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Highlights

Highlights

A schematic of the directed evolution pathway that holds promise for accelerating the discovery and design of new materials.
A schematic of the directed evolution pathway that holds promise for accelerating the discovery and design of new materials.
May 4, 2018
Northwestern Materials Research Science and Engineering Center

Discovering and Designing New Materials Using Directed Evolution
In a new seed project within the Northwestern University MRSEC, a novel approach for discovering and designing materials is being developed using directed evolution. While directed evolution approaches have been successfully applied in areas such as therapeutics or catalysis, this strategy has not been fully explored in materials science and engineering.
Mixed anion systems such as the oxynitride compound on the left provide a rational pathway toward solid-state spin crossover materials that are inspired by analogous molecular systems such as the example on the right.
Mixed anion systems such as the oxynitride compound on the left provide a rational pathway toward solid-state spin crossover materials that are inspired by analogous molecular systems such as the example on the right.
May 4, 2018
Northwestern Materials Research Science and Engineering Center

Harnessing Mixed Anion Materials for Novel Magnetic Properties
Precise synthetic control of the local electronic structure of metal centers within materials offers the potential to realize exotic physical properties. In particular, tuning the electronic structure of metal centers enables the creation of strongly correlated electron systems, enabling the exploration of fundamental questions about magnetism and superconductivity. In a new seed project within the Northwestern University MRSEC, novel classes of mixed anion materials are being synthesized in an effort to realize new correlated electron properties and related quantum phenomena.
Anion orders compatible with the parent Ruddlesden-Popper structure. From left to right: polar, antipolar layers, and antipolar-in-layer anion order. The gray anions at the octahedral vertices indicate the position of the fluoride ion.
Anion orders compatible with the parent Ruddlesden-Popper structure. From left to right: polar, antipolar layers, and antipolar-in-layer anion order. The gray anions at the octahedral vertices indicate the position of the fluoride ion.
May 4, 2018
Northwestern Materials Research Science and Engineering Center

Polyhedral Assembly of Heteroanionic Materials
A route has been formulated that leverages heteroleptic building units to lift inversion symmetry in heteroanionic materials from balancing short-range and long-range interactions favoring octahedral tilting in perovskite-derived structures. The resulting increase in the number of noncentrosymmetric (NCS) materials is important for improving the performance of compounds found in actuator, imaging, and data storage technologies.
Heat map of the convex hull distance of A+B3+OX (X=S, Se, and Te) compounds. Diamond, triangle, pentagon, hexagon, inverted triangle, and square represent P4/nmm, P21/c, Pmc21, Pca21, P21, and other space groups, respectively. The white circle means the compound is unstable.
Heat map of the convex hull distance of A+B3+OX (X=S, Se, and Te) compounds. Diamond, triangle, pentagon, hexagon, inverted triangle, and square represent P4/nmm, P21/c, Pmc21, Pca21, P21, and other space groups, respectively. The white circle means the compound is unstable.
May 3, 2018
Northwestern Materials Research Science and Engineering Center

Computational Discovery of New Oxychalcogenide Compounds
High-throughput density functional theory (DFT) calculations are used to accelerate the discovery of new oxychalcogenide compounds. In particular, experimentally-known crystal structures are decorated with essentially all possible combinations of elements in the periodic table, generating thousands of potential compounds.
(top) Bilayer and monolayer MoS2 are interfaced with metal-core phthalocyanine molecules. (bottom) A low-energy absorption peak emerges due to charge transfer across the Pc-MoS2 heterojunction.
(top) Bilayer and monolayer MoS2 are interfaced with metal-core phthalocyanine molecules. (bottom) A low-energy absorption peak emerges due to charge transfer across the Pc-MoS2 heterojunction.
May 3, 2018
Northwestern Materials Research Science and Engineering Center

Electronic Coupling in Organic-Transition Metal Dichalcogenide Heterojunctions

Heterojunctions containing two-dimensional materials can give rise to unique effects at the interface or enhance existing optical properties of the composite layers. Using organic molecules in these heterojunctions has the advantage to enable synthetically tunable electronic and optical properties.
Reconfigurable defect structure in MoS2 enables a new circuit element, a “memtransistor,” with high potential for neuromorphic computing.
Reconfigurable defect structure in MoS2 enables a new circuit element, a “memtransistor,” with high potential for neuromorphic computing.
May 3, 2018
Northwestern Materials Research Science and Engineering Center

