In this MRS TV interview from the 2017 MRS Spring Meeting, Jennifer Dionne and James Rondinelli discuss the work behind their awards.
Inside Out—Visualizing Chemical Transformations and Light-Matter Interactions with Nanometer-Scale Resolution
In Pixar’s Inside Out, Joy proclaims, “Do you ever look at someone and wonder, what’s going on inside?” My group asks the same question about nanomaterials whose function plays a critical role in energy and biologically-relevant processes. This presentation will describe new techniques that enable in situ visualization of chemical transformations and light-matter interactions with nanometer-scale resolution. We focus in particular on i) ion-induced phase transitions; ii) optical forces on enantiomers; and iii) nanomechanical forces using unique electron, atomic, and optical microscopies. First, we explore nanomaterial phase transitions induced by solute intercalation, to understand and improve materials for energy storage applications. As a model system, we investigate hydrogen intercalation in palladium nanocrystals. Using environmental electron microscopy and spectroscopy, we monitor this reaction with sub-2-nm spatial resolution and millisecond time resolution. Particles of different sizes, shapes, and crystallinities exhibit distinct thermodynamic and kinetic properties, highlighting several important design principles for next-generation energy storage devices. Then, we investigate optical tweezers that enable selective optical trapping of nanoscale enantiomers, with the ultimate goal of improving pharmaceutical and agrochemical efficacy. These tweezers are based on plasmonic apertures that, when illuminated with circularly polarized light, result in distinct forces on enantiomers. In particular, one enantiomer is repelled from the tweezer while the other is attracted. Using atomic force microcopy, we map such chiral optical forces with pico-Newton force sensitivity and 2 nm lateral spatial resolution, showing distinct force distributions in all three dimensions for each enantiomer. Finally, we present new nanomaterials for efficient and force-sensitive upconversion. These optical force probes exhibit reversible changes in their emitted color with applied nano- to micro-Newton forces. We show how these nanoparticles provide a platform for understanding intra-cellular mechanical signaling in vivo, using C. elegans as a model organism.
About Jennifer Dionne
Jennifer Dionne is an associate professor of materials science and engineering at Stanford University. Jen received her Ph.D. degree in Applied Physics at California Institute of Technology, advised by Harry Atwater, and B.S. degrees in Physics and Systems & Electrical Engineering from Washington University in St. Louis. Prior to joining Stanford, she served as a postdoctoral researcher in chemistry at the University of California, Berkeley, advised by Paul Alivisatos. Dionne’s research develops new nano and optical materials for applications ranging from high-efficiency energy conversion and storage to bioimaging and manipulation. This research has led to demonstration of negative refraction at visible wavelengths, design of optical tweezers for nano-specimen trapping, demonstration of a metamaterial fluid, and synthesis of high-efficiency and active upconverting materials. Most recently, Dionne has developed in situ techniques to visualize chemical transformations and light-matter interactions with nanometer-scale spatial resolution. She is the recipient of the Adolph Lomb Medal, Sloan Foundation Fellowship, the Presidential Early Career Award for Scientists and Engineers, and the inaugural Kavli Early Career Lectureship in Nanoscience, and was recently featured on Oprah’s list of “50 Things that will make you say ‘Wow’!”. She is also a recipient of the NSF CAREER award, AFOSR Young Investigator Award, and TR-35. When not in the lab, Dionne enjoys teaching three classes (Materials Chemistry, Optoelectronics, and Science of the Impossible), exploring the intersection of art and science, and cycling the latest century.
Discovering New Tricks in Older Complex Oxides
Transition-metal oxides offer an exciting platform for electronics owing to the allure of phenomena they offer, including ferroic functionality, correlated-electron behavior, and coexisting contraindicated properties. Owing to the sensitivity of their properties on (local and crystal) structure and composition, picoscale structure-property relationships are necessary to design function. Here, I briefly provide an overview of our progress in identifying these relationships and finding new phases through quantum-mechanical approaches combined with multiple materials-theory methods. Then, I describe two examples of how external perturbations to picometer scale distortions of bond lengths and angles produce unanticipated phenomena in thin films and bulk oxides of the form An+1BnO3n+1 (n = 1-∞), originally discovered by Ruddlesden and Popper (RP) in the 1950s. First, although large epitaxial strains are believed to induce ferroelectricity, I show that biaxial strain induces an unforeseen polar-to-nonpolar (P-NP) transition in (001) thin films of Ca3Ti2O7 (n = 2) at experimentally accessible biaxial compressive and tensile strains owing to strain-tunable BO6 octahedral rotation modes. Second, I describe how to use local electrostatic interactions among atomic metal-monoxide planes (AO and A'O) to induce differential bond distortions. These changes in local structure produce massive and gap changes of up to ∼2 eV without modifying chemical composition and even drive a metal-insulator transitions in the band insulator LaSrAlO4. I conclude by emphasizing that older complex oxides, which are now understood to exhibit nontrivial lattice mode anharmonicities, offer a plentiful playground for realizing new functionalities with both static and dynamic fields in thin film and bulk form.
About James M. Rondinelli
James M. Rondinelli is the Morris E. Fine Junior Professor in Materials and Manufacturing at Northwestern University in the Materials Science and Engineering (MSE) Department, where he leads the Materials Theory and Design Group. His interests are in electronic structure theory and first-principles design of functional inorganic materials using picoscale structure–property relationships.
In 2016, he received a Sloan Research Fellowship in Physics, the Presidential Early Career Award for Scientists and Engineers (PECASE) and the 3M Non-Tenured Faculty Award. Additional honors include a NSF-CAREER Award (2015), DARPA Young Faculty Award (2012) and the ARO Young Investigator Program (YIP) Award (2012). He received the 2014 Ross Coffin Purdy Award from The American Ceramic Society and was named an Emerging Young Investigator by the Royal Society of Chemistry (J. Mater. Chem. C, 2016) and the American Chemical Society (Chem. Mater., 2014).
Rondinelli has (co)-authored more than 100 peer-reviewed publications and holds one patent. He is a member of the APS, MRS, ACS, TMS, and ACerS, and has organized multiple symposia for these societies on the physics and chemistry of transition-metal compounds. He serves as an editorial board member of the Journal of Physics: Condensed Matter and npj Computational Materials. Rondinelli is also a member of the MRS Academic Affairs Committee and the Argonne Center for Nanoscale Materials (CNM) Users’ Executive Committee.
He received a BS degree in MSE from Northwestern University (NU) (2006) and a PhD degree in Materials from the University of California, Santa Barbara (2010). From 2010 to 2011, he was the Joseph Katz Named Fellow in the X-Ray Science Division at Argonne National Laboratory. Prior to joining NU, he was an assistant professor at Drexel University (2011–2014).