Manufacturing method and gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium

Abstract

The present invention relates to a manufacturing method and a gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium. The method includes: feeding natural abundance silane gas into a gas diffusion cascade including a gas diffusion separation device, compressing the silane gas before it enters the gas diffusion separation device in each of the gas diffusion cascades using a high-speed magnetic levitation gas compressor, and obtaining silicon-28 isotope with an abundance of more than 99% using silane as a medium from the light fraction end of the gas diffusion cascade.

Description

Technical Field

[0001] The present invention relates to a manufacturing method and a gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99%, belonging to the technical field of isotope separation. Background Art

[0002] Stable isotopes are currently widely used in the fields of medicine, biology, agriculture, environment, industrial manufacturing, scientific research, etc. There are three isotopes of silicon element in nature, namely silicon-28 ( 28 Si), silicon-29 ( 29 Si) and silicon-30 ( 30 Si), and their natural abundances are 92.22%, 4.69% and 3.09% respectively. Silicon-28 isotope is mainly applied to the fields of semiconductors, quantum computing, and metrology. Using silicon-28 materials with an abundance of more than 99% to prepare semiconductor components can reduce lattice defects caused by silicon-29 and silicon-30, reduce phonon scattering, and improve thermal conductivity; and has advantages such as lower gate voltage and faster switching speed, and can be used to manufacture high-speed CPUs, high-power devices, high-performance sensors, etc. The nuclear spin of silicon-28 isotope is 0, and high-abundance silicon-28 can be used to prepare key materials with long spin coherence time in quantum information devices to remove 29 Si interference. Using isotope-pure silicon-28 materials to prepare single crystal spheres can measure more accurate Avogadro constant values.

[0003] In practical applications, the abundance requirements for silicon-28 isotope materials are very high. Usually, the abundance of silicon-28 isotope is required to be higher than 99%, and sometimes even required to reach more than 99.7%. The natural abundance of silicon-28 isotope is 92.22%. At present, low-temperature rectification methods (SiH 4 , SiCl 4 or SiH 3 CH 3 system), gas centrifuge method (the medium is SiF 4 or SiHCl 3 ), chemical exchange method (separation system of SiF 4 and different complexing agents), and laser method (Si 2 F 6 ) for separating silicon isotopes have achieved certain results, but the industrial production research of silicon isotopes has not yet achieved a breakthrough. The separation coefficient of the low-temperature rectification method for silicon isotopes is small, the efficiency of the gas centrifuge method for separating light gases is low, the output of the laser separation method is very low and the cost is high, and the economics for industrial production are not good.

[0004] Early metal porous membranes were widely used in the separation of uranium isotopes by diffusion, but they were costly. Organic polymer membranes have excellent performance and extremely low costs and have been widely used in industrial manufacturing. However, their application in the production of high-abundance silicon-28 isotopes has not been studied much.

[0005] In addition, due to the significant differences in the design and operation of gas diffusion cascades for different gas media and / or different target isotopes, it cannot be taken for granted that a separation method using a gas diffusion cascade for a certain gas media and / or a certain target isotope can be applied to another gas media and / or another target isotope. Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing high-abundance silicon-28 isotopes using silane as the medium. This method has a large separation coefficient, a large flow rate, and low costs, and is suitable for industrial applications. Further, silicon-30 isotope by-products can also be obtained synchronously.

[0008] The purpose of the present invention is also to provide a gas diffusion cascade for preparing high-abundance silicon-28 isotopes using silane as the medium. This gas diffusion cascade has a large separation coefficient, a large flow rate, and low costs, and is suitable for industrial applications. Further, silicon-30 isotope by-products can also be obtained synchronously.

