A software package is presented for performing reduction and analysis of small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS) data. A graphical interface has been developed to visualize and quickly reduce raw SANS and USANS data into one- or two-dimensional formats for interpretation. The resulting reduced data can then be analyzed using model-independent methods or non-linear fitting to one of a large and growing catalog of included structural models. The different instrumental smearing effects for slit-smeared USANS and pinhole-smeared SANS data are handled automatically during analysis. In addition, any number of SANS and USANS data sets can be analyzed simultaneously. The reduction operations and analysis models are written in a modular format for extensibility, allowing users to contribute code and models for distribution to all users. The software package is based on Igor Pro, providing freely distributable and modifiable code that runs on Macintosh and Windows operating systems.

/pdf/reduction-and-analysis-of-sans-and-usans-data-using-igor-pro-2ky2mzzlm6.pdf

Reduction and analysis of SANS and USANS data using IGOR Pro

Metallic zinc (Zn) has been regarded as an ideal anode material for aqueous batteries because of its high theoretical capacity (820 mA h g–1), low potential (−0.762 V versus the standard hydrogen electrode), high abundance, low toxicity and intrinsic safety. However, aqueous Zn chemistry persistently suffers from irreversibility issues, as exemplified by its low coulombic efficiency (CE) and dendrite growth during plating/ stripping, and sustained water consumption. In this work, we demonstrate that an aqueous electrolyte based on Zn and lithium salts at high concentrations is a very effective way to address these issues. This unique electrolyte not only enables dendrite-free Zn plating/stripping at nearly 100% CE, but also retains water in the open atmosphere, which makes hermetic cell configurations optional. These merits bring unprecedented flexibility and reversibility to Zn batteries using either LiMn2O4 or O2 cathodes—the former deliver 180 W h kg–1 while retaining 80% capacity for >4,000 cycles, and the latter deliver 300 W h kg–1 (1,000 W h kg–1 based on the cathode) for >200 cycles.

/pdf/highly-reversible-zinc-metal-anode-for-aqueous-batteries-3kbaiooprq.pdf

Highly reversible zinc metal anode for aqueous batteries.

Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion

http://norbbi.com/public/publications/Kucerka_BBA(2011).pdf

Fluid Phase Lipid Areas and Bilayer Thicknesses of Commonly Used Phosphatidylcholines as a Function of Temperature

Although Portland cement concrete is the world’s most widely used manufactured material, basic questions persist regarding its internal structure and water content, and their effect on concrete behaviour. Here, for the first time without recourse to drying methods, we measure the composition and solid density of the principal binding reaction product of cement hydration, calcium–silicate–hydrate (C–S–H) gel, one of the most complex of all gels. We also quantify a nanoscale calcium hydroxide phase that coexists with C–S–H gel. By combining small-angle neutron and X-ray scattering data, and by exploiting the hydrogen/deuterium neutron isotope effect both in water and methanol, we determine the mean formula and mass density of the nanoscale C–S–H gel particles in hydrating cement. We show that the formula, (CaO)1.7(SiO2)(H2O)1.80, and density, 2.604 Mg m−3, differ from previous values for C–S–H gel, associated with specific drying conditions. Whereas previous studies have classified water within C–S–H gel by how tightly it is bound, in this study we classify water by its location—with implications for defining the chemically active (C–S–H) surface area within cement, and for predicting concrete properties.

/pdf/composition-and-density-of-nanoscale-calcium-silicate-26znkzlx6c.pdf

Composition and density of nanoscale calcium–silicate–hydrate in cement

Two high-resolution, general-purpose, small-angle neutron scattering instruments have been constructed at the National Institute of Standards and Technology's Center for Neutron Research. The instruments are 30 m long and utilize mechanical velocity selectors, pinhole collimation and high-data-rate two-dimensional position-sensitive neutron detectors. The incident wavelength, wavelength resolution and effective length of the instruments are independently variable, under computer control, and provide considerable flexibility in optimizing beam intensity and resolution. The measurement range of the instruments extends from 0.0015 to 0.6 A−1 in scattering wavevector, corresponding to structure in materials from 10 A to nearly 4000 A. The design and characteristics of the instruments, and their modes of operation, are described, and data are presented which demonstrate their performance.

/pdf/the-30-m-small-angle-neutron-scattering-instruments-at-the-1sablk6lv8.pdf

The 30 m Small-Angle Neutron Scattering Instruments at the National Institute of Standards and Technology

An ultra-high-resolution small-angle neutron scattering (USANS) double-crystal diffractometer (DCD) is now in operation at the NIST Center for Neutron Research (NCNR). The instrument uses multiple reflections from large silicon (220) perfect single crystals, before and after the sample, to produce both high beam intensity and a low instrument background suitable for small-angle scattering measurements. The minimum detector background to beam intensity ratio (noise-to-signal, N/S) for q ≥ 5 × 10−4 A−1 is 4 × 10−7. The instrument uses 2.38 A wavelength neutrons on a dedicated thermal neutron beam port, producing a peak flux on the sample of 17300 cm−2 s−1. The typical measurement range of the instrument extends from 3 × 10−5 A−1 to 5 × 10−3 A−1 in scattering wavevector (q), providing information on material structure over the size range from 0.1 µm to 20 µm. This paper describes the design and characteristics of the instrument, the mode of operation, and presents data that demonstrate the instrument's performance.

/pdf/design-and-performance-of-a-thermal-neutron-double-crystal-3n7p9si6c7.pdf

Design and performance of a thermal-neutron double-crystal diffractometer for USANS at NIST

A description and the performance of the very small angle neutron scattering diffractometer at the National Institute of Standards and Technology are presented.

https://journals.iucr.org/j/issues/2022/02/00/ge5109/ge5109.pdf

J. J. Moyer

Papers

The 30 m Small-Angle Neutron Scattering Instruments at the National Institute of Standards and Technology

Design and performance of a thermal-neutron double-crystal diffractometer for USANS at NIST

The very small angle neutron scattering instrument at the National Institute of Standards and Technology