Measurement of inorganic particle size using dynamic light scattering method.

We would like to introduce a case of particle size measurement of cathode active materials using laser diffraction conducted by our company. In air or in a liquid, laser light is irradiated onto the particles, and the angular dependence of the intensity of the light scattered by the particles is measured. By measuring the angular dependence of the scattered light intensity, the particle size distribution (particle size distribution) is calculated from the data. Using commercially available reagents as samples, measurements were conducted in a dry state without dispersing in a solvent. The results of the particle size measurement of NMC oxide showed that the particles were in a monodisperse state with sizes below several tens of micrometers, and the median diameter was calculated to be 12 micrometers.

Dynamic light scattering allows for the measurement of particle size and size distribution without separating nanoparticles dispersed in a liquid. Here, we present examples of particle size measurement for silica and alumina particles in an aqueous medium. Particles in a solution exhibit Brownian motion that depends on their size, and the fluctuations of the scattered light generated when the particles are illuminated depend on their size. By observing and analyzing these fluctuations, we can determine the particle size and size distribution. [Alumina Measurement Results and Discussion] - As alumina approaches neutrality from strong alkaline conditions, it nears its isoelectric point. - The surface charge of the particles decreases. - The repulsion between particles diminishes. - Evidence of particle aggregation can be observed. [Silica Measurement Results and Discussion] - It is believed that the isoelectric point is on the strong acidic side. - In the pH range of 3 to 10, no particle aggregation occurs. - Particle sizes are maintained below 50 nm.