METHOD FOR GROWING Fe1-XGaXBO3 SINGLE CRYSTALS

Abstract

FIELD: inorganic chemistry.SUBSTANCE: invention can be used in magnetic, optical, magneto-optical, X-ray and resonance studies, as well as in new generation synchrotron technologies. A charge is prepared comprising, by wt.%: (Fe2O3 + Ga2O3) 4.9; B2O3 58.3; PbO 25.0; PbF2 11.8. The prepared charge is melted in small portions into a platinum crucible at 870 °C, which is then placed in the gradient-free zone of the growth furnace and heated for melting to 900 °C for 4 hours. A platinum crystal holder is lowered into the resulting melt solution, rotating it at a speed of 20-60 rpm, and homogenized at this temperature, holding for 20-24 hours. After this, temperature surges are carried out cyclically, consisting of rapid cooling with holding and heating with holding. During the first and second cycles of temperature surges, the temperature is sharply reduced to 800-820 °C for 20 minutes and maintain at this temperature for 2-4 hours, then heat to 900 °C for 20 minutes and maintained at this temperature for 4-12 hours. In the third cycle, the temperature is sharply reduced to 800-810 °C for 20 minutes and kept at this temperature for 2-3 hours, then heated to 830-835 °C in 20 minutes and maintained at this temperature for 3-4 hours. After the specified temperature changes, the temperature is sharply reduced in 15 minutes to 805-810 °C and isothermal holding is carried out for 0.5-1 hour, during which the rotation of the crystal holder is turned off. Then smooth cooling is carried out at a rate of 0.1-0.3 °C / h up to 780 °C, the synthesized crystals are released from the crucible by smoothly removing the crystal holder from it at a speed of 0.5 cm / min. Final cooling of the furnace is carried out for 4-6 hours to a temperature of 500 °C with subsequent shutdown. The invention makes it possible to grow single crystals of Fe1-xGaxBO3, where 0≤x<0.2, in the form of plates up to 5 mm in diameter.EFFECT: improved performance.1 cl, 2 dwg, 3 ex

Description

[0001] The technical solution relates to the field of obtaining Fe single crystals 1- x Ga x BO3 for magnetic, optical, magneto-optical, X-ray and resonance research, as well as for high-tech practical applications, in particular, new generation synchrotron technologies.

[0002] A method is known for producing FeBO3 single crystals from a melt solution [USSR Author's Certificate No. 1059029, IPC C30B 9 / 12, C30B 29 / 22. published 07.12.1983], including dissolving the components of a charge containing Fe2O3, B2O3, PbO and PbF2, upon heating and crystallization upon cooling the melt solution, characterized in that, in order to increase the size of the single crystals, a charge is used containing, by weight %: Fe2O3 4.8 - 4.9; PbO 7.55 - 7.75; PbF2 3 6.55 - 36.80; B2O3 the rest; dissolution is carried out at 950-970°C with continuous movement of a rotating crystal carrier, then crystallization is carried out on it upon cooling to 830-845°C, maintaining at this temperature and subsequent cooling with an increase in the rate of temperature reduction from 1 to 4 degrees / day.

[0003] A method for growing gallium borate GaBO3 single crystals is known [Patent No. 2019584 C1 Russian Federation, IPC C30B 9 / 12, C30B 29 / 22. Method for growing gallium borate GaBO3 single crystals: No. 4931917 / 26: declared 29.04.1991: published 15.09.1994 / G. A. Petrakovsky, V. V. Rudenko, G. N. Stepanov; applicant L. V. Kirensky Institute of Physics SB RAS].

[0004] Brief description of the analogue

[0005] To obtain GaBO3, controlled solution-melt crystallization is used: the solution-melt containing Ga2O3, B2O3, PbO, PbF2 is overheated to 950-1000°C with stirring, cooled to 815 - 845°C, maintained for 22 - 24 hours with stirring, then the temperature is raised to 820 - 850°C with subsequent decrease according to the law (10 -7 -10 -8 )t 3 up to 810 - 840°C, where t is time in hours. The components are taken in the following ratio, wt.%: GaO - 16.8 - 18.6; BO - 42.4 - 42.9; PbO - 27.3 - 28.2; PbF - 11.7 -12.1.

