Design method for growth temperature field of lanthanum gallium niobate group crystal

Abstract

The invention discloses a method for designing a growth temperature field of a lanthanum gallium niobate group crystal, which belongs to the technical field of crystal growth, and is characterized in that the temperature gradient required by crystal growth is adjusted by designing the non-uniform thickness change of a temperature field material, which is different from the conventional same thickness design of a traditional pulling method temperature field material. An irregular temperature field is designed based on the non-uniform thickness of a temperature field material, the temperature field is thin at the lower part and thick at the upper part, the thin lower part can increase the temperature gradient at a solid-liquid interface, a proper supercooling degree is provided for crystal shoulder expansion to 4 inches, and the thick upper part is beneficial to heat preservation of the crystal and prevents the crystal from cracking. The thermal field design method is beneficial to providing an appropriate thermal field gradient for the growth of the large-size lanthanum gallium niobate crystal, realizes the growth of the crystal with uniform components, and finally obtains the high-quality large-size lanthanum gallium niobate single crystal.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth, and more particularly to a method for designing a growth temperature field for lanthanum gallium niobate crystals. Background Art

[0002] The growth of crystals by the CZ method is a solid-liquid phase transition process from the melt phase to the crystal phase. The degree of supercooling is positively correlated with the driving force of phase change and the crystal growth rate. A large degree of supercooling can dissipate the latent heat of crystallization generated during the crystal growth process in time, and the growth rate is fast, but it is easy to introduce defects such as inclusions and scattering particles; a small degree of supercooling cannot dissipate the latent heat of crystallization generated during the crystal growth process in time, and the growth rate is slow, which is easy to cause component supercooling and difficult to grow large-sized single crystals. The temperature gradient of the temperature field is the key to ensuring the stable growth of crystals and the quality of crystals during the CZ method crystal growth process. The size and distribution of the temperature gradient are mainly determined by the type and thickness of the temperature field material. High-quality crystal growth requires that the temperature field can provide appropriate supercooling, maintain the temperature of crystal growth, and obtain crystals of a certain diameter and length in a short time. In the traditional CZ method of growing crystals, in order to ensure the stable growth of crystals, the temperature field materials are generally designed with the same thickness, which is more conducive to the growth of small-sized crystals. However, for large-sized lanthanum gallium niobate crystals (large-sized lanthanum gallium niobate crystals refer to those with an equal diameter of 4 inches and grown by the Czochralski method), the same temperature gradient is not conducive to providing sufficient supercooling for the shoulder expansion process of large-sized crystals, which is not conducive to obtaining large-sized crystals.

[0003] Therefore, there is an urgent need to provide a good solution for growing high-quality, large-size lanthanum gallium niobate single crystals. Summary of the invention

[0004] In view of this, the present invention aims at the problem of difficulty in growing large-sized lanthanum gallium niobate crystals and provides a method for designing a temperature field for the growth of lanthanum gallium niobate crystals. By designing a temperature field with non-uniform thickness, it is convenient to provide a suitable temperature field gradient for the growth of large-sized lanthanum gallium niobate crystals, which is conducive to obtaining large-sized, high-quality lanthanum gallium niobate single crystals.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a method for designing a growth temperature field of a lanthanum gallium niobate crystal, the method comprising:

[0007] Design a temperature field with non-uniform thickness, where the thickness of the upper area of ​​the temperature field is greater than that of the lower area;

[0008] The temperature field size is adjusted according to the target conditions for the growth of lanthanum gallium niobate crystals.

[0009] Preferably, a temperature field with adjustable thickness is designed by irregular processing, which is consistent with the pulling growth direction of the lanthanum gallium niobate crystal; the lower area of ​​the temperature field is used to increase the temperature gradient at the solid-liquid interface, and the upper area of ​​the temperature field is used to keep the crystal warm.

[0010] Preferably, the temperature field is composed of two thermal insulation materials: zirconia bricks and zirconia wool blankets.

[0011] Preferably, the irregular temperature field is designed by changing the thickness of the two thermal insulation materials simultaneously or separately.

