Nanoparticle Superlattice Formation | Qian Chen

 

2024 Outstanding Early-Career Investigator Award recipient Qian Chen sits down with MRS TV to discuss her innovative work using liquid phase electron microscopy.

Neuromorphic Computing | Mark C. Hersam

 

Mark Hersam, 2024 MRS Mid-Career Researcher Award recipient, shares with MRS TV his thoughts on neuromorphic computing and its potential to create more energy efficient AI. 

Accessible Science Communication for a Sustainable Future

MRS Impact Award Winner Mark Miodownik joins MRS TV virtually to discuss his book "Stuff Matters" and to discuss why climate scientists need to prioritize strong communication with the general public.

4-D X-ray Microtomography

Nikhilesh Chawla sits down with MRS TV to reflect on the work that earned him MRS's 2024 Innovation in Materials Characterization Award.

 

2024 MRS Communications Lecture

Yury Gogotsi, Drexel University

MXene in the Environment and for the Environment

Written by Molly McDonough

Two-dimensional (2D) materials have long been of interest to the scientific community due to their unique properties and their wide variety of applications in shrinking electronics and energy storage devices. One challenge of 2D materials is their environmental stability, since 2D materials are typically more reactive than their bulk counterparts and may adsorb molecules from the atmosphere like water or oxygen, which can negatively affect their properties. One family of 2D materials, called MXenes, have become of interest in recent years due to their unique properties such as high electrical conductivity. MXenes have the formula M_n+1X_nT_x, where M is a transition metal, X is carbon and/or nitrogen, and T represents the surface termination of the material. Yury Gogotsi seeks to study MXenes and examine their environmental stability to provide insight into functional applications of these 2D materials.

Gogtsi’s MRS Communications Lecture focused on the environmental stability of MXenes by intercalation of N-methylformamide (NMF). MXenes are 2D materials, typically about 1 nm thick, and have a transition metal/hydroxide like surface. By changing the surface termination of the MXene, properties like electrical conductivity can be tuned. In MXenes, the changes in surface termination do not eliminate the electrical conductivity, like in graphene. Additionally, MXenes can be comprised of up to 7 different transition metals to make high entropy MXenes. MXenes can be synthesized in a variety of ways, including in solution, by selective etching precursor materials, or in bulk by chemical vapor deposition (CVD).

One of the challenges with MXenes is that they are hydrophilic, which allows them to be easily processed in aqueous solutions, but also means they can degrade in the presence of water near defects like metal vacancies. The presence of water can also cause a reduction in the properties of the MXene, such as the electrical conductivity. Controlling the degradation of these materials is an important challenge to overcome to enable their applications.

Gogotsi’s group synthesized Ti₃C₂T_x by selective etching Al from Ti₃AlC₂ using a mixture of HCl and HF. Then, the MXene was delaminated into MXene nanosheets through Li⁺ intercalation. The MXene was then suspended in a water solution and an NMF solution. The MXene was far more stable in the NMF than in water, per UV-Vis absorption spectroscopy and x-ray diffraction measurements. The change in sheet resistance of MXenes in water and NMF was also tested by Gogotsi’s group. The research team demonstrated that in NMF, the loss in electrical conductivity over the span of 15 days is significantly lower than the loss observed in water. For long term storage, it is clear NMF is a better option than water.

Despite the challenges the hydrophilicity of MXenes causes, Gogotsi’s group and others have discovered ways to mitigate or reverse the effects of water on MXenes. One method that can be used is removing the water by heating up the MXenes, which has been shown to restore some of the electrical conductivity of these materials. Another option is to use an inert atmosphere, such as an argon-rich atmosphere, to reduce the effects of oxygen and water on the surface of these materials. Controlling the stability in these materials opens doors for applications of MXenes.

Overall, Gogotsi’s work demonstrates how the stability of MXenes can be optimized by changing the synthesis and storage methods. Additionally, this work demonstrates the possible applications, from energy storage to use as inks. The properties of MXenes and the simplicity of their synthesis indicate that MXenes could provide a solution to challenges in energy storage technology.

