Sample preparation

The material has to be ground down to an average grain size of about 2-3 µm while the maximum grain size should be less than 6 µm.

The fine starting material should be hot-pressed in a piston cylinder apparatus at around 1 GPa and 1200 °C. Depending on the assembly, a cylindrical sintered sample of few cubic millimeter is produced.

The recovered sample should be cut in fine slices using a diamond saw or a wire saw. Sometimes slices form automatically due to fast decompression.

The slices should be polished down to 10-15 µm thickness.

Both sides of the slices should coated with 100 nm of platinum.

In each slices, 20 to 50 µm diameter samples are cut with a femto-second laser.

A laser-drilled rhenium foil is used as gasket.

Dry MgO fine-grains are squeezed between carbide seats in order to produce 5-10 µm thick flakes that are employed as pressure medium. If one has to avoid MgO, the same can be done with KCl, alternatively (Make sure to dry the KCl properly to avoid too much water).

The sample is placed at the center of the gasket hole between the two MgO layers.