Although Xie et al.  successfully generated 4000 K by using a boron-doped diamond (BDD) heater, this BDD was synthesized at a pressure of 15 GPa and a temperature of 2300 K, which requires too much time and efforts for use of routine experiments. On the other hand, BDD has been synthesized by the chemical-vapor-deposition method commercially. We therefore purchased commercially sold BDD plates and shaped to cylindrical shapes using electric discharging machining or laser cutting. By using the CVD-synthesized cylindrical heater, we successfully generated temperatures to 27 GPa at a pressure of 30 GPa in a multi-anvil assembly with sintered-diamond (SD) anvils.
Although we developed the stripe-type BDD furnace in the next development [Nishida et al., 2020], the structure of the cylindrical furnace is much simpler, and therefore more suitable for ultrahigh-pressure experiments especially using SD anvils. We acutually generated a pressure of 50 GPa and a temperature of 3000 K simultaneously by combination of the BDD heater and SD anvils. The transparency of BDD to hard X-rays is of course useful for synchrotron radiation experiments.
A optical microscope photo of the CVD-synthesized BDD cylinder
Heating records by the CVD-synthesized BDD heater cut by laser.
Xie, L., Yoneda, A., Liu, Z., Nishida, K., Katsura, T., Boron-doped diamond synthesized by chemical vapor deposition as a heating element in a multi-anvil apparatus, High Pressure Research 40, 369-378, 2020.