CN115613113A - Batch preparation method of ultra-pure zirconium titanate single crystal - Google Patents

Batch preparation method of ultra-pure zirconium titanate single crystal Download PDF

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CN115613113A
CN115613113A CN202211344061.0A CN202211344061A CN115613113A CN 115613113 A CN115613113 A CN 115613113A CN 202211344061 A CN202211344061 A CN 202211344061A CN 115613113 A CN115613113 A CN 115613113A
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crystal growth
heat storage
single crystal
zirconium titanate
furnace chamber
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吴宪君
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Suzhou Jingsheng New Material Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B1/00—Single-crystal growth directly from the solid state
    • C30B1/02—Single-crystal growth directly from the solid state by thermal treatment, e.g. strain annealing
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/32—Titanates; Germanates; Molybdates; Tungstates

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Abstract

The invention belongs to the technical field of single crystal growth, and particularly relates to a batch preparation method of an ultra-pure zirconium titanate single crystal. The method comprises the following steps: placing titanium dioxide and zirconium dioxide in a crystal growth vessel; step two: placing the crystal growth container in a hollow heat storage block material with an accommodating cavity to form crystal growth unit cells; step three: tightly stacking a plurality of crystal growth unit cells to form a unit cell assembly; step four: stacking solid heat storage blocks around the unit cell assembly to form a heat storage assembly; step five: placing the heat storage assembly in an atmosphere furnace to replace inert gas; step six: heating to completely melt the raw materials; step seven: opening a heat dissipation gap on the furnace chamber, and naturally cooling and crystallizing. The invention can prepare the zirconium titanate single crystal with ultrahigh purity and high uniformity in batch by using the titanium dioxide and the zirconium dioxide with low purity grade as raw materials under the condition of lower economic cost.

Description

Batch preparation method of ultra-pure zirconium titanate single crystal
Technical Field
The invention belongs to the technical field of single crystal growth, and particularly relates to a batch preparation method of an ultra-pure zirconium titanate single crystal.
Background
Zirconium titanate can be used as a vapor deposition material for a high-refractive-index coating, and a formed film layer has a very high refractive index in the visible light and near infrared spectrum ranges, so that zirconium titanate has very important application in the field of manufacturing of optoelectronic devices, such as display imaging devices, light output devices, light integrated devices and the like.
At present, polycrystalline zirconium titanate is mainly used as an evaporation material for the evaporation preparation of the zirconium titanate coating, although the cost of the polycrystalline zirconium titanate is lower than that of single-crystal zirconium titanate, certain impurities exist between crystal grains of the polycrystalline zirconium titanate, impurities and air holes are easily introduced into a formed coating in the coating process, and the uniformity of the coating is difficult to ensure. Therefore, the preparation of single crystal zirconium titanate, especially ultra-high purity single crystal zirconium titanate, is of decisive importance for the preparation of high quality zirconium titanate coatings.
Disclosure of Invention
The invention provides a batch preparation method of ultra-pure zirconium titanate single crystals, aiming at the problems that few zirconium titanate single crystal growth technologies are reported in the prior art and a method for producing the ultra-pure zirconium titanate single crystals in a large scale is not available. Aims to realize the mass preparation of the ultra-high purity zirconium titanate single crystal by using raw materials with lower purity grade at relatively lower cost.
The batch preparation method of the ultrapure zirconium titanate single crystal comprises the following steps:
the method comprises the following steps: placing titanium dioxide and zirconium dioxide, which are raw materials for preparing zirconium titanate, in a non-sealed crystal growth container with a cover;
step two: placing the crystal growth container with the stored raw materials into a hollow heat storage block with an accommodating cavity to form crystal growth unit cells;
step three: tightly stacking a plurality of crystal growth unit cells to form a unit cell assembly;
step four: solid heat storage blocks are stacked around the unit cell assemblies, so that the solid heat storage blocks completely wrap the unit cell assemblies to form heat storage assemblies;
step five: placing the heat storage assembly in an atmosphere furnace, sealing the furnace chamber, and replacing the original gas in the furnace chamber with inert gas;
step six: heating the furnace chamber of the atmosphere furnace to not less than 1900 ℃, and preserving the heat to completely melt the raw materials in the crystal growth container;
step seven: and opening a heat dissipation notch on the furnace chamber to naturally cool the furnace chamber, and slowly cooling the melted raw materials along with the furnace to obtain the ultrapure zirconium titanate single crystal.
