CN221752882U - Gas diffusion cascade for the preparation of silicon-28 isotope abundance above 99% using silane as medium - Google Patents

Abstract

The utility model relates to a gas diffusion cascade for preparing silicon-28 isotopes with abundance of more than 99% by taking silane as a medium. The gas diffusion cascade comprises: a plurality of gas diffusion and separation devices, and a high-speed magnetic levitation gas compressor located before each of the gas diffusion and separation devices in a flow direction of silane gas; and obtaining silicon-28 isotopes with the abundance of more than 99% by taking silane as a medium from the light fraction end of the gas diffusion cascade.

Description

Gas diffusion cascade for the preparation of silicon-28 isotope abundance above 99% using silane as medium

Technical Field

The utility model relates to a gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% by taking silane as a medium, and belongs to the technical field of isotope separation.

Background Art

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 in nature, namely silicon-28 ( ²⁸ Si), silicon-29 ( ²⁹ Si) and silicon-30 ( ³⁰ Si), with natural abundances of 92.22%, 4.69% and 3.09% respectively. Silicon-28 isotopes are mainly used in semiconductors, quantum computing, and metrology. The use of 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 it has the advantages of 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 isotopes is 0. 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 isotopically pure silicon-28 material to prepare single crystal spheres can measure more accurate values of Avogadro's constant.

In practical applications, the abundance of silicon-28 isotope materials is very high, usually requiring the abundance of silicon-28 isotope to be higher than 99%, and sometimes even requiring it to reach more than 99.7%. The natural abundance of silicon-28 isotope is 92.22%. At present, the research on separation of silicon isotopes using cryogenic distillation (SiH ₄ , SiCl ₄ or SiH ₃ CH ₃ system), gas centrifugation (medium is SiF ₄ or SiHCl ₃ ), chemical exchange (separation system of SiF ₄ and different complexing agents), and laser method (Si ₂ F ₆ ) at home and abroad has achieved certain results, but the research on industrial production of silicon isotopes has not yet achieved a breakthrough. The separation coefficient of silicon isotope cryogenic distillation method is small, the efficiency of gas centrifugation method in separating light gas is low, and the output of laser separation method is very low and the cost is high, and the economic efficiency of industrial production is not good.

Early metal porous membranes were widely used in the diffusion separation of uranium isotopes, but they were relatively expensive. Organic polymer membranes have excellent performance and extremely low cost, and have been widely used in industrial manufacturing. However, there is still a lack of research on their application in the manufacture of high-abundance silicon-28 isotopes.

In addition, since the design and operation of gas diffusion cascades are very different for different gas media and/or different target isotopes, it cannot be taken for granted that a gas diffusion cascade for a certain gas medium and/or a certain target isotope can be applied to another gas medium and/or another target isotope.

Utility Model Content

Problems to be solved by utility models

The utility model aims to provide a gas diffusion cascade for preparing high-abundance silicon-28 isotope using silane as a medium. The gas diffusion cascade has a large separation coefficient, a large flow rate, and a low cost, and is suitable for industrial application. Furthermore, a silicon-30 isotope by-product can be obtained synchronously.

Solutions for solving problems

Through careful research, it is found that the above technical problems can be solved by implementing the following technical solutions:

[1] A gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium, characterized in that it comprises:

a plurality of gas diffusion separation devices, and

a high-speed magnetically suspended gas compressor located before each of the gas diffusion separation devices in the flow direction of the silane gas;

From the light fraction end of the gas diffusion cascade, silicon-28 isotope with an abundance of more than 99% is obtained, which is prepared using natural abundance silane as a medium.

[2] A gas diffusion cascade according to [1], wherein the gas diffusion cascade is composed of a gas diffusion separation device having a silane basic total separation coefficient of 1.009 to 1.011 obtained by experimental measurement of a four-stage full reflux diffusion cascade: a plurality of gas diffusion separation devices are connected in parallel to form a separation stage, and a plurality of the separation stages are then connected in series.

[3] A gas diffusion cascade according to [2], wherein the silane-based total separation coefficient measured by a four-stage full reflux diffusion cascade experiment is not less than 1.010.

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

[5] A gas diffusion cascade according to any one of [1] to [3], wherein the feed stage of the gas diffusion cascade is located 3 to 100 stages away from the heavy fraction end, preferably 5 to 50 stages away, the light fraction flow rate 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.

