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Ferroelectric-Hafnia-Singh

Musfeldt Leverages Pressure for Future Energy Storage

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A group of researchers including Jan Musfeldt, Ziegler professor of chemistry at the University of Tennessee, recently published in the Proceedings of the National Academy of Sciences (PNAS). The article details the discovery that pressure can be used to create and control the phase and properties of hafnia.

Hafnium oxide, or hafnia, is a material that has interested researchers for many decades. Highly insoluble and temperature stable, hafnia has been leveraged in applications as diverse as optical coatings for glasses and camera lenses, fuel cells, and passive building insulation. Advanced electronics and energy storage applications are, however, generating the most excitement.

Since 2007, amorphous hafnia thin films have been employed as gate dielectrics in CMOS technology, enabling the continuation of Moore’s scaling of DRAM chips. Ferroelectricity and silicon compatibility make hafnia an attractive candidate for nonvolatile ferroelectric FET devices as well as negative capacitance heterostructures. Recent break-throughs impacting the development of advanced chip technologies include the discovery of flat phonon bands and their connection to the energy landscape in the vicinity of the polar phase and the incredibly rich variety of competing phases in crystalline thin films of hafnia.

“I love this project!” said Musfeldt. “It brings together the fundamental science of phase competition under external stimuli and work at the Frontier Infrared Spectroscopy beamline at the National Synchrotron Light Source II with the growth of whole families of high-quality single crystals and complementary first-principles theory to predict phase stability, signatures, and properties. It’s also a great chance to work with friends from Rutgers, Rochester, and Brookhaven.”

One challenge in this field involves the use of very high temperature laser floating zone and rapid quenching process of the crystal growth combined with an yttrium stabilizer in concentrations of up to 20%. While effective, the high levels of yttrium used impacts the purity of the material, which in turn affects performance.

Musfeldt and her collaborators wanted to investigate an alternative means of creating the various phases of hafnia using less stabilizer. They settled on compression (or pressure) as a technique with the potential to do the job. The fact that pressure changes bond lengths and angles provides access to exciting new and stable phases of materials. A similar approach was used in the development of synthetic diamonds.

Hafnia crystal photographed by Jan Musfeldt.

Musfeldt’s team, including post-doctoral researcher Yanhong Gu, conducted a series of experiments using pressure to coax hafnia into the desired antiferroelectric phase. They found that not only did this method work, but the material also remained stable once pressure was removed. Repeated analysis of the product led them to conclude that the material was indefinitely stable at room temperature.

“The material remains stable both with time and through high-temperature annealing,” said Gu.

In addition to showing that compression was a suitable means of achieving a stable antiferroelectric state in hafnia, Musfeldt’s team also confirmed this “pressure-induced chemical reaction” could be done at room temperature with 36% less yttrium stabilizer than previously required by high temperature growth techniques.

“Reducing the among of yttrium stabilizer is crucial to preserving the fundamental performance of these materials”, says Musfeldt.

At the same time, the team was able to use even higher pressures to create the tetragonal form of hafnia. This phase had been theoretically predicted to exist but never confirmed until now.

To identify these previously elusive phases, Musfeldt’s team used predictions developed by her collaborators at the University of Rochester and Rutgers University. Sobhit Singh, David Vanderbilt, and Karin Rabe specialize in computationally predicting the properties of materials. They calculated that compression could be used to stabilize both the antiferroelectric and tetragonal forms of hafnia as well as the vibrational fingerprints that were matched with the experimental measurements.

This figure from the publication summarizes the pressure pathways and various phases of hafnia, including the theorized tetragonal phase, confirmed by Musfeldt.

“Our first-principles calculations unambiguously predict the phase transition from the mixed-phase structure to the desired pure-metastable phase of hafnia at pressures above 6 GPa,” said Sobhit Singh, co-author and assistant professor at the University of Rochester.

“It’s exciting when theory and experiment dovetail so beautifully”, says Musfeldt.

PNAS is one of the world’s most-cited and comprehensive multidisciplinary journals. The full article can be found here. 

Feature image courtesy of Sobhit Singh, University of Rochester.