Further, in the method for batch preparation of the ultra-pure zirconium titanate single crystal, in the first step, the purity of both titanium dioxide and zirconium dioxide is not less than 99.0%, and the molar ratio of titanium dioxide to zirconium dioxide actually contained in the raw material is in the range of 1.97-1.03.
Further, in the method for mass production of an ultrapure zirconium titanate single crystal, in the first step, a molybdenum crucible with a lid is used as a crystal growth container; the titanium dioxide and the zirconium dioxide are uniformly mixed, pre-sintered and molded and then placed into a crystal growth container.
Further, in the batch preparation method of the ultra-pure zirconium titanate single crystal, in the second step, the hollow heat storage block material is made of a hexagonal boron nitride ceramic material and comprises a cubic containing block and a filling block; the cubic containing block is provided with an opening, and a containing cavity is formed inside the cubic containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is plugged by a plugging block, so that a crystal growth unit cell is formed.
Further, in the method for preparing the ultra-pure zirconium titanate single crystal in batches, in the third step, crystal growth unit cells are tightly stacked according to a simple cubic stacking form to form a unit cell assembly; at least 3 crystal growth unit cells are arranged in each direction of length, width and height in the unit cell assembly.
Further, in the method for preparing the ultra-pure zirconium titanate single crystal in batches, in the fourth step, the solid heat storage block material is made of the same material as the hollow heat storage block material; the distance from each surface of the unit cell assembly to the outer surface of the heat storage assembly is not less than the maximum value of the length, the width and the height of the unit cell assembly.
Furthermore, in the fourth step of the batch preparation method of the ultra-pure zirconium titanate single crystal, the ratio of the volume of the heat storage assembly to the volume of the furnace chamber is 1.8-2.5.
Furthermore, in the method for preparing the ultra-pure zirconium titanate single crystal in batches, in the sixth step, the furnace chamber of the atmosphere furnace is heated to 1910-1950 ℃, and then the temperature is kept for 5-12 hours to completely melt the raw materials in the crystal growth container.
Further, in the batch preparation method of the ultra-pure zirconium titanate single crystal, in the seventh step, a heat dissipation pipeline is arranged at the top of the furnace chamber, the periphery of the heat dissipation pipeline is wrapped with a heat insulation material, and a heat dissipation notch is formed at an opening at the top of the heat dissipation pipeline; the ratio of the height to the inner diameter of the heat dissipation pipe is 24-30.
Further, in the batch preparation method of the ultra-pure zirconium titanate single crystal, the area of the heat dissipation notch is S, the volume of the heat storage assembly is V1, and the volume of the furnace chamber is V2;
S＝K×(V1×V2) 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range.
Advantageous effects
The method for preparing the ultra-pure zirconium titanate single crystal in batches can prepare the ultra-pure zirconium titanate single crystal in batches by using the titanium dioxide and the zirconium dioxide with low purity grade as raw materials under the condition of lower economic cost. By adopting the method, the zirconium titanate single crystal with the purity level of 99.95% can be prepared under the condition that the purity level of the raw material is 99%, and the zirconium titanate single crystal with the purity level of 99.99% can be prepared under the condition that the purity level of the raw material is 99.5%. The zirconium titanate crystal prepared by the method has excellent quality, uniform crystal components and good crystallinity, and the crystal prepared in the crystal growth unit cells at different parts has high uniformity.
Drawings
Fig. 1 is an exploded view of a crystal growth cell.
FIG. 2 is a perspective view of the cell assembly of the present invention.
FIG. 3 is a cross-sectional view of a cell assembly according to the present invention.
Fig. 4 is a schematic structural view of the heat storage assembly.
Fig. 5 is a schematic view of the regenerative assembly placed in an atmospheric furnace.
Fig. 6 is a schematic structural view of the heat dissipation pipe.
Detailed Description
The invention is further illustrated by the following specific examples, which are exemplary, intended to illustrate the problem and explain the invention, but not to limit it.
