PARTICLE SIZE ANALYSIS

At Phosphor Technology we are equipped to perform particle size analysis on materials ranging from approximately 1 micron up to 150 microns using in-house equipment.

All materials supplied by Phosphor Technology Ltd are tested for particle size data and the results sent with the material as part of the service we provide. For a modest charge we can also analyse materials provided by a customer.

A Coulter Multisizer™ 3 provides primary identification of particle size median and spread. All measurements are confirmed through microscopic analysis so materials that suffer from severe agglomeration or hydrolysis will not generate incorrect results.

A procedure has been established to measure particle size using a non-aqueous electrolyte. With this procedure we can measure materials that will react with the standard aqueous electrolyte we use.

Results are reported in a way that represents the spread of particle sizes as well as the median particle size. Following common industry practice results are reported by listing a particle size against a percentage number. These percentages remain constant: 5%, 25%, 50%, 75%, 95%; as shown in the example below.

Each percentage represents a bottom fraction of the particle size range; the particle size is the largest particle size in that fraction. Fractions are based on the volume of material so we talk about 5% of the total volume of taken up by the material rather than 5% of the number of particles. Reading from the example we can say that the bottom 5% of particle sizes are less than or equal to 2.4 microns and that the bottom 25% of particle sizes are less than or equal to 3.5 microns. The particle size reported at 50% is the median particle size.

A quartile deviation is also calculated from the values at 25% and 75%. The calculation is as follows:

Q. D. = ([75%]-[25%]) / ([75%]+[25%])

e.g., Q. D. = (6.5-3.5) / (6.5+3.5) = 3.0 / 10.0 = 0.30

Typical values will range from 0.20 to 0.35, anything less is said to have a very narrow spread and anything more is said to have a very broad spread.

As a further service we can also obtain scanning electron micrographs (SEMs) of the material. As well as showing the general particle size an SEM can also indicate the morphology of the material.

To submit samples for testing please relay any information you have regarding the samples to us. A general idea on particle size and any information on possible instability of the material will allow the testing to proceed more efficiently.