Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session V5: Industrial Applications of Neutron Scattering |
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Sponsoring Units: DCMP FIAP Chair: Michael Crawford, DuPont Room: Portland Ballroom 256 |
Thursday, March 18, 2010 8:00AM - 8:36AM |
V5.00001: Application of Neutron Measurements to Advance Semiconductor Manufacturing: Next-Generation Lithography and Nanoporous Thin Films Invited Speaker: As feature sizes in microelectronic devices continue to decrease to sub-32 nm dimensions, new measurement methods are needed to understand the physical phenomena used in state-of-the-art lithography methods that may limit their fabrication and probe the structure and properties of new electronics materials. Neutron (and x-ray) beams have emerged as powerful probes of new manufactured structures with characteristic length scales ranging from (1 to 100) nm in thin films and in the bulk. In particular, X-ray reflectivity (XR), neutron reflectivity (NR), small angle neutron scattering (SANS), and small angle X-ray scattering (SAXS) can be applied in novel ways to address fundamental issues important to the microelectronics industry. This talk with highlight the application of neutron and x-ray measurement methods to investigate important problems in the development of photoresist materials used in lithography and of nanoporous low-dielectric-constant materials needed for next generation integrated circuits. Specific topics include: 1) the direct measurement of the reaction-diffusion front with nanometer resolution from ideal line-edges to probe image blur and roughness from photoacid diffusion 2) identification and measurement of a ``residual swelling fraction'' during the development and 3) measurements of the pore structure of low-dielectric constant thin films. Insights from these studies can provide guidelines and opportunities for the further extension of photoresist technology into the future and the integration of new materials into integrated circuits. [Preview Abstract] |
Thursday, March 18, 2010 8:36AM - 9:12AM |
V5.00002: Neutron Scattering Studies of Cement Invited Speaker: Despite more than a century of research, basic questions remain regarding both the internal structure and the role of water in Ordinary Portland cement (OPC) concrete, the world's most widely used manufactured material. Most such questions concern the primary hydration product and strength-building phase of OPC paste, the calcium silicate hydrate (C-S-H) gel. When cement and water are mixed, this phase precipitates as clusters of nanoscale (nearly amorphous) colloidal particles with an associated water-filled inter-particle pore system. Most attempts to characterize the C-S-H gel and the behavior of the associated water involve drying or other processes that, themselves, change the bound water content within and around the gel. Neutron scattering methods do not suffer from this disadvantage. Furthermore, the neutron isotope effect and the neutron's sensitivity to molecular motion have enabled considerable progress to be made in recent years by: (i) determining the C-S-H composition, density and gel structure in small-angle neutron scattering (SANS) H/D contrast variation studies; (ii) elucidating the changing state of water within cement as hydration progresses using quasielastic neutron scattering (QENS); and (iii) measuring the production and consumption of nanoscale calcium hydroxide (CH), a by-product of cement hydration that co-exists with the C-S-H gel, using inelastic neutron scattering (INS). These experiments have provided new insights into the physics and chemistry of cement hydration, and have implications for the design of new concretes with pozzolanic cement additions that are intended to address environmental concerns and sustainability issues. [Preview Abstract] |
Thursday, March 18, 2010 9:12AM - 9:48AM |
V5.00003: Residual Stress Analysis for Industry Using Neutron Scattering at Oak Ridge National Laboratory Invited Speaker: Oak Ridge National Laboratory is home for two of the highest flux neutron sources in the world: the High Flux Isotope Reactor, HFIR, and the Spallation Neutron Source, SNS. Two engineering materials science instruments have been built - NRSF2 at HFIR began operation in 2006 and VULCAN at SNS began commissioning in late 2009. The instrument at HFIR is called NRSF2 as it is the 2nd generation Neutron Residual Stress mapping Facility. It is primarily used for high spatial resolution diffraction mapping of residual stresses throughout the thickness of samples and for measurement of material behavior during in situ and/or real-time processes. NRSF2 is extensively used by industry as well as academia for non-destructive stress and phase mapping through thickness of actual components as well as mock-ups. designed for testing