RU2542019C1 - Method of producing glass - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method includes melting a mixture of glass-forming oxides containing silicon oxide, magnesium oxide, aluminium oxide and bismuth oxide on air. Activated carbon is further added to the mixture as a basic reducing agent and potato starch is added as a damping reducing agent in amount of 1.5 wt % and 33 wt %, respectively, relative to the weight of the glass-forming oxides, followed by melting the mixture at 1600°C.

EFFECT: invention reduces the absorption coefficient of glass with luminescence with a band crest in the spectral range of 1260-1360 nm, which reduces energy losses in the glass.

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Description

The invention relates to optical glass and can be used to create optical amplifiers in the wavelength range of the second transparency window (1260-1360 nm) of optical fibers based on magnesium aluminum-quartz glass.

It is known that real optical gain, i.e. the excess of gain over loss was obtained only in the range 1150-1215 nm on bismuth-doped aluminosilicate optical fibers (ASB fibers), the luminescence spectrum of which covers the wavelength range 1100-1300 nm. With optical pumping at a wavelength of λ _P = 808 nm, the luminescence maximum is observed at λ _max = 1100 nm, and with a pump of λ _P = 1058 nm, λ _max = 1150 nm. With the aim of shifting the gain band of bismuth-doped glasses and optical fibers based on them further into the IR region to the wavelength band 1260-1700 nm [E.M. Dianov, S.V. Firstov, V.F. Hepin et al. Bismuth fiber lasers and amplifiers operating in the region of 1.3 μm // Quantum Electronics. - 2008. - t. 38, No. 7. - S.615-617] [1] phosphorogermanosilicate glasses doped with bismuth and not containing Al ₂ O ₃ (PGSB glasses and fibers) were chosen as the core of the fiber. The mass concentration of bismuth in the glasses was below 0.1%. Blanks for PGSB fibers were manufactured using MCVD technology. In PGSB glasses and optical fibers drawn from them, the luminescence spectrum is shifted to the IR region much further than the spectrum of ASB optical fibers: with optical pumping λ _P = 1058 nm, the luminescence maximum is observed at λ _max = 1250 nm.

It is known [RU 2463264, IPC С03С 4/12, С03С 3/12, publ. 10.10.2012] [2] obtaining glass from oxides at 900-1200 ° С, containing P ₂ O ₅ and / or Ba ₂ O ₃ as glass-forming components and bismuth in the subvalent state as a source of luminescence. In this case, the glasses luminesce in the region of 1000-1700 nm with a maximum of the luminescence band at ~ 1200-1300 nm when excited by radiation of 500-900 nm and provide amplification of the optical signal in the range of 1050-1500 nm and 1050-1300 nm. Depending on the composition, technological parameters and bismuth concentration, the luminescence spectrum of such glasses is characterized by two bands with maxima at 1200 and 1300 nm or one wide band with a maximum at 1250-1300 nm. Used very high concentrations of bismuth (3-50 mol.% In terms of Bi ₂ O ₃ ). At a concentration of Bi ₂ O ₃ in the glass equal to 0.001 mol%, no luminescence was observed in it. Data on the absorption coefficient of the synthesized glasses are not given.

Glasses synthesized in the above sources containing P ₂ O ₅ and Ba ₂ O ₃ in their composition are characterized by low resistance to high temperatures, moisture and chemical reagents, which significantly narrows their scope.

A known method of producing glass by synthesizing from oxides a luminescent glass composition: 57 SiO ₂ , 30 MgO and 13 Al ₂ O ₃ , characterized by a high melting point, resistance to chemicals and moisture. Bi ₂ O ₃ with concentrations of 0.025-0.25 mol% in excess of 100 mol% of glass-forming oxides was used as an activator. The synthesis and pouring of glass was carried out in a nitrogen atmosphere in an iridium crucible at a temperature of 1850 ° C, i.e. under reducing conditions close to those of silicate fiber production [Denker BI, Galagan BI, Shulman IL, Sverchkov SE, Dianov EM Bismuth valence states and emission centers in Mg-Al-Silicate Glass. Applied Physics B: Lasers and Optics, 2011, vol. 103, no.3, pp. 681-685] [3].

