Method of producing optically active glass-ceramic based on fluoride glass doped with rare earth compounds. RU patent 2520114.

FIELD: chemistry.

SUBSTANCE: method involves adding nanopowder of a rare earth fluoride into a mixture - fluoride glass powder, mechanical mixing of the fluoride glass powder and the rare earth fluoride nanopowder while simultaneously grinding the fluoride glass to particle size of 0.1-0.5 mcm and pressing. The mixture is placed into a mould for pressing. The required pressure is applied, followed by heating to glass-transition temperature without reducing the pressure.

EFFECT: endowing fluoride glass with new properties via activation with rare earth fluorides.

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The invention relates to the field of production of optically active ceramics on the basis of fluoride glasses and can be used at the enterprises of glass and optical industry for materials, conducting of laser radiation.

One of the topical problems of modern materials science is the search for suitable environments for the transmission of laser radiation, which is now widely used as a basic tool in different branches of industry and in medical purposes. From a practical point of view the decision criteria are characteristics of radiation and value of production of lasers. Most modern solid-state lasers based on doped rare earth elements (REE), more precisely, connections REE, YAG crystals (Y 3 Al 5 O 12 ), whereas among powerful gas lasers are the most widespread CO2 lasers. This is due to their use in laser surgery, because the maximum absorption of human tissues falls at a wavelength of 10.6 flash off. In the transmission of laser radiation (Nd:YAG, light wavelength=2.94 flash off; CO 2 , light wavelength=4.8-5.5 flash off) in quartz fibers most of the power is lost as heat. Therefore, highly relevant search of new conducting media. In this respect, a very promising fluoride glass because of their transparency in a wide range of 0.3-10 flash off. Unlike oxide glasses, fluoride, having in its composition heavy, with large radius, likhoborskie cations, are characterized by low energy phonons and, accordingly, the expanded area of bandwidth.

Active glass ceramics get different methods, in particular the crystallization of glass at temperatures close to the glass transition temperature, pressing of powders of metal fluorides at high temperatures [P.P. Fedorov, V.V., Osiko, TT Basiev, Orlov YU.V., C.V. Dukelsky, I.A. Mironov, V. Demidenko, A.N. Smirnov. Optical fluoride nanoceramics // Russian nanotechnology, v.2, №5-6, 2007, P.95-105].

Today when receiving active nanoceramics on the basis of fluoride glasses connection REE introduced in the initial charge, heat the mixture to a temperature 900-1000 C and at these temperatures cook glass within 15-30 minutes. To eliminate smiley (glassy inclusions, with different properties from the main glass) thus obtained glass crushed and pressed the glass transition temperature. The result is a glass with uniformly distributed REE in a glass matrix [P.A. Tick, N.F. Borelli, I.M. Reaney Opt. Mater. (Amsterdam), 15, 81 (2000)]. However, the connection of REE in the famous way the glass is distributed evenly on the molecular level (in the form of individual molecules) and do not form crystals, needed to activate it. In order to transfer them to the nanocrystalline state, the necessary directional crystallization of glass. This process, which requires strict control of the heat mode and speed of crystal growth, is very complicated due to the irregularity of this growth and does not provide stable results: the nanocrystalline state REE in the matrix glass is achieved only in isolated cases.

The closest to the proposed technical solution is the way described in U.S. patent number 4388097, publ. 14.01.1983, "Fluoride glass, obtained by hot pressing, which includes preliminary (the way) receiving fluoride glasses on the basis ZrF 4-BaF 2 & HfF 4-BaF 2 , including fluorides REE (CeF 3 to LuF 3 ), sample preparation, mainly solid fluoride glass (possibly fragments or powder), containing fluoride REE, placing it in the form, for pressing, heat up to temperature, ensuring the transition, which is between the softening point glass and its crystallization point, and hot pressing at the attained temperature and then cooled to room temperature. Received fluoride glass, with transparency in the middle pane of the IR spectrum, find high quality and does not require additional processing.

However, in the famous glass fluorides REE distributed at the molecular level, the crystalline phase allows the activation of Windows, missing and these glasses do not detect the optical activity

The objective of the invention consists in developing an efficient way to obtain optically active ceramics with nanocrystals fluoride REE embedded in a matrix of fluoride glass.

