Rayappa Shrinivas Mahale As this is a powder then it's a laser diffraction experiment (not DLS) e.g. Mastersizer 3000 and you can measure dry without any solvents.

Respected Sir,

@ Alan F Rawle

Thank you sir for your valuable suggestions. I am using Dynamic Light Scattering Instrument (Zeta Particle Size) for PSA analysis so solvent is essential for testing. Please help me with your suggestions.

Thank You Sir.

Rayappa Shrinivas Mahale Do you have a rough idea of size? The density of steel means that the particles will sediment quickly in most simple liquids (note, it isn't a solvent you want but a dispersion medium).

Therefore, you may need to use a liquid with a suitable high viscosity. But you will need an accurate estimate of the viscosity and refractive index.

Perhaps a silicone oil?

However, you are going to need to ensure the steel particles are redispersed appropriately which means employing a technique like ultrasonication which will be difficult in a high viscosity medium. You'll also need to know the complex optical properties of the steel particles for DLS unless you know for sure you have a monomodal particle size distribution.

Ultimately, because you are imposing a constraint (using DLS), you are going to be challenged. As Alan F Rawle suggests, I would not use DLS given the option.

Respected Sir,

@ John Francis Miller

Thank you for your valuable suggestions.

Respected Sir,

@ Vadim S. Gorshkov

Thank you sir for your valuable suggestions.

Rayappa Shrinivas Mahale You do not have any free, discrete, independent particles < 100 nm in a powder. You need laser diffraction. The Zetasizer is completely useless for this application and you will get meaningless results. You may as well say that you have a ruler - bigger range too: 0 - 30 cm - to measure your particles - the outcome is the same (just because you have the tool doesn't mean it's correct for the application. You don't use a Mercedes to plow a field)... Your results will be meaningless and not be publishable.

Get access to a Mastersizer or similar.

See:

Dispersion and nanotechnology

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat

Adhesion and cohesion

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W180725AdhesionCohesion

Rayappa Shrinivas Mahale Put a small sample of your powder into water and watch it settle to the bottom. Carry out a simple Stokes' Law calculation (as shown in ASTM E2490-09(2021) Standard Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Photon Correlation Spectroscopy (PCS)) to indicate what materials of density ~ 7.5 - 8 g/cm3 will stay in suspension. You'll find that the particles will need to be

Dear Rayappa Shrinivas Mahale . See the following useful link: https://www.tandfonline.com/doi/pdf/10.1080/17458080600960002#:~:text=The%20production%20techniques%20for%20these,%E2%80%9312%5D%2C%20etc.)

Kindly check see also the following useful link: https://www.academia.edu/8421685/PARTICLE_SIZE_ANALYSIS_Particle_Size_Distribution

Also check please the following useful RG link: Article The influence of particle size distribution on the propertie...

The following link is also very useful: https://iopscience.iop.org/article/10.1088/1757-899X/257/1/012035/pdf

Rayappa Shrinivas Mahale Take a look at the second-to-last paper, for example. I've downloaded and attached it here. Look at the median sizes for the 3 powders indicated in the paper viz. 33.0, 7.91 and 4.04 μm. These are way above the top limit for DLS with a material density ~ 7.7 g/cm3...

Respected Sir,

@ Alan F Rawle thank you sir for your valuable suggestions.

With good sample preparation you can have a pretty good idea of size with SEM, without the effects of agglomeration influencing size.

Teo Atz Dick So the transport and dusting properties of an agglomerate are the same as a primary particle?

Alan F Rawle Sorry I wasn't clear. Agglomeration, decantation etc won't be a factor inhibiting him from measuring single particle size by SEM.

Teo Atz Dick OK then, are agglomerates and aggregates reflecting a larger and real particle size? Or are aggregates essentially crystallites that can't be separated from the overall particle size and thus reflect the overall properties of the particulate/powder system?

It's important to know what we're measuring and whether it's fit for purpose or not. Critical Quality Attributes and Product Performance Indicators are essential.

As Heywood put it in 1966: 'However, it must be realised that particle size analysis is not an objective in itself but is a means to an end, the end being the correlation of powder properties with some process of manufacture, usage or preparation' H Heywood Proc. 1st Particle Size Anal. Conf. September 1966 p 355 – 359 (Heffer)