RU2767628C1 - Terahertz silver halide nanoceramic - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: invention relates to optical terahertz (THz) materials, specifically to terahertz nanoceramics based on solid solutions of silver halides, transparent in terahertz, millimetre, infrared and visible ranges, which can be used in making fibre-optic devices for medicine, infrared fibre and laser optics, optoelectronics and photonics. Terahertz silver halide nanoceramic is based on solid solution AgBr_0.6I_0.4 and silver chloride with the following ratio of ingredients, wt. %: solid solution AgBr_0.6I_0.4 70.0–80.0; silver chloride 30.0–20.0.

EFFECT: nanoceramic is plastic (high fluidity of material) and is non-toxic, since it is made on the basis of silver halides, having disinfecting properties.

1 cl, 3 ex, 1 dwg

Description

The invention relates to optical terahertz (THz) materials, specifically to terahertz nanoceramics based on solid solutions of silver halide, transparent in the terahertz, millimeter, infrared and visible ranges, which has high plasticity, non-toxicity, chemical and radiation resistance. The frequency range of electromagnetic radiation 0.1 - 10.0 THz, which corresponds to wavelengths of 3000.0 - 30.0 μm, is a universal definition of the terahertz region and one of the advanced and breakthrough areas of fundamental science and technology.

Terahertz silver halide nanoceramics is a promising material for laser and infrared (IR) fiber optics, for the manufacture of optoelectronics and photonics devices, for use in medicine, since terahertz radiation is safe compared to X-ray [Terahertz optoelectronics and its application / A. S. Akhmanov and etc. // Modern laser-information technologies: a collective monograph edited by academician V. Ya. Panchenko and professor F. V. Lebedev. M. : Interkontakt Nauka, 2014, pp. 758-785.].

Known optical nanoceramics aluminum-magnesium spinels (MgAl ₂ O ₄ ), doped with cations (Fe ²⁺ , Cu ²⁺ , Cr ³⁺ and others), transmitting in the range of 0.2 - 5.5 μm, with high radiation and mechanical resistance [Kiryakov A.N. "Defective structure and electron-optical properties of transparent nanoceramics of aluminum-magnesium spinel", abstract of dissertation. for the competition uch. step. c.f.-m. sciences on special 04/01/07 - Condensed Matter Physics, Yekaterinburg, 2021;

Zou Y. Nanosintering mechanism of MgAl ₂ O ₄ transparent ceramics under high pressure, Materials Chemistry and Physics, 2010, Vol. 123, No. 2-3, P. 529-533;

Gluchowski P. Luminescence studies of Cr ³⁺ doped MgAl ₂ O ₄ nanocrystalline powders, Chemical Physics, 2009, Vol. 358, No. 1-3, P. 52-56]. But ceramics are not transparent in the terahertz range, as well as in the infrared region from 5.5 to 45.0 microns. Ceramics is not plastic, and therefore unsuitable for fabrication of IR light guides by extrusion. In addition, the authors talk about the high transparency of nanoceramics, but do not give its value as a percentage.

Known terahertz silver halide ceramics based on two solid solutions of cubic and rhombic phases of the system AgBr - AgI - TlBr - TlI. Ceramics is transparent in the terahertz and millimeter ranges, and is also transparent without absorption windows in the visible, near, mid and far infrared ranges [Zhukova L.V., Salimgareev D.D., Korsakov A.S., Lvov A.E., Promising terahertz materials: crystals and ceramics: textbook. Yekaterinburg: UMC UPI Publishing House LLC, 2020. c. 151-171;

Zhukova, L., Salimgareev, D. D., Lvov, A. E., Yuzhakova, A. A., Korsakov, A. S., Belousov, D. A., Lipustin, K., & Kondrashin, V. M. (2021). Highly transparent ceramics for the spectral range from 1.0 to 60.0 mu m based on solid solutions of the system AgBr-AgI-TlI-TlBr. Chinese Optics Letters, 19(2), 021602]. However, ceramics contain monovalent thallium halides, which is unacceptable for use in medicine; in addition, the authors show optical transparency and transmission spectra in a wide spectral range mainly for single crystals of the AgBr–AgI–TlBr–TlI system.