Example 1
The embodiment provides a batch preparation method of an ultra-pure zirconium titanate single crystal, which comprises the following steps:
step one
The raw materials titanium dioxide and zirconium dioxide for the preparation of zirconium titanate were placed in an unsealed capped crystal growth vessel. Specifically, titanium dioxide and zirconium dioxide are taken as raw materials, the titanium dioxide and the zirconium dioxide are obtained in the market, the purity of the titanium dioxide and the zirconium dioxide is chemical purity (99.5%), the titanium dioxide and the zirconium dioxide are respectively placed in a constant-temperature oven at 200 ℃ and dried to constant weight, the titanium dioxide and the zirconium dioxide are respectively sieved by a 100-mesh sieve, the titanium dioxide and the zirconium dioxide which are sieved are loaded into a V-shaped mixer according to the stoichiometric ratio of 1. Pouring the mixed raw materials into a cylindrical die, and applying pressure to the mixed raw materials in the die by an oil press at the pressure of 35MPa to form a dry pressing blank body. And sintering the dry pressed blank at 1680 ℃ for 8 hours under the protection of nitrogen flow to form a sintered blank. And placing the sintered green body in a molybdenum crucible of a crystal growth container, and covering the crucible cover.
Step two
And placing the crystal growth container with the stored raw materials into a hollow heat storage block material with an accommodating cavity to form a crystal growth unit cell. Specifically, the molybdenum crucible with the sintered green body obtained in the first step is placed in a hollow heat storage block material. The hollow heat storage block is made of a hexagonal boron nitride ceramic material, the hexagonal boron nitride has the advantages of low hardness, chemical stability, high temperature resistance and the like, the hardness is low, the hexagonal boron nitride is easy to machine into a required shape, the high temperature resistance and the chemical stability are excellent, and the maximum use temperature in an inert atmosphere can reach 2800 ℃. As shown in fig. 1, the hollow heat storage block includes a cubic containing block and a filling block; the cubic containing block is provided with an opening, and a containing cavity is formed inside the cubic containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is blocked by a plugging block, so that a crystal growth unit cell is formed.
Step three
A plurality of crystal growth unit cells are closely stacked to form a unit cell assembly. Specifically, as shown in fig. 2, 64 crystal growth unit cells are closely stacked in a simple cubic packing manner of 4 × 4 × 4 to form a unit cell assembly, and the internal structure of the unit cell assembly formed by stacking is shown in fig. 3.
Step four
And stacking solid heat storage blocks around the unit cell assembly, so that the solid heat storage blocks completely wrap the unit cell assembly to form the heat storage assembly. Specifically, as shown in fig. 4, 4 layers of solid heat storage blocks are stacked on each side of the unit cell assembly to form a cube of 12 × 12 × 12. The solid heat storage block material is made of the same material (hexagonal boron nitride) as the hollow heat storage block material.
Step five
As shown in fig. 5, the heat-accumulating assembly is placed in an atmosphere furnace, and the furnace chamber is closed. The volume V1 of the heat storage assembly is 1.73m 3 The volume V2 of the atmosphere furnace chamber is 3.40m 3 The ratio of the volume V1 of the heat accumulation assembly to the volume V2 of the furnace chamber is 1.97. And replacing the original air in the furnace chamber with inert gas nitrogen, and sealing the furnace chamber after replacement.
Step six
And heating the furnace chamber of the atmosphere furnace to 1910 ℃, and keeping the temperature for 5 hours to completely melt the raw materials in the crystal growth container.
Step seven
After the raw materials are completely melted and the temperature field in the furnace chamber is stable, a heat dissipation notch is opened on the furnace chamber to naturally cool the furnace chamber, specifically, as shown in fig. 6, a heat dissipation pipeline is arranged on the top of the furnace chamber, the periphery of the heat dissipation pipeline is wrapped with a heat insulation material, and the top of the heat dissipation pipeline is opened to form the heat dissipation notch; the ratio of the height to the inner diameter of the heat dissipation pipe is 25. And slowly cooling the melted raw materials along with the furnace to be lower than 50 ℃, opening the furnace and taking out the crucible to obtain the ultrapure zirconium titanate single crystal.
The area of the heat dissipation notch is S and is calculated according to the following formula:
S＝K×(V1×V2) 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range;
wherein, the volume of heat accumulation assembly is V1, and the volume of furnace chamber is V2.
