Welcome to the 3D Materials Lab. We use computational tools, including first-principles methods and machine learning, to discover and design functional materials for energy conversion and storage, next-generation microelectronics, and environmental sustainability. We are based at the Rensselaer Polytechnic Institute (Troy, New York) and the National Renewable Energy Lab (Golden, Colorado). Find out the current openings in our team: Openings
Materials Discovery
Materials Design
Inverse Design
Our research and outreach activities are funded by the National Science Foundation, U. S. Department of Energy (Basic Energy Sciences), Advanced Research Projects Agency–Energy (ARPA-E), National Renewable Energy Laboratory and Rensselaer Polytechnic Institute.
News
Victoria Bradford Wins First Place in Mines NSF-REU Poster Session
Victoria Bradford (from University of Connecticut) ended her summer on a high note, winning first place in the Colorado School of Mines NSF-REU poster session! Congratulations, Victoria! Watch out for some exciting results she will be publishing soon and presenting at conferences. She was blessed with two excellent mentors – Cheng-Wei Lee and Thi Nguyen Xuan. It was joy to see them come together as a team to test a new idea we have been exploring within the realm of wurtzite ferroelectrics. The project was partly funded by our National Science Foundation (NSF) DMREF award.
Defects and Oxygen Impurities in Ferroelectric Wurtzite Al1-xScxN Alloys
It is useful to think of crystalline materials as ideal, periodic structures, but in reality, they contain native and extrinsic defects, e.g., dopants. There is ample evidence on the influence of defects on the ferroelectric behavior in oxide perovskites and fluorites. In this study, we begin to understand the defect makeup and their effect on the ferroelectric properties of wurtzite (Al,Sc)N alloys. Contrary to the general belief that defects are “bad”, we find that native defects (e.g., nitrogen vacancy) and impurities (e.g., oxygen) may, in fact, facilitate polarization switching! Published in Applied Physics Letters.
Chemistry of Materials Lectureship and Best Paper Award 2023
Prashun received the 2023 Chemistry of Materials Lectureship and Best Paper Award at the ACS Spring Meeting in New Orleans (March 2024). He and his collaborators received this award for their paper “Devil is in the Defects: Electronic Conductivity in Solid Electrolytes” published in Chemistry of Materials. Read the interview editorial published in ACS Axial.
Michael Toriyama Defends His PhD Thesis
Dr. Michael Toriyama, from Jeff Snyder’s group at Northwestern University and co-advised by Prashun, defended his PhD thesis in June 2024. Michael has positively impacted our research group in more than one way. He did some amazing work, from defect chemistry of thermoelectric materials to discovery of low-temperature thermoelectrics and topological insulators. But what’s more amazing is his willingness to be a team player and helping others along the way! We are certain that Dr. Toriyama will go on to become a future star!
Switching it up: New Mechanisms Revealed in Wurtzite-type Ferroelectrics
Polarization switching in wurtzite-type ferroelectrics is more complex than initially thought, involving multi-barrier transitions. We revealed fundamentally new polarization switching mechanisms in wurtzite-type materials. We found that the switching in tetrahedrally-coordinated materials proceeds via a variety of non-polar intermediate structures. We unveiled two distinct mechanisms – collective and individual, with the latter associated with lower switching barriers (coercive fields). Paper published in Science Advances.
Defect Control Strategies for Al1-xGdxN Alloys
Tetrahedrally-bonded III-N and related alloys are useful for a wide range of applications, from optoelectronics to dielectric electromechanics. In this study, we investigate the native point defects and unintentional impurities in Al1-xGdxN alloys. We find that thin-film growth under N-rich conditions will reduce the concentration of deep defects – desired for optoelectronic, and piezo- and ferro-electric applications. Paper published in J. Applied Physics as part of a special collection on Defects in Semiconductors.
Emerging Materials and Design Principles for Wurtzite-type Ferroelectrics
Low-energy compute-in-memory architectures promise to reduce the energy demand for computation and data storage. Wurtzite-type ferroelectrics are promising options for both performance and integration with existing semiconductor processes. (Al,Sc)N alloy is among the few wurtzite-type materials that exhibit polarization switching, but the coercive field required to switch the polarization is too high (few MV/cm). To address this, we performed a large-scale computational search of multinary wurtzite-type compounds and identified four promising ternary nitrides and oxides. Our results disproved the existing design principle to lower coercive field by reducing the wurtzite c/a lattice parameter ratio. We identified two fundamental materials parameters – ionicity and bond strength – that influence the coercive field. Paper published in Matter.
Defect Chemistry and Doping of Lead Phosphate Oxo Apatite Pb10(PO4)6O
Failed experimental attempts to reproduce room-temperature superconductivity in LK-99 i.e., Cu-doped Pb10(PO4)6O, raised many questions about the reported composition, possible off-stoichiometry, and incorporation of unintentional dopants. Using first-principles defect calculations, we provide useful insights to answer these questions. We also predict high levels of unintentional sulfur incorporation in lead phosphate oxo apatite. Paper published in ACS Energy Letters. Preprint on ChemRxiv.