The MRS Communications Lecture recognizes excellence in the field of materials research through work published in MRS Communications during the previous year.

2023 MRS Fall Meeting Best Poster Awards

Selected by the Meeting Chairs on the basis of the poster’s technical content, appearance, graphic excellence and presentation quality (not necessarily equally weighted).

Monday

Monday poster winners: Andrea Corazza (University of Basel), Fan Feng (The University of Melbourne), Xiaolin Guo (University of Louisville), Sangmin Song (Korea Institute of Science and Technology, Seoul National University), Taemin Kim (Korea Advanced Institute of Science and Technology). 

Tuesday

Tuesday  poster winners: Hyuk Jae (Gwangju Institute of Science and Technology), Ana Palacios Saura (Helmholtz-Zentrum Berlin für Materialien und Energie, Freie Universität Berlin), Anna Goestenkors (Washington University in St. Louis), Áine Coogan (Trinity College Dublin, The University of Dublin), Kayla Hellikson (Texas A&M University). 

Wednesday

Wednesday poster winners: Andre Niyongabo Rubungo (Princeton University), Ahyoung Jeong (Sungkyunkwan University), Marios Constantinou (University of Cyprus), Shawn Michael Maguire (Princeton University), Ross Kerner (National Renewable Energy Laboratory), Chenyang Shi (PNNL). 

2023 MRS Award Recipients – Lightning Talks and Panel Discussion

Written by Vineeth Venugopal

Moderated by Suveen Mathaudhu, Chair of the MRS Awards Committee, the 2023 MRS Fall Meeting featured a session of Lightning Talks and a panel discussion by the award recipients. This year's awards continued the tradition of recognizing both seasoned and emerging researchers in materials science. Mathaudhu encouraged the audience to nominate deserving individuals, particularly from underrepresented groups in the field. Each winner presented a 15-minute presentation of their work which was followed by a general panel discussion.

 

Delia J. Milliron, MRS Medal Recipient - The University of Texas at Austin

Delia J. Milliron, a distinguished researcher from The University of Texas at Austin, received the prestigious MRS Medal for her groundbreaking work in the development of optically tunable metal oxide nanomaterials. Her research focuses on the transformative application of these materials in creating energy-saving electrochromic windows. Milliron's work integrates the realms of nanotechnology and materials science to address crucial energy efficiency challenges. Her unique approach involves manipulating the optical properties of semiconductor nanocrystals, such as indium tin oxide (ITO), to control solar heat gain and visible glare in smart window applications. This technology not only promises significant energy savings in buildings but also paves the way for innovations in solar energy utilization and molecular detection.

 

Chris Van de Walle, Materials Theory Award Recipient - University of California, Santa Barbara

Chris Van de Walle, from the University of California, Santa Barbara, was honored with the Materials Theory Award for his exceptional contributions to understanding point defects and their impact on light emission in wide-bandgap semiconductors. His work involves meticulous ab initio methodologies, significantly advancing our comprehension of semiconductors' optoelectronic properties. His work accurately accounts for the emission behavior of green light-emitting diodes at high current densities by taking into account a special class of optical phenomena called the Auger-Meitner process. In addition, by accounting for multi photon processes, this work can be extended to other wavelengths. Van de Walle's research has far-reaching implications for improving the performance of solar cells, light-emitting diodes, and other optoelectronic devices. He has been instrumental in identifying new theoretical approaches, thereby providing novel insights into the behavior of materials and unlocking new potentials in semiconductor technology.

