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CN209941144U - Graphite crucible for growing rare earth ion doped fluoride crystal by heat exchange method - Google Patents

Graphite crucible for growing rare earth ion doped fluoride crystal by heat exchange method Download PDF

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CN209941144U
CN209941144U CN201920190721.1U CN201920190721U CN209941144U CN 209941144 U CN209941144 U CN 209941144U CN 201920190721 U CN201920190721 U CN 201920190721U CN 209941144 U CN209941144 U CN 209941144U
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crucible
crystal
graphite crucible
heat dissipation
cylinder
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薛艳艳
徐军
吴锋
徐晓东
李东振
王东海
王庆国
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Nanjing Tongli Crystal Materials Research Institute Co Ltd
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Nanjing Tongli Crystal Materials Research Institute Co Ltd
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Abstract

The utility model provides a graphite crucible for growing rare earth ion doped fluoride crystal by a heat exchange method, which comprises a crucible body, wherein the graphite crucible is a porous cylinder graphite crucible, and the bottom of the cylinder is of a convex structure; a penetrating cylinder heat dissipation hole is arranged along the axial center line of the cylinder, the top end of the heat dissipation hole is open, and the bottom of the heat dissipation hole is closed; 3-24 cavities are distributed around the heat dissipation holes, the surface of each cavity is covered with a crucible cover, and the crucible cover is provided with vent holes. The porous graphite crucible has the advantages of simple structure and easy processing, can grow a plurality of fluoride crystals doped with rare earth ions of different types and different concentrations in a single time, and each crucible is provided with an independent crucible cover, so that the volatilization of a melt is reduced to the maximum extent, and the cross contamination among different crystals is prevented.

