Small Angle X-Ray Scattering (Saxs) Study of Coarsening Kinetics in an Aluminum-Lithium Alloy

1984 ◽  
Vol 41 ◽  
Author(s):  
Stephen Spooner
Keyword(s):  
Particle Size ◽  
Kinetic Constant ◽  
Time Dependent ◽  
X Ray ◽  
X Ray Scattering ◽  
Aluminum Lithium Alloy ◽  
Dependent Behavior ◽  
Aluminum Lithium ◽  
Coarsening Kinetics ◽  
Interparticle Interference

AbstractCoarsening kinetics was studied in a A190. 6 Li9. 4 alloy aged at 100°C, 128°C, 165°C, 178 ° C, and 209 °C. The time-dependent behavior of the average precipitate radius followed t1/3 behavior. The precipitate/ matrix interfacial energy obtained from analysis of the kinetic constant was 0.015 J/M2 and was largely independent of temperature. The scattering curves exhibit interparticle interference which prevents us from calculating a particle size distribution.

scholarly journals Synthesis and Advanced Characterization of Polymer-Protein Core-Shell Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Core Shell ◽  
Assembly Process ◽  
Shell Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Core Shell Nanoparticles ◽  
Ray Scattering

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

Tracking the Catalyst Layer Depth-Dependent Electrochemical Degradation of a Bimodal Pt/C Fuel Cell Catalyst: A Combined Operando Small- and Wide-Angle X-Ray Scattering Study

2021 ◽  
Author(s):  
Johanna Schröder ◽  
Rebecca K. Pittkowski ◽  
Isaac Martens ◽  
Raphaël Chattot ◽  
Jakub Drnec ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cell ◽  
Ostwald Ripening ◽  
Catalyst Layer ◽  
Wide Angle ◽  
Layer Depth ◽  
X Ray ◽  
Fuel Cell Catalyst ◽  
X Ray Scattering ◽  
Size Population

The combination of operando small- and wide-angle X-ray scattering (SAXS, WAXS) is here presented to provide insights into the changes in mean particle sizes and phase fractions in fuel cell catalyst layers during accelerated stress tests (ASTs). As fuel cell catalyst, a bimodal Pt/C catalyst was chosen that consists of two distinguishable particle size populations. The presence of the two different sizes should favor and uncover electrochemical Ostwald ripening as degradation mechanism, i.e., the growth of larger particles in the Pt/C catalyst at the expense of the smaller particles via the formation of ionic metal species. However, instead of electrochemical Ostwald ripening, the results point toward classical Ostwald ripening via the local diffusion of metal atoms on the support. Furthermore, the grazing incidence mode provides insights into the catalyst layer depth-dependent degradation. While the larger particles show the same particle size changes close to the electrolyte-catalyst interface and within the catalyst layer, the smaller Pt nanoparticles exhibit a slightly decreased size at the electrolyte-catalyst interface. During the AST, both size populations increase in size, independent of the depth. Their phase fraction, i.e., the ratio of smaller to larger size population, however, exhibits a depth-dependent behavior. While at the electrolyte-catalyst interface the phase fraction of the smaller size population decreases, it increases in the inner catalyst layer. The results of a depth-dependent degradation suggest that employing a depth-dependent catalyst design can be used for future improvement of catalyst stability.

scholarly journals X-Ray Dynamical Diffraction in Powder Samples with Time-Dependent Particle Size Distributions - ADDENDUM

MRS Advances ◽  
2020 ◽  
Vol 5 (29-30) ◽  
pp. 1623-1623
Author(s):  
Adriana Valério ◽  
Sérgio L. Morelhão ◽  
Alex J. Freitas Cabral ◽  
Márcio M. Soares ◽  
Cláudio M. R. Remédios
Keyword(s):  
Particle Size ◽  
Time Dependent ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Powder Samples

Time-Resolved Imaging of Correlation-Driven Charge Migration in Light-Induced Molecular Magnets by X-ray Scattering

2020 ◽  
Author(s):  
Jean-Christophe Tremblay ◽  
Gunter Hermann ◽  
Vincent Pohl ◽  
Gopal Dixit
Keyword(s):  
Molecular Magnets ◽  
Time Dependent ◽  
Electron Dynamics ◽  
Charge Migration ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Induced Charge ◽  
Time Resolved Imaging ◽  
The Stability

In this contribution, we investigate the effect of correlation-induced charge migration on the stability of light-induced molecular magnets. Laser-driven electron dynamics is simulated using density-matrix based time-dependent configuration interaction. The...

scholarly journals Structural Study of the Photo-Mediated Growth of Silver Nanoprisms

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5413
Author(s):  
Matti Knaapila ◽  
Ulla Vainio ◽  
Sophie E. Canton ◽  
Gunnel Karlsson
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Volume Ratio ◽  
Direct Methods ◽  
Saxs Data ◽  
Aqueous Dispersions ◽  
X Ray ◽  
Silver Nanoprisms ◽  
X Ray Scattering ◽  
Ag Particles

We present a small-angle X-ray scattering (SAXS) study of the anisotropic photoinduced growth of silver (Ag) nanoprisms in aqueous dispersions. The growth of nearly spherical (<10 nm) Ag particles into large (>40 nm) and thin (<10 nm) triangular nanoprisms induced by 550 nm laser is followed in terms of particle size using indirect and direct methods for irradiation times up to 150 min. During the process, the surface-to-volume ratio of the particles decreased. The SAXS data of the initial solution fit well to the model of polydisperse spheres with pronounced average diameters around 7.4 nm and 10 nm. The data after 45 min irradiation fit well to the model containing approximately the same amount of the initial particles and the end product, the nanoprisms.

Determination of Particle Size of a Dispersed Phase by Small-Angle X-ray Scattering

1989 ◽  
Vol 171 ◽  
Author(s):  
Frank C. Wilson
Keyword(s):  
Particle Size ◽  
High Resolution ◽  
Spherical Particles ◽  
Dispersed Phase ◽  
X Ray ◽  
X Ray Scattering ◽  
Resultant Data ◽  
Log Normal ◽  
Log Normal Distribution

ABSTRACTA method for determining particle diameters up to ca 500 rnm is described. X-ray data are obtained with an ultra-high resolution Bonse-Hart diffractometer and subsequently desmeared. The resultant data, viewed as the invariant argument h l(h), are interpreted as arising from a log-normal distribution of independent spherical particles. The distribution is characterized by its median value and breadth.

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