[0012] Preferably, the lanthanum gallium niobate crystals include any one of lanthanum gallium niobate, lanthanum gallium silicate, lanthanum gallium tantalate and solid solution mixed crystals.

[0013] Preferably, the target conditions for the growth of the lanthanum gallium niobate crystal include: crystal size, growth temperature, growth time and shouldering speed.

[0014] In a second aspect, the present invention further provides a growth temperature field for a lanthanum gallium niobate crystal, which is designed by applying the above-mentioned design method for a growth temperature field for a lanthanum gallium niobate crystal, and the thickness of the upper region of the temperature field is greater than the thickness of the lower region.

[0015] Preferably, the temperature field is composed of two thermal insulation materials: zirconia bricks and zirconia wool blankets.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0017] The present invention provides a method for designing a temperature field for growing a lanthanum gallium niobate crystal. By designing a temperature field with a non-uniform thickness, it is convenient to provide a suitable temperature field gradient for growing large-sized lanthanum gallium niobate crystals, which is beneficial to obtaining large-sized, high-quality lanthanum gallium niobate single crystals.

[0018] 2. The present invention can optimize the temperature gradient distribution by designing the non-uniform thickness change of the temperature field material, thereby providing a reasonable crystal growth temperature field and ensuring the best radial and lateral temperature gradients, providing a suitable degree of supercooling for crystal shoulder expansion, and finally obtaining large-sized, high-quality lanthanum gallium niobate crystals with uniform composition.

[0019] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0023] Figure 1 A schematic flow chart of a method for designing a growth temperature field for lanthanum gallium niobate crystals provided in an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of three temperature field structures designed and optimized according to embodiments of the present invention.

[0025] Figure 3 A physical schematic diagram of a conventional temperature field provided in an embodiment of the present invention.

[0026] Figure 4 A physical schematic diagram of an irregular temperature field designed and optimized by the present invention is provided for an embodiment of the present invention.

[0027] Figure 5 Schematic diagram comparing a crystal grown in a conventional temperature field (left) and a crystal grown in an irregular temperature field (right) provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0029] In the description of the present invention, it should be noted that: in some processes described in the specification and drawings of this application, multiple operations appearing in a specific order are included, but it should be clearly understood that these operations may not be performed in the order in which they appear in this document or may be performed in parallel. In addition, various serial numbers are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 As shown, an embodiment of the present invention provides a method for designing a temperature field for growing lanthanum gallium niobate crystals, and designs a temperature field with non-uniform thickness (the lower area of ​​the temperature field is thin, and the upper area of ​​the temperature field is thick). The thin lower area can increase the temperature gradient at the solid-liquid interface, and provide a suitable degree of supercooling for expanding the crystal shoulder to an equal diameter of 4 inches. The thick upper area is beneficial to the insulation of the crystal and prevents the crystal from cracking. The irregular temperature field design method provides a suitable temperature field gradient for the growth of large-sized lanthanum gallium niobate crystals, which is beneficial to the final growth of high-quality large-sized lanthanum gallium niobate single crystals.

[0032] In an optional embodiment, an irregular processing method with a thin bottom and a thick top is adopted by designing the growth temperature field, which is consistent with the direction of crystal pulling growth, wherein the length and thickness of the lower thin layer area of ​​the irregular temperature field are related to the crystal growth size. By controlling the height and thickness of the lower thin layer area of ​​the temperature field, the supercooling required for shoulder expansion during crystal growth can be adjusted to provide an internal driving force for the growth of lanthanum gallium niobate crystals. The lanthanum gallium niobate crystals here include any one of lanthanum gallium niobate, lanthanum gallium silicate, lanthanum gallium tantalate and solid solution mixed crystals. According to the target conditions such as crystal size, growth temperature and growth time, the processing size of the irregular temperature field is controlled to meet the supercooling of large-size crystal growth, and finally grow high-quality large-size single crystals.