[0009] Solutions for Solving the Problems

[0010] According to the intensive research of the inventors of the present invention, it is found that by implementing the following technical solutions, the above technical problems can be solved:

[0011] [1]. A manufacturing method for preparing silicon-28 isotopes with an abundance of more than 99% using silane as the medium, characterized by comprising:

[0012] Feeding natural-abundance silane gas into a gas diffusion cascade including a gas diffusion separation device, using a high-speed magnetic levitation gas compressor to compress the silane gas before it enters each gas diffusion separation device in the gas diffusion cascade, and obtaining silicon-28 isotopes with an abundance of more than 99% using silane as the medium from the light fraction end of the gas diffusion cascade.

[0013] [2]. The manufacturing method according to [1], wherein the gas diffusion cascade is composed of gas diffusion separation devices with a silane basic overall separation coefficient of 1.009 - 1.011 measured through a four-stage total reflux diffusion cascade experiment: multiple gas diffusion separation devices are connected in parallel to form a separation stage, and then multiple such separation stages are connected in series.

[0014] [3]. The manufacturing method according to [2], wherein the substantially complete separation coefficient of silane measured through a four-stage total reflux diffusion cascade experiment is not less than 1.010.

[0015] [4]. The manufacturing method according to any one of [1] to [3], wherein the total number of stages of the gas diffusion cascade is 200 to 600 stages, preferably 280 to 300 stages.

[0016] [5]. The manufacturing method according to any one of [1] to [4], wherein the feed stage of the gas diffusion cascade is located at a position 3 to 100 stages, preferably 5 to 50 stages, away from the heavy fraction end. The flow rate of the light fraction of the gas diffusion cascade is 0.01 to 0.05 times the feed flow rate of the feed stage, and the total flow rate of the gas diffusion cascade is 1800 to 3500 times the feed flow rate of the feed stage.

[0017] [6]. The manufacturing method according to any one of [1] to [5], wherein the silicon-28 isotope abundance of the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade is less than 92.1%, and the heavy fraction contains silicon-30 isotope by-products.

[0018] [7]. The manufacturing method according to any one of [1] to [6], wherein the purity of the silane gas with natural abundance is higher than 99.9%.

[0019] [8]. A gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium, characterized by comprising:

[0020] a plurality of gas diffusion separation devices, and

[0021] a high-speed magnetic levitation gas compressor located before each of the gas diffusion separation devices in the flow direction of the silane gas;

[0022] Silicon-28 isotope with an abundance of more than 99% prepared using silane with natural abundance as a medium is obtained from the light fraction end of the gas diffusion cascade.

[0023] Effects of the Invention

[0024] In the present invention, the gas diffusion method can be used on the gas diffusion cascade to separate silicon-28 isotope using silane as a medium. The separation coefficient is large, the flow rate is large, and the cost is low, which is suitable for industrial application. Further, silicon-30 isotope by-products can be obtained at the heavy fraction end.

[0025] Specifically, silane (SiH 4), compared with other potential substances that can be used as the separation medium for Si isotopes, it has a small relative molecular mass and a relatively large gas diffusion separation coefficient. The gas diffusion separation process is a physical separation process without introducing other impurities. Moreover, a high-speed magnetic levitation compressor can effectively compress light gases. Therefore, the method of the present invention, due to using a gas diffusion cascade, effectively compressing light gases with a high-speed magnetic levitation compressor, and using silane with a relatively large separation coefficient as the separation medium, has the advantages of large flow rate, high efficiency, and high purity of the prepared high-abundance silicon-28 isotope.

[0026] On the above basis, the present invention can adjust the target isotope abundance (even an abundance of more than 99.9%) by flexibly adjusting the length (number of stages) and flow rate (light fraction flow rate, total flow rate, etc.) of the gas diffusion cascade. On the other hand, in the present invention, even when the cascade length does not exceed 600 stages, the abundance of silicon-28 isotope can be concentrated to more than 99%, which has good economy. Brief Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the gas passing through the membrane principle inside a single-stage single separator according to an embodiment of the present invention.

[0028] Figure 2 It is a schematic diagram of the principle of preparing high-abundance silicon-28 isotope by a gas diffusion cascade according to an embodiment of the present invention.