Description

Graphite crucible for growing rare earth ion doped fluoride crystal by heat exchange method
Technical Field
The utility model belongs to the crystal growth field relates to a rare earth ion doped fluoride crystal growth method, in particular to a porous graphite crucible for growing rare earth ion doped fluoride crystal by a heat exchange method.
Background
Fluoride crystals, as a more traditional material, have many superior properties compared to oxide crystals: comprises a very wide light transmission range from far ultraviolet to middle infrared; the constant and low average refractive index and local refractive index can limit the nonlinear effect under the action of high-intensity laser pumping; low phonon energy, reduced non-radiative relaxation between adjacent energy levels, and higher luminescent quantum efficiency of the active ions in the fluoride host crystal. In addition, the fluoride crystal also has the characteristics of very stable physicochemical characteristics, large relative dispersion, high damage threshold value and the like. Therefore, the fluoride crystal is suitable for window materials in vacuum ultraviolet to infrared bands and is also widely applied to industrial and scientific research.
The Czochralski method is one of the methods for growing fluoride crystals. The crystal growth condition of the fluoride crystal can be well observed in real time by utilizing the pulling method, and the crystal quality is improved by controlling processes such as necking and the like. However, the Czochralski method has some defects, such as only one crystal can be grown at a time, the production cost is high, and the industrial production of fluoride crystals is not facilitated; the fluoride is volatilized more in the growth process, and equipment is corroded seriously; and the hardness of the fluoride is lower than that of the oxide, and the bearing of the seed crystal is limited, so that the large-size growth of the fluoride crystal is not facilitated. At present, the temperature gradient method and the Bridgman method are the main methods for fluoride crystal growth. The traditional temperature gradient method and the Bridgman method have the same defect that only one crystal can be grown at a time, the crystal utilization rate is low, the industrial production is not facilitated, and the Bridgman method single crystal growth furnace is a non-vacuum furnace, so that the grown fluoride crystal is easily oxidized. Chinese patent (CN201610808276) discloses growth equipment and a growth method for preparing magnesium fluoride crystals by a multi-crucible descent method, wherein a plurality of magnesium fluoride crystals can be grown simultaneously by the method, but the crucible is an assembly crucible and is complex to operate; because the crucible covers do not correspond to the crucible holes one by one, only one crystal can be grown at a time, otherwise, the crystal can be subjected to vacuum pumping or cross contamination in the growth process.
Disclosure of Invention
The utility model aims at overcoming the problems of low growth efficiency and single growth type of the existing traditional method, and in order to achieve the purpose, the utility model provides a porous graphite crucible for fluoride crystal and crystal growth method which can grow a plurality of different types and different concentrations of rare earth ions at one time by a heat exchange method. The specific technical scheme is as follows:
a porous graphite crucible for growing rare earth ion doped fluoride crystal by a heat exchange method comprises a crucible body, wherein the porous graphite crucible is a cylinder, and the bottom of the cylinder is of a convex structure; a penetrating cylinder heat dissipation hole is arranged along the axial center line of the cylinder, the top end of the heat dissipation hole is open, and the bottom of the heat dissipation hole is closed; 3-24 cavities with openings at the upper ends and closed lower ends are distributed around the heat dissipation holes, the cavities are a seed crystal area and a crystal growth area from bottom to top in sequence, crucible covers cover the surfaces of the cavities, a vent hole is formed in the center of each crucible cover, and the diameter of the seed crystal area is smaller than that of the crystal growth area.
As an improvement, the diameter of the vent hole is 0.5-1.5 mm.
Meanwhile, the growth method for growing the rare earth ion doped fluoride crystal by the heat exchange method comprises the following steps:
s01, putting seed crystals into the seed crystal area of the porous graphite crucible for fluoride crystals, weighing raw materials and an oxygen scavenger accounting for 0.5-1.8% of the mass of the raw materials in proportion, fully and uniformly mixing, and putting the mixture into the crystal growth area of the porous graphite crucible for fluoride crystals;
s02, vacuumizing, and introducing inert gas as protective atmosphere;
s03, heating to 200 +/-10 ℃, and keeping the temperature for 3-7h to remove the water in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 4-8h, and controlling the seed crystal not to be melted by controlling the power and the speed of introducing inert gas;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 750-;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
As an improvement, the seed crystal in the S01 is a fluoride single crystal and is cylindrical, the diameter of the seed crystal is 0.2-0.5mm smaller than that of the hole in the seed crystal area, and the length of the seed crystal is the same as the depth of the hole in the seed crystal area.
As a refinement, the rare earth ions in S01 are: pr ion, Dy ion, Er ion, Ho ion, fluoride is LaF3、PbF2、CaF2、SrF2Any of the above.
As an improvement, the purity of the raw material of S01 is 4N or more, and the oxygen content is below 200 ppm.
As a modification, the inert gas in S02 is high-purity helium.
As an improvement, in S04, the heating power is 15-45KW, and the inert gas introduction rate is 50-80L/min.
Has the advantages that: compared with the prior art, the utility model has the advantages of it is following: (1) the porous graphite crucible has the advantages of simple structure and easy processing, can grow a plurality of fluoride crystals doped with rare earth ions of different types and different concentrations in a single time, and each crucible is provided with an independent crucible cover, so that the volatilization of a melt is reduced to the maximum extent, and the cross contamination among different crystals is prevented. (2) The fluoride crystal is grown by using a heat exchange method, the crucible, the crystal and the heat exchanger are not moved in the growth process, no mechanical disturbance exists, the crystal growth interface is stable, the internal defects of the crystal are reduced, and the optical quality of the crystal is effectively improved. (3) The crystal is still kept in a hot area after growing, the temperature change and the furnace environment are controlled by controlling the heating power and the protective gas flow, the in-situ annealing of the crystal is realized, and the defects of internal stress, dislocation and the like of the crystal are reduced. (4) The whole crystal growth process can realize full automation, labor is saved, and production cost is reduced.
The above description is only an overview of the technical solution of the present invention, and in order to make the technical means of the present invention clearer and can be implemented according to the content of the description, the following detailed description is made with reference to the preferred embodiments of the present invention and accompanying drawings.
Drawings
FIG. 1 is a schematic view of a porous graphite crucible according to the present invention.
Fig. 2 is a sectional view of the porous graphite crucible of the present invention.
In the figure, 1 is a crucible cover, 2 is a crucible body, 3 is a vent hole, 4 is a cavity, 5 is a seed crystal hole, and 6 is a heat dissipation hole.
