Diamond hits the anvil with ultra-high pressure exceeding 500 GPa pressure

Recently, Professor Huang Xiaoli from the School of Physics at Jilin University, Professor Tang Aoqing from Jilin University, Professor Cui Tian from Ningbo University, and others have made significant progress in pressure loading technology based on diamond anvil devices. They have achieved a breakthrough of 500 GPa pressure for the first time in China. The research results, titled "Unified equation of state of tungsten up to 527 GPa using modified torsional diamond anvil cells," were published in the journal Phys. Rev. B 111, 21, 4101 (2025).

 

In recent years, significant progress has been made in high-pressure loading technology, but obtaining pressures above 400 GPa using traditional diamond anvil cell (DAC) still faces significant challenges. Previous experimental studies have shown that the double cup-shaped deformation of diamond is a limiting factor for achieving a pressure of 400 GPa based on traditional DAC. Developing new ultra-high voltage loading technology is an effective way to solve the urgent problems in this field. At present, a two-stage DAC (ds DAC) using nanocrystalline diamond (NCD) hemisphere as the secondary anvil can achieve a pressure of 1 TPA. However, the complex experimental operation difficulty of ds DAC and the extreme size and shape of the NCD hemisphere limit its further application in sample loading and in-situ measurement. In 2018, the Dewaele and Jenei teams independently proposed circular diamond anvil cell (t-DAC) models for achieving pressures above 500 GPa, but subsequent experiments failed to break through the pressure limit of 500 GPa. At present, the design parameters and stress distribution pattern of t-DAC are still unclear, so it is crucial to reveal its anvil surface pressure distribution and deformation mechanism under ultimate pressure.

 

The research team extended the isothermal state equation of tungsten (W) metal to the current record of 527 GPa extreme high pressure based on the gold equation of state (EoS) obtained from synchrotron radiation X-ray diffraction experiments using improved annular diamond anvil cells (mt DACs). The research results indicate that when compressed to a maximum pressure of 527 GPa, the crystal structure of tungsten still maintains its body centered cubic (bcc) structure and no phase transition occurs. By adopting an improved annular machining process to optimize the force distribution of mt DAC, the traditional DAC's pressure limit of 400 GPa has been successfully exceeded, achieving ultra-high pressures above 500 GPa. Finite element analysis shows that Boehler Almax type mt DAC has extremely low maximum equivalent stress and maximum principal strain, which is crucial for improving the pressure limit. This research result will provide important reference for expanding pressure loading technology and calibrating experimental pressure under extreme conditions.

 

The first author of the article is Ding Yingji, a doctoral student at the National Key Laboratory of High Voltage and Superhard Materials, Jilin University. The corresponding authors are Professor Huang Xiaoli and Associate Professor Jiang Shuqing from the School of Physics, Jilin University, and Professor Cui Tian from Ningbo University. This study received funding from the National Key Research and Development Program for Young Scientists, as well as strong support from the Shanghai Synchrotron Radiation Source and the French ESRF Source.

 

Full text link of the paper:

https://journals.aps.org/prb/pdf/10.1103/PhysRevB.111.214101