As we discovered material modifications that contradict well-established chemical principles
Scientists of NITU "MISiS" together with Russian and foreign colleagues have proved the possibility of creating materials that are unrealistic from the point of view of the usual understanding of the laws of chemistry. By subjecting beryllium oxide to pressure hundreds of thousands of times higher than atmospheric, the researchers achieved a “peri-orientation” of the crystal structure of the material to five and six oxygen atoms surrounded by beryllium, although it was previously believed that the maximum possible number could be only four. The results of the experiment and its theoretical justification of the scientists presented in the journal Nature Communications.
Imagine that before you a mountain of cubes, and you are going to build something from them, - the authors of the research describe their work. - You can collect a lot of various designs, but still their number is limited due to the shape of “building materials”, because they can only be connected with each other in a certain way. Now imagine that you have the opportunity to change the shape of these cubes - to stretch them, add edges, in a word, modify them so that the number of possible combinations of the resulting "building materials" increases countless times.
Laboratory Director I. Abrikosov (left) with staff.
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The cubes in question are nothing more than elements of the crystal structure of materials, by modifying which, you can “reward” materials with fundamentally new properties. But certain transformations are impossible within the framework of familiar ideas.
Solving this problem - overcoming the “impossibility” - is the work of scientists from NITU “MISiS” together with colleagues from the University of Bayreuth and the DESY Research Center (Germany), Lynchöpinsky University (Sweden), and the Russian Academy of Sciences (Institute of Earth Sciences and Kola Scientific Center ).
As shown by the results of their joint research — a laboratory experiment and its theoretical modeling — it is quite possible to obtain “impossible” modifications of materials — and for this it is necessary to subject them to ultrahigh pressures hundreds of thousands of times higher than atmospheric.
Tetrahedrally coordinated beryllium oxide
“We worked with hellbutite, a form of beryllium with the chemical formula CaBe2P2O8. Under classical conditions, it has a tetrahedral structure - beryllium forms tetrahedral pyramids with oxygen atoms, and until recently it was thought that this is the maximum possible coordination of beryllium. However, our colleagues from Germany conducted an experiment, as a result of which it became clear that the crystal structure can be rearranged. During the experiment, the material was placed in a diamond anvil, where it was subjected to ultrahigh pressures.
Pentahedral coordinated beryllium oxide
Thus, at a pressure of 17 GPa (170 thousand Earth atmospheres), the number of oxygen atoms of the surrounding beryllium increased to five, and at a pressure of 80 GPa (800 thousand Earth atmospheres), the crystal was rebuilt so that this number increased to six. This is an incredible result, never before presented by anyone. That is why he also needed a theoretical substantiation, the study of which we started independently on our supercomputer , ”says Professor Igor Abrikosov , scientific director of the laboratory“ Modeling and Development of New Materials ”at NITU“ MISiS ”.
Hexagon Coordinated Beryllium Oxide
Theoretical simulation of the experiment results was carried out by scientists of NUST “MISiS” in record time - in just one month. To solve the Dirac equation with the given variables, the entire computational power of the supercomputer cluster of the lab “Modeling and development of new materials” was used. Without the use of such a supercomputer, it would never be possible to perform calculations of such complexity — conventional computers simply would not have enough power. The results of the calculations almost completely coincided with the results of the experiment - the differences are minimal, and are within the permissible limits of error.
Supercomputer NITU "MISIS"
As Professor Abrikosov notes, in many respects beryllium was chosen as an experimental material because it is particularly popular in mechanical engineering and the space industry. However, the work done is largely fundamental - by studying the modifications of specific materials, you can build a general theoretical model that allows you to systematize the processes and conditions necessary to create "impossible materials". In the near future, scientists plan to continue research, in particular, with such a class of materials as polynitrides.
Reference:
Professor Igor Abrikosov - Doctor of Physical and Mathematical Sciences, Scientific Director of the Laboratory "Modeling and Development of New Materials" NITU "MISiS", Head of the Department of Theoretical Physics of the Institute of Physics, Chemistry and Biology, Linköping University, Academician of the Royal Swedish Academy of Sciences.
The scientific team under his leadership is working on theoretical modeling of processes taking place in materials under high and superhigh pressure conditions.