Detailed Description
The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.
The utility model provides a heat exchange method growth tombarthite ion doped fluoride graphite crucible for crystal, includes the crucible body 2, graphite crucible is the graphite crucible of porous cylinder, and the cylinder bottom is the type structure of dogging. Wherein the diameter is 10-20mm, the length is 180-300mm, and preferably 210 mm.
A through cylindrical heat dissipation hole 6 is arranged along the axial center line of the cylinder, the top end of the heat dissipation hole 6 is open, and the bottom of the heat dissipation hole is closed; 3-24 cavities 4 with openings at the upper ends and closed lower ends are distributed around the heat dissipation holes 6, the diameters of the cavities 4 can be the same or different, and the cavities are not fixed at the positions away from the heat dissipation holes 6.
The cavity 4 is sequentially provided with a seed crystal area and a crystal growth area from bottom to top, the surface of the cavity 4 is covered with crucible covers 1, the central position of each crucible cover 1 is provided with a vent hole 3, and the diameter of the seed crystal area is smaller than that of the crystal growth area; and a seed crystal hole 5 is arranged in the seed crystal area. The diameter of the vent hole 3 is 0.5-1.5 mm. The diameter of the seed crystal is 4-10mm, and the length is 15-30 mm. The seed crystal type in each cavity 4 may be the same or different.
Meanwhile, the growth method for growing the rare earth ion doped fluoride crystal by the heat exchange method comprises the following steps:
s01, putting seed crystals into the seed crystal area of the porous graphite crucible for fluoride crystals, weighing raw materials and an oxygen scavenger accounting for 0.5-1.8% of the mass of the raw materials in proportion, fully and uniformly mixing, and putting the mixture into the crystal growth area of the porous graphite crucible for fluoride crystals;
s02, vacuumizing, and introducing inert gas as protective atmosphere;
s03, heating to 200 +/-10 ℃, and keeping the temperature for 3-7h to remove the water in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 4-8h, and controlling the seed crystal not to be melted by controlling the power and the speed of introducing inert gas;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 750-;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
Wherein the rare earth ions in S01 are: one or more of Pr ion, Dy ion, Er ion and Ho ion, and the fluoride is LaF3、PbF2、CaF2、SrF2Either one or any combination of the two. The raw material purity of S01 is 4N or more, and the oxygen content is 200ppm or less. The inert gas of S02 is high-purity helium. In S04, the heating power is 15-45KW, and the inert gas is introduced at a speed of 50-80L/min.
Example 1
The crucible used is a 12-hole graphite crucible, namely, 12 cavities with the diameter of 10mm and the length of 210 mm.
S01, firstly, pure lanthanum fluoride crystal seeds with the diameter of 5mm and the length of 20mm are loaded. According to DyxLa(1-x)F3(x is 0.01,0.02,0.03 …) and weighing all the high-purity raw materials and 1% of oxygen scavenger (PbF) in the total mass of the raw materials according to the proportion2Crystal material), fully and uniformly mixed and then respectively loaded into a porous graphite crucible;
s02, vacuumizing, and introducing helium as a protective atmosphere;
s03, heating to 200 ℃, and keeping the temperature for 5 hours to remove the moisture in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 5h, and controlling the seed crystal not to be melted by controlling the power and the speed of introducing inert gas;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 900 ℃ at 1.5-3.0 ℃/h, and finishing the annealing process;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
Example 2
The crucible used is a 12-hole graphite crucible, namely, 12 cavities with the diameter of 20mm and the length of 210 mm.
S01, firstly, pure calcium fluoride crystal seeds with the diameter of 5mm and the length of 20mm are loaded. According to RexCa(1-x)F2+x(Re is Pr, Dy, Ho, Tb …, x is 0.01,0.02,0.03 …) chemical formula, weighing all high-purity raw materials and an oxygen scavenger accounting for 1% of the total mass of the raw materials respectively according to the proportion, fully mixing the raw materials uniformly, and then respectively filling the raw materials into a porous graphite crucible;
s02, vacuumizing, and introducing helium as a protective atmosphere;
s03, heating to 200 ℃, and keeping the temperature for 5 hours to remove the moisture in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 5h, and controlling the seed crystal not to be melted by controlling the power and the speed of introducing inert gas;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 800 ℃ at 1.5-3.0 ℃/h, and finishing the annealing process;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
Example 3
The crucible used is an 8-hole graphite crucible, namely 8 cavities, the diameter of which is 10mm and the length of which is 210 mm. The corresponding transparent calcium fluoride crystal doped with rare earth ions of different types and different concentrations can also be obtained by adopting the process conditions of the embodiment 2 without adding calcium fluoride seed crystals and adopting the seed-free crystal growth.
Example 4
The crucible used is a 20-hole graphite crucible, namely 20 cavities with the diameter of 15mm and the length of 300 mm.
S01, firstly, pure calcium fluoride crystal seeds with the diameter of 4mm and the length of 30mm are loaded. According to RexCa(1-x)F2+x(Re is Pr, Dy, Ho, Tb …, x is 0.01,0.02,0.03 …) chemical formula, weighing all high-purity raw materials and an oxygen scavenger accounting for 1.8% of the total mass of the raw materials respectively according to the proportion, fully mixing the raw materials uniformly, and then respectively filling the raw materials into a porous graphite crucible;
s02, vacuumizing, and introducing helium as a protective atmosphere;
s03, heating to 210 ℃, and keeping the temperature for 3 hours to remove the moisture in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 4h, and controlling the seed crystal not to be melted by controlling the power and the helium introducing rate;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 750 ℃ at 1.5-3.0 ℃/h, and finishing the annealing process;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
Example 5
The crucible is a graphite crucible with 5 holes, namely, 5 cavities with the diameter of 20mm and the length of 180 mm.
S01, firstly, pure calcium fluoride crystal seeds with the diameter of 10mm and the length of 15mm are loaded. According to RexCa(1-x)F2+x(Re is Pr, Dy, Ho, Tb …, x is 0.01,0.02,0.03 …) chemical formula, weighing all high-purity raw materials and an oxygen scavenger accounting for 1.8% of the total mass of the raw materials respectively according to the proportion, fully mixing the raw materials uniformly, and then respectively filling the raw materials into a porous graphite crucible;
s02, vacuumizing, and introducing helium as a protective atmosphere;
s03, heating to 190 ℃, and preserving heat for 7 hours to remove moisture in the raw materials;
s04, continuing to heat until the raw materials are completely melted, carrying out constant-temperature heat treatment for 8h, and controlling the seed crystal not to be melted by controlling the power and the helium introducing rate;
s05, slowly cooling at the speed of 0.5-1.0 ℃/h to crystallize the melt in the crucible from bottom to top;
s06, after the crystal growth is finished, reducing the temperature to 980 ℃ at a speed of 1.5-3.0 ℃/h, and finishing the annealing process;
s07, cooling to room temperature according to the cooling rate of 10-30 ℃/h, and taking out the crystal.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims (2)