However, in this way it is impossible to synthesize glass with the necessary combination of properties: low light absorption coefficient (which is a prerequisite for gaining amplification in the fiber) and luminescence with a band maximum at ~ 1300 nm. At a high concentration of Bi ₂ O ₃ (0.25 mol.% Over 100 mol.%) The glass had a very high absorption coefficient (opaque), and at a low concentration of Bi ₂ O ₃ (0.025 mol.% Over 100 mol.% Glass-forming oxides ) it did not luminesce.

The technical result consists in decreasing the absorption coefficient of glass with luminescence with a band maximum in the spectral range of 1260-1360 nm (in the second transparency window), which leads to a decrease in energy losses in the glass.

The essence of the invention lies in the fact that in the method for producing glass, which consists in melting in air a mixture of glass-forming oxides containing silicon oxide, magnesium oxide, aluminum oxide and bismuth oxide, activated carbon is additionally introduced into the mixture as the main reducing agent and potato starch as damping reducing agent in amounts of 1.5 and 33 wt.%, respectively, of the mass of glass-forming oxides, followed by melting of the mixture at a temperature of 1600 ° C.

The method is as follows. A series of glass samples of the composition was synthesized: 55-57 SiO ₂ , 30-28 MgO, 13-16 Al ₂ O ₃ . Bi ₂ O _{3 was} added to the batch of glass-forming oxides in small amounts: from 0.03 to 0.12 mol% in excess of 100 mol% of glass-forming oxides and two reducing agents: activated carbon as the main and potato starch as damping, respectively 1 , 5 and 3.3 wt.% By weight of glass-forming oxides.

The synthesis is as follows. Both reducing agents were added to the mixture of glass-forming oxides and Bi ₂ O ₃ taken in specific ratios. The resulting mixture was dried at 180 ° C for about 2 hours, mixed and activated in a ball mill for 15-30 minutes at 160-200 rpm, respectively, placed in a crucible and heated in a resistance furnace for 3 hours to 1600 ° C . At this temperature was maintained for 3 hours without stirring with a stirrer. The synthesized glass is immediately poured onto a massive metal plate preheated to 600 ° C. The cooled glass was not subjected to additional annealing to relieve stresses in it (500-600 ° C, 1 h).

Reducing agents were added to the mixture of glass-forming oxides, based on the following considerations. In [1-3], it is believed that sources of luminescence with a band maximum in the region of 1260–1360 nm upon photoexcitation of luminescent centers by light with a wavelength of 808 nm are Bi ^{n +} ions, where 0 <n <3, i.e. recovered compared to Bi ³⁺ . But according to thermodynamic calculations using data [4-5], confirmed experimentally, at a concentration of Bi ₂ O ₃ <1 mol% (in excess of 100 mol% of glass-forming oxides) the reaction of formation of Bi ^{n +} (0 <n <1) at 1450 ° C in air becomes thermodynamically impossible.

However, it was experimentally found that luminescence centers with a band maximum in the region of 1260–1360 nm in glass with a low Bi ₂ O ₃ content can be obtained due to the defect formation reaction in Bi ₂ O ₃ proceeding according to the equation

, двух электронов в решетке (расплаве) и выделением газообразного кислорода (О₂) из узла решетки (О_х).with the formation of a doubly charged oxygen vacancy $$({\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="00000005.png,00000007.png"\; state="\{\{state\}\}">V</figure-callout>}}_0^{••})$$

, two electrons in the lattice (melt) and the release of gaseous oxygen (O ₂ ) from the lattice site (O _x ).

