Microscopic Measurement of the Homogeneity of Nanoscale Mixtures

Abstract

Powder mixing is a typical operation in particle technology. This work presents a method for the determination of the homogeneity of dry nanoparticle powder mixtures to measure the limit of mixing quality. The research results given here reflect the experimental effort required to study nanoscale solid mixtures consisting of a two-component system of Aerosil 200 and the titanium dioxide additive P25. The experimental effort can be evaluated by means of statistical methods. The parameter measured is the so-called homogeneity or mixing efficiency. It is determined by means of an energy-dispersive X-ray spectroscopy detector attached to a transmission electron microscope. The results will show that the optimal homogeneity depends on the additive concentration, the magnification of the transmission electron microscope, and the number of agglomerates, which have to be analyzed.

Quantitative Characterization of Mixing in Multicomponent Nanoparticle Aggregates

“…Equation (7) is not valid. This is also evident in Figure 9b, where the deviation of the 3D heterogeneous coordination number and 3D cluster size dependent on the 3D cluster size (all data calculated using threshold t = 0.11, Equations (15) and (16)) is shown. Above the identified limit of self-similarity (3-4 particles per cluster) the deviations of originally simulated 3D heterogeneous coordination number and 3D cluster size were below 30% and mostly below 20%.…”

“…An evaluation of the deviation of the exact 3D heterogeneous coordination number and cluster size and the data calculated from 2D was calculated by a relative error according to Equations (15) and (16) using the simulated 3D heterogeneous coordination number (Equation (14)) and calculated 3D cluster size (Equation (13)…”

“…These methods mainly use image analyses to qualitatively discuss mixing . Daumann et al investigated the qualities of shear mixing tools for nanosized aggregates in the range of 140–300 nm and used the concentration of the components within transmission electron microscopy (TEM) images to evaluate mixing . They further suggested that parameters, such as fractal dimension or agglomerate size, are not suitable for the characterization of mixing.…”

“…[13,14] Daumann et al investigated the qualities of shear mixing tools for nanosized aggregates in the range of 140-300 nm and used the concentration of the components within transmission electron microscopy (TEM) images to evaluate mixing. [15,16] They further suggested that parameters, such as fractal dimension or agglomerate size, are not suitable for the characterization of mixing. According to the authors, the determination of the mass concentration using energy-dispersive X-ray spectroscopy (EDX) is the correct way to characterize nanoparticle mixtures on aggregated scale.…”

Influence of Mixing Technology and the Potential to Modify the Morphological Properties of Materials used in the Manufacture of Lithium‐Ion Batteries

“…[23,24] In Ref. [25], Daumann at al. studied the influence of the type and intensity of loading on the morpholo- gy of nanoscaled products and came to the result that loading causes a corresponding modification of the structure (it has a fractal dimension).…”