Multi-anvil sample assembly. (a) Cross-section of the assembly along the sample axis. The sample is located in the centre of the octahedral MgO cell. Adjacent anvils are separated by pyrophyllite gaskets. Arrows indicate positions of receivers. Receivers 1 and 2 are placed directly in line with the sample axis. Receivers 3–8 are placed at ±70.5° with the sample axis. (b) Detailed cross-section of the MgO cell: (1) sample, (2), steel buffer rods, (3) MgO sleeve, (4) Mo furnace, (5) ZrO₂ sleeve, (6) MgO octahedron and (7) thermocouple.