The technical result of the invention consists in giving new properties fluoride glasses by their activation using fluoride REE.

This technical result is achieved by the method of producing optically active ceramics on the basis of fluoride glasses containing fluorides of rare-earth elements, including the preparation of a powder fluoride glass with fluorides of rare-earth elements, placing it in the form, for pressing, heat up to temperature, providing transition, compressing and cooling, in which, in contrast to the known, the preparation of powder fluoride glass with fluorides of rare earth elements is carried out by introduction of the latter in the form of nanopowder with a particle size of not more than 50 nm in powder fluoride glass with its simultaneous grinding till the sizes of particles of 0.1-0.5 mm with mechanical stirring, and the pressing is carried out by applying the pressure to the form containing the powder in the cold, and then carry out heat, without reducing the applied pressure.

The method is as follows.

Prepare a portion of the charge, including powder fluoride glass, obtained by preliminary grinding, and additive (about 1%) selected fluoride REE in the form of powder with a particle size of not more than 50 nm, mainly 10-50 nm. Then the mixture is ground and carefully mix, for example, using or planetary mixer mills up to the size of particles fluoride glass of 0.1-0.5 MK, placed into the mold of a given size and pressed under the pressure of 2-3 tons per cm 2 . Then, without reducing the pressure, the mixture is heated up to the glass transition temperature (almost a few degrees above) and stand 5-10 minutes Then the temperature slowly (for a period of not less than 10 min) reduces to room. The result is a transparent optically active ceramics in the form of discs, diameter and thickness which to set the mold.

The proposed method allows to obtain a stable and don't need additional processing high-volume samples optically active ceramics on the basis of fluoride glass, including uniformly distributed in a glass matrix nanocrystals fluoride REE.

The claimed process parameters determined experimentally, with the criterion of an estimation was received as optically active ceramic while controlled by the presence of crystalline phases fluoride REE in the form of a uniformly distributed nanoparticles.

Examples of specific of the method

Example 1.

To obtain 50 grams of ceramic cook a portion of the charge, which includes glass ZBLAN (mol %): 53 ZrF 4 20 BaF 2 4 LaF 3 3 AlF 3 20 NaF and the addition of fluoride erbium ErF 3 in the amount of 1%by weight, why give 49,5 g glass ZBLAN and 0.5 grams of the specified fluoride.

To pre-crushed glass ZBLAN add weighted number ErF 3 in the form of nanopowder with particle size from 10 to 50 nm, the charge is then crushed and at the same time carefully mix with the mixer mill for 20 minutes (up to size of particles of glass ZBLAN 0,1 MK), lay in a mold using the form in diameter 60 mm, and pressed under pressure 2 t/cm 2 . Then, without reducing the pressure, the mixture is heated up to 300 C and stand 5 minutes

As a result, after cooling is formed drive from transparent optically active nanoceramics.

In the obtained sample methods of electron microscopy with the use of electronic scanning microscope Hitachi S 5500 at maximum magnification, x 2000000 found that nanoparticles of fluoride REE evenly distributed in the volume of the sample and their size has not changed in the process of obtaining ceramic.

Example 2.

To obtain 50 grams of ceramic cook a portion of the charge, including glass ZBLAN with the addition of 1% of fluoride europium EuF 3 in the form of nanopowder particle size from 10 to 50 nm, which weighed 49,5 g glass ZBLAN and 0.5 g EuF 3 .

Then the mixture is treated according to example 1, crushing to the size of particles of glass ZBLAN of 0.5 MK, and pressed under pressure 2 t/cm 2 . Then, without reducing the pressure, the mixture is heated up to 300 C and stand 10 minutes

The results are similar to results obtained in example 1.

Example 3.

To obtain 50 grams of active ceramic cook a portion of the charge, including glass composition (mol %): 40AlF 3-12BaF 2-22CaF 2-16YF 3-10SrF 2 with the addition of 1% of fluoride europium EuF 3 in the form of nanopowder with a particle size of 10-50 nm, which weighed 49,5 g glass specified structure and 0.5 g EuF 3 .

Then the mixture is treated in example 1 using the mold with a diameter of 40 mm, pressed under pressure 3 t/cm 2 . Then, without reducing the pressure, the mixture is heated up to 315 degrees C and stand 10 minutes

The results are similar to results obtained in example 1.