Jones Receives the NVIDIA GPU Award for Best GPU Poster

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Grier Jones Award

Grier Jones, fifth year chemistry PhD student, won a poster competition at the spring meeting of the American Chemical Society (ACS). His poster, titled “Exploring the topology of electronic correlation with graph neural networks” earned the NVIDIA GPU Award for Best GPU Poster. The award targets excellent computational chemistry research using a graphical processing unit (GPU). 

GPUs are most often associated with the high-quality images seen on gaming computers. However, the highly parallelized architecture of GPUs offers an acceleration platform that can outperform central processing units (CPUs) when processing large amounts of data in parallel. This has implications for scientific computing and machine learning applications, which have traditionally used CPUs.

Jones has developed a novel computational model that incorporates GPUs with graph neural networks (GNNs) and topological data analysis (TDA) to explore the topology of electron correlation. Jones notes this project is unique in that it allows him and fellow researchers to look at electron correlation in the context of machine learning from a new perspective.  

Jones joined the UT Department of Chemistry as a graduate student in 2018. He began working with Associate Professor Konstantinos Vogiatzis, whose lab and research group supported Jones and helped develop the work featured in his award-winning poster. 

“It was amazing to win this award because there are many successful scientists in our field, a few of which I know personally, that have won this award,” Jones said. He went on to express his gratitude for the Graduate Student Senate Travel Award and Vogiatzis’ NSF-CAREER award, which made it possible for him to participate in the ACS Spring 2023 meeting and the poster competition. 

Shortly after winning the poster award, Jones was also named a Gleb Mamantov Graduate Chemistry Scholar by the Department of Chemistry. The poster award, which provided a professional workstation-level NVIDIA GPU, and the Mamantov prize allowed Jones to build an exceptional PC.

“I am very grateful for both awards because building my own PC was a dream come true that I did not think I was going to be able to do until after graduate school,” said Jones. “I have it set up for both work-related computational tasks, which I run daily, and Windows, which lets me edit documents with Microsoft Office and do some gaming.”

Jones’ research was developed with GPUs provided by the Infrastructure for Scientific Applications and Advanced Computing (ISAAC) cluster at UT. Jones described the opportunities and support available at the university as a great environment that has contributed to his intellectual growth and academic exploration. 

Prior to joining the chemistry department at UT, Jones earned his undergraduate degree at the College of Charleston, where he became very passionate about computational science as it applies to machine learning and chemistry. Pursuing the Interdisciplinary Graduate Minor in Computational Science and working with Vogiatzis has allowed him to continue exploring these research areas. 

“Professor Vogiatzis has really pushed me to new heights, while allowing me to integrate my passions into our projects. I would say this is exactly what any student would want from their graduate school experience; freedom, intellectual satisfaction, and recognition of their achievements,” said Jones. 

Since joining the university, Jones has co-authored three publications in journals such as the Journal of Physical Chemistry Letters and Inorganic Chemistry Frontiers, and has contributed to the book, Molecular Representations for Machine Learning.

Welcome New Department Members

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The Department of Chemistry welcomed two new faculty members and one new lecturer for the academic year 2023-2024. The new additions bring our department up to 24 faculty members and 10 lecturers, and will expand both our research and teaching capacity.

Yingwen Cheng – Assistant Professor, Analytical Chemistry

Yingwen Cheng earned dual bachelor’s degrees in chemistry and chemical engineering from Shandong University, China, and a PhD in chemistry from Duke University. After completing his postdoctoral training at the Pacific Northwest National Laboratory, he began his academic career at Northern Illinois University as an assistant professor in 2018. He is a recipient of the Doctoral New Investigator Award from the American Chemical Society Petroleum Research Fund, and was featured as an Emerging Investigator by journals Nanoscale and Energy & Fuels. Cheng’s research aims to develop new chemical principles to explain and control electrochemical processes for inter conversion of electrical and chemical energy. The results of this work contribute to electricity-driven chemical manufacturing and renewable electricity storage for transportation and smart power grids. 

