Memristive Materials and Neuromorphic Devices, Part 2

Nov 27, 2016 1:30pm ‐ Nov 27, 2016 5:30pm

Identification: Tutorial EM10.2

Due to the technological limitation of flash memory, a significant number of new nonvolatile memories are now being proposed. The tutorial covers the fundamental physics behind the emerging nonvolatile memories. Resistive switching memory (ReRAM) technologies (based on non-phase change materials) and its application will be the focus of this tutorial. Presentations by two leading researchers will cover the fundamental background of devices.


Daniele Ielmini will describe the various modeling options at the physical and electronic level, concluding with an overview of how they can be used to realize neuromorphic devices and systems with a huge potential for adoption in many applications, such as accelerated machine learning and brain-inspired computation.


Formation of Advanced Metal Alloys via Ultrafast Laser-Driven Extreme States

Nov 28, 2016 1:15pm ‐ Nov 28, 2016 2:00pm

Identification: GS03

Developing classes of metal alloys, such as stabilized nano-crystalline alloys and multicomponent High Entropy Alloys (HEA), exhibit extraordinary mechanical and chemical properties. The structure of conventional alloys based on a single host element derive primarily from the chemical interactions of the components and the free energy as depicted in the equilibrium phase diagram. In nano-crystalline alloys or HEAs minimizing strain, minimizing surface energy, or increasing configurational entropy become primary factors controlling the crystal structure and microstructure often with surprising results. A multitude of alloys can be made using various combinations of elements known to be compatible, and many have already been created. However, for some alloys, chemical incompatibility leads to separation of elements in the liquid phase and makes production by conventional casting or splat quenching difficult[1]. We demonstrate a new method to form alloys from the liquid phase via irradiation of periodic thin films with a femtosecond laser.


We will present Transmission Electron Microscopy (TEM) of nano-crystalline NiW alloy, similar to those produced by electrodeposition[2], that was produced by irradiating a 23 nm thick film composed of 12 alternating layers of 1.4 nm W and 2.4 nm Ni. Femtosecond laser pulses are absorbed in the near surface heating the top 40 nm layer to extreme temperatures and pressures on the order of 6000 C and 50 GPa within a few picoseconds so the layer remains at solid density. The thermodynamic relaxation of the film passes into the “vapor dome” in the Temperature-Density phase diagram, a region of liquid-vapor coexistence where the bonding energy between atoms is low and the kinetic energy is very high. We propose under these extreme conditions Ni and W are allowed to mix thoroughly, then thermal transport into the substrate quenches the mixed layer within a few nanoseconds. It should be noted metals irradiated with a single ultrashort pulse do not resolidify nano-crystalline, but instead regrow epitaxially from the substrate. The thermal and mechanical relaxation of femtosecond laser irradiated multilayer films includes unique, extreme thermodynamic states and thereby provides a new route to synthesize stable nano-crystalline alloys or multicomponent HEAs from the liquid phase.


Mechanical Properties of Low-Bandgap Organic Semiconductors

Nov 28, 2016 2:00pm ‐ Nov 28, 2016 2:45pm

Identification: GS01

Knowledge of the mechanical properties of organic semiconductors is critical for the long-term stability of flexible devices fabricated using roll-to-roll printing techniques. Moreover, increasing the elastic range and resistance to fracture of these materials will enable stretchable and ultra-flexible devices for portable, wearable, implantable, and disposable applications. Despite the importance of the mechanical properties of low-bandgap (i.e., donor-acceptor) conjugated polymers, there are no design rules available that have the goal of maximizing the charge transport properties along with the mechanical deformability. This talk describes my group’s experimental and theoretical approaches to understanding the molecular and microstructural determinants of the mechanical properties of these materials. Our approach began with the measurement of a large library containing over 50 donor-acceptor conjugated polymers. Among the design rules that emerged from this study is the importance of (1) branched side chains and (2) isolated rings (e.g., bithiophene) as opposed to fused rings (e.g., thienothiophene) along the backbone. To obtain a deeper understanding of these properties, we are developing a coarse-grained molecular dynamics approach to determine the glass transition temperature, elastic moduli, Poisson ratio, and toughness of a representative subset of these materials. Among our findings are that the density of entanglements, which critically determines the fracture energy and toughness, is highly dependent on the conformation of the chains in solution prior to deposition. Finally, we describe the first study of the mechanical properties of solution-processed small-molecule semiconductors. These materials exhibit a surprisingly high ductility in pure form, with some films able to withstand ≥10% tensile strain without fracture.