[0029] Figure 3 It is a diagram of a double-pipe diffusion cascade device used in the preparation of high-abundance silicon-28 isotope with silane as the medium according to an embodiment of the present invention.

[0030] Figure 4 It is a schematic diagram showing the series connection form of each separation stage according to an embodiment of the present invention.

[0031] Figure 5 It is a distribution diagram of the abundance of silicon-28 isotope in each stage of the gas diffusion cascade according to an embodiment of the present invention. Detailed Description of the Embodiments

[0032] The following will detail various exemplary embodiments, features, and aspects of the present invention. The special word "exemplary" here means "serving as an example, embodiment, or illustrative". Any embodiment described as "exemplary" here does not have to be construed as superior or better than other embodiments.

[0033] In addition, for better illustration of the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can still be implemented without certain specific details. In some other instances, methods, means, equipment, and steps well-known to those skilled in the art are not described in detail to highlight the gist of the present invention.

[0034] Unless otherwise specified, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors or design constraints in industrial production and approximate the corresponding values. This document may provide examples of parameters containing specific values, but these parameters do not necessarily equal the corresponding values exactly.

[0035] In this specification, the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., are only with reference to the directions in the accompanying drawings and are not used to limit the protection scope of the present invention.

[0036] In this specification, the meaning expressed by using "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0037] In this specification, the "some specific / preferred embodiments", "some other specific / preferred embodiments", "embodiments", etc. mentioned refer to the specific elements (e.g., features, structures, properties, and / or characteristics) related to the embodiments, which are included in at least one of the embodiments described herein, and may or may not exist in other embodiments. Additionally, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0038] In this specification, the numerical range expressed by using "numerical value A to numerical value B" refers to the range including the endpoint numerical values A and B.

[0039] The manufacturing method of silicon-28 isotope with an abundance of more than 99% by using silane as a medium in the present invention includes: feeding natural abundance silane gas into a gas diffusion cascade including a plurality of gas diffusion separation devices, compressing the silane gas before entering the gas diffusion separation devices in the gas diffusion cascade by using a high-speed magnetic levitation gas compressor, and obtaining silicon-28 isotope with an abundance of more than 99% prepared by using silane as a medium from the light fraction end of the gas diffusion cascade.

[0040] By adopting the above method, the present invention provides a method for preparing high-abundance silicon-28 isotope by using silane as a medium. This method has a large separation coefficient, a large flow rate, and a low cost, and is suitable for industrial application.

[0041] Figure 1Schematic diagram of the principle for preparing highly enriched silicon-28 isotope by a gas diffusion cascade according to an embodiment of the present invention.

[0042] In an embodiment of the present invention, the gas diffusion cascade is composed of a plurality of gas diffusion separation devices connected in series and / or in parallel. A specific example of the series and parallel connection mode is as Figure 3 shown.

[0043] The separation of the working medium by the gas diffusion separation device is a relative separation rather than an absolute separation. Usually, the required abundance of the final product cannot be obtained only through a single separation stage. Therefore, a connection mode of connecting a plurality of separation stages in series as Figure 4 shown is often adopted to form a gas diffusion cascade. Among them, each separation stage can be composed of a plurality of gas diffusion separation devices connected in parallel. Figure 4 The parallel form of a plurality of gas diffusion separation devices inside each separation stage is not shown in . In some preferred embodiments, a plurality of gas diffusion separation devices are connected in parallel to form a separation stage, and then a plurality of separation stages are connected in series, which can realize the gradual increase of the target isotope abundance and finally reach the required product abundance; the parallel connection of a plurality of gas diffusion separation devices can increase the flow rate of a single stage to meet the production output required for industrial production. During the parallel connection process of the above gas diffusion separation devices, each gas diffusion separation device is not interfered by other machines in the same separation stage in terms of hydraulic parameters, so it is convenient to carry out scale-up design in production in principle.