Brendon McNicholas – Assistant Professor, Inorganic Chemistry

Brendon McNicholas completed his bachelor’s degree in chemistry at the University of California, Berkeley in 2014. While at Berkeley, he conducted undergraduate research in Professor John Arnold’s group. In 2020, he earned his PhD in physical inorganic chemistry from the California Institute of Technology in Pasadena while working in the research groups of Professors Harry Gray and Robert Grubbs. After a four month postdoctoral appointment in Gray’s group, he accepted a Resnick Postdoctoral Scholar position at CalTech in 2020 with the research group of Professor Ryan Hadt. McNicholas’s research lab uses spectroscopic and electrochemical techniques to develop and characterize next-generation energy conversion and storage technologies. McNicholas is also engaged in the development of more efficient and stable catalysts for small molecule reduction and oxidation, specifically those related to photoelectrochemical water oxidation, fuel cell technology, CO2 reduction, and N2 fixation.

Amanda Clune – Lecturer

Originally from Haymarket Virginia, Amanda Clune completed her bachelor’s degree in chemistry at Hofstra University in 2013.  While at Hofstra, she conducted research under Nanette Wachter. In 2021, she obtained her PhD in physical chemistry in the research group of Janice Musfeldt from UT. Shortly after, she served as a Visiting Associate Professor of Chemistry at Miami University from 2021 until 2023.  

Nobel Laureate Visits UT

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Shrock

This past spring, the Department of Chemistry co-hosted a lecture featuring Nobel Laureate Richard R. Schrock. Schrock was invited as part of the East Tennessee chapter of the American Chemical Society’s S.C. Lind Lecture Series, which is designed to bring exceptional scientists and researchers to East Tennessee. 

Richard Schrock received the Nobel Prize in Chemistry in 2005 for his work on “the development of the metathesis method in organic synthesis.” In 1990 Schrock successfully produced a metallic compound that aids in metathesis, a process that has contributed to more effective and environmentally sound practices in industry. Schrock shared this award with Yves Chauvin and Robert H. Grubbs.

In his lecture, “How Molybdenum and Tungsten-Based Olefin Metathesis Catalysts are formed from Olefins,” Schrock addressed how heterogeneous and homogeneous alkylidene complexes are formed from olefins. 

More than 100 students and faculty members from the Department of Chemistry, the university, and the East Tennessee chapter of the ACS were in attendance. Following the lecture, Schrock answered questions and engaged with students one-on-one, providing a unique opportunity for graduate students to discuss research with an internationally renowned scientist.

Schrock earned his PhD from Harvard University, followed by a postdoctoral appointment at the University of Cambridge. In 1975 he joined the faculty at the Massachusetts Institute of Technology (MIT), and became a full professor in 1980. Schrock was named the Frederick G. Keyes Professor of Chemistry at MIT in 1989 and is now Professor Emeritus. In 2019, he joined the faculty of his alma mater, the University of California, Riverside, where he is now the Distinguished Professor and George K. Helmkamp Founder’s Chair of Chemistry.

Selected Faculty Updates and Publications for Fall 2023

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Bhavya Sharma, associate professor, was recently awarded a grant by the Wellcome Leap Foundation as part of a $50 million initiative to investigate improved treatment of depression through biologically-matched strategies. 

Grier Jones, fifth year chemistry PhD student, and Associate Professor Konstantinos Vogiatzis recently published a new data-driven quantum chemistry method, based on the reduced-density matrix (RDM) formulation of quantum mechanics, in the Journal of Physical Chemistry Letters. This publication was developed in collaboration with University of Tennessee, Knoxville alumnus Professor A. Eugene DePrince (’05) and his research group at Florida State University.

The Jenkins Lab published their research “Giving Gold Wings: Ultrabright and Fragmentation Free Mass Spectrometry Reporters for Barcoding, Bioconjugation Monitoring, and Data Storage” in the international journal Angewandte Chemie. Graduate students Isabel Jensen and Gurkiran Kaur were co-authors on the piece. The Jenkins Lab also published their research “Statistical copolymer metal organic nanotubes” in the journal Chemical Science. Graduate student Jacob Barrett co-authored the publication.

Tessa Calhoun recently published “Facilitating flip-flop: Structural tuning of molecule-membrane interactions in living bacteria” in Biophysical Journal. The article investigates how the structure of small molecules impacts their initial adsorption and eventual desinations within membranes in the context of living cells.