There is a problem in the development of terahertz silver halide nanoceramics, highly transparent in the terahertz range from 0.05 to 10.0 THz, as well as in the range from 0.35 to 45.0 μm, plastic and non-toxic, chemically and radiation-resistant with access to finished optical products from 80 to 90% and intended for medicine, infrared fiber and laser optics, optoelectronics and photonics.

The solution to the problem is achieved due to the fact that terahertz silver halide nanoceramics, characterized by the fact that it is made on the basis of a solid solution of AgBr_0.6I_0.4And silver chloride in the following ratio of ingredients, wt. %:

solid solution AgBr _0.6 I _0.4 – 70.0 – 80.0; silver chloride - 30.0 - 20.0.

The essence of the invention lies in the fact that a new terahertz silver halide nanoceramic based on AgBr solid solution has been created._0.6I_0.4And silver chloride. It is plastic (high fluidity of the material) and non-toxic, since it is made on the basis of silver halides, which have disinfecting properties, which contributes to its wide application in the manufacture of fiber-optic devices for medicine. Nanoceramics consists of densely packed crystalline cubic (NaCl type) and nanocrystalline hexagonal (wurtzite type) phases of solid solutions of silver halides of different chemical composition, uniformly distributed in each other and having similar refractive indices, which suppresses the growth of nanograins of the hexagonal phase with a grain size of 40-60 nm (see figure 1) and voids between them. This explains the high transparency of nanoceramics in the terahertz region from 0.05 to 10.0 THz, where it is transparent with absorption windows, and in the range from the visible to the far IR range (0.35–45.0 μm) it is transparent without absorption windows (see .examples).

Terahertz nanoceramics are chemically resistant, i.e., non-hygroscopic and resistant to ultraviolet, β and γ radiation, since it contains a radiation-resistant solid solution AgBr _0.6 I _0.4 .

A terahertz silver halide nanoceramic has been created with a yield of up to 80–90% in optical products - windows, lenses, films, as well as IR light guides, not only due to the mechanism of solid solution hardening with close-packed nanograins, but also due to an effective production technology that includes hydrochemical dissolution of the starting materials in certain solvents and crystallization of nanoceramics of a given composition with its subsequent remelting by the method of directional crystallization.

Example 1

Terahertz nanoceramic composition in wt.%:

solid solution AgBr _0.6 I _0.4 – 80.0; silver chloride – 20.0

obtained by dissolving the starting materials and subsequent crystallization of nanoceramics in solvents of a certain composition. Then the nanoceramics were remelted by the method of directed crystallization. Nanoceramic lathes were used to cut plates for measuring optical properties and workpieces for extrusion of nanocrystalline IR light guides. The yield was 90%. Nanocrystalline wafers were processed by hot pressing to obtain plane parallelism and optical surface. A photograph of the nanostructure of a terahertz silver halide nanoceramic obtained using scanning electron microscopy (SEM) is shown in Figure 1.

The transmission spectra of terahertz nanoceramics in the terahertz region were recorded on an STD-21 spectrophotometer with a backward wave lamp (BWO is a THz radiation source) and using a Tidex Golay cell as a detector. In the visible and infrared regions, the spectra were taken on a Shimadzu UV-1800 spectrophotometer (190 - 1100 nm), IR-Prestige-21 (1.28 - 41.7 μm) and Vertex 80, Bruker (14.7 - 60.6 µm).

Nanoceramics transmits in the terahertz region:

- from 0.05 to 0.3 THz (corresponds to the wavelength range 6000.0 - 1000.0 µm) with a transparency of 62%;

- from 0.35 to 0.9 THz (850.0 - 350.0 microns) with a transparency of 50%;

- from 6.5 to 10.0 THz (45.0 - 30.0 µm) with a transparency of 76%.

Nanoceramics transmit without absorption windows from the visible to the far IR range:

- in the visible and near IR range from 0.35 to 2.0 microns with a transparency of 65-68%;

- in the middle and far IR region from 2.0 to 45.0 microns with a transparency of 68-74%.