[0006] A method for growing single crystals is also known57 FeBO3 of high structural perfection, [RU Patent No. 2740126, IPC C30B 9 / 04, C30B 9 / 12, C30B 29 / 22, published 11.01.2021]. In this method, the charge containing 57 Fe2O3, B2O3, PbO, PbF2 are heated with constant stirring, maintained at a constant temperature, and cooled. The components are taken in the following ratio, wt.%: 57 Fe2O3- 4.9, B2O3- 58.3, PbO - 25.0, PbF2- 11.8. The resulting melt solution is heated with stirring to 900-950 °C for 20-30 minutes and held for 10-12 hours, then the temperature is sharply reduced in 15 minutes to 810-820 °C and then smoothly cooled at a rate of 0.1-0.2 °C / hour to a temperature of 760-790 °C, after which the container is removed from the furnace and smoothly turned around the horizontal axis, ensuring the draining of the melt solution into the crucible lid and the release of the synthesized crystals, continue cooling the furnace to 500 °C for 4-6 hours and turn it off, the crucibles are removed and opened.

[0007] The disadvantage of the above analogs is that the methods do not provide for the production of Fe single crystals 1- x Ga x BO3 containing gallium.

[0008] The method for growing Fe single crystals was chosen as a prototype 1-x Ga x BO3(0≤х<0.2), described in the work of N.I. Snegirev, Structure, magnetic properties and nuclear gamma resonance in single crystals based on iron borate FeBO3 [Snegirev, N.I., Dissertation for the degree of candidate of physical and mathematical sciences, Moscow, 2023, 176 p.], including melting the charge into a platinum crucible, installing the crucible in the gradient-free zone of the growth furnace, heating to melt the components for 4 hours, holding the solution-melt, cyclic repetition of temperature surges consisting of sharp cooling with holding and heating with holding, smooth cooling, release of the synthesized crystals from the crucible and final cooling of the furnace.

[0009] A disadvantage of the above method is the use of a closed crucible, which precludes the use of a seed holder and prevents the extraction of grown crystals until the solution-melt has completely cooled. As a result, the crystals solidify directly in the solidified solution-melt, leading to the development of mechanical stresses. These stresses significantly reduce the structural perfection of the crystals and often cause their fracture during subsequent extraction.

[0010] The invention is based on the task of developing a method for growing Fe single crystals 1- x Ga x BO3.

[0011] The technical result consists in providing the possibility of obtaining Fe single crystals 1- x Ga x BO3 containing gallium, where 0≤x<0.2.

[0012] The stated objective is achieved by the fact that the method of growing Fe single crystals 1-x Ga xBO3, where 0≤x<0.2, including melting the charge into a platinum crucible, installing the crucible in a gradient-free zone of the growth furnace, heating to melt the components for 4 hours, holding the melt solution, cyclically performing temperature surges consisting of sharp cooling with holding and heating with holding, smooth cooling, releasing the synthesized crystals from the crucible and final cooling of the furnace, according to the invention, the charge components are taken in the ratio, wt.%: (Fe2O3 + Ga2O3) - 4.9; B2O3 - 58.3; PbO - 25.0; PbF2- 11.8, the charge is melted at a temperature of 870°C, and heated for melting - up to 900°C, a platinum crystal holder is lowered into the resulting melt solution, rotating it at a speed of 20-60 rpm, and homogenized at this temperature, holding for 20-24 hours, temperature jumps are carried out in the following cycles: in the first and second cycles, the temperature is sharply reduced to 800-820°C in 20 minutes and held at this temperature for 2-4 hours,then heated to 900°C for 20 minutes and held at this temperature for 4-12 hours, and in the third cycle the temperature is sharply reduced to 800-810°C for 20 minutes and held at this temperature for 2-3 hours, then heated to 830-835°C for 20 minutes and held at this temperature for 3-4 hours, after carrying out temperature surges the temperature is sharply reduced in 15 minutes to 805-810°C and isothermal holding is carried out for 0.5-1 hour, during which the rotation of the crystal holder is turned off, smooth cooling is carried out at a rate of 0.1-0.3°C / hour to 780°C, the synthesized crystals are released from the crucible by smoothly removing the crystal holder from it at a rate of 0.5 cm / min, and the final cooling of the furnace is carried out for 4-6 hours to a temperature 500°C with subsequent switching off.,

[0013] Common features with the prototype are:

[0014] - melting the charge into a platinum crucible,

[0015] - installation of the crucible in the gradient-free zone of the growth furnace,

[0016] - heating to melt the components in 4 hours,

[0017] - holding of the melt solution,

[0018] - cyclic implementation of temperature surges, consisting of rapid cooling with holding and heating with holding,

[0019] - smooth cooling,

[0020] - release of synthesized crystals from the crucible and final cooling of the furnace.