[0033] In an optional embodiment, the thickness of the lower thin layer region of the irregular temperature field is determined by the size required for crystal growth. The larger the crystal growth size, the smaller the thin layer thickness, and the thin layer thickness is inversely proportional to the crystal size. The thickness of the lower thin layer region is preferably 1mm-50mm, and the thickness of the upper thick layer region is greater than the thickness of the lower thin layer region.

[0034] In an optional embodiment, the temperature field is composed of two thermal insulation materials, zirconia bricks and zirconia wool blankets. The two thermal insulation materials can be thinned simultaneously or separately to design an irregular temperature field to achieve a suitable temperature gradient effect. Figure 2 Three temperature field structures designed and optimized by the present invention are shown in the figure, where R5 represents the protrusion between the upper and lower nests, which is a semi-ellipse with a radius of 5 mm, and 7.5 mm is the distance from the center of the raised groove to the inner wall (if the temperature field is only stacked up by plane contact and self-weight, the structure will be unstable, so this multi-layer nesting method is used to stack it up to make it more stable).

[0035] The design method of the present invention is further described below with specific embodiments:

[0036] Embodiment 1:

[0037] Taking the growth of 4-inch lanthanum gallium niobate single crystal as an example, the present invention designs an irregular temperature field scheme as follows: temperature field size (outer diameter is 330mm, inner diameter is 230mm, total height is 200mm), the upper thick layer area is 150mm high and 50mm thick, and the lower thin layer area is 50mm high and 20mm thick; the insulation materials selected in this implementation are zirconia bricks and zirconia wool blankets, wherein the zirconia bricks are processed into an irregular temperature field according to the above design scheme, and the zirconia wool blanket can further increase the temperature gradient of the thin layer area. Compared with the conventional regular temperature field (see Figure 3 shown), irregular temperature field (see Figure 4 As shown in the figure, the size change of the temperature field can be adjusted according to the size of the growing crystal and the speed of shoulder release, wherein the overall outer diameter of the temperature field is adjusted to adjust the temperature gradient, thereby obtaining the best supercooling degree for crystal growth and ensuring the growth of high-quality large-size crystals. In this embodiment, the crystals grown in the irregular temperature field are as follows Figure 5 As shown in the middle right part, the crystal grown in the conventional temperature field is Figure 5 Shown in the middle left portion.

[0038] Embodiment 2:

[0039] Taking the growth of large-size lanthanum gallium silicate single crystals as an example, the present invention designs an irregular temperature field scheme as follows: temperature field size (outer diameter is 290mm-330mm, inner diameter is 200mm-230mm, total height is 150mm-200mm), the upper thick layer area is 100mm-150mm long and 30mm-50mm thick, and the lower thin layer area is 1mm-50mm long and 1mm-20mm thick; the thermal insulation materials selected by the present invention are zirconia bricks and zirconia cotton blankets, which are processed into an irregular temperature field. According to the size of the growing crystal and the speed of shouldering, the size change of the temperature field is adjusted to ensure the optimal supercooling of the crystal growth and grow high-quality large-size crystals.

[0040] Embodiment 3:

[0041] Taking the growth of large-sized lanthanum gallium tantalate single crystals as an example, the irregular temperature field design scheme is shown in Example 2, and the temperature field insulation material is also processed into an irregular temperature field with uneven thickness from top to bottom as shown in Example 2, or the relative thickness of the lower thin layer and the upper thick layer of the zirconia wool blanket can be adjusted (the thickness difference between the upper and lower layers is 1-15mm), and the size change of the temperature field is adjusted according to the size of the growing crystal and the speed of shoulder release to grow high-quality large-sized crystals.

[0042] Embodiment 4:

[0043] Taking the growth of large-sized lanthanum gallium silicate solid solution mixed crystal as an example, the irregular temperature field design scheme is shown in Example 2, and the temperature field insulation material is also processed into an irregular temperature field with uneven thickness from top to bottom as shown in Example 2, and the relative thickness of the lower thin layer and the upper thick layer of the zirconia wool blanket is also adjusted. For the above two temperature field insulation materials, the two insulation materials are thinned at the same time or thinned separately to design an irregular temperature field to achieve a suitable temperature gradient effect. According to the size of the growing crystal and the speed of shouldering, the size change of the temperature field is adjusted to grow high-quality large-sized crystals.