1. A graphite crucible for growing rare earth ion doped fluoride crystal by a heat exchange method comprises a crucible body (2), and is characterized in that the graphite crucible is a cylindrical porous graphite crucible, and the bottom of the cylinder is of a convex structure; a through cylinder heat dissipation hole (6) is arranged along the axial center line of the cylinder, the top end of the heat dissipation hole (6) is open, and the bottom of the heat dissipation hole is closed; 3-24 cavities (4) with openings at the upper ends and closed lower ends are distributed around the heat dissipation holes (6), the cavities (4) are a seed crystal area and a crystal growth area from bottom to top in sequence, crucible covers (1) cover the surfaces of the cavities (4), a vent hole (3) is arranged at the center of each crucible cover (1), wherein the diameter of the seed crystal area is smaller than that of the crystal growth area; and a seed crystal hole (5) is arranged in the seed crystal region.
2. The graphite crucible as set forth in claim 1, wherein: the diameter of the vent hole (3) is 0.5-1.5 mm.
CN201920190721.1U 2019-02-12 2019-02-12 Graphite crucible for growing rare earth ion doped fluoride crystal by heat exchange method Active CN209941144U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114836831A (en) * 2022-04-11 2022-08-02 同济大学 A kind of Er, Dy co-doped lead fluoride mid-infrared laser crystal and its preparation method and application

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114836831A (en) * 2022-04-11 2022-08-02 同济大学 A kind of Er, Dy co-doped lead fluoride mid-infrared laser crystal and its preparation method and application
CN114836831B (en) * 2022-04-11 2024-02-27 同济大学 Er, dy co-doped lead fluoride mid-infrared laser crystal and preparation method and application thereof

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