high through-put simulation and molecular self-assembly. So there’s something for everybody whether you’re an experimentalist, a theorist, a computationalist, or you just like a good scaling relation, you should make like the letters and come on by,” Wang said.
Mary Elizabeth Wagner, a graduate student in the group of Associate Professor of Metallurgy Antoine Allanore, is working on a sustainable way to refine precious metals from nature and from recycled materials. “The problem is these expensive elements, silver, gold, platinum, are found in very, very tiny amounts, comparatively to copper, but they make up so much of the cost,” Wagner said.
“My idea in my research focuses on one system that can host electrochemistry for gold, for silver, and for platinum group metals,” Wagner said. Molten sulfide electrolytes are one promising system. “We should be able to treat all of these metals in one go, which should be able to provide an environmentally sustainable as well as a cost-effective way to treat these metals,” she said.
Vrindaa Somjit, a graduate student under Prof. Bilge Yildiz, is examining the effect of dopants on hydrogen solubility in alumina using a computational, first principles approach. Hydrogen may become a fuel of the future, but one of the main problems in making this a reality is the storage and transport of hydrogen. Hydrogen can penetrate steel and cause it to fail.
“One way to mitigate this problem of hydrogen embrittlement is by the use of permeation barrier coatings, and alpha-alumina is a promising candidate,” Somjit said. She set out to determine if dopants, extra chemical elements added to a compound, could improve the performance of alpha-alumina in resisting hydrogen penetration. “What we found is that actually dopants do not help in decreasing the hydrogen solubility because alpha-alumina itself lies at the bottom of the hydrogen solubility valley,” Somjit said.
Graduate student Chang Sub Kim, in Professor Harry Tuller’s group, conducts research to electrochemically pump oxygen in and out of a thin film of layered cuprate, which has potential as a cathode material. “An interesting fact is that it can accommodate both oxygen vacancies as well as interstitials. So in this study, I show you that I can control the region where I can access oxygen-access and also oxygen-deficient regions, and then show that I can simultaneously measure different materials properties such as oxygen surface reaction kinetics as well as in-plane conductivity, which agrees very well with the expected defect chemistry.”
Postdoc Yuming Chen in Professor Ju Li’s group, spoke about a project to develop a sodium-ion battery anode using nitrogen-doped carbon. Chen introduces nitrogen atoms into the structure of hollow carbon tubes to create larger spacing that allows sodium to penetrate the carbon tube and yield higher performance. These carbon tubes can be used as freestanding electrodes with long cycling life.
Ananya Balakrishna, a postdoc in Professor W. Craig Carter’s group, developed theoretical and computational models to investigate the link between material properties and microstructure. “In my research, I probe questions like what determines microstructural patterns, can we engineer microstructures to control macroscopic material properties,” she said. Her poster featured two projects describing microstructure in ferroelectric materials and in lithium battery electrodes.
“In lithium batteries, microstructures form during a typical charge/discharge cycle. In these microstructures, the underlying lattice symmetry has an effect on material properties, for example, certain lattice arrangements facilitate the faster propagation of diffusion of lithium ions and certain lattice arrangements cause non-uniform expansion of electrodes,” Balakrishna said. She is working on a phase field crystal model that couples lattice symmetry with the concentration field to describe electrode microstructure.
Menghsuan Sam Pan, a graduate student in Professor Yet-Ming Chiang’s group, focuses on using water-based sulfur batteries for low-cost energy storage. “It’s one of the lowest cost per stored charge in any electrochemically active materials, only behind water and oxygen,” Pan said. “When we work in soluble electrodes, we found that the sulfur can only be reversibly cycled between a di-sulfide and a tetra-sulfide regime, and with this we did some technical economic modeling to see the installed costs of the electrode. What surprised us is that the component that’s used to hold the electrode is more costly than the active material itself.”
Experiments showed these sulfide species cycle reversibly, precipitating into the electrode and then dissolving very well when they are cycled back, Pan said. “We cycled for more than 1,600 hours, more than two months,” he said, noting a 30 percent cost reduction in terms of cost per stored capacity.
Working under Professor Jeehwan Kim, graduate student Scott Tan is developing hardware for neural networks for artificial intelligence. He makes silicon-germanium cross-bar arrays with a reversible silver conductance channel to toggle the conductance state of these synaptic devices. “We’ve also used these devices in a simulation and showed that they can perform handwriting recognition with accuracy up to 95 percent,” Tan said.
Mechanical engineering graduate student Nicholas T. Dee presented work in Professor A. John Hart’s group on scalable roll-to-roll graphene production for membrane applications. “We’ve developed a roll-to-roll CVD reactor for this process that is unique in that it has two different zones, one specifically for annealing the substrate and catalyst and one zone for growth of the graphene,” Dee said. The researchers tuned the gas composition to achieve full coverage of monolayer graphene and explored the tradeoff between production rate and quality of the graphene. “We have demonstrated using our graphene produced in this high-throughput manner to produce nano-porous, atomically thin membranes for potential desalination applications,” he said.
Brad R. Nakanishi, a graduate student in Professor Antoine Allanore’s group, introduced his research on high-temperature materials chemistry in refractory metals. “What we’ve done, where experiment by conventional methods or prediction by first principles prove very complex and challenging, we’ve basically modified a floating zone furnace which has provided us with enhanced experimental throughput and also very unique ability to see and probe the properties of these refractory liquids,” Nakanishi said. His poster showed an image of the first direct electrolytic decomposition of aluminum oxide to oxygen gas and aluminum metal. “We’ve been using this approach to make fundamental thermodynamic property measurements like chemical potential,” he said. This work has implications for discovery of new materials for applications from aerospace to nuclear as well as discovery of new processes for materials extraction.
Chosen by guests who attended the Materials Day Poster Session, this year's Poster Session prize winners were Postdoc Dena Shahriari, electrical engineering and computer science; graduate student Vera Schroeder, chemistry; and Postdoc Sebastian Pattinson, mechanical engineering.
The annual MIT Materials Research Laboratory [MRL] Materials Day Symposium and Poster Session were held on Wednesday, Oct. 11, 2017.
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