 

Qi Dong, MRS Nelson "Buck" Robinson Science and Technology Award for Renewable Energy Recipient - Purdue University

Qi Dong, incoming professor at Purdue University, was recognized with the MRS Nelson "Buck" Robinson Science and Technology Award for Renewable Energy for his innovative exploration of electrified methods in materials and chemical synthesis. His work is instrumental in leveraging renewable electricity to decarbonize industrial sectors. In postdoctoral work that made the cover of Nature, Dong demonstrated a reactor tube with internal carbon heating elements that vastly improved the efficiency and selectivity of chemical reactions. He showed that by applying pulsed currents high value chemical compounds could be selectively synthesized from methane. Dong's research includes the electrified synthesis of high-entropy micro- and nanoparticles, with potential applications in catalysis and energy storage. He also focuses on sustainable and energy-efficient approaches to convert macromolecules into valuable products, demonstrating significant advancements in processes such as methane pyrolysis and ammonia synthesis. Dong's contributions are crucial in addressing global energy and environmental challenges, marking a significant step toward sustainable chemical manufacturing.

 

Michael Saliba, The Kavli Foundation Early Career Lectureship in Materials Science Recipient - University of Stuttgart

The Kavli Foundation Early Career Lectureship in Materials Science was awarded to Michael Saliba from the University of Stuttgart. His research on the versatility of perovskite materials for optoelectronics has made a significant impact in the field. Saliba's talk highlighted the appeal of perovskite solar cells (PSCs), focusing on a high-quality multication model that promises robust materials with enhanced reproducibility and stability. He showed, for example, that by combining two, three, or four cations together, we end up with a library of 651 possible materials - that could potentially be explored in a high throughput manner. These compounds could be critical in overcoming the Shockley-Queisser limit which sets the theoretical maximum performance for solar cells. He underscored the importance of integrating polymeric protection layers at interfaces to boost the performance of PSCs. Saliba's work not only contributes to the advancement of solar cell technology but also sets a roadmap for extending multicomponent engineering to a diverse range of applications, marking a critical step in the evolution of photovoltaic materials.

 

Panel Discussion

During the engaging discussion session that followed their presentations, the panelists addressed a variety of questions from the audience. Saliba offered insightful observations on the current state of solar cell technology. He highlighted the remarkable affordability of silicon-based solar cells, now cheaper than bathroom tiles, underscoring the challenge other materials face in competing with silicon due to its economies of scale. With an annual production of 70 billion solar cells, silicon's dominance in the market is a significant hurdle for alternative materials. Dong responded to inquiries about the efficiency of his carbon filament-based reactors in manufacturing nanoparticles. He speculated that the rapidity of pulsed currents in the reactors likely prevented the atoms in the nanoparticles from becoming dislocated, thus contributing to their effectiveness.

A key question posed to all participants was the relevance of their work in addressing climate change. Saliba, Dong, and Van de Walle emphasized how their respective researches contribute to significant improvements in the efficiency of devices and chemical manufacturing processes. This enhancement, they noted, plays a crucial role in reducing the energy footprint across various industries. Milliron added a broader perspective to the discussion, suggesting that in addition to developing efficient technologies, it is vital to consider the overall energy consumption patterns. The panelists collectively agreed that addressing climate change requires a comprehensive socio-technological approach, underscoring the need for integrated solutions that encompass both technological advancements and societal changes.

MRS acknowledges the generosity of Dr. Gwo-Ching Wang and Dr. Toh-Ming Lu  in endowing the MRS Medal and the Materials Theory Award. MRS acknowledges the generosity of Sophie Robinson for endowing this award in memory of her father, Nelson "Buck" Robinson. The Kavli Foundation is dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work.

2023 Von Hippel Award

Reshef Tenne, Weizmann Institute of Science

Inorganic Nanotubes: From WS₂ to "Misfit" Layered Compounds

Written by Rahul Rao

On Tuesday evening, MRS bestowed its Von Hippel Award upon Reshef Tenne of the Weizmann Institute of Science. The Von Hippel Award rewards transcending the boundaries of conventional disciplines. Tenne spoke about some of the research that earned him the award: nanotubes grown with an ever-increasing variety of 2D materials.