[6] A gas diffusion cascade according to any one of [1] to [3], wherein the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade has a silicon-28 isotope abundance of less than 92.1%, and the heavy fraction contains a silicon-30 isotope byproduct.

[7] A gas diffusion cascade according to any one of [1] to [3], wherein the purity of the naturally abundant silane gas is higher than 99.9%.

Effect of utility model

In the utility model, the silicon-28 isotope can be separated by using the gas diffusion method in the gas diffusion cascade with silane as the medium, and the separation coefficient is large, the flow rate is large, and the cost is low, which is suitable for industrial application. Furthermore, the silicon-30 isotope byproduct can be obtained at the heavy fraction end.

Specifically, silane (SiH ₄ ) as a separation medium has a smaller relative molecular mass and a relatively large gas diffusion separation coefficient compared to other potential substances that can be used as Si isotope separation media. The gas diffusion separation process is a physical separation process and does not introduce other impurities. Moreover, a high-speed magnetic levitation compressor can effectively compress light gases. Therefore, the gas diffusion cascade of the utility model has the advantages of large flow, high efficiency, and high purity of the prepared high-abundance silicon-28 isotope, because it uses a high-speed magnetic levitation compressor to effectively compress light gases and adopts silane with a relatively large separation coefficient as the separation medium.

On the basis of the above, the utility model can adjust the target isotope abundance (even achieving 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 utility model, even when the cascade length does not exceed 600 stages, the silicon-28 isotope abundance can be concentrated to more than 99%, which has good economic efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing the principle of gas passing through a membrane in a single-stage single separator according to an embodiment of the present utility model.

FIG. 2 is a schematic diagram showing the principle of preparing high-abundance silicon-28 isotope by gas diffusion cascade according to an embodiment of the present invention.

FIG. 3 is a diagram of a double-pipeline 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.

FIG. 4 is a schematic diagram showing a series connection of the separation stages according to an embodiment of the present invention.

FIG. 5 is a diagram showing the isotope abundance distribution of silicon-28 at each stage of the gas diffusion cascade according to an embodiment of the present invention.

DETAILED DESCRIPTION

Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used herein means "used as an example, embodiment or illustrative". Any embodiment described herein as "exemplary" is not necessarily to be interpreted as being superior or better than other embodiments.

In addition, in order to better illustrate the utility model, many specific details are given in the specific embodiments below. It should be understood by those skilled in the art that the utility model can also be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the main purpose of the utility model.

Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the utility model should be understood to include the inevitable systematic errors in industrial production or approximate corresponding values within the design constraints. This article may provide demonstrations of parameters containing specific values, but these parameters do not need to be exactly equal to the corresponding values.

In this specification, directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only used to refer to the directions of the drawings and are not intended to limit the scope of protection of the present utility model.

In this specification, the word "may" includes both performing a certain process and not performing a certain process.

In this specification, the references to "some specific/preferred embodiments", "other specific/preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and/or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

The utility model discloses a gas diffusion cascade for preparing silicon-28 isotopes with an abundance of more than 99% by using silane as a medium, comprising: a plurality of gas diffusion separation devices, and a high-speed magnetic suspension gas compressor located before each of the gas diffusion separation devices in the flow direction of the silane gas; silicon-28 isotopes with an abundance of more than 99% prepared by using silane with natural abundance as a medium are obtained from the light fraction end of the gas diffusion cascade.

By adopting the gas diffusion cascade, the utility model provides a gas diffusion cascade for preparing high-abundance silicon-28 isotope using silane as a medium. The gas diffusion cascade has a large separation coefficient, a large flow rate, and a low cost, and is suitable for industrial application.

FIG1 is a schematic diagram showing the principle of preparing high-abundance silicon-28 isotope by gas diffusion cascade according to an embodiment of the present invention.

In the embodiment of the present utility model, the gas diffusion cascade is composed of a plurality of gas diffusion separation devices connected in series and/or in parallel. An example of a specific series and parallel configuration is shown in FIG3 .

The separation of the working medium by the gas diffusion separation device is a relative separation, not an absolute separation. It is usually impossible to obtain the required abundance of the final product through only a single separation stage. Therefore, a plurality of separation stages are often connected in series as shown in FIG4 to form a gas diffusion cascade, wherein each separation stage can be composed of a plurality of gas diffusion separation devices in parallel. FIG4 does not show the parallel connection of the plurality of gas diffusion separation devices in each separation stage. In some preferred embodiments, a plurality of gas diffusion separation devices