FEA models of processes. Examples of studies from the vehicle technologies industry and nuclear power industry conducted at NRSF2 will be presented. These include studies of stresses due to welding, heat-treating, casting, and metal forming. Many strain/stress mapping studies at NRSF2 are used to optimize materials processes such as welding or to test validity of FEA models. Examples of industrial projects with Caterpillar on changes in weld metal to improve fatigue life, John Deere to test and validate casting models, Metalsa-Roanoke to characterize stress distribution about holes in steel vehicle frames, and EPRI to test and validate models of residual stresses about dissimilar metal welds. Industry-University collaborations have used the mapping facilities to study in situ such phenomena as the state of charge in Li-ion batteries and the critical bend stress in gears as a function of loading. Three different collaborative routes are available to industry to use NRSF2: the HTML User Program, which is sponsored by DOE-EERE-Vehicle Technologies; DOE Cooperative Research and Development Agreements (CRADAs); and industry sponsored projects. [Preview Abstract] |
Thursday, March 18, 2010 9:48AM - 10:24AM |
V5.00004: Neutron Scattering Studies of Thermoelectric Materials for Automotive Applications Invited Speaker: Solid-state thermoelectric (TE) technology uses electrons and holes as the working fluid for heat pumping and power generation, and has the virtues of no moving parts and high reliability. Advances in TE materials can lead to high thermal-to-electrical energy conversion efficiency and hence significant energy savings by generating electricity from waste heat. A good TE material should simultaneously possess high thermopower, low electrical resistivity, and low thermal conductivity. Most of the work in the past decade has been focused on lowering materials lattice thermal conductivity. Neutron diffraction and inelastic neutron scattering provide unique opportunities to understand the vibrational properties of thermoelectric materials. I will review some of our recent neutron studies on skutterudites, prospective high efficiency TE materials. Our studies have attempted to elucidate the crucial factors in these compounds relating to the filling-atom sublattices, particularly with respect to composition, nature of mixed fillers, dynamic disorder, phase coherence, and phonon scattering mechanisms. [Preview Abstract] |
Thursday, March 18, 2010 10:24AM - 11:00AM |
V5.00005: Why Particle Dispersions Matter: Product Discovery and Problem Solving in the Hydrocarbon Industry Through Neutron Scattering Invited Speaker: A surprisingly wide range of matter consists of dispersions of one material in another. In the hydrocarbon industry we often work with mixtures of solid, liquid, and gas as a consequence of the production of hydrocarbons. For example, in deep sea oil production solid phases of wax or gas hydrates can form in pipelines due to low temperatures and high pressures. Dispersions also arise in the products we design; examples include polymers, fuel additives, and lubricants. Hence, understanding such dispersions is a key technology. Size of the dispersed phase (supermolecular) and sensitivity of the structure to the presence of a fluid phase (high-vacuum imaging methods are difficult), makes the small-angle scattering technique, using light, x-rays, and neutrons, a preferred method of structure determination. We focus in this talk on neutron scattering, and this method has several strengths: 1) contrast matching to highlight features is easily achieved through use of various isotopes, for example $^{1}$H vs $^{2}$H, 2) an unprecedented range of length scales is accessible (several $\mu $m to nm) through the combined use of SANS and USANS, and 3) the concentration of scattering entities is precisely determined because scattering is routinely measured on an absolute basis. When one considers small-angle scattering from a dispersion, simple models such as Debye scattering, where the magnitude of the momentum transfer (q=2$\pi $ Sin($\theta )$/$\lambda )$ is comparable to the size of the dispersed phases (R*q$\sim $1), is often used to estimate the size of the dispersed phase. However, this simple approach fails in many real-world cases where we must deal with, for example, high concentrations of solids or highly-anisotropic dispersed phases. In this talk we will illustrate how we have utilized combined SANS / USANS data along with contrast matching techniques to understand the structure-property relations governing behavior in several areas of interest, including self-assembly of polymers in fuel additives, polymer-modified gas-hydrate slurries, and organoclay dispersion/exfolation as thickening agents. [Preview Abstract] |
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