Professor Janice Musfeldt and graduate student Kevin Smith were recently featured by Lawrence Berkeley National Laboratory for their work with the Advanced Light Source (ALS). The highlight described the work in their paper entitled “Real-Space Infrared Spectroscopy of Ferroelectric Domain Walls in Multiferroic h-(Lu,Sc)FeO3” published in ACS Applied Matter Interfaces.

Associate Professor of Chemistry Konstantinos Vogiatzis, in collaboration with Professor of Mathematics Vasileios Maroulas and Eastman Chemical Company, has published a new machine learning model for predicting the properties of new polymeric materials. Their publication “Polymer graph neural networks for multitask property learning” in npj Computational Materials details the development of the open access machine learning architecture.

Assistant Professor Joshua Baccile recently published “Membrane Permeant Analogs for Independent Cellular Introduction of the Terpene Precursors Isopentenly- and Dimethylallyl-Pyrosphate” in the journal ChemBioChem. This publication was co-authored by visiting scientist Frank M. Rossi, graduate students Dillon McBee, Thomas Trybala, and Zackary Hulsey. REU student Camilla Gonzalez Curbelo and undergraduate student William Mazur were also contributing authors.

This spring Johnathan Brantley, assistant professor, published his article “Exploring the influence of rigid carbocycles on terpenoid copolymer properties” in the Journal of Polymer Science. His article investigates the use of terpenoid materials in addressing the grand challenge of enhancing understanding of the relationship between structure and properties in macromolecules. 

Assistant Professor Ampofo Darko’s publication “Effects of Tethered, Axially Coordinated Ligands (TACLs) on Dirhodium (II,II) Catalyzed Cyclopropanation: A Linear Free Energy Relationship Study” was recently featured in a Virtual Issue. This issue was presented by The Journal of Organic Chemistry, Organic Chemistry Letters, Inorganic Chemistry, Organic Process Research & Development, and Organometallics to highlight the work of early-career researchers. Those included in the issue were nominated by the Editors and Editorial Advisory Board members of the participating journals, and leaders of the ACS Division of Organic Chemistry and Division of Inorganic Chemistry. Researchers were selected based on the quality and novelty of their research, the contributions made during their careers thus far, and their potential to influence the future of chemistry. 

Thanh Do and graduate students Damilola Oluwatoba and Miranda Limbach recently published “Self-Assembly of Cysteine into Nanofibrils Precedes Cystine Crystal Formation: Implications for Aggregation Inhibition” in ACS Appl. Mater. Interfaces. The article explores the relationship between CYS-forming amyloid fibrils and hexagonal CTE crystals. 

Fred Heberle and graduate student Emily Chaisson recently published “Building Assymmetric Lipid Bilayers from Molecular Dynamics Simulations: What Methods Exist and How to Choose One” in the journal Membranes. The article discusses the underlying source of discrepancies in protocols used for creating asymmetric bilayer models. 

Michael Best recently accepted the position of Associate Head of Undergraduate Education in the Department of Chemistry. He replaces David Jenkins, who has stepped down in order to focus on his well-funded research program. Best previously managed the department’s REU program. This year he returned to his alma mater, the University of Texas at Austin, to deliver a Distinguished Alumni Lecture. 

Brian Long published “Atomic Level Interactions and Suprastructural Configuration of Plant Cell Wall Polymers in Dialkylimidazolium Ionic Liquids” in the journal Biomacromolecules. The publication featured the work of a team of UT researchers from Chemistry, the UT Center for Renewable Carbon, and the School of Natural Resources, as well as Oak Ridge National Laboratory and the USDA-Forest Service.

Professor Bin Zhao published “Crystallization-driven Nanoparticle Crytsalsomes” in Angewandte Chemie. The article describes a bottom-up approach for fabricating spherical gold nanoparticle assemblies that mimic colloidosomes.

Chemistry Undergraduates Named Volunteers of Distinction

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Two undergraduate chemistry students were named 2023 Volunteers of Distinction. Drake Robins and Clay West were nominated by faculty members and joined the ranks of students from across the university being honored.