[0044] From the description of the above embodiments, those skilled in the art can know that: the present invention provides a method for designing a temperature field for the growth of lanthanum gallium niobate crystals, which adjusts the temperature gradient required for crystal growth by designing the non-uniform thickness change of the temperature field material, which is different from the conventional uniform thickness design of the temperature field material of the traditional Czochralski method. An irregular temperature field is designed based on the non-uniform thickness of the temperature field material (the lower part of the temperature field is thin, and the upper part of the temperature field is thick). The thin lower part can increase the temperature gradient at the solid-liquid interface and provide a suitable degree of supercooling for the crystal to expand to 4 inches. The thick upper part is conducive to the insulation of the crystal and prevents the cracking of the crystal. The temperature field design method provides a suitable temperature field gradient for the growth of large-sized lanthanum gallium niobate crystals, which is conducive to the growth of crystals with uniform components, and finally obtains high-quality large-sized lanthanum gallium niobate single crystals.

[0045] Furthermore, the present invention also provides a growth temperature field for lanthanum gallium niobate crystals, which is designed using the design method for a growth temperature field for lanthanum gallium niobate crystals described in the above embodiment. The temperature field is composed of two thermal insulation materials, zirconia bricks and zirconia cotton blankets, and adopts a non-uniform thickness design. The thickness of the upper area of ​​the temperature field is greater than that of the lower area.

[0046] The present invention provides a temperature field for growing lanthanum gallium niobate crystals, and its implementation principle and technical effects are the same as those of the aforementioned method embodiment. For the sake of brief description, for parts not mentioned in this embodiment, reference can be made to the corresponding contents in the aforementioned method embodiment, which will not be repeated here.

[0047] It should be noted that the word "comprising" does not exclude the presence of components or steps not listed in the claims. The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other.

[0048] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for designing a temperature field for growing lanthanum gallium niobate crystals, characterized in that: The method includes: Design a temperature field with non-uniform thickness, where the thickness of the upper area of ​​the temperature field is greater than that of the lower area; The temperature field size is adjusted according to the target conditions for the growth of lanthanum gallium niobate crystals.

2. The method for designing a temperature field for growth of a lanthanum gallium niobate crystal according to claim 1, characterized in that: A temperature field with adjustable thickness is designed by an irregular processing method, which is consistent with the pulling growth direction of the lanthanum gallium niobate crystal; the lower area of ​​the temperature field is used to increase the temperature gradient at the solid-liquid interface, and the upper area of ​​the temperature field is used to keep the crystal warm.

3. The method for designing a temperature field for growth of a lanthanum gallium niobate crystal according to claim 2, characterized in that: The temperature field is composed of two kinds of thermal insulation materials: zirconia bricks and zirconia wool blankets.

4. The method for designing a temperature field for growth of a lanthanum gallium niobate crystal according to claim 3, characterized in that: The irregular temperature field is designed by changing the thickness of two insulation materials simultaneously or separately.

5. The method for designing a temperature field for growth of lanthanum gallium niobate crystals according to claim 1, characterized in that: The lanthanum gallium niobate crystals include any one of lanthanum gallium niobate, lanthanum gallium silicate, lanthanum gallium tantalate and solid solution mixed crystals.

6. The method for designing a temperature field for growth of a lanthanum gallium niobate crystal according to claim 1, characterized in that: The target conditions for the growth of the lanthanum gallium niobate crystal include: crystal size, growth temperature, growth time and shouldering speed.

7. A temperature field for growing lanthanum gallium niobate crystals, characterized in that: The method for designing a growth temperature field for a lanthanum gallium niobate crystal as described in any one of claims 1 to 5 is used to design the temperature field, and the thickness of the upper region of the temperature field is greater than the thickness of the lower region.

8. The growth temperature field of lanthanum gallium niobate crystals according to claim 7, characterized in that: The temperature field is composed of two insulation materials: zirconia bricks and zirconia cotton blankets.

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