Previously, scientists have already proved the possibility of the existence of "unrealistic" modifications of silica and nitrides , as well as the transformation of a hematite insulator into a conductor - and all this at pressures exceeding atmospheric pressure in hundreds of thousands (and sometimes in millions).
Imagine that before you a mountain of cubes, and you are going to build something from them, - the authors of the research describe their work. - You can collect a lot of various designs, but still their number is limited due to the shape of “building materials”, because they can only be connected with each other in a certain way. Now imagine that you have the opportunity to change the shape of these cubes - to stretch them, add edges, in a word, modify them so that the number of possible combinations of the resulting "building materials" increases countless times.
Laboratory Director I. Abrikosov (left) with staff.
')
The cubes in question are nothing more than elements of the crystal structure of materials, by modifying which, you can “reward” materials with fundamentally new properties. But certain transformations are impossible within the framework of familiar ideas.
Solving this problem - overcoming the “impossibility” - is the work of scientists from NITU “MISiS” together with colleagues from the University of Bayreuth and the DESY Research Center (Germany), Lynchöpinsky University (Sweden), and the Russian Academy of Sciences (Institute of Earth Sciences and Kola Scientific Center ).
As shown by the results of their joint research — a laboratory experiment and its theoretical modeling — it is quite possible to obtain “impossible” modifications of materials — and for this it is necessary to subject them to ultrahigh pressures hundreds of thousands of times higher than atmospheric.
Tetrahedrally coordinated beryllium oxide
“We worked with hellbutite, a form of beryllium with the chemical formula CaBe2P2O8. Under classical conditions, it has a tetrahedral structure - beryllium forms tetrahedral pyramids with oxygen atoms, and until recently it was thought that this is the maximum possible coordination of beryllium. However, our colleagues from Germany conducted an experiment, as a result of which it became clear that the crystal structure can be rearranged. During the experiment, the material was placed in a diamond anvil, where it was subjected to ultrahigh pressures.
Pentahedral coordinated beryllium oxide
Thus, at a pressure of 17 GPa (170 thousand Earth atmospheres), the number of oxygen atoms of the surrounding beryllium increased to five, and at a pressure of 80 GPa (800 thousand Earth atmospheres), the crystal was rebuilt so that this number increased to six. This is an incredible result, never before presented by anyone. That is why he also needed a theoretical substantiation, the study of which we started independently on our supercomputer , ”says Professor Igor Abrikosov , scientific director of the laboratory“ Modeling and Development of New Materials ”at NITU“ MISiS ”.
Hexagon Coordinated Beryllium Oxide
Theoretical simulation of the experiment results was carried out by scientists of NUST “MISiS” in record time - in just one month. To solve the Dirac equation with the given variables, the entire computational power of the supercomputer cluster of the lab “Modeling and development of new materials” was used. Without the use of such a supercomputer, it would never be possible to perform calculations of such complexity — conventional computers simply would not have enough power. The results of the calculations almost completely coincided with the results of the experiment - the differences are minimal, and are within the permissible limits of error.
Supercomputer NITU "MISIS"
As Professor Abrikosov notes, in many respects beryllium was chosen as an experimental material because it is particularly popular in mechanical engineering and the space industry. However, the work done is largely fundamental - by studying the modifications of specific materials, you can build a general theoretical model that allows you to systematize the processes and conditions necessary to create "impossible materials". In the near future, scientists plan to continue research, in particular, with such a class of materials as polynitrides.
Reference:
Professor Igor Abrikosov - Doctor of Physical and Mathematical Sciences, Scientific Director of the Laboratory "Modeling and Development of New Materials" NITU "MISiS", Head of the Department of Theoretical Physics of the Institute of Physics, Chemistry and Biology, Linköping University, Academician of the Royal Swedish Academy of Sciences.
The scientific team under his leadership is working on theoretical modeling of processes taking place in materials under high and superhigh pressure conditions.
Previously, scientists have already proved the possibility of the existence of "unrealistic" modifications of silica and nitrides , as well as the transformation of a hematite insulator into a conductor - and all this at pressures exceeding atmospheric pressure in hundreds of thousands (and sometimes in millions).
Source: https://habr.com/ru/post/459692/
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