Because the melting temperature of diamond is extremely high, which has not been successfully measured so far, electrically boron-doped diamond (BDD), which is electrically conductive differently from pure diamond, is expected to generate ultrahigh-temperatures. Ultrahigh-temperature generation using a BDD heater was developed by Okayama University to successfully generate temperatures to 4000 K (Fig. 1) [Xie et al., RSI 2017].
We import this technology but have recognized that ultrahigh-temperature generation using this heating element requires high experimental skill. Therefore, we are currently making efforts so that the usual multi-anvil worker can generate such ultrahigh temperatures without extremely high experimental skill.
Fig. 1. Ultrahigh-temperature generation using BDD heaters at 15 GPa. The BDD with 3.0 wt.% of B can generate a temperature of 3700 C by electric power of 690 W (violet) From Xie et al. [RSI 2017].
Our recent efforts have been published as Xie et al. [RSI, 2021], Nishida et al. , and Xie et al. . Nishida et al.  generated temperatures to 3000 K at a pressure of 15 GPa using carbide anvils. Xie et al.  generated temperatures to 3300 K at a pressure over 50 GPa using sintered-diamond anvils.
Xie, L., Chanyshev, A., Ishii, T., Bondar, D., Nishida, K., Chen, Z., Bhat, S., Farla, R., Higo, Y., Tange, Y., Su, X., Yan, B., Ma, S., Katsura, T., Simultaneous generation of ultrahigh pressure and temperature to 50 GPa and 3300 K in multi-anvil apparatus, Rev. Sci. Instr., 92, 103902, 2021.
Nishida, K., Xie, L., Kim, E.J., Katsura, T., A strip-type boron-doped diamond heater synthesized by chemical vapor deposition for large volume presses, Rev. Sci. Instr., 91, 095108, 2020.
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 Press. Res., 40, 369-378, 2020.
Xie, L.J., Yoneda, A., Yoshino, T., Yamazaki, D., Tsujino, N., Higo, Y., Tange, Y., Irifune, T., Shimei, T., Ito, E., 2017. Synthesis of boron-doped diamond and its application as a heating material in a multi-anvil high-pressure apparatus. Rev. Sci. Instrum. 88, 093904.