In this example, K is 1.11, corresponding to S =2.01cm 2 Namely, a side heat dissipation pipeline with the inner diameter of 16mm is selected.
Example 2
The embodiment provides a batch preparation method of an ultra-pure zirconium titanate single crystal, which comprises the following steps:
step one
The raw materials titanium dioxide and zirconium dioxide for the preparation of zirconium titanate were placed in an unsealed capped crystal growth vessel. Specifically, titanium dioxide and zirconium dioxide are taken as raw materials, the titanium dioxide and the zirconium dioxide are obtained in the market, the purity of the titanium dioxide and the zirconium dioxide is chemical purity (99.5%), the titanium dioxide and the zirconium dioxide are respectively placed in a constant-temperature oven at 200 ℃ and dried to constant weight, the titanium dioxide and the zirconium dioxide are respectively sieved by a 100-mesh sieve, the titanium dioxide and the zirconium dioxide which are sieved are loaded into a V-shaped mixer according to the stoichiometric ratio of 1. Pouring the mixed raw materials into a cylindrical mold, and applying pressure to the mixed raw materials in the mold by adopting an oil press under the pressure of 35MPa to form a dry-pressed green body. And sintering the dry pressed blank at 1680 ℃ for 8 hours under the protection of nitrogen flow to form a sintered blank. And placing the sintered green body in a molybdenum crucible of a crystal growth container, and covering a crucible cover.
Step two
And placing the crystal growth container with the raw materials in a hollow heat storage block with an accommodating cavity to form crystal growth unit cells. Specifically, the molybdenum crucible with the sintered green body obtained in the step one is placed in a hollow heat storage block material. The hollow heat storage block is made of a hexagonal boron nitride ceramic material, the hexagonal boron nitride has the advantages of low hardness, chemical stability, high temperature resistance and the like, the hardness is low, the hexagonal boron nitride is easy to machine into a required shape, the high temperature resistance and the chemical stability are excellent, and the maximum use temperature in an inert atmosphere can reach 2800 ℃. As shown in fig. 1, the hollow heat storage block includes a cubic containing block and a filling block; the cube containing block is provided with an opening, and a containing cavity is formed inside the cube containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is plugged by a plugging block, so that a crystal growth unit cell is formed.
Step three
A plurality of crystal growth unit cells are closely stacked to form a unit cell assembly. Specifically, as shown in fig. 2, 64 crystal growth unit cells are tightly stacked in a simple cubic packing manner of 4 × 4 × 4 to form a unit cell assembly, and the internal structure of the unit cell assembly formed by packing is shown in fig. 3.
Step four
And stacking solid heat storage blocks around the unit cell assembly to enable the solid heat storage blocks to completely wrap the unit cell assembly to form the heat storage assembly. Specifically, as shown in fig. 4, 4 layers of solid heat storage blocks are stacked on each side of the unit cell assembly to form a cube of 12 × 12 × 12. The solid heat storage block material is made of the same material (hexagonal boron nitride) as the hollow heat storage block material.
Step five
As shown in fig. 5, the heat-accumulating assembly is placed in an atmosphere furnace, and the furnace chamber is closed. The volume V1 of the heat storage assembly is 1.73m 3 The volume V2 of the atmosphere furnace chamber is 3.40m 3 The ratio of the volume V1 of the heat accumulation assembly to the volume V2 of the furnace chamber is 1.97. And replacing the original air in the furnace chamber with inert gas nitrogen, and sealing the furnace chamber after replacement.
Step six
And heating the furnace chamber of the atmosphere furnace to 1930 ℃ and preserving the heat for 7 hours to completely melt the raw materials in the crystal growth container.
Step seven
After the raw materials are completely melted and the temperature field in the furnace chamber is stable, opening a heat dissipation notch on the furnace chamber to naturally cool the furnace chamber, specifically as shown in fig. 6, the top of the furnace chamber is provided with a heat dissipation pipeline, the periphery of the heat dissipation pipeline is wrapped with a heat insulation material, and the top opening of the heat dissipation pipeline forms the heat dissipation notch; the ratio of the height to the inner diameter of the heat dissipation pipeline is 25. And slowly cooling the melted raw materials along with the furnace to below 50 ℃, opening the furnace and taking out the crucible to obtain the ultrapure zirconium titanate single crystal.
