Figure 7. Typical sample assembly and geometry at high pressure and high temperature conditions.

(a) Schematic drawing of sample encapsulation. The middle layer secondary gasket, laser-cut from a 15 μm thick sheet of single-crystal MgO (also shown in b), prevents the sample from spreading out radially during axial compression. (b) Microscope photograph of a laser-machined MgO crystal micro-gasket, typical thickness ≈ 10 μm. Scale bar, 100 μm. (c) Microscope photograph of the sample chamber as viewed through the diamond window. Red circle in the middle of the molybdenum sample denotes the FWHM of the X-ray probe profile (see Methods). Scale bar, 50 μm. (d) Image of temperature distribution collected during a typical heating at a pressure of 63 GPa; the temperatures are recorded the point of circular area (4 μm in diameter), denoted by white circle; the outline of the sample is denoted by the dashed curve. Scale bar, 50 μm.