Reconfigurable 2D Materials with Neuromorphic Functionality
Solid-state electronics and advanced computation has spurred significant interest in artificial intelligence and neuromorphic (i.e., brain-like) computing. However, the deterministic correlations between input and action in conventional silicon microelectronics are not well-matched to information processing in biological systems.
Image of silicon metalens mounted on a transparent, stretchy polymer film, without any electrodes. The colorful interior is produced by the large number of nanostructures courtesy of the Capasson Laboratory. Alan She, Shuyan Zhang, Samuel Shian, David R. Clarke, and Federico Capasso, “Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift,” Sci. Adv. 4, eaap9957 (2018) [DOI: 10.1126/sciadv.aap9957]
Image of silicon metalens mounted on a transparent, stretchy polymer film, without any electrodes. The colorful interior is produced by the large number of nanostructures courtesy of the Capasson Laboratory. Alan She, Shuyan Zhang, Samuel Shian, David R. Clarke, and Federico Capasso, “Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift,” Sci. Adv. 4, eaap9957 (2018) [DOI: 10.1126/sciadv.aap9957]
May 1, 2018
Harvard Materials Research Center (2014)

Forward-looking Metalens

David R. Clarke (Materials Science)
Inspired by the human eye, a team led by Clarke at the Harvard MRSEC has reported in Science Advances an adaptive metalens that is a flat, electronically-controlled artificial eye. This new lens which combines breakthroughs in artificial muscle and lens technologies simultaneously controls focus, astigmatism, and image shift.
May 1, 2018
Harvard Materials Research Center (2014)

Crushing Soda Cans: Predicting the Stability Landscape of Shell Buckling

Michael P. Brenner (AppMath), John W. Hutchinson (MechEng),  and Shmuel M. Rubinstein (AppPhy)
Crushing a soda can from top to bottom is easier if it is dented initially on the side. Predicting the force needed to crush a dented can, however, which is of critical importance for structural reliance of materials engineering is quite challenging.
Figure 1. Visualizations of the charge density of the two electrons trapped in an oxygen vacancy at zero field in (a) MgO, (b) CaO, (c) SrO, and (d) BaO. Similar visualizations at a field of 22 MV/cm in the +x direction are shown for (e) MgO, (f), CaO, (g) SrO, and (h) BaO. Red, blue, cyan, green, and grey spheres represent O, Mg, Ca, Sr, and Ba ions, respectively.
Figure 1. Visualizations of the charge density of the two electrons trapped in an oxygen vacancy at zero field in (a) MgO, (b) CaO, (c) SrO, and (d) BaO. Similar visualizations at a field of 22 MV/cm in the +x direction are shown for (e) MgO, (f), CaO, (g) SrO, and (h) BaO. Red, blue, cyan, green, and grey spheres represent O, Mg, Ca, Sr, and Ba ions, respectively.
Apr 27, 2018
MIT Center for Materials Science and Engineering (2014)

Strong Electric Fields Tune the Stability of Ionic Defects in Oxides

Bilge Yildiz and Krystyn Van Vliet
Intellectual Merit: No ceramic crystal is perfect, and structural imperfections including point defects are responsible for many technologically desirable properties of ceramics. Applications such as modern computer memories rely on controlling defects inside a crystal by exposing them to large electric fields. High field effects on defective crystals, however, remain challenging to control and address.
Figure 1: The stiffness of mucus can be modified by targeting different associative groups on the mucin molecules. By performing both micro- and macro-rheological measurements on these gels, additional insight into the structural rearrangements leading to the observed differences in the bulk mechanical properties (such as heterogeneity) can be inferred.
Figure 1: The stiffness of mucus can be modified by targeting different associative groups on the mucin molecules. By performing both micro- and macro-rheological measurements on these gels, additional insight into the structural rearrangements leading to the observed differences in the bulk mechanical properties (such as heterogeneity) can be inferred.
Apr 27, 2018
MIT Center for Materials Science and Engineering (2014)

How Mucus Keeps You Healthy

Katharina Ribbeck and  Garreth McKinley
Intellectual Merit:

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