The area of the heat dissipation notch is S and is calculated according to the following formula:
S＝K×(V1×V2) 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range;
wherein, the volume of heat accumulation assembly is V1, and the volume of furnace chamber is V2.
In this example, K is 1.41, corresponding to S =2.54cm 2 Namely, a side heat dissipation pipeline with the inner diameter of 18mm is selected.
Example 3
The embodiment provides a batch preparation method of an ultra-pure zirconium titanate single crystal, which comprises the following steps:
step one
The raw materials titanium dioxide and zirconium dioxide for preparing zirconium titanate were placed in an unsealed crystal growth vessel with a lid. Specifically, titanium dioxide and zirconium dioxide are taken as raw materials, the titanium dioxide and the zirconium dioxide are obtained in the market, the purity of the titanium dioxide and the zirconium dioxide is chemical purity (99.5%), the titanium dioxide and the zirconium dioxide are respectively placed in a constant-temperature oven at 200 ℃ and dried to constant weight, the titanium dioxide and the zirconium dioxide are respectively sieved by a 100-mesh sieve, the titanium dioxide and the zirconium dioxide which are sieved are loaded into a V-shaped mixer according to the stoichiometric ratio of 1. Pouring the mixed raw materials into a cylindrical die, and applying pressure to the mixed raw materials in the die by an oil press at the pressure of 35MPa to form a dry pressing blank body. And sintering the dry pressed blank at 1680 ℃ for 8 hours under the protection of nitrogen flow to form a sintered blank. And placing the sintered green body in a molybdenum crucible of a crystal growth container, and covering the crucible cover.
Step two
And placing the crystal growth container with the raw materials in a hollow heat storage block with an accommodating cavity to form crystal growth unit cells. Specifically, the molybdenum crucible with the sintered green body obtained in the step one is placed in a hollow heat storage block material. The hollow heat storage block is made of a hexagonal boron nitride ceramic material, the hexagonal boron nitride has the advantages of low hardness, chemical stability, high temperature resistance and the like, the hardness is low, the hexagonal boron nitride is easy to machine into a required shape, the high temperature resistance and the chemical stability are excellent, and the maximum use temperature in an inert atmosphere can reach 2800 ℃. As shown in fig. 1, the hollow heat storage block material includes a cubic containing block and a plugging block; the cube containing block is provided with an opening, and a containing cavity is formed inside the cube containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is blocked by a plugging block, so that a crystal growth unit cell is formed.
Step three
A plurality of crystal growth unit cells are closely stacked to form a unit cell assembly. Specifically, as shown in fig. 2, 64 crystal growth unit cells are tightly stacked in a simple cubic packing manner of 4 × 4 × 4 to form a unit cell assembly, and the internal structure of the unit cell assembly formed by packing is shown in fig. 3.
Step four
And stacking solid heat storage blocks around the unit cell assembly, so that the solid heat storage blocks completely wrap the unit cell assembly to form the heat storage assembly. Specifically, as shown in fig. 4, 4 layers of solid heat storage blocks are stacked on each side of the unit cell assembly to form a cube of 12 × 12 × 12. The solid heat storage block material is made of the same material (hexagonal boron nitride) as the hollow heat storage block material.
Step five
As shown in fig. 5, the regenerative assembly is placed in an atmospheric furnace, and the furnace chamber is closed. The volume V1 of the heat storage assembly is 1.73m 3 The volume V2 of the atmosphere furnace chamber is 3.40m 3 The ratio of the volume V1 of the heat accumulation assembly to the volume V2 of the furnace chamber is 1.97. Replacing the original air in the furnace chamber with inert gas nitrogen, and sealing the furnace chamber after completing the replacement.
Step six
And heating the furnace chamber of the atmosphere furnace to 1950 ℃ and preserving the heat for 12 hours to completely melt the raw materials in the crystal growth container.
Step seven
After the raw materials are completely melted and the temperature field in the furnace chamber is stable, a heat dissipation notch is opened on the furnace chamber to naturally cool the furnace chamber, specifically, as shown in fig. 6, a heat dissipation pipeline is arranged on the top of the furnace chamber, the periphery of the heat dissipation pipeline is wrapped with a heat insulation material, and the top of the heat dissipation pipeline is opened to form the heat dissipation notch; the ratio of the height to the inner diameter of the heat dissipation pipe is 25. And slowly cooling the melted raw materials along with the furnace to below 50 ℃, opening the furnace and taking out the crucible to obtain the ultrapure zirconium titanate single crystal.