[0044] Each gas diffusion separation device is based on the isotope separation effect of SiH 4 passing through a porous organic membrane for separation. Figure 2 Schematic diagram of the principle of gas passing through a membrane inside a single separator of a single stage according to an embodiment of the present invention.

[0045] In some preferred embodiments, the basic overall separation coefficient of silane obtained by a four-stage total reflux diffusion cascade experiment for the gas diffusion separation device is 1.009 - 1.011.

[0046] In some particularly preferred embodiments, the gas diffusion cascade is composed of gas diffusion separation devices with a basic overall separation coefficient of silane obtained by a four-stage total reflux diffusion cascade experiment being 1.009 - 1.011: a plurality of gas diffusion separation devices are connected in parallel to form a separation stage, and then a plurality of said separation stages are connected in series.

[0047] For the separation stage, the relationship between the pressure before the membrane, the pressure ratio before and after the membrane and the separation coefficient is mastered, and it is found that the separation coefficient increases with the decrease of the pressure before the membrane and increases with the increase of the pressure ratio before and after the membrane. Based on this, through further reasonable design, in some preferred embodiments, in the method of the present invention, the basic overall separation coefficient of silane obtained by a four-stage total reflux diffusion cascade experiment is preferably not less than 1.010.

[0048] In the present invention, the measurement of the basic separation factor of silane in the four-stage total reflux diffusion cascade experiment is carried out by the common mass spectrometry analysis method in the art, and the specific implementation approach is not limited. The definition of the basic separation factor is the separation factor corresponding to the difference in unit molar mass.

[0049] In the present invention, there is no particular limitation on the total number of stages of the gas diffusion cascade, and it can be appropriately adjusted according to actual needs. In some preferred embodiments, the total number of stages of the gas diffusion cascade can be 200 to 600 stages, and more preferably 280 to 300 stages.

[0050] In some preferred embodiments, in the gas diffusion cascade, preferably, the feed stage is located at a position 3 to 100 stages away from the heavy fraction end, more preferably at a position 5 to 50 stages away from the heavy fraction end, and further preferably at a position 5 to 30 stages away from the heavy fraction end.

[0051] In the present invention, there is no particular limitation on the light fraction flow rate of the gas diffusion cascade, and it can be appropriately adjusted according to actual needs. In some preferred embodiments, the light fraction flow rate of the gas diffusion cascade is preferably 0.01 to 0.05 times the feed flow rate of the feed stage, more preferably 0.015 to 0.045 times, and further preferably 0.02 to 0.04 times.

[0052] In the present invention, there is no particular limitation on the total flow rate of the gas diffusion cascade, and it can be appropriately adjusted according to actual needs. In some preferred embodiments, the total flow rate of the gas diffusion cascade is preferably 1800 to 3500 times the feed flow rate of the feed stage, and more preferably 2000 to 3000 times.

[0053] In some preferred embodiments, the silicon-28 isotope abundance of the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade is less than 92.1%, and further, the heavy fraction contains silicon-30 isotope by-products.

[0054] In some preferred embodiments, the purity of the silane gas with natural abundance is higher than 99.9%. The silane gas with natural abundance can be a commercially available product.

[0055] In some preferred embodiments, the high-speed magnetic levitation compressor used is preferably a high-speed magnetic levitation compressor that can be used under negative pressure conditions. For example, the high-speed magnetic levitation compressor used under negative pressure conditions described in CN209510664U (the content of this patent is incorporated herein by reference in its entirety).

[0056] In addition, one or more (e.g., 2 to 4) high-speed magnetic levitation compressors may be present before each gas diffusion separation device.

[0057] In some other preferred embodiments, after compression by the high-speed magnetic levitation compressor, the single-stage pressure ratio of the silane gas before and after passing through the gas diffusion separation device (i.e., before and after passing through the membrane) is at least 4.5, more preferably above 4.8, and even as high as above 5.0, for example, 5.2.