Drake Robins was a fourth-year senior studying analytical chemistry when he received the award. He is a member of the Air Force ROTC and has been working in Associate Professor Bhavya Sharma’s lab since his junior year. Robins expressed his gratitude for the award and his time at UT.

“Academics and research have always been a top priority for me throughout my time at UT, and I feel extremely blessed to be recognized for it this close to graduation,” said Robins.

Robins has since graduated and was commissioned into the United States Air Force as a 2nd Lieutenant. After the summer, Robins plans to attend Undergraduate Pilot Training at Columbus Air Force Base in Mississippi. 

Clay West, also a fourth-year senior when he received his award, was a student in the department’s American Chemical Society certified bachelor’s degree program. West stated he was grateful to receive the Volunteer of Distinction Award and considers it to be a reflection of the work he has put into earning his degree.

Prior to graduation, West participated in the department’s annual Undergraduate Research Symposium, where he presented research conducted under the supervision of Professor Shawn Campagna. West plans to spend the next year applying to graduate schools and preparing to pursue a PhD in organic chemistry. 

The Volunteer of Distinction Awards were created in 2021 by the university to recognize students across campus who exhibit extraordinary academic achievement, professional promise, or excellence in research. Previous award winners from the chemistry department include Maggie Eslinger, Hannah Hagewood, Elijah Hix, Galvin McCarver, and Wilson Wang.

Polymer

UT Leads World in Polymer Science

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From your clothing to the fiber-optic cables bringing you high-speed internet, polymers are everywhere, with applications in nearly all fields of science and industry. Polymer science plays a crucial role in providing solutions to global needs including food, clean and abundant water, air, energy, and health.

Researchers at the University of Tennessee, Knoxville, in fields including chemistry, physics, chemical engineering, biosystems engineering, and forestry are investigating polymers through a variety of fundamental scientific problems with real-world impact—from designing and creating new advanced materials to improving industrial processes to creating sustainable biofuels.

As an indication of the significance of their work, UT has been ranked the top global university for polymer science in U.S. News and World Report’s Best Global Universities. The ranking is based on research performance from 2015 through 2019 as well as citations from publications through April 29, 2021.

Polymer science research within UT’s College of Arts and Sciences includes work being conducted by the research group of UT-ORNL Governor’s Chair for Polymer Science Alexei Sokolov. The team is advancing fundamental understanding and design of novel polymeric materials for various current and future technologies—from gas separations and carbon capture to 3D printing.

Sokolov’s group also works on polymer electrolytes for use in new generations of solid-state batteries and other energy storage technologies.

“We are working on polymers with dynamic bonds that are recyclable and have self-healing ability,” said Sokolov. “These polymers might replace current plastics and drastically reduce pollution.”

A segment of a bulky polymer chain, polynorbornene, showing elements of carbon (in black), oxygen (in red), silicon (in green), and hydrogen (in white). This unique polymer is one of several developed by Associate Professor Brian Long’s research group to study advanced gas separation membranes.

An illustration of a unique polymer chain, polynorbornene, that was developed by Associate Professor Brian Long’s research group to study advanced gas separation membranes.

Another area of focus, led by the research group of Associate Professor of Chemistry Brian Long, is creating new synthetic materials to separate greenhouse gases such as carbon dioxide from nonharmful gases in a more energy-efficient and cost-effective manner. This research has shown tremendous promise, with implications for reducing industrial greenhouse gas emissions.

“Think about what your body is touching right now—your clothing, your chair, your phone or computer. What are you touching that’s not a polymer or that doesn’t contain polymers? Polymers have provided solutions to almost every societal need in modern human history—even the DNA, RNA, and proteins in our body are polymers,” said Long.

Researchers at UT are even tackling one of the most pressing global needs today—how to minimize or eliminate waste plastics in the environment. For example, research efforts led by Professor Mark Dadmun and Assistant Professor Johnathan Brantley seek to develop new chemical methods to aid recycling of waste plastics, improve the properties of new products and materials made from mixed plastic waste streams, and create a circular plastics economy.