[0021] Distinctive features from the prototype are:

[0022] - change in the composition of the charge: the components are taken in the ratio, wt.%: (Fe2O3 + Ga2O3) - 4.9; B2O3 - 58.3; PbO - 25.0; PbF2 - 11.8,

[0023] - the charge is melted at 870°C, and the heating for melting is up to 900°C,

[0024] - a platinum crystal holder is lowered into the melt solution, rotating it at a speed of 20-60 rpm, and homogenized at 900°C for 20-24 hours,

[0025] - temperature surges are carried out in the following cycles: in the first and second cycles, the temperature is sharply reduced to 800-820°C in 20 minutes and maintained at this temperature for 2-4 hours, then heated to 900°C in 20 minutes and maintained at this temperature for 4-12 hours,

[0026] - in the third cycle, the temperature is sharply reduced to 800-810°C in 20 minutes and maintained at this temperature for 2-3 hours, then heated to 830-835°C in 20 minutes and maintained at this temperature for 3-4 hours,

[0027] - after carrying out temperature surges, sharply reduce the temperature in 15 minutes to 805-810°C and carry out isothermal holding for 0.5-1 hour, during which the rotation of the crystal holder is turned off,

[0028] - smooth cooling is carried out at a rate of 0.1-0.3°C / hour up to 780°C,

[0029] - the release of crystals is carried out by smoothly removing the crystal holder from the crucible at a speed of 0.5 cm / min,

[0030] - final cooling of the furnace is carried out to 500°C for 4-6 hours, followed by switching off.

[0031] The method is implemented as follows.

[0032] The charge is mixed in the ratio, wt.%: (Fe2O3 + Ga2O3) - 4.9; B2O3 - 58.3; PbO - 25.0; PbF2 - 11.8. In this case, the components (Fe2O3 + Ga2O3) = 4.9 wt.% are taken taking into account the obtained experimental dependence shown in Fig. 1. (The horizontal axis shows the ratio of the masses of iron and gallium oxides in the charge; the vertical axis shows the content of iron ions Fe 3+ in the synthesized crystal; the dots show the average values ​​(1 -x crystal ) in synthesized Fe crystals 1- x Ga xBO3, vertical bars show the spread of iron content in single crystals extracted from a single crucible). The resulting batch is thoroughly crushed and mixed in a mechanical stirrer for 8 hours. The batch is melted into a platinum crucible in small portions (2-3 g) at a temperature of 870°C. The crucible with the resulting solution-melt is placed in the gradient-free zone (ΔT = ±1°C) of the growth furnace. To melt the solution-melt, it is heated to 900°C for 4 hours. Then, a platinum crystal holder is lowered, rotating it at a speed of 20-60 rpm, thereby achieving mixing of the solution-melt.The temperature of 900°C is maintained for 20-24 hours, then the following temperature surge cycles are performed: in the first and second cycles, the temperature is sharply reduced to 800-820°C in 20 min and held at this temperature for 2-4 hours, then heated to 900°C in 20 min and held at this temperature for 4-12 hours, and in the third cycle, the temperature is sharply reduced to 800-810°C in 20 min and held at this temperature for 2-3 hours, then heated to 830-835°C in 20 min and held at this temperature for 3-4 hours. Then, sharp cooling is performed for 15 minutes to 805-810°C, an isothermal hold is performed for 0.5-1 hour, during which the rotation of the crystal holder is turned off. Next, the furnace is cooled at a rate of 0.1-0.3°C / hour to a temperature of 780°C, after which the crystal holder is smoothly removed from the crucible (0.5 cm / min), releasing the synthesized crystals. The furnace is then cooled to 500°C for 4-6 hours and then turned off.

[0033] Example 1

[0034] Crystallization was carried out in the system:57 Fe2O3(8.33 g) - B2O3(99.12 g) - PbO (42.51 g) - PbF2 (20.06 g) using the following temperature regime: heating to 900°C for 4 hours and holding for 20 hours (immersion of the crystal holder in the melt solution, switching on rotation), rapid cooling to 800°C for 20 min, holding at this temperature for 3 hours, heating to 900°C for 20 min, holding for 6 hours, rapid cooling to 800°C for 20 min, holding at this temperature for 3 hours, heating to 900°C for 20 min, holding for 6 hours, rapid cooling to 800°C for 20 min, holding at this temperature for 3 hours, heating to 830°C for 20 min, holding for 3 hours, cooling to 810°C for 15 min, Hold for 1 hour (turn off the crystal holder rotation), gradually cool at a rate of 0.13°C / hour to 780°C (at 780°C, gradually remove the crystal holder from the crucible). Then cool the furnace to 500°C over 4 hours and turn it off, allowing the furnace to cool naturally to room temperature.

[0035] Crystals were found on the crystal holder and crucible walls after digestion in a 20% nitric acid solution. The average diameter was up to 5 mm.

