(a) Reconstructed volume of the sample and surrounding at room conditions and under pressure at 0.5 GPa (top and bottom images show reconstructed slices and volume, respectively). The contrast at room conditions (RC) allows to distinguish boundaries from graphite furnace, hBN and diamond capsules as denoted by the arrows. (b) Plot of the reconstructed volume integrated over y and z as a function of the radial position in the direction −x at RC (red line) and 0.5 GPa (black dashed line). This profile shows the geometrical deviations from the perfect cylinder corresponding to the presence of porosity at RC. Under pressure, the sample fills the capsule homogeneously as seen from both reconstructed volume and integration profile.