Non-Destructive Imaging on Synthesised Nanoparticles

Abstract

Our recently developed non-destructive imaging technique was applied for the characterisation of nanoparticles synthesised by X-ray radiolysis and the sol-gel method. The interfacial conditions between the nanoparticles and the substrates were observed by subtracting images taken by scanning electron microscopy at controlled electron acceleration voltages to allow backscattered electrons to be generated predominantly below and above the interfaces. The interfacial adhesion was found to be dependent on the solution pH used for the particle synthesis or particle suspension preparation, proving the change in the particle formation/deposition processes with pH as anticipated and agreed with the prediction based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. We found that our imaging technique was useful for the characterisation of interfaces hidden by nanoparticles to reveal the formation/deposition mechanism and can be extended to the other types of interfaces.

Tracking colloidal silica particles to evaluate their dispersion and interactions in concentrated suspensions under shear force applications

“…This agrees with literature [56] showed that the higher the σ , the more the negative potential energy. Moreover, the difference in the potential energies explains the higher viscosity at low shear rate (around < 0.1 s −1 ) at pH 10 than pH 6 (Figure D‐1(A)) but it cannot be explained by the classical DLVO theory that indicates the higher repulsion with the higher zeta potential of silica particles at higher pH [11]. By comparing Figure 5A–C, they indicate that there is no significant difference on potential energies using different surface charge densities reported in literature that used the same particle type and conditions as our experiments.…”

“…Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is one of the best known theories for describing particle-particle interactions and thus particle dispersion/coagulation with the summation of the van der Waals potential and electrostatic potential. This is a straightforward theory that can explain particle dispersion/coagulation in many different colloidal systems [10][11][12]. On the other hand, there are several cases that the DLVO theory cannot explain, including the cases in high solid concentrations or confined environment.…”

Editorial for the Special Issue: “Characterization and Processing of Complex Materials”

“…Elphick et al [ 8 ] applied their scanning electron microscopy (SEM)-based non-destructive imaging technique for the characterization of nanoparticles synthesized using X-ray radiolysis and the sol-gel method. They observed the interfacial conditions between the nanoparticles and the substrates by subtracting images taken by SEM at controlled electron acceleration voltages to allow backscattered electrons to be generated predominantly below and above the interfaces.…”