The area of the heat dissipation notch is S and is calculated according to the following formula:
S＝K×(V1×V2) 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range;
wherein, the volume of the heat accumulation assembly is V1, and the volume of the furnace chamber is V2.
In this example, K is 1.74, corresponding to S =3.14cm 2 Namely, a side heat dissipation pipeline with the inner diameter of 20mm is selected.
Example 4
The embodiment provides a batch preparation method of an ultra-pure zirconium titanate single crystal, which comprises the following steps:
step one
The raw materials titanium dioxide and zirconium dioxide for the preparation of zirconium titanate were placed in an unsealed capped crystal growth vessel. Specifically, titanium dioxide and zirconium dioxide are taken as raw materials, the titanium dioxide and the zirconium dioxide are commercially available, the purity levels of the titanium dioxide and the zirconium dioxide are respectively 99% compared with those of other examples, the titanium dioxide and the zirconium dioxide are respectively placed in a constant-temperature oven at 200 ℃ and dried to constant weights, the titanium dioxide and the zirconium dioxide are respectively sieved by a 100-mesh sieve, the sieved titanium dioxide and the sieved zirconium dioxide are loaded into a V-shaped mixer according to a stoichiometric ratio of 1. Pouring the mixed raw materials into a cylindrical mold, and applying pressure to the mixed raw materials in the mold by adopting an oil press under the pressure of 35MPa to form a dry-pressed green body. And sintering the dry pressed blank at 1680 ℃ for 8 hours under the protection of nitrogen flow to form a sintered blank. And placing the sintered green body in a molybdenum crucible of a crystal growth container, and covering the crucible cover.
Step two
And placing the crystal growth container with the raw materials in a hollow heat storage block with an accommodating cavity to form crystal growth unit cells. Specifically, the molybdenum crucible with the sintered green body obtained in the step one is placed in a hollow heat storage block material. The hollow heat storage block is made of a hexagonal boron nitride ceramic material, the hexagonal boron nitride has the advantages of low hardness, chemical stability, high temperature resistance and the like, the hardness is low, the hexagonal boron nitride is easy to machine into a required shape, the high temperature resistance and the chemical stability are excellent, and the maximum use temperature in an inert atmosphere can reach 2800 ℃. As shown in fig. 1, the hollow heat storage block material includes a cubic containing block and a plugging block; the cube containing block is provided with an opening, and a containing cavity is formed inside the cube containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is plugged by a plugging block, so that a crystal growth unit cell is formed.
Step three
A plurality of crystal growth unit cells are tightly stacked to form a unit cell assembly. Specifically, as shown in fig. 2, 64 crystal growth unit cells are closely stacked in a simple cubic packing manner of 4 × 4 × 4 to form a unit cell assembly, and the internal structure of the unit cell assembly formed by stacking is shown in fig. 3.
Step four
And stacking solid heat storage blocks around the unit cell assembly, so that the solid heat storage blocks completely wrap the unit cell assembly to form the heat storage assembly. Specifically, as shown in fig. 4, 4 layers of solid heat storage blocks are stacked on each side of the unit cell assembly to form a cube of 12 × 12 × 12. The solid heat storage block material is made of the same material (hexagonal boron nitride) as the hollow heat storage block material.
Step five
As shown in fig. 5, the heat-accumulating assembly is placed in an atmosphere furnace, and the furnace chamber is closed. The volume V1 of the heat storage assembly is 1.73m 3 The volume V2 of the atmosphere furnace chamber is 3.40m 3 The ratio of the volume V1 of the heat accumulation assembly to the volume V2 of the furnace chamber is 1.97. And replacing the original air in the furnace chamber with inert gas nitrogen, and sealing the furnace chamber after replacement.
Step six
And heating the furnace chamber of the atmosphere furnace to 1930 ℃ and preserving the heat for 12 hours to completely melt the raw materials in the crystal growth container.
