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Characterization of Nanoparticles from Spark Ablation
Published in Andreas Schmidt-Ott, Spark Ablation, 2019
It is fairly common to analyze spark-ablated particles using powder XRD with a lab source, but the spectra very often have low signal-to-noise ratios. An important consideration when preparing specimens for such measurements is to deposit the particles onto a substrate that interferes with the signal of the particles as little as possible, since the substrate will often dominate the measurements. To get a useful signal one needs to deposit enough material on the substrate; how much depends on the quality of the X-ray lab source and the detector used, and the particles to be analyzed. For small crystallites (nanoparticles), the small size will contribute to a broadening of the Bragg peaks, according to the Scherrer equation. This enables estimation of the particle size. Basically, this broadening also means that the smaller the particles are, the lower the signal-to-noise ratio will be. XRD has, for example, been used to demonstrate that the addition of hydrogen to the carrier gas results in the production of spark-ablated Bi particles instead of BiO particles that are produced when no hydrogen is added [15]. XRD has also been combined with small-and wide-angle X-ray scattering (SWAXS) in the analysis of magnetic spark-ablated nanoparticles [21]. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) are variations of XRD techniques where the X-rays scattered to small and wide angles, respectively, are analyzed.
Characterization Techniques
Published in Chandan Das, Sujoy Bose, Advanced Ceramic Membranes and Applications, 2017
SAXS (small-angle x-ray scattering) is an analytical method to determine the information related to averaged particle sizes, shapes, geometry and bulk morphology at a molecular level for a wide variety of samples, such as metals, ceramics, polymers, biological molecules, etc., in the forms of solids, liquids, liquid dispersions, films, gels, ground powders, and molecules in gaseous phase. When such a sample is exposed by x-rays, the sample scatters the radiation differently depending on its constituents to create a contrast that helps to draw conclusions about the particle structure and its arrangement in the system. Apart from this basic information, much other information can be obtained from SAXS—namely, characteristic distances of partially ordered materials, radius of gyration (Rg) to calculate particle dimensions, molecular weight of particles, structures, polydispersity analysis, molecular interactions, their orientations, degree of crystallinity, etc.
Structures of Polymer/Nanofiller Interfaces
Published in Toshikatsu Tanaka, Takahiro Imai, Advanced Nanodielectrics, 2017
Toshikatsu Tanaka, Muneaki Kurimoto
Small-angle X-ray scattering (SAXS) is a technique of measuring X-rays scattered at a small angle of < 5° and is used to analyze the structure of a specimen 1–100 nm in size. Figure 7.11a shows the SAXS profiles of a nanocomposite consisting of colloidal silica with a particle size of 110 nm and resin. The profiles were obtained using the high-brilliance synchrotron radiation generated at SPring-8 [10]. The peak in the range of q = 0.02–0.06 nm−1 shifts rightward with increasing filling amount of nanofiller. Peaks of q ≥ 0.08 nm−1 agree among different filling amounts, indicating that there is no aggregation of nanofiller particles. Figure 7.11b shows the distance between nanofiller particles calculated on the basis of the peak values. With increasing filling amount of nanofiller, the number density of nanofiller particles increases and the distance between nanofiller particles decreases. The results in Fig. 7.11b were observed to be similar to those obtained by electron microscopy observation.
Optimization of sample thickness for small angle X-ray scattering (SAXS)
Published in Instrumentation Science & Technology, 2023
Haijuan Wu, Rongchao Chen, Zhihong Li
Small-angle X-ray scattering (SAXS) is a physical method that may derive the geometric structure information of materials at nanometer scale such as fractal dimensions, scatterer volume percentage, specific surface area, and scatterer size and distribution.[1,2] SAXS is able to measure almost any sample with fluctuations in electron density, such as polymers, surfactants, colloids, protein solutions, porous media, nanoparticles, and nanocomposites.[3–9] In SAXS, the signal is caused by scatterers with a certain electron density (such as particles in space and pores in continuum) immersed in a medium with another electron density. The scattering pattern reflects the spatial relationship of the scatterers and is an average over time. The scattering intensity versus angle is related to the shape, size, and spatial distribution of the scatterers in the system and is proportional to the difference of electron density between the scatterer and the medium.[1]
Adsorption Properties of Cs(I) and Co(II) on GMZ Bentonite Colloids
Published in Nuclear Technology, 2022
Yanhui Wang, Qiao Jiang, Yexin Yang, Jianfeng Cheng, Chenyang Bao, Yuelong Pan, Yu Liu, Gang Yang, Yangchun Leng, Xianguo Tuo
Small angle X-ray scattering (SAXS) is mainly used to study the sub-microstructural and morphological characteristics of samples. An appropriate model can deduce and calculate the size and shape of the measured samples. In this work, the spherical model with a log-normal size distribution was selected for fitting. Figure 12 shows the SAXS fitting curves before and after adsorption of Cs(I) or Co(II). Using the formula d = 2π/q (Refs. 18 and 47), it can be seen that the peak of the GMZ bentonite colloids at logq = 0.4915 represented d = 2.01 nm, and by theoretical model analysis, this peak represented a continuous regular structure of the GMZ colloidal particles.18 Based on the morphology obtained by SEM and the structure of montmorillonite itself, it was speculated that this peak indicates that the colloidal samples had a regular lamellar structure. According to the XRD results, the colloidal samples had a value of d = 1.52 nm. This result was because SAXS can be directly performed on colloidal samples, while XRD characterization of the samples requires that the surfaces of the samples be dry and flat; the colloidal samples lost much water during drying, and the support of interlayer water molecules was reduced, resulting in this difference in the layer spacing.
Microreactor for the characterization of zeolite hydrothermal synthesis by small angle X-ray scattering (SAXS)
Published in Instrumentation Science & Technology, 2023
Peng Xiao, Shiwei Cao, Qi Liu, Yafen Ge, Zikang Chen, Chengying Sun, Yanjun Gong, Zhihong Li
Small angle X-ray scattering (SAXS) is an advanced method for investigating the structure of nanomaterials (1–100 nm) such as polymers, colloidal solutions, biomacromolecules, and carbon materials.[8–10] Both liquid and solid samples may be directly measured by a simple process, and the statistical information of materials are easily obtained. Particularly, the crystallization of zeolite may be studied in-situ by SAXS.