In the early 1990s, not long after scientists first fashioned 2D carbon into nanotubes, Tenne and colleagues did the same with tungsten disulfide (WS₂) and molybdenum disulfide (MoS₂), whose structures contain one metal atom layer sandwiched between two layers of sulfur atoms. This configuration leaves dangling bonds at the edge that, when the compound is folded, are ripe for zipping up into nanotubes. These nanotubes are metastable and easy to make; three decades later, Tenne’s laboratory can spin out tungsten sulfide nanotubes that are as long as 500 µm.

Further research revealed that these nanotubes have some curious properties. For one, WS₂ nanotubes are very flexible and strong, capable of straining 10-12% without snapping. For another, although WS₂ and MoS₂ are indirect-bandgap materials, folding them into nanotubes shrinks the gap’s width and makes it direct.

 

 

Tenne discussed a few applications: WS₂ nanotubes are useful for reinforcing polymers; strong MoS₂ nanoparticles have already been commercialized as a heavy-duty lubricant. More recently, some of Tenne’s collaborators at the Beijing Institute of Technology have harnessed WS₂’s electro-optical properties to create a rudimentary artificial vision system: By applying different biases to WS₂ nanotubes, researchers created a 4 × 4 pixel grid that can capture a picture and store it in memory.

MoS₂ and WS₂ are hardly the only inorganic compounds that can form nanotubes. Tenne’s work also focuses on so-called “misfit” layered compounds, which contain alternating layers of a transition metal dichalcogenide (such as tantalum disulfide) and a rock salt (such as lead sulfide or lanthanum sulfide). The titular “misfit” comes from the fact that the dichalcogenide’s atomic structure does not align with the rock salt’s. As a result, one type of layer tends to expand while the other type contracts, encouraging the material to fold.

Tenne and his colleagues have, in the past decade, been able to create all kinds of misfit-compound nanotubes. They are now focusing on these nanotubes’ properties, like their chemical selectivity, stability, and electrical conductivity. For instance, nanotubes created from tantalum disulfide and samarium sulfide show superperiodicity between zigzag and armchair lattices in their layers; they also elegantly transition into superconductors at low temperatures.

Tenne received the Von Hippel Award for “spearheading modern research on nano-2D materials through the discovery of nanotube- and fullerene-like inorganic layered compounds.”

The Von Hippel Award, the Materials Research Society's highest honor, recognizes those qualities most prized by materials scientists and engineers—brilliance and originality of intellect, combined with vision that transcends the boundaries of conventional scientific disciplines.

2023 David Turnbull Lectureship

Mark Asta, University of California, Berkeley, and Lawrence Berkeley National Laboratory

Concentrated Alloys: Order, Disorder, and the Vast Space in Between

Written by Elizabeth Wilson

Concentrated alloys – materials that contain several or more different atoms in similar proportions – were only a curiosity when they were hypothesized decades ago. Scientists began synthesizing them less than 20 years ago.

In the past decade, interest in these concentrated alloys has exploded. Mark Asta has been developing theories that illuminate and predict these materials' behaviors.

“What made field take off is that we started to learn as a community that these materials had very special properties not seen in simpler materials,” Asta said at the MRS meeting in Boston, where he received the David Turnbull Lectureship Award.

They have potential use as ceramics, catalysts, and in extreme environments. For example, CrCoNi at low temperatures has among highest fracture toughness ever observed. “It's just shocking this happens because it's such a simple material,” said Asta.

His research focuses on the crucial phenomenon of short-range order (SRO) that arises randomly in atomic clusters. Though these small spots of order in the disordered bulk material are on the scale of nanometers, their effects can be far reaching.

 

 

For example, in semiconductor alloys, changes in short range order can change bonds and have big effects on band structure and electronic properties of a material.

These effects are not always desirable. They can, for instance, interfere with processes that reduce alloy corrosion. If a substance begins to corrode an alloy, atoms can percolate through the alloy and form a protective film. But in these concentrated alloys, ordered groups of atoms can spring up, blocking the percolation and inhibiting the film formation.

