Advanced Photon Source

A U.S. Department of Energy, Office of Science,
Office of Basic Energy Sciences national synchrotron x-ray research facility

Publications from before 2000

Anomalous ultra-small-angle X-ray scattering from evolving microstructures during tensile creep. P. Jemian, G.G. Long, F. Lofaj and S.M. Wiederhorn. Cited: Applications of Synchrotron rediation techniques to Materials Science, 1999, 590

A nano-composite poly(methyl-methacryalte) bone cement. A.H. Gomoll, A. Bellare, W. Fitz, T.S. Thornhill, R.D. Scott, P. Jemian and G.G. Long. Cited: Nanophase and Nanocomposite Materials III, 1999, 581

Fractal analysis of flame-synthesized nanostructured silica and titania powders using small-angle X-ray scattering. The morphology of flame-generated silica and titania aggregates is characterized by small-angle X-ray scattering(SAXS). Nearly all these powders display mass-fractal morphologies, which are composed of ramified aggregates of nanoscale primary particles. Primary particle size, aggregate size, fractal dimension, and specific surface area are obtained from this analysis. The mass-fractal dimension varies from 2.5 to 1.6 for flame generated silica and titania aggregates in single and double diffusion flame reactors. However, titania powders made in a single diffusion flame reactor appear as nonaggregates and nonfractals. Silica powders synthesized with an imposed electric field in a laminar, premixed flame reactor are mass fractals with narrowly confined fractal dimensions from 1.5 to 1.9 regardless of aggregate size.

J. Hyeon-Lee, G. Beaucage, S.E. Pratsinis and S. Vemury. Cited: Langmuir, 1998, 14 (20), Sep 29, p 5751-5756.

The Effect of the Shape Function on Small-Angle Scattering Analysis by the Maximum-Entropy Method. Analysis of small-angle scattering data to obtain a particle-size distribution is dependent upon the shape function used to model the scattering. From a maximum-entropy analysis of small-angle scattering data, the effect of shape-function selection on the obtained size distribution is demonstrated using three different shape functions to describe the same scattering data from each of two alloys. The alloys have been revealed by electron microscopy to contain a distribution of randomly oriented and mainly noninteracting irregular ellipsoidal precipitates. A comparison is made between the different forms of the shape function. The effect of an incident-wavelength distribution is also shown. The importance of testing appropriate shape functions and validating these against other microstructural studies is discussed.

P.R. Jemian and A.J. Allen. Cited: Journal of Applied Crystallography, 1994, 27 Oct 1, p 693-702.

Ultra-Small-Angle X-Ray-Scattering to Bridge the Gap between Visible-Light Scattering and Standard Small-Angle Scattering Cameras. This paper reports the performance of an ultra-small-angle X-ray scattering facility on beamline X23A3 at the National Synchrotron Light Source. Based on a Bonse-Hart double-crystal design, the instrument combines: continuously tunable optics with asymmetric first monochromator crystal, high-flux throughput, high-precision crystal rotators, independently-mounted reflecting crystals, photodiode detector and high-resolution X-ray video camera. This combination of features permits rapid small-angle X-ray scattering measurements in the scattering wave-vector range of 0.005-2.0 nm-1 (depending on the sample), with mum-positioning accuracy of a typical 3 x 3 mm2 beam on the sample.

A.J. Allen, P.R. Jemian, D.R. Black, H.E. Burdette, R.D. Spal, S. Krueger and G.G. Long. Cited: Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment, 1994, 347 (1-3), Aug 11, p 487-490.

High-Resolution Small-Angle X-Ray-Scattering Camera for Anomalous Scattering. The design and operation of a new small-angle X-ray scattering instrument, optimized for high throughput at a synchrotron source, high angular and wave-length resolution, large sample cross-sectional area, accurate energy tunning, excellent signal-to-noise ratio and harmonic rejection are presented. The principles of design and implementation are given, as are the details of primary calibration of absolute intensity and experimental desmearing. The instrument has been tested for application to anomalous-scattering measurements near the chromium K edge. Preliminary results on samples of a heat-treated steel are presented as a demonstration of the capability of this experiment to separate the microstructure evolution as a function of temperature of a chromium-rich precipitate from the thermal behavior of other precipitates in the steel.

G.G. Long, P.R. Jemian, J.R. Weertman, D.R. Black, H.E. Burdette and R. Spal. Cited: Journal of Applied Crystallography, 1991, 24 Feb 1, p 30-37.

Characterization of 9cr-1movnb Steel by Anomalous Small-Angle X-Ray-Scattering. The size distribution and volume fraction of Cr23C6 precipitates in 9Cr-1MoVNb steel have been isolated from the distributions of all other precipitates by the technique of anomalous small-angle X-ray scattering. Three X-ray wavelengths near the Cr K absorption edge were used to vary the scattering contrast of Cr23C6 while that of the other precipitates was left unchanged. Size distributions calculated from each scattering curve using a maximum entropy method were combined by a scattering contrast gradient analysis to isolate the volume-fraction size distribution of the chromium carbides. Behavior of these carbides was studied as a function of isothermal aging temperature. Mean diameter is smallest and Cr23C6 number density is highest after aging at 811 K. Above 811 K, the mean diameter of the chromium carbides increases with increasing aging temperature.

P.R. Jemian, J.R. Weertman, G.G. Long and R.D. Spal. Cited: Acta Metallurgica Et Materialia, 1991, 39 (11), Nov, p 2477-2487.