Challenges to Reduce Weight in Transportation Applications

Nov 28, 2016 4:00pm ‐ Nov 28, 2016 5:00pm

Identification: GS02

New solutions are needed to reduce the weight of the machines that move people and goods on land, sea and air. The potential for reducing weight using high-strength steels, aluminum, titanium and magnesium alloys is well established. Key is to achieve the weight reduction economically. This requires optimization of the material properties and processes together with robust design tools and joining technologies to enable multi-material structures. Lightweight Innovations for Tomorrow (LIFT) was established to accelerate the adoption of advanced metals and serves as the bridge between basic research and final product commercialization. Our industry partners in collaboration with an extensive network of universities and the national and federal laboratories are developing the next generation of advanced manufacturing processes. This talk will provide on overview of the challenges and describe how new materials and processes, coupled with Integrated Computational Materials Engineering, are advancing the technology.


Scientific Writing for Academia and Industry: How to Write Effective Research Proposals and Grants Applications in Science

Nov 30, 2016 8:00am ‐ Nov 30, 2016 8:45am

Identification: GS-SWAI-1

In this session, Marder will engage the audience in a discussion about the essential steps and strategies employed to help researchers write effective proposals. Attendees will identify the key elements of a proposal, including introductions—that will provide the context for their work (including a literature review)—as well as a clear statement of the research problem. Marder will also describe how to effectively use figures that capture the main goals of a proposal, thus making it easier for the reader to quickly understand both what you are attempting to accomplish and why you are attempting to do so. Finally, participants will learn about the mechanics of a proposal, which do not specifically indicate a “winning” proposal, but if not done properly can significantly decrease the probability of a proposal being successful.

The Structrual Evolution at Sulfur Based Solid Electrolytes (β-Li 3PS 4, 70Li 2S-30P 2S 5 Glass Ceramic (LPS-GS), Li 10GeP 2S 12 (LGPS)) and Au Electrode Interface during Lithium Deposition and Stripping Processes - An in Operando Observation

Nov 30, 2016 10:15am ‐ Nov 30, 2016 11:00am

Identification: GS05

Solid state electrolytes (SEs) in Li batteries are believed to be the ultimate solution to the electrode dissolution problems and safety hazards of liquid electrolyte (LE) systems. Sulfur based bulk type SE attracts great interest due to their relatively high ionic conductivities. Besides the bulk lithium ion conductivity, physical contact, structural evolution and redox reaction kinetics at SE and electrode interface during battery processes are other key factors that dictate the efficiency of battery cycling performances. The current challenge of studying the interfacial processes in operando in all solid battery systems is the difficulty of assembling an air-tight spectro-electrochemical cell with good electrical contact and optical accessibility to the interface of interest. In this work, a spectro-electrochemical cell is designed for an in operando Raman measurement at SE/Au interface during Li deposition and stripping processes. Three representative sulfur based SEs (β-Li3PS4, 70Li2S-30P2S5 glass ceramic (LPS-GS) and Li10GeP2S12 (LGPS)) were investigated. Spectroscopic data shows that, in general, partially reversible structural interconversion occurs among PS43-, P2S63-, P2S73- and other unidentified P-S anion species. Corresponding variations in cell impedance also supports these interfacial structural evolutions. Result reveals that in all solid Li battery systems, oxidation/reduction of Li+ occurs along with breaking and reformation of the Li+-Anion interactions, which are usually accompanied by some unexpected, partially irreversible structural evolution of the counter ions. The resulted byproducts are later accumulated at the electrode/electrolyte interfaces. This result not only help build the electrochemical fundamentals of the molecular details at solid-solid interface but also guide the choice of materials and interfaces in all solid Li battery systems.


Interactions between Simulant Vitrified Nuclear Wastes and Idealised Cement Leachates

Nov 30, 2016 12:30pm ‐ Nov 30, 2016 1:15pm

Identification: GS06

Within the United Kingdom (UK) , it is proposed that nuclear waste will be disposed in a geological disposal facility, 200 m to 1 km underground1. This facility will incorporate an engineered barrier system that will be optimised to physically and chemically impede the transport of radionuclides to the biosphere. The facility will house a large volume of cemented Intermediate Level Waste (ILW), in addition to vitrified ILW. A significant volume of concrete will be used in its construction. Interaction of groundwater with the cementitious components of the facility (both the waste and construction materials) will lead to the presence of high pH conditions within a repository. The effect of cement leachates on vitrified wasteforms is not well understood.