Step seven
After the raw materials are completely melted and the temperature field in the furnace chamber is stable, a heat dissipation notch is opened on the furnace chamber to naturally cool the furnace chamber, specifically, as shown in fig. 6, a heat dissipation pipeline is arranged on the top of the furnace chamber, the periphery of the heat dissipation pipeline is wrapped with a heat insulation material, and the top of the heat dissipation pipeline is opened to form the heat dissipation notch; the ratio of the height to the inner diameter of the heat dissipation pipeline is 25. And slowly cooling the melted raw materials along with the furnace to below 50 ℃, opening the furnace, taking out the solid in the crucible, and cutting off waste materials at the upper end and the lower end to obtain the ultrapure zirconium titanate single crystal sample.
The area of the heat dissipation notch is S and is calculated according to the following formula:
S＝K×(V1×V2) 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range;
wherein, the volume of the heat accumulation assembly is V1, and the volume of the furnace chamber is V2.
In this example, K is 0.44, corresponding to S =0.79cm 2 Namely, a side heat dissipation pipeline with the inner diameter of 5mm is selected.
Characterization and testing
After completion of crystal growth, the crystal growth unit cells in the 4 × 4 × 4 unit cell assemblies of examples 1 to 4 were sampled, and two crystal growth unit cells were taken for each unit cell assembly, one crystal growth unit cell was randomly taken at 8 apex positions, and one crystal growth unit cell was taken at 8 positions near the center. And taking out the solid in the crystal growth unit cell, and cutting off the waste materials at the upper end and the lower end to obtain the ultra-pure zirconium titanate single crystal sample.
As described above, two samples were taken for each example for a total of 8 samples. Each sample was tested for refractive index (n) at a different wavelength (. Lamda.) according to GB/T7962.12-1987 colorless optical glass test methods, the results of which are shown in Table 1.
In addition, the purity of the crystals was determined by detecting the components of each crystal sample by a Glow Discharge Mass Spectrometer (GDMS), and the results are shown in table 2.
TABLE 1 refractive index test results
Figure BDA0003916547250000151
TABLE 2 purity test results
Sample examples Purity of
Example 1 (center) 99.99％
Example 1 (vertex) 99.99％
Example 2 (center) 99.99％
Example 2 (apex) 99.99％
Example 3 (center) 99.99％
Example 3 (vertex) 99.99％
Example 4 (center) 99.95％
Example 4 (apex) 99.95％
The results of tables 1 and 2 show that the zirconium titanate crystals prepared by the present invention are excellent in quality, have a stable refractive index and have an ultra-high purity. Although the raw materials with the purities of 99.5% and 99% are low-purity raw materials for single crystal growth, the invention can prepare high-purity single crystals in large batch by the scheme, the purity of the single crystal prepared from the raw material with the purities of 99.5% can reach the level of 99.99%, and the purity of the single crystal prepared from the raw material with the purities of 99% can reach the level of 99.95%. In addition, the refractive indexes of samples grown at different positions of different embodiments are basically consistent, which shows that the crystal prepared in batches has uniform components, good crystallinity and good uniformity, and the scheme provided by the invention is a set of feasible scheme which is stable and reliable and can prepare the zirconium titanate single crystal in batches.
The above embodiments are exemplary only, and are intended to illustrate the technical concept and features of the present invention so that those skilled in the art can understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A batch preparation method of ultra-pure zirconium titanate single crystals is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: placing titanium dioxide and zirconium dioxide, which are raw materials for preparing zirconium titanate, in a non-sealed crystal growth container with a cover;
step two: placing the crystal growth container with the stored raw materials into a hollow heat storage block material with an accommodating cavity to form crystal growth unit cells;
step three: tightly stacking a plurality of crystal growth unit cells to form a unit cell assembly;
step four: stacking solid heat storage blocks around the unit cell assembly to enable the solid heat storage blocks to completely wrap the unit cell assembly to form a heat storage assembly;
step five: placing the heat storage assembly in an atmosphere furnace, sealing the furnace chamber, and replacing the original gas in the furnace chamber with inert gas;
step six: heating the furnace chamber of the atmosphere furnace to a temperature not lower than 1900 ℃, and preserving the heat to completely melt the raw materials in the crystal growth container;
step seven: and opening a heat dissipation notch on the furnace chamber to naturally cool the furnace chamber, and slowly cooling the melted raw materials along with the furnace to obtain the ultrapure zirconium titanate single crystal.