According to published data [6, 7], the formed oxygen vacancies capture 2 electrons, turning into electrically neutral F centers, which at a sufficiently high concentration form associates that absorb at λ = 500, 700, 800, ~ 1030 nm and color the glass red . If the concentration of F centers is insufficient for the formation of associates, then the glass is colorless. In the case of the formation of F centers with an energy of ~ 2 eV (λ _P = 600 nm), the glass is colored blue. Luminescence centers absorbing at 500, 700 nm give a luminescence band with a maximum at λ = 1100–1150 nm, and absorbing centers at 800 and 1000 nm give a luminescence band with a maximum at λ = 1260–1300 nm.

The balance of reaction (1) can be shifted to the right by adding a reducing agent that binds the released oxygen, for example, activated carbon, to the reaction mixture. However, it was experimentally established that it is too hard a reducing agent, causing the formation of non-luminescent colloidal particles of metallic bismuth by the reaction

At high concentrations of Bi ₂ O ₃ in the charge, metallic Bi ⁰ is released as a separate phase.

To prevent the formation of Bi ^0? As a damping substance, along with activated charcoal, potato starch is added to the charge, upon combustion of which, along with CO, gaseous H ₂ O is released, which prevents the formation of colloidal bismuth, oxidizing it.

The optical and luminescent characteristics of the synthesized glasses are presented in table 1, based on Fig. 1-2.

From table 1 it follows that to obtain glass with a maximum luminescence in the region of 1260-1360 nm and a low light absorption coefficient, Bi ₂ O ₃ in the amount of 0.05-0.06 mol should be added to the mixture of oxides SiO ₂ , MgO, Al ₂ O ₃ % over 100 mol.% glass-forming oxides, and a mixture of reducing agents: activated carbon and potato starch in the amount of 1 wt.% and 33 wt.%, respectively.

The following are examples of the production of luminescent glasses.

Example 1. Glass containing 0.12 mol.% Bi ₂ O ₃ .

To a mixture of 8.55 g SiO ₂ , 3.00 g MgO, 3.60 g Al ₂ O _{3 was} added 0.15 g Bi ₂ O ₃ , 0.25 g activated carbon and 4.75 g potato starch. The mixture was mixed and activated in a planetary mill, dried at ~ 180 ° C for 2 h, placed in a crucible, in a resistance furnace, heated to 1600 ° C for 3 h, kept at this temperature. The melt was poured onto a massive metal substrate. The synthesized glass was not subjected to additional annealing at 600 ° С to relieve mechanical stresses.

Example 2. Glass containing 0.06 mol.% Bi ₂ O ₃ .

To a mixture of 8.55 g SiO ₂ , 3.00 g MgO, 3.60 g Al ₂ O _3, 0.075 g Bi ₂ O ₃ , 0.25 g activated carbon and 4.75 g potato starch were added. The mixture was mixed and activated in a planetary mill, dried at ~ 180 ° C for 2 h, placed in a crucible, in a resistance furnace, heated to 1600 ° C for 3 h, kept at this temperature. The melt was poured onto a massive metal substrate. The synthesized glass was not subjected to additional annealing at 600 ° С to relieve mechanical stresses.

Example 3. Glass containing 0.05 mol.% Bi ₂ O ₃ .

To a mixture of 8.55 g of SiO ₂ , 3.00 g of MgO, 3.60 g of Al ₂ O _3, 0.070 g of Bi ₂ O ₃ , 0.25 g of activated carbon and 4.75 g of purchased potato starch were added. The mixture was mixed and activated in a planetary mill, dried at ~ 180 ° C for 2 h, placed in a crucible, in a resistance furnace, heated to 1600 ° C for 3 h, kept at this temperature. The melt was poured onto a massive metal substrate. The synthesized glass was not subjected to additional annealing at 600 ° С to relieve mechanical stresses.

Example 4. Glass containing 0.03 mol.% Bi ₂ O ₃ .