[0036] Example 2

[0037] Crystallization was carried out in the system: Fe2O3 (4.06 g) - Ga2O3 (0.84 g) - B2O3 (58.3 g) - PbO (25.0 g) - PbF2 (11.8 g) using the following temperature regime: heating to 900 ° C for 4 hours and holding for 24 hours (immersion of the crystal holder in the melt solution, turning on the rotation), rapid cooling to 820 ° C for 20 min, holding at this temperature for 4 hours, heating to 900 ° C for 20 min, holding for 6 hours, rapid cooling to 810 ° C for 20 min, holding at this temperature for 2 hours, heating to 900 ° C for 20 min, holding for 4 hours, rapid cooling to 800 ° C for 20 min, hold at this temperature for 4 hours, heat to 830°C in 20 min, hold for 4 hours, cool to 810°C in 15 min, hold for 0.5 hour (turn off the rotation of the crystal holder), smooth cooling at a rate of 0.1°C / hour to 780°C (at 780°C, smoothly remove the crystal holder from the crucible). Then cool the furnace to 500°C in 4 hours and turn it off, naturally cool the furnace to room temperature.

[0038] Crystals (see Fig. 2) were found on the crystal holder and crucible walls after digestion in a 20% nitric acid solution. The average diameter was up to 5 mm. X-ray fluorescence analysis (XRF) revealed that the average iron content in the synthesized crystals was 0.95.

[0039] Example 3

[0040] Crystallization was carried out in the system: Fe2O3 (2.5 g) - Ga2O3 (2.4 g) - B2O3 (58.3 g) - PbO (25.0 g) - PbF2 (11.8 g) using the following temperature regime: heating to 900 ° C for 4 hours and holding for 24 hours (immersion of the crystal holder in the melt solution, turning on the rotation), rapid cooling to 800 ° C for 20 min, holding at this temperature for 3 hours, heating to 900 ° C for 20 min, holding for 12 hours, rapid cooling to 810 ° C for 20 min, holding at this temperature for 2 hours, heating to 900 ° C for 20 min, holding for 12 hours, rapid cooling to 810 ° C for 20 min, hold at this temperature for 2 hours, heat to 835°C in 20 min, hold for 3 hours, cool to 810°C in 15 min, hold for 0.5 hour (turn off the rotation of the crystal holder), smooth cooling at a rate of 0.2°C / hour to 780°C (at 780°C, smoothly remove the crystal holder from the crucible). Then cool the furnace to 500°C in 4 hours and turn it off, naturally cooling the furnace to room temperature.

[0041] Crystals were found on a crystal holder and on the crucible walls after digestion in a 20% nitric acid solution. The average diameter was 3-5 mm. X-ray fluorescence analysis (XRF) revealed that the average iron content in the synthesized crystals was 0.83.

[0042] The method makes it possible to obtain Fe single crystals 1- x Ga x BO3 containing gallium, where 0≤x<0.2.

Claims

Method for growing Fe single crystals 1-x Ga xBO3, where 0≤x<0.2, including melting the charge into a platinum crucible, installing the crucible in a gradient-free zone of a growth furnace, heating to melt the components for 4 hours, holding the melt solution, cyclically performing temperature surges consisting of sharp cooling with holding and heating with holding, smooth cooling, releasing the synthesized crystals from the crucible and final cooling of the furnace, characterized in that the charge components are taken in the ratio, wt.%: (Fe2O3 + Ga2O3) - 4.9; B2O3 - 58.3; PbO - 25.0; PbF2- 11.8, the charge is melted at a temperature of 870°C, and heated for melting - up to 900°C, a platinum crystal holder is lowered into the resulting melt solution, rotating it at a speed of 20-60 rpm, and homogenized at this temperature, holding for 20-24 hours, temperature jumps are carried out in the following cycles: in the first and second cycles, the temperature is sharply reduced to 800-820°C in 20 minutes and held at this temperature for 2-4 hours,then heated to 900°C for 20 minutes and held at this temperature for 4-12 hours, and in the third cycle, the temperature is sharply reduced to 800-810°C for 20 minutes and held at this temperature for 2-3 hours, then heated to 830-835°C for 20 minutes and held at this temperature for 3-4 hours, after carrying out temperature surges, the temperature is sharply reduced in 15 minutes to 805-810°C and isothermal holding is carried out for 0.5-1 hour, during which the rotation of the crystal holder is turned off, smooth cooling is carried out at a rate of 0.1-0.3°C / hour to 780°C, the synthesized crystals are released from the crucible by smoothly removing the crystal holder from it at a rate of 0.5 cm / min, and the final cooling of the furnace is carried out for 4-6 hours to a temperature 500°C with subsequent switching off.,

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