Powder grinding and nano-particle sizing: Sound, light and enlightenment

Abstract

In this work, a sub-micron quartz powder produced by high energy grinding was used to explore the information contained in the particle size distribution (PSD) curves obtained by electro-acoustic spectroscopy (EAS) and dynamic light scattering (DLS). Results show that although the customarily volume-based PSD curve and its median value (d50 = 135 nm) are more amenable to differences in measurement phenomena and sample preparation methods, the area and number-based representations are more sensitive to the presence of finer particles (35 and 65 nm, respectively for the number and area-based curves obtained by EAS). These values were supported by the crystallite size calculated from X-ray diffraction (d = 44 nm) and the equivalent spherical diameter calculated from specific surface area measurements (d = 43 nm). Thus, a reliable description of the particle size of a powder requires the use of complementary techniques, suggested by the envisioned application or the particular stringency of a given processing step.