Structural Evolution of Ag–Co and Ag–Ni Alloys Studied by Anomalous Small-Angle X-ray Scattering

1998 ◽  
Vol 31 (5) ◽  
pp. 783-788 ◽  
Author(s):  
C. Revenant-Brizard ◽  
J. P. Simon ◽  
J. R. Regnard ◽  
I. Manzini ◽  
B. Rodmacq

The structural evolution of co-sputtered Ag–20 (and 35) at.% Co and Ag–20 (and 35) at.% Ni was studied by anomalous small-angle X-ray scattering in the as-deposited state and after different anneals for 10 min at 573, 623 and 723 K. Anomalous scattering was used to separate the part of the scattering signal due to the transition metal particles from the signal of other heterogeneities. Strong segregation, involving about two-thirds of the Co (or Ni) atoms, already exists for the as-deposited state. After a 573 K anneal, the phases (Ag matrix and Co or Ni well defined particles) have almost reached equilibrium,i.e.complete immiscibility. Most of the magnetic particles are three dimensional with an average radius of 5–25 Å and the average distance between the particles varies from 17 to 110 Å, depending on the magnetic element and its concentration, and on the annealing conditions. The size distribution does not correspond to that of usual coarsening, but becomes broader after extended annealing. This is probably due to heterogeneous precipitation at grain boundaries of the Ag matrix.

2004 ◽  
Vol 37 (5) ◽  
pp. 757-765 ◽  
Author(s):  
L. E. Levine ◽  
G. G. Long

A new transmission X-ray imaging technique using ultra-small-angle X-ray scattering (USAXS) as a contrast mechanism is described. USAXS imaging can sometimes provide contrast in cases where radiography and phase-contrast imaging are unsuccessful. Images produced at different scattering vectors highlight different microstructural features within the same sample volume. When used in conjunction with USAXS scans, USAXS imaging provides substantial quantitative and qualitative three-dimensional information on the sizes, shapes and spatial arrangements of the scattering objects. The imaging technique is demonstrated on metal and biological samples.


2010 ◽  
Vol 46 (9) ◽  
pp. 1866-1877 ◽  
Author(s):  
Zhiyong Jiang ◽  
Yujing Tang ◽  
Jens Rieger ◽  
Hans-Friedrich Enderle ◽  
Dieter Lilge ◽  
...  

2009 ◽  
Vol 42 (4) ◽  
pp. 649-659 ◽  
Author(s):  
J. J. K. Kirkensgaard ◽  
J. K. Holm ◽  
J. K. Larsen ◽  
D. Posselt

Small-angle X-ray scattering (SAXS) patterns are calculated from a three-dimensional model of photosynthetic thylakoid membranes. The intricate structure of the thylakoids is represented by sampling random `electron density points' on geometric surfaces. The simulation setup works as a virtual instrument, allowing direct comparison with experimental data. The simulations qualitatively reproduce experimental data and thus clarify the structural origin of the scattering features. This is used to explain recent SAXS measurements and as a guideline for new experiments and future quantitative modeling. The setup has general applicability for model testing purposes when modeling scattering from membrane systems of complex geometries.


2008 ◽  
Vol 41 (1) ◽  
pp. 134-142 ◽  
Author(s):  
Byeongdu Lee ◽  
Chieh-Tsung Lo ◽  
P. Thiyagarajan ◽  
Dong R. Lee ◽  
Zhongwei Niu ◽  
...  

The multiple scattering effects present in grazing-incidence small-angle X-ray scattering (GISAXS) data and interference between them are addressed theoretically as well as experimentally with measurement of a series of patterns at different incident angles, referred to as `incident-angle-resolved GISAXS' (IAR-GISAXS). X-ray reflectivity (XR), GISAXS and IAR-GISAXS of virus particles on Si-substrate supported-polystyrene films have been measured and all the data have been analyzed with appropriate formalisms. It was found that under certain conditions it is possible to extract the correct structural features of the materials from the GISAXS/IAR-GISAXS data using the kinematic SAXS formalisms, without the need to use the distorted-wave Born approximation. Furthermore, the Kiessig fringes in GISAXS enable the measurement of the average distance between the particle and the substrate, similar to the measurement of film thickness using the fringes in the XR data. It is believed that the methods developed here will expand the application of GISAXS as they enable the application of model-independent and kinematic SAXS theories to nanostructured two-dimensional ordered films.


1997 ◽  
Vol 30 (5) ◽  
pp. 633-636 ◽  
Author(s):  
D. R. dos Santos ◽  
I. L. Torriani ◽  
A. Y. Ramos ◽  
M. Knobel

The structural evolution of the nanocrystalline material obtained from the amorphous compound Fe73.5CuNb3Si13.5B9 was investigated by small-angle X-ray scattering. Four sets of amorphous metallic ribbons were produced by melt spinning using different quenching rates. Samples of each set were annealed above the crystallization temperature; X-ray diffraction analysis showed the formation of an ordered Fe–Si solid solution with average grain sizes ranging from 9 to 11 nm. Small-angle scattering curves of the samples in the initial amorphous states revealed different intensities for different quenching rates, caused by the presence of heterogeneities with dimensions larger than those of the crystallites formed after thermal treatment. In addition, scattering measurements carried out in situ during isothermal annealing showed an intensity evolution as a function of time, attributed to electron-density contrast variation caused by the atomic diffusion process that occurs during crystallization.


2014 ◽  
Vol 47 (2) ◽  
pp. 810-815 ◽  
Author(s):  
Andreas Hofmann ◽  
Andrew E. Whitten

Small-angle X-ray scattering has established itself as a common technique in structural biology research. Here, two novel Java applications to aid modelling of three-dimensional macromolecular structures based on small-angle scattering data are described.MolScatis an application that computes small-angle scattering intensities from user-provided three-dimensional models. The program can fit the theoretical scattering intensities to experimental X-ray scattering data.SAFIRis a program for interactive rigid-body modelling into low-resolution shapes restored from small-angle scattering data. The program has been designed with an emphasis on ease of use and intuitive handling. An embedded version ofMolScatis used to enable quick evaluation of the fit between the model and experimental scattering data.SAFIRalso provides options to refine macromolecular complexes with optional user-specified restraints against scattering data by means of a Monte Carlo approach.


2021 ◽  
Author(s):  
Tianjuan Yang ◽  
Jiahao Zhang ◽  
Jianyuan Ma ◽  
Shiyuan Liu ◽  
Xiuguo Chen

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