2. The batch production method of an ultrapure zirconium titanate single crystal according to claim 1, characterized in that: in the first step, the purity of the titanium dioxide and the zirconium dioxide is not lower than 99.0%, and the molar ratio of the titanium dioxide to the zirconium dioxide actually contained in the raw materials is within a range of 1.97-1.03.
3. The batch production method of an ultrapure zirconium titanate single crystal according to claim 2, characterized in that: in the first step, a molybdenum crucible with a cover is used as a crystal growth container; the titanium dioxide and the zirconium dioxide are uniformly mixed, pre-sintered and molded and then placed into a crystal growth container.
4. The batch production method of an ultrapure zirconium titanate single crystal according to claim 1, characterized in that: in the second step, the hollow heat storage block is made of a hexagonal boron nitride ceramic material and comprises a cubic containing block and a filling block; the cubic containing block is provided with an opening, and a containing cavity is formed inside the cubic containing block; and after the crystal growth container is placed into the accommodating cavity, the opening is blocked by a plugging block, so that a crystal growth unit cell is formed.
5. The batch production method of an ultrapure zirconium titanate single crystal according to claim 4, characterized in that: in the third step, the crystal growth unit cells are tightly stacked according to a simple cubic packing form to form a unit cell assembly; at least 3 crystal growth unit cells are arranged in each direction of length, width and height in the unit cell assembly.
6. The batch production method of an ultrapure zirconium titanate single crystal according to claim 5, characterized in that: in the fourth step, the solid heat storage block is made of the same material as the hollow heat storage block; the distance from each surface of the unit cell assembly to the outer surface of the heat storage assembly is not less than the maximum value of the length, the width and the height of the unit cell assembly.
7. The batch production method of an ultrapure zirconium titanate single crystal according to claim 6, characterized in that: in the fourth step, the ratio of the volume of the heat accumulation assembly to the volume of the furnace chamber is 1.8-2.5.
8. The batch production method of an ultrapure zirconium titanate single crystal according to claim 1, characterized in that: in the sixth step, the furnace chamber of the atmosphere furnace is heated to 1910-1950 ℃, and then the temperature is kept for 5-12 hours to completely melt the raw materials in the crystal growth container.
9. The batch production method of an ultrapure zirconium titanate single crystal according to claim 7, characterized in that: step seven, a heat dissipation pipeline is arranged at the top of the furnace chamber, heat insulation materials are wrapped on the periphery of the heat dissipation pipeline, and a heat dissipation notch is formed in an opening at the top of the heat dissipation pipeline; the ratio of the height to the inner diameter of the heat dissipation pipeline is 24-30.
10. The batch production method of an ultrapure zirconium titanate single crystal according to claim 9, characterized in that: setting the area of the heat dissipation gap as S, the volume of the heat storage assembly as V1 and the volume of the furnace chamber as V2;
S=K×（V1×V2） 1/3 ；
k is a dimensionless constant, K is 0.3X 10 -4 To 2.0X 10 -4 Within the range.
CN202211344061.0A 2022-10-31 2022-10-31 Batch preparation method of ultra-pure zirconium titanate single crystal Pending CN115613113A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005049497A1 (en) * 2003-11-20 2005-06-02 The Australian National University The synthesis of ordered zirconium titanate
CN102814569A (en) * 2012-08-06 2012-12-12 深圳市因沃客科技有限公司 Eutectic furnace
CN104088015A (en) * 2014-07-30 2014-10-08 上海晶生实业有限公司 Bridgman-stockbarger growth method for zirconium titanate crystals
US20170137961A1 (en) * 2013-04-03 2017-05-18 Kwang Jong KIM Monocrystalline zirconia without low-temperature degradation properties and method for growing same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005049497A1 (en) * 2003-11-20 2005-06-02 The Australian National University The synthesis of ordered zirconium titanate
CN102814569A (en) * 2012-08-06 2012-12-12 深圳市因沃客科技有限公司 Eutectic furnace
US20170137961A1 (en) * 2013-04-03 2017-05-18 Kwang Jong KIM Monocrystalline zirconia without low-temperature degradation properties and method for growing same
CN104088015A (en) * 2014-07-30 2014-10-08 上海晶生实业有限公司 Bridgman-stockbarger growth method for zirconium titanate crystals

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