Commenting on the announcement of the ranking, Vice Chancellor for Research Deborah Crawford said, “Our researchers deserve this recognition for their work advancing our understanding of polymers and how they can contribute to making life and lives better. At UT, our commitment is to contribute to the creation of a more just, prosperous, and sustainable future through world-class research and scholarship. Our polymer scientists and engineers are doing just that!”

About the ranking

The polymer science ranking is determined by 10 indicators, including the impact of citations and research publications. Impact is calculated based on data from the Clarivate Web of Science, a web-based research platform. The Web of Science is a web-based research platform that covers more than 21,100 of the most influential and authoritative scholarly journals worldwide in the sciences, social sciences, and arts and humanities.

water jug

UT Professors Investigate Solutions for “Forever Chemicals”

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University of Tennessee, Knoxville faculty members Shawn Campagna, professor and associate department head in chemistry, and Frank Loeffler, Governor’s Chair professor in microbiology, have made a discovery that could lead to new capabilities for managing environmental contamination.

Commercially used per- and polyfluoroalkyl substances (PFAS) were developed in the 1940’s and made their way into a variety of common household products. Today, PFAS are used for plastic and rubber manufacturing and in food wrappers, umbrellas, firefighting foam and more.

PFAS have also been called “forever chemicals” due to their resistance to breaking down in both the environment and the human body. PFAS have been discovered lingering in rivers, Arctic sea ice, human breast milk and in the blood of 97% of Americans. Most troublesome is their potential impact on human health and PFAS have been linked to metabolic disruption, obesity, diabetes, immune suppression, and cancer.

Loeffler and Campagna’s work, recently published in Environmental Science and Technology, explores a potential avenue for decreasing broad contamination with these chemicals. Their team found that a naturally occurring soil bacterium, Pseudomonas sp. strain 273, was capable of degrading and detoxifying 1,10-difluorodecane, a fluorinated compound that could be a model for dealing with PFAS. Surprisingly, this bacterium was also able to use the fluorine containing byproducts to build lipid bilayers, or cellular membranes, which indicates that we don’t yet know all that we should about the fate of this type of compounds in biological systems.

“This research is important since fluorinated organic chemicals are emerging contaminants, and we do not yet know how and if they enter the food web,” said Campagna. “The fact that bacteria can incorporate breakdown products of these molecules into their biomass indicates that we don’t fully understand the environmental impact of these contaminants.”

This discovery developed from a long-standing series of collaborations between Campagna and Loeffler and leverages the capabilities of both the Center for Environmental Biotechnology and the Biological and Small Molecule Mass Spectrometry Core.

“There is a pressing need to demonstrate that natural degradation processes for PFAS exist – that they are not forever chemicals,” said Loeffler. “The new findings emerged through collaborative efforts at the interface of disciplines, specifically environmental microbiology and analytical chemistry. My group obtained and characterized the unique microorganism, and Dr. Campagna’s group had the instrumentation and expertise to perform the analytical procedures. The results are a product of teamwork and neither group individually would have succeeded.”

Campagna and Loeffler hope their work can lead to further discoveries of bacteria capable of degrading the entire range of fluorinated pollutants, which could lead to removing PFAS from contaminated areas like drinking water.

As part of the bipartisan infrastructure law funding initiative, the U.S. Environmental Protection Agency is making available $1 billion in grant funding, the first of $5 billion through the law. This initiative aims at reducing PFAS in drinking water specifically in communities facing disproportionate impacts.

Both Loeffler and Campagna have been contacted by the Tennessee Department of Environment and Conservation (TDEC) regarding state mandated PFAS monitoring in drinking water. Their capabilities are facilitating statewide efforts to improve the quality of life for all residents of the state of Tennessee.

Brantley Group Published in JACS

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The Brantley group recently published a paper in JACS entitled “Electroediting of Soft Polymer Backbones” Alan Fried, Breana Wilson, and Nick Galan contributed to the research, under the supervision of Johnathan Brantley.

The paper discusses new methodology for degradation and functionalization of olefin-containing polymers through electrochemistry. This method can be carried out in both homogeneous and heterogeneous systems, in addition to using mild conditions and being experimentally simple.

The work was completed in memory of Alan Fried.