Super critical, very simple?

The following article comes from WeChat public account: principle, author Gaviota

We have a very deep understanding of material's behavior under the temperature and pressure of material, but the situation of material under high temperature and high pressure is very vague.

The pressure of carbon dioxide-temperature phase diagram. (Figure inBen Finney, Mark Jacobs, Wikimedia Commons)

As shown in the figure above, when the material in the high temperature and high pressure state surpasses the critical point, the difference between the liquid and gaseous gesture seems to have disappeared. This supercritical substance is considered to be hot and dense, and is average. Scientists believe that there are many new physics to be unveiled about this supercritical substance.

Recently, a new study has two key new discoveries for supercritical substances. Research through two parameters found that supercritical substances show certain universality, and they may be amazing and simple. This new discovery recently published in "Scientific Progress" is expected to help us get a new understanding.

The universality of supercritical substances

The main problem of understanding supercritical substances is that the theory of gesture, liquid and solid state is not applicable. It is unclear that when the boundary of the traditional solid liquid gas becomes blurred, which physical parameters can reveal the most prominent feature of the supercritical state.

With the early understanding of the liquid at lower temperature and lower pressure, the researchers chose two parameters to describe the supercritical substance.

The first parameter is a relatively commonly used properties, that is, the heat capacity of the system that measures the heat absorption of the system, which contains basic information about system freedom.

The second parameter is relatively not so common. It is the length that waves can spread in the system. This length dominates the phase space available. When this length reaches its possible minimum value and is equal to the atomic interval, the real interesting thing will happen.

Scientists have found that as far as these two parameters are concerned, substances under extreme conditions at high pressure and high temperatures become very common.

This universality includes two aspects. First of all, in the relationship diagram of the heat capacity and wave transmission length of different systems, there is a fixed fixed reflection point.

This anti -discrimination point corresponds to the transition between the two physical supercritical (liquid -like and qi -like states). When crossing this point, the supercritical substance will change the key physical properties and change from liquid -like to a gesture. The important thing is that the reverse point is a clear way to distinguish between these two states.

The hot capacity of carbon dioxide-dynamic length diagram. (Figure kCockRell, C. & Trachenko, K., 2022)

Secondly, in all types of systems that are studied, the position of this counter -point point is very close.

The heat capacity of different systems-dynamic length diagram. Their anti -disclosure points are similar. (Figure kCockRell, C. & Trachenko, K., 2022)

This is obviously different from all other known transitions. For example, the two in these transition points, all material states (liquid gas solid) coexist, and the critical point of the end of the gas fluid boiling line, the differences in different systems are very large.

On the other hand, this universality may also tell us that supercritical substances may be quite simple.

Basic understanding and practical application

Researchers believe that in addition to the basic understanding of material and phase maps, the understanding of supercritical substances also brings many practical applications.

For example, hydrogen and pupa are supercritical among giant stars such as Jupiter and Saturn, so they dominate their physical characteristics. In green environmental protection applications, supercritical fluids have also been proven to be very effective in destroying hazardous waste, but engineers are increasingly hoping to obtain theoretical guidance and improve the efficiency of the supercritical process.

On a giant giant star like Jupiter, the gas is supercritical. (Figure aNasa, ESA, and J. Nichols, University of Leicter)

Kostya Trachenko, a professor of physics at the University of London, said: "The generality of this supercritical substance is the new physics of substances under extreme conditions. From the perspective of basic physics, from the perspective of understanding and predicting the application of green environment, astronomy, and other fields, this is a exciting prospect. "

At the same time, this also made scientists see some exciting possibilities in the future. For example, this research also leads to a question: Is the fixed background point related to the traditional high -level phase change? Can it be described by the existing ideas involved in the theory of phase change, or do they need to introduce some very different new things?

When we break through our known boundaries, we can gradually confirm these new exciting questions and start looking for more answers.

#Groupe OD creation:

Written article: Gaviota

Capture: Wenwen

#Reference source:

https://www.eurekalert.org/news-releases/961447

https://www.liverscience.com/supercripical-matter-simplicity.html

https://www.science.org/doi/10.1126/sciadv.abq5183#Picture source:

Cover: daniel kux, pexels

First picture: NASA, ESA, and J. Nichols, University of Leicers

This article is reproduced from WeChat public account by authorization: Principle Author: Gaviota

Reprinted content only represents the author's point of view

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It does not represent the high energy office of the Chinese Academy of Sciences

Edit: Matthalin pig

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