Barium titanate

In our first test, we used 20 g of sample and started grinding with 2 mm Ø grinding balls.

To maintain a motor oil like slurry (for an optimum grinding result), we added 45 ml of water.

To avoid over pressure, we ground the sample in steps of 3 minutes, followed by a programmed pausing time of 10 minutes. After several cycles, the outside temperature of the bowl should be checked (remain below 80°C); grinding time or programmed pausing time might be readjusted afterwards. This is counting for the following grinding trial too.

For a proper detection of fine particles (< 2 µm), Mie parameters are required. We don’t provide proper parameters for barium titanate and used best fitting. With this parameters, we found d50 < 150 nm after a total grinding time of 15 minutes. By proceeding grinding, equal d50 has been detected after 30 minutes of grinding too. For this, the used 2 mm grinding balls didn’t achieve a better grinding result.

A change of balls might be required (e.g. < 0,1 mm Ø) to improve the grinding result. We packed this sample for demonstration and used an equal perpetrated sample for pre grinding in result 2.

In this trial, we started grinding with 2 mm Ø grinding balls for the first 15 minutes analogue result 1 and changed the balls to 0,1 mm Ø afterwards.

Now we proceeded grinding with 0,1 mm Ø grinding balls for 30 minutes (total 45 min) and checked the fineness again with the same Mie parameters we used in result 1. After a total of 45 minutes, the result has been almost equal without big changes.

We proceeded grinding for a further hour (total 105 min.) and found a d50 < 125 nm. For this, even with smallest available grinding balls, particle size does not change significantly.

For a better grinding result, it might be possible using grinding agents like acids, bases, tensides or salts which might be able to improve the grinding process and show a better fineness. Also other liquids like organic solvents (benzine, hexane, ethanol, etc) are plausible as well.

If proper Mie parameters can be provided, a recalculation of the measurements is possible to give a more precise result.