The team of Beijing High Pressure Scientific Research Center successfully invented the “diamond nano-high pressure chamber”

“Preserving the state of matter at extremely high pressure to atmospheric pressure” has always been a long-term pursuit of basic research and material applications. Recently, the research team led by Zeng Qiaoshi, a researcher at the Beijing High Voltage Scientific Research Center, has made an important breakthrough towards this dream. They prepared a nano-pressure chamber made of diamond that permanently and safely sealed substances with extremely high pressure states. This breakthrough enables high-pressure substances to successfully get rid of the shackles of traditional complex pressure devices and can exist independently like ordinary materials, removing a major obstacle to the basic research and application of high-pressure substances.

This latest achievement was published in the top international academic journal Nature on August 17, 2022, entitled “Preservation of high-pressure volatiles in nanostructured diamond capsules”.

Image source: Beijing High Voltage Science Research Center

Materials are the cornerstone of modern technology. Therefore, the progress and innovation of science and technology often rely heavily on the development of new advanced materials with special properties. For a specific material, only need to change the applied pressure it is subjected to, often can significantly change the various properties of the material, so as to provide a broad space and possibility for the exploration of optimized, or even new material properties. Regrettably, however, most of the superior properties found under pressure can only exist under high pressure. Therefore, the strong and thick pressurization device in order to generate and maintain pressure becomes an insurmountable barrier between the high-pressure material and the people. Over the past century, scientists have made various efforts to try to overcome this difficulty. They extensively studied different material systems and found that there is a special class of high-pressure synthetic metastable materials that can be retained to atmospheric pressure. A typical example is the diamond made from ordinary carbon materials under high pressure conditions that can still exist under atmospheric pressure after being unloaded under external pressure, and maintain its shiny appearance and various excellent properties. Unfortunately, there are very few examples of such luck. Therefore, high-pressure substances are more important for basic research in laboratories, and rarely can enter industrial applications on a large scale and play a wide role in people’s daily lives.

A collaborative research team from the Beijing High Voltage Scientific Research Center and Stanford University and Argonne National Laboratory has invented a new approach. Using this method, they succeeded in retaining the extremely high-pressure state and its properties of the gas, which are usually difficult to bind, to the atmospheric pressure environment. They first pressurized a carbon material called “glass carbon” with argon to a high pressure of about 50 GPa (500,000 atmospheres), and then heated the glass carbon to about 1800 degrees Celsius. Glass carbon at atmospheric pressure is a material with good airtightness, but they found that under high pressure, glass carbon can absorb argon like a sponge. High temperature and pressure promote the transformation of high-pressure glass carbon into diamond. Then, when the entire sample was removed from the pressure device and placed in a normal pressure environment, it was accidentally found that argon was permanently sealed in the nanopores of the strong, sealed diamond; More importantly, the pressure inside the argon sample in the nanopores did not disappear with the removal of the external pressure, but maintained a very high pressure state, forming a composite material wrapped in a high-pressure nano-argon particles by the nanodiamond matrix – “diamond nano-high pressure chamber”. The pressure inside the argon particles obtained under this experimental condition is as high as 22 GPa, which is about 220 times the pressure at the bottom of the Mariana Trench, the deepest part of the Earth’s ocean. In this composite, the thickness of the diamond wrapped in high-pressure argon particles was surprisingly found to require only a few tens of nanometers. Therefore, most of the advanced research detection methods of modern materials, such as electron microscopy, which require working in atmospheric pressure or vacuum environments, can be directly detected and studied.

Image credit: Nature

“We can directly see the nano-sized high-pressure argon grains embedded in the matrix of the nanodiamond through high-resolution electron microscopy; Therefore, we named this special high-pressure composite diamond nano-high-pressure chamber. Zeng Zhengdan, the first author of the work and a researcher at the Beijing High Pressure Scientific Research Center (Shanghai Branch), said, “One of the keys to realizing the innovative concept of diamond nano-high pressure chamber is to choose the right precursor carbon material.” For example, the precursor’s carbon atoms are not densely connected to each other, and nanopores containing a large number of discrete nanopores can serve as sample chambers for storing high-pressure material. As long as these two conditions are met, many carbon materials, including crystalline, amorphous, low-dimensional carbon materials, etc., can become precursor materials for diamond nano-high-pressure chambers, thus providing a broad space for further optimizing the synthesis process and products of diamond nano-high-pressure chamber materials. ”

Researcher Zeng Qiaoshi explained: “The use of a variety of advanced detection methods with complementarity to obtain self-consistent results is an important feature of modern materials research. However, for the study of high-pressure material science, due to the barrier of the ‘thick’ traditional high-pressure cavity wall, to detect the structure and properties of matter under high pressure, it often requires a probe with high penetration, such as high-energy hard X-rays. Therefore, many advanced detection technologies with weak penetration capabilities that require proximity to the vacuum working environment, such as electron microscopy, vacuum ultraviolet spectroscopy, soft X-ray spectroscopy, etc., are often not used for high-pressure material research, which seriously hinders the development of high-pressure material science. Zeng Qiaoshi added, “And the creation and invention of the diamond nano-high-pressure chamber allows us to find an effective way out of this long-term dilemma.” We can now maintain pressure without relying on traditional high-pressure devices, while the pressure of the material can be regulated by design. Since there is no additional pressure device to limit and bind, all the techniques and methods previously used for atmospheric pressure material research will also be directly applied to the study of materials in high pressure states. Many of the previously difficult to obtain critical information such as the structure, composition, and bonding of high-pressure materials will no longer be a problem. I look forward to breakthroughs in many previously unsolved high-pressure materials problems, and even more that our results will lead to a large number of unexpected discoveries that subvert existing knowledge in the vast unknown space of high-pressure materials. ”

“In addition to the gases we have already experimented with, the concept of a diamond nano-high-pressure chamber can be applied to a variety of initial materials, including solids.” Professor Wendy Mao of Stanford University in the United States said, “In addition, in principle, diamond nano-high-pressure chamber materials can be synthesized many times and aggregated into large materials, so that high-pressure materials can be widely used in daily life like atmospheric pressure materials; Instead of just tiny samples tied inside a high-pressure device, as before, it is only for scientists to use for basic research. So, I think our job is a crucial first step toward achieving a large number of high-pressure materials that are not normally unloaded and retained to obtain possible applications. ”

The research results have benefited from years of close cooperation from an international team of researchers from the Beijing High Voltage Scientific Research Center, Stanford University and Argonne National Laboratory, and have received strong support from the National Key Research and Development Program and the National Natural Science Foundation of China. (Source: Science Network)

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