Unique properties: Russian scientists have created a material for a new generation of optics

Scientists of the Moscow Institute of Physics and Technology (MIPT), Institute of Biochemical Physics.

N.M.

Emanuel RAS and the Institute of Physics.

L.V.

Kirensky SB RAS found a new material for obtaining crystalline films used in new generation optics.

This was reported to RT by the Ministry of Education and Science of the Russian Federation.

The results of the study are published in the journal npj 2d Materials and Applications.

In recent years, scientists around the world have been developing two-dimensional materials - this is the name given to thin films consisting of a single layer of the crystal lattice of atoms.

The best-known material of this class is graphene, in which carbon atoms are arranged in a hexagonal lattice one atom thick.

Such materials have unique properties and are necessary for the creation of complex electronics, quantum cryptography, and modern optics.

As a rule, the individual layers of such material are held together by van der Waals bonds.

The van der Waals bond is not chemical, but electrostatic in nature and occurs between molecules and atoms.

This is a weak bond, which is noticeably inferior in strength to chemical bonds.

According to the authors of the work, such films are difficult to scale and apply in practice precisely because of the fragility of the bonds connecting the individual layers of the material.

Therefore, scientists have concentrated on creating such films, the layers of which will be held together by strong chemical bonds - covalent.

A covalent bond occurs when the nuclei of atoms approach each other and they share a common electron pair.

Covalent bonds, in particular, form the structure of some crystals.

The researchers managed to find such a crystal, the monatomic films of which continue to be held together by covalent bonds even after delamination.

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It turned out to be indium and gallium sulfide (InGaS3).

It turned out that after the separation of the crystal into layers, individual films continue to be held together due to covalent bonds, but at the same time they have the properties of two-dimensional layered materials.

The authors of the work studied the physicochemical properties of the new material, in particular, its optical properties.

It was found that such a layered crystal has a high refractive index (n > 2.5).

For comparison: for glass, this figure is about 1.52.

Substances with a refractive index greater than 2 are very rare in nature.

For example, they include a diamond, in which this coefficient is 2.4.

The scientists also found that the new material does not absorb light in the visible and infrared ranges, that is, passing through films of indium and gallium sulfide, the light will not lose intensity.

“First, using computer simulations, we predicted the possibility of the existence and production of a two-dimensional layer from a covalent InGaS3 crystal by breaking chemical bonds along a certain direction.

Then, having carried out a huge series of experiments, we managed to obtain such a layer by the method of micromechanical cleavage and study its optical and electronic properties.

They turned out to be outstanding, including a wide band gap (a section of a photonic crystal where the nature of the propagation of an electromagnetic wave changes.

) and the refractive index.

Thanks to them, the material can become the main platform for the development of next-generation optical devices.

For example, it can be used to create subdiffractive waveguides used in integrated circuits in machine learning tasks, ”explained Georgy Ermolaev, MIPT researcher to RT.

According to scientists, the material can be used in a new generation of optics for the production of complex medical equipment, integrated circuits, photonic computing devices, as well as devices for the projection of volume holograms.