What exactly is “Ice No. 7”?

Since the news that people can wear short sleeves in the Arctic was reported, people have started to worry about the situation of the ocean, believing that under this trend, it will not be long before it invades the land with great fanfare and completely swallows up the homes built by people. At this time, someone opened his mind and pointed out that the solution to this problem is also simple, just find a way to freeze all the oceans on the earth.

By then, the earth may become an ice ball

You may think that this idea is too far-fetched, and even science fiction movies don't dare to do it. But in fact, it is really possible to do it, and a piece of "Ice No. 7" is enough. So, what is this "Ice No. 7"? Can it really freeze all the oceans on Earth?

Is there really such magical ice on Earth?

Ice has many phases

When it comes to ice No. 7, many people must be full of questions. How can ice made from frozen water be classified into different grades? We have never heard of this term in our daily lives. In fact, scientists have been classifying ice for a long time. The reason for classification is that there are indeed great differences between different types of ice from a microscopic perspective.

Obviously, if you just observe from the surface, it is difficult to see the difference between the various types of ice. It is necessary to analyze the crystal structure of ice in the microscopic world.

According to this standard, the ice we often see in daily life belongs to No. 1 ice. Due to its internal structure, people also call it hexagonal ice.

Schematic diagram of the molecular structure of ice 1

Of course, initially people thought that ice in nature should be "mass-produced" and that they were all exactly the same. But later people realized that when the temperature and pressure change, the hydrogen bonds between water molecules will show different grid structures and strengths, thus presenting many complex ice phases, and each ice phase has its own characteristics.

According to current research, humans have discovered more than a dozen ice crystal structures, most of which were obtained in the laboratory. Because in the natural environment, it is difficult to make the pressure and temperature that meet people's requirements appear at the same time. Among them, only hexagonal ice Ih and cubic ice Ic can form and exist naturally in nature.

Schematic diagram of the conditions for the three states of water

In this way, people began to explore the ice phase of ice in 1900. At that time, people obtained hydrogen-ordered ice No. 2 by simply applying pressure. However, due to the poor observation equipment, the structure of ice No. 2 was not analyzed until 1964 by single crystal X-ray diffraction.

Later, as experimental devices became more and more sophisticated and observation equipment became more and more advanced, people discovered more ice phases, including Ice 7, which we are going to talk about today. So how was Ice 7 discovered? Who exactly is it?

Does No. 7 ice look different from ordinary ice?

The magical "Ice No. 7"

First of all, it should be pointed out that when scientists explore ice phases, they do use numbers to sort and name them, but they usually add Roman numerals after the ice, such as ice 7 will be expressed as ice VII. Therefore, whether it is ice 7 or ice VII, in essence, it refers to the same thing.

According to the data, Klotz and others, the discoverer of ice 7, found in the laboratory that by reducing the pressure of ice VI in an environment below 95K, high-pressure phase ice VII can be obtained. And after that, some researchers said that ice 7 can exist stably under a pressure of 22kbar. As for the internal structure of ice 7, it is composed of two mutually structured cubic ice lattices, and there are no connecting hydrogen bonds between the sublattices.

Schematic diagram of the molecular structure of ice-7

If we compare it with the common ice 1, we will find that the density of ice 7 is very high, about 1.5 times that of ice 1. In this way, ice 7 is much more "solid" than we think. In addition, compared with ice 1, the freezing point of ice 7 is higher.

As we all know, generally speaking, water will only solidify when the temperature is below 0 degrees Celsius. However, ice 7 is a representative of a different approach. It can solidify at 4.9 degrees Celsius. Judging from the temperature alone, it seems to be very easy to appear in daily life.

Normally, water freezes at 0 degrees

But temperature alone is not enough. As we just said in the previous article, the change of ice phase is affected by the combined effects of pressure and temperature. Although the freezing temperature of ice 7 is relatively high, its pressure requirement is also ridiculously high.

According to research data, freezing a piece of ice 7 requires a pressure of 3 billion Pascals, while our standard atmospheric pressure is only 101.325 kilopascals. Even if we enter the deepest Mariana Trench on the surface, we are still far from the figure of 3 billion Pascals.