To a mixture of 8.55 g of SiO ₂ , 3.00 g of MgO, 3.60 g of Al ₂ O _3, 0.034 g of Bi ₂ O ₃ , 0.25 g of activated carbon and 4.75 g of purchased potato starch were added. The mixture was mixed and activated in a planetary mill, dried at ~ 180 ° C for 2 h, placed in a crucible, in a resistance furnace, heated to 1600 ° C for 3 h, kept at this temperature. The melt was poured onto a massive metal substrate. The synthesized glass was not subjected to additional annealing at 600 ° С to relieve mechanical stresses. No luminescence with a band maximum at 1300 nm was observed in the synthesized glass.

Compared with the known solutions, the proposed one allows one to obtain glass having both a low absorption coefficient and luminescence with a band maximum in the spectral range of 1260–1360 nm (in the second transparency window).

Table 1 No. p / p The concentration of Bi ₂ O ₃ in the mixture (in excess of 100 mol.% Glass-forming oxides) The nature and amount of reducing agent / Synthetic glass color The presence of the maxima of the absorption bands in the spectrum at The absorption coefficient of the glass k, cm ^-1 The presence of maxima of the luminescence bands at λ = 500 nm λ = 700 nm λ = 800 nm λ = 900 nm λ = 1000 nm λ = 1100-1150 nm λ = 1260-1300 nm one 0.12 Activated carbon 1 wt.% + Starch 33 wt.% / Orange + + + + + 0.7 + + 2 0.06 Activated carbon 1 wt.% + Starch 33 wt.% / Light orange + + + + + 0.1 + + 3 0.05 Activated carbon 1 wt.% + Starch 33 wt.% / Pale orange + + + + + 0,07 + - four 0,03 Activated carbon 1 wt.% + Starch 33 wt.% / Colorless - - - - - + - Note. The value of k glasses shown in table 1 was determined at the wavelength of the maximum absorption curve of the glass (λ _max = 500 nm). Luminescence was excited by light with λ _P = 500 nm (maximum band at λ = 1100 nm) and λ _P = 800 nm (maximum band at λ = 1260–1300 nm).

Literature

1. E.M. Dianov, S.V. Firstov, V.F. Hepin et al. Bismuth fiber lasers and amplifiers operating in the region of 1.3 μm // Quantum Electronics. - 2008. - T.38, No. 7. - S.615-617.

2. Sulimov VB, Romanov AN, Fattakhova Z.T. and others. Optical glass with the ability to luminescence in the range of 1000 - 1700 nm. Methods for producing such glass (options) and fiber optic fiber // Russian Patent No. RU 2463264 dated 10.10.2012. Bull. No. 28.

3. Denker B.I., Galagan B.I., Shulman I.L., Sverchkov S.E., Dianov E.M. Bismuth valence states and emission centers in Mg-Al-Silicate Glass. Applied Physics B: Lasers and Optics, 2011, vol. 103, no.3, pp. 681-685.

4. G.K. Moiseev, N.A. Vatolin, N.V. Belousova. Calculation of the thermochemical properties of Bi ₂ O ₅ and BiO ₂ // Journal of Physical Chemistry. - 2000. - T.74, No. 12. - S.2124-2128.

5. Karapetyants M.Kh., Karapetyants M.L. Basic thermodynamic constants of inorganic and organic substances. - M .: Chemistry, 1968 .-- 472 p.

6. Moizhes B.Ya. Physical processes in the oxide cathode. - M .: Nauka, 1968 .-- 400 p.

7. Nikonov B.P. Oxide cathode. - M .: Energy, 1979. - 240 p.

Claims (1)

A method for producing glass, which consists in melting in a crucible in air a mixture of glass-forming oxides containing silicon oxide, magnesium oxide, aluminum oxide and bismuth oxide, characterized in that activated carbon is also added as a main reducing agent and potato starch as a damping reducing agent in amounts of 1.5 and 33 wt.%, respectively, of the mass of glass-forming oxides, followed by melting of the mixture at a temperature of 1600 ° C.

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