[0058] The following refers to Figure 5 and in combination with specific embodiments, the method for preparing high-abundance silicon-28 isotope using silane as a medium provided by the present invention will be described in detail. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0059] Natural abundance silane with a chemical purity higher than 99.9% is fed into the gas diffusion cascade, and silane with a silicon-28 isotope abundance of more than 99% is obtained at the light fraction end of the gas diffusion cascade. For SiH 4 Based on the isotope separation effect of the porous organic membrane, a high-speed magnetic levitation gas compressor is used to effectively compress the SiH 4 gas, and the gas diffusion method is used for the production and preparation of silicon-28 isotope. The specific embodiments are as follows.

[0060] Figure 3 It is a diagram of a double-pipe diffusion cascade device used in the preparation of high-abundance silicon-28 isotope using silane as a medium according to an embodiment of the present invention.

[0061] The gas diffusion cascade is composed of a series and parallel connection of gas diffusion separation devices with a silane basic separation coefficient of 1.010. The total number of stages is 291, and the feed stage is located 10 stages away from the heavy fraction end.

[0062] The light fraction flow rate of the gas diffusion cascade is 0.0366 times the feed flow rate, the total flow rate of the gas diffusion cascade is 2716 times the feed flow rate, and the silicon-28 isotope abundance in the heavy fraction is 91.96%. The abundance distribution of silicon-28 isotope in each stage of the gas diffusion cascade is as Figure 5 shown.

[0063] As can be seen from the above embodiments, the method for preparing high-abundance silicon-28 isotope using silane as a medium provided by the present invention has the advantages of large flow rate, high efficiency, and low cost, and can be used to prepare silicon-28 isotope with an abundance of more than 99%. At the same time, the gas diffusion separation process is a physical separation process without introducing other impurities, and the prepared high-abundance silicon-28 isotope has high chemical purity. Applying this method to the preparation of high-abundance silicon-28 isotope is suitable for industrial applications.

[0064] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A manufacturing method for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium, characterized in that, it includes: Feeding natural abundance silane gas into a gas diffusion cascade including a plurality of gas diffusion separation devices, using a high-speed magnetic levitation gas compressor to compress the silane gas before it enters the gas diffusion separation device in each of the gas diffusion cascades, and obtaining silicon-28 isotope with an abundance of more than 99% prepared using silane as a medium from the light fraction end of the gas diffusion cascade.

2. The manufacturing method according to claim 1, characterized in that, the gas diffusion cascade is composed of gas diffusion separation devices with a silane basic overall separation coefficient of 1.009 - 1.011 measured by a four-stage total reflux diffusion cascade experiment: a plurality of gas diffusion separation devices are connected in parallel to form a separation stage, and then a plurality of the separation stages are connected in series.

3. The manufacturing method according to claim 2, characterized in that, the silane basic overall separation coefficient measured by a four-stage total reflux diffusion cascade experiment is 1.010 - 1.

011.

4. The manufacturing method according to any one of claims 1 - 3, characterized in that, the total number of stages of the gas diffusion cascade is 200 - 600 stages.

5. The manufacturing method according to claim 4, characterized in that, the total number of stages of the gas diffusion cascade is 280 - 300 stages.

6. The manufacturing method according to any one of claims 1 - 3, characterized in that, the feed stage of the gas diffusion cascade is located at a position 3 - 100 stages away from the heavy fraction end; the light fraction flow rate of the gas diffusion cascade is 0.01 - 0.05 times the feed flow rate of the feed stage; the total flow rate of the gas diffusion cascade is 1800 - 3500 times the feed flow rate of the feed stage.

7. The manufacturing method according to any one of claims 1 - 3, characterized in that, the feed stage of the gas diffusion cascade is located at a position 5 - 50 stages away from the heavy fraction end.

8. The manufacturing method according to any one of claims 1 - 3, characterized in that, the abundance of silicon-28 isotope in the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade is less than 92.1%, and the heavy fraction contains silicon-30 isotope by-products.

9. The manufacturing method according to any one of claims 1 - 3, characterized in that, the purity of the natural abundance silane gas is higher than 99.9%.

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