The pressure at the deepest part of the ocean trench can reach 110 MPa

Of course, there are many things in the world. Scientists originally thought that ice 7 would never be found in the natural environment, but unexpectedly, an American research team accidentally discovered a diamond in 2018. Diamonds are precious, but in essence, they are not rare. The problem is that the rare ice 7 appeared in the diamond.

It turns out that this diamond unexpectedly became a laboratory for the condensation of Ice-7. It is important to know that it not only meets the pressure requirements of Ice-7, but also keeps the temperature below a certain limit by locking it in the body. In this case, a fairly mini Ice-7 was born.

Diffraction pattern of ice-7 in diamond

Scientists were very excited after discovering this, but some people were very worried because in many imaginative descriptions, the existence of Ice-7 is not a good thing for humans, on the contrary it may be used by criminals as a weapon to destroy the earth.

Could it be that just one piece of ice No. 7 could really freeze the Earth's oceans?

By then, humans may not even need to learn how to swim.

Can Ice 7 Freeze the Ocean?

In fact, the claim that ice 7 can freeze the ocean cannot be considered "made up out of thin air", because the characteristics of ice 7 do fit this assumption.

According to scientists' research, if ice 7 is formed under natural conditions and the air pressure and temperature at the time meet the requirements for its continued freezing, then it will spread out from that "point" like crazy. In just one hour, it can even freeze the surrounding 1,600 kilometers.

Ice 7 under computer simulation

Therefore, some people believe that if people are given a piece of ice 7, under the right conditions and time, it can indeed freeze the entire ocean. However, through the above introduction, everyone understands that temperature alone is not enough, and the earth's surface does not have the pressure required for the formation of ice 7.

In this case, even if someone threw a complete piece of Ice 7 into the sea, it would not freeze the ocean as expected. It is more likely that Ice 7 had already melted when it entered the ocean.

It's over before I even start...

Of course, the fact that such an environment does not exist on Earth does not mean that it does not exist on other planets. According to scientists' research, an exoplanet more than 20 light years away from Earth may have the potential to breed ice 7. After all, the pressure and temperature on this planet can meet the needs of ice 7, and more importantly, there seems to be no land on its surface, but it is completely covered by the ocean.

In short, theoretically, ice 7 does have the ability to freeze the ocean. But it needs too many prerequisites to do this, and the Earth obviously cannot meet them. Therefore, it is impossible to freeze the Earth's ocean with just a piece of ice.

"Want to freeze me? Practice more!"

It is worth mentioning that in addition to the often-mentioned No. 7 ice, which has the special ability of "quick freezing", there is also a magical No. 18 ice, which has frequently been on the hot discussion list since it was discovered.

Superionic ice phase-Ice 18

If it is shocking that ice 7 can condense at room temperature, then ice 18 will once again overturn our cognition. As early as 1988, physicists who were obsessed with studying ice phases made a prediction about "high-temperature freezing".

Although it seems incredible, he believes that in an extreme environment of high temperature and high pressure, oxygen ions can be locked in a solid cubic lattice, while hydrogen ions can move freely in it.

Schematic diagram of the molecular structure of ice-18

In this case, the ice crystal structure will be more stable and the melting point will be higher. This prediction was finally confirmed 30 years later.

It is reported that in 2018, LLNL physicist Millot and others found the first clue to the existence of superionic ice. They compressed liquid water, turning it into solid ice in a few nanoseconds. The conductivity increased hundreds of times in a short period of time, which means that water ice has turned into a "superionic" state.

What would superionic ice look like?

Similar to the physicist's prediction, ice 18 can appear smoothly when the pressure is between 249 and 278 GPa and the temperature is between 2000 and 3000 K. In this case, this piece of ice has really been "reborn from the ashes".

What do you think about this? Welcome to leave a message in the comment area. Follow CHN Jiuxiang Technology, and through popular science, you will find that there are too many wonderful things in this world.