Asta described molecular dynamics simulations of CrCoNi, which explained how the energies of atoms involved in SRO enhanced the strength of the alloy.

Machine learning and databases generated from high-throughput experiments will play roles in expanding scientists’ understanding of these new exciting materials, Asta said. “If we want to progress, we need more theory.”

Asta was awarded the David Turnbull Lectureship for “seminal contributions to theory, computational modeling, and education on the structural, thermodynamic, and kinetic properties of phases, surfaces, and interfaces of materials.” Read more about Asta’s research in a recent issue of MRS Bulletin.

The David Turnbull Lectureship recognizes the career contribution of a scientist to fundamental understanding of the science of materials through experimental and/or theoretical research. In the spirit of the life work of David Turnbull, writing and lecturing also can be factors in the selection process.

2023 Innovation in Materials Characterization Award

Franz Giessibl, University of Regensburg, Germany
Atomic Force Microscopy 3.0

Written by Sophia Chen

Franz Giessibl is the 2023 recipient of the Innovation in Materials Characterization Award. Over more than three decades, the physicist at University of Regensberg in Germany has worked to develop and popularize the technology known as the atomic force microscope (AFM), which has allowed materials scientists to characterize subatomic such as the shape of electron clouds. “As far as I know, it [has] the best spatial resolution of any microscopy,” Giessibl says.

But it took just about Giessibl’s entire career so far for the field to achieve subatomic resolution. He delivered a virtual presentation tracing the evolution of the technology. Giessibl began working on AFM as a graduate student at ETH Zürich under Nobel laureate Gerd Binnig, who won the prize for co-inventing the scanning tunneling microscope. (Giessibl chose atomic force microscopy over Binnig’s other two suggested research topics, gravitational waves or sequencing DNA using the scanning tunneling microscope. “What project would you have chosen?” he asked the audience.)

Binnig had co-invented the AFM in 1986, just prior to Giessibl joining his team. The microscope images a material by scanning the surface with an extremely fine tip on the end of a cantilever. Early models of the microscope used silicon as a cantilever material and could not achieve atomic resolution, Giessibl said. It also used a piezoresistive material that required significant electric current, and thus produced heat, to sense motion in the tip. This presented a technical challenge, as researchers were interested in studying materials in a cryogenic setting.

The field grew in the 1990s, with Seizo Morita of University of Osaka starting the International Conference on Non-contact Atomic Force Microscopy, which is still held today. Still, Giessibl noted that atomic force microscopes didn’t sell, with only about 80 sold worldwide at the time. During that time, he pivoted to management consulting at McKinsey in Germany to try to understand the business aspects.

During his time at McKinsey, Giessibl began to develop what is now the QPlus sensor, a new type of force sensor for the AFM. Instead of a silicon cantilever, the QPlus uses a quartz one. Instead of piezoresistive material, they use piezoelectric material, which doesn’t heat up as prior models. In addition, the QPlus sensor converts the surface of the material into a vibration.

In the early 2000s, more groups began to develop this new type of microscope with a stiffer probe. Giessibl noted that it was easier to convince scientists from the scanning electron microscopy field than from atomic force microscopy. In 2008, Giessibl and his colleagues measured the force it took to push a single atom. In 2009, Leo Gross of IBM and his team discovered that adding a carbon monoxide molecule of the tip improved the resolution.

At the end of the talk, Giessibl showed the progression in the AFM’s imaging capability with a series of photos from 1995 to 2015. There are now more than 400 atomic force microscopes with QPlus sensors worldwide, he said. He noted that the field has finally demonstrated subatomic imaging in 2015 and 2019, and that he is now working on achieving ultrafast time resolution with atomic force microscopy.

The Innovation in Materials Characterization Award has been endowed by Gwo-Ching Wang and Toh-Ming Lu.