Example 2

Terahertz nanoceramic composition in wt. %:

solid solution AgBr _0.6 I _0.4 - 70.0; silver chloride – 30.0

received analogously to example 1. The yield was 80%. The measurement of spectral characteristics was carried out analogously to example 1. Figure 1 shows a close-packed nanoceramic structure obtained using SEM.

Nanoceramics transmits in the terahertz region:

- from 0.05 to 0.3 THz (corresponds to the wavelength range 6000.0 - 1000.0 µm) with a transparency of 64%;

- from 0.35 to 0.9 THz (850.0 - 350.0 microns) with a transparency of 45%;

- from 6.5 to 10.0 THz (45.0 - 30.0 µm) with a transparency of 78%.

Nanoceramics transmit without absorption windows from the visible to the far IR range:

- in the visible and near IR range from 0.35 to 2.0 microns with a transparency of 65-68%;

- in the middle and far IR region from 2.0 to 45.0 microns with a transparency of 68-78%.

Example 3

Terahertz nanoceramic composition in wt. %:

solid solution AgBr _0.6 I _0.4 – 75.0; silver chloride – 25.0

received analogously to example 1. The yield was 85%. The measurement of spectral characteristics was carried out analogously to example 1. The figure shows a close-packed structure of nanoceramics.

The measurement of the spectral transmission range was carried out on the manufactured nanocrystalline plates, as in example 1.

Nanoceramics transmits in the terahertz region:

- from 0.05 to 0.3 THz (corresponds to the wavelength range 6000.0 - 1000.0 µm) with a transparency of 63%;

- from 0.35 to 0.9 THz (850.0 - 350.0 microns) with a transparency of 50%;

- from 6.5 to 10.0 THz (45.0 - 30.0 µm) with a transparency of 77%.

Nanoceramics transmit without absorption windows from the visible to the far IR range:

- in the visible and near IR range from 0.35 to 2.0 microns with a transparency of 65-68%;

- in the middle and far IR region from 2.0 to 45.0 microns with a transparency of 68-76%.

The optimal compositions of the developed terahertz nanoceramics of the AgBr _0.6 I _0.4 – AgCl system, given in the formula, were established on the basis of modeling their structure and confirmed by experimental studies. In the case of a decrease in the content of silver chloride in nanoceramics (less than 20 wt.%), the short-wavelength edge shifts to a longer wavelength region, and with an increase in the content of silver chloride (more than 30 wt.%), the transmission of nanoceramics to the far IR range shifts to 35–40 μm and less .

Technical result. A new terahertz silver halide nanoceramic based on the radiation-resistant solid solution AgBr _0.6 I _0.4 and silver chloride, highly transparent in the terahertz range from 0.05 to 10.0 THz with absorption windows, and highly transparent in the range from 0.35 to 45.0 μm, has been developed. without absorption windows. In this case, the yield into finished optical products is from 80 to 90%. The presence of silver chloride in the composition of nanoceramics expands the short-wavelength absorption edge to 0.35 μm, compared with the analogue - 0.46 μm [Zhukova L.V., Salimgareev D.D., Korsakov A.S., Lvov A.E., Promising terahertz materials: crystals and ceramics: textbook. Yekaterinburg: LLC "Publishing house UMC UPI", 2020. p. 151], and also creates a high defectiveness of the crystal lattice and a decrease in the size of nanograins to 40 - 60 nm (see figure 1). The promising application of nanoceramics should be noted:

- The densely packed structure of nanoceramics, in which there are no crystallographic axes (compared to single crystals), provides a single extrusion process when obtaining nanocrystalline IR fibers. It should be noted that multiple extrusion, which requires reloading of the preform, leads to contamination of the optical fibers.

- The new highly plastic and non-hygroscopic nanoceramics is a promising material for the production of low-dimensional 1D structures by hot pressing and the extrusion of photonic-crystal light guides of 2D structures for photonics and optoelectronics.

Claims (2)

Terahertz silver halide nanoceramics, characterized in that it is made on the basis of a solid solution of AgBr _0.6 I _0.4 and silver chloride in the following ratio of ingredients, wt. %: solid solution AgBr _0.6 I _0.4 70.0–80.0 silver chloride 30.0–20.0

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