We present results from a glass durability study using idealised cement leachates to develop our understanding of glass durability mechanisms in these complex repository like environments. Simulant ILW glasses relevant to the UK disposal program have been utilised. We also investigated a simulant UK high level waste glass (MW-25%) and the International Simple Glass2 (ISG), a 6 component borosilicate glass, with components that are common to most borosilicate nuclear glasses. Glass powders were exposed to idealised cement leachates of “intermediate” and “old” ages, approximately representative of GDF conditions at ~1000 and ~10,000 years of operation, according to the product consistency test B3. Analysis of the normalised mass loss and normalised leaching rate of these glasses as a function of cement leachate composition was achieved through analysis of solution concentrations. Simultaneously we present analysis of monolith sample alteration layers by SEM/EDX and GA-XRD. Collectively, these data support a mechanistic understanding of glass dissolution in the context of a complex geological disposal environment for vitrified UK waste


Scientific Writing for Academia and Industry: Writing Scientific Papers

Nov 30, 2016 2:45pm ‐ Nov 30, 2016 3:30pm

Identification: GS-SWAI-2

Scientific writing is an integral part of what a scientist does, and the value of a well-written paper should not be underestimated. Though it may seem overwhelming, the writing process can help to guide experiments and enable a deeper understanding of experimental results.


Although writing styles and processes can differ tremendously between authors, there are a host of characteristics that are common to effective writing strategies and well-written scientific papers. In this session we will discuss the elements of well-written papers; strategies by which to efficiently translate ideas to experiments to high-quality publications; how to prepare effective figures; and how to respond to reviewer comments to get your paper accepted.


By the end of this session, you will come to realize that scientific writing can be easy, enjoyable, efficient, and rewarding.


Ultra-Breathable Carbon Nanotube Pores

Nov 30, 2016 4:30pm ‐ Nov 30, 2016 5:00pm

Identification: GS08

Previous reports for pressure-driven transport through CNT membranes demonstrated CNT permeability values that were orders of magnitude larger than those predicted by Knudsen diffusion theory for gases (~102 fold enhancement) and by Hagen-Poiseuille equation for liquids (103-105 fold). While these results spurred great interest in CNTs for efficient membrane separations, it remains an open question if driving forces other than pressure could result in similar transport rate enhancements. A positive answer would greatly extend the promises and application space of CNTs as fluidic channels.
In this work, we provide the first experimental evidence of enhanced gas transport in CNTs driven by a concentration rather than a pressure gradient. We fabricated cm2, free-standing, flexible, 1-5 nm SWNT/parylene membranes with well-aligned nanotubes as only transporting pores, and we measured the water vapor diffusion rate through the membrane when each surface is exposed to a different relative humidity. Our measurements demonstrate that these membranes exhibit rates of water vapor transport (~8000 gr/m2day) that surpass those of commercial breathable fabrics, even though the CNT pores are only a few nm wide and the overall porosity is less than 5.5%. Measured permeability of our CNT channels is 24 times larger than Knudsen diffusion prediction, and this flow enhancement is close to that measured for pressure-driven transport of nitrogen.[1] Membranes made from 1-3 nm SWNT forests with higher number densities (> 1012/cm2) display even larger gas-transport enhancements.
This ultrafast rate of water vapor transport in CNTs suggests that CNT membranes hold great potential for pervaporation, membrane distillation, and as building block of breathable and protective fabrics. For the last application, a membrane shall be able to block dangerous components while permitting perspiration. By demonstrating complete rejection of 3-nm charged dyes, 5-nm uncharged gold (Au) nanoparticles, and ~40-60-nm Dengue virus from aqueous solutions during filtration tests, we provide evidence that, in addition to outstanding breathability, our CNT membranes provide a high degree of protection from bio-threats by size exclusion.

Scientific Writing for Academia and Industry: How Major Funding Agencies Screen Proposals

Dec 1, 2016 8:00am ‐ Dec 1, 2016 8:45am

Identification: GS-SWAI-3

Different funding agencies all have their own unique missions and selection criteria for choosing which proposals to fund. This can make crafting proposals directed toward these organizations quite a difficult task.


In this workshop, Gnade will discuss what criteria different funding agencies look for in successful proposals. The discussion will cover how to evaluate funding opportunities in order to develop a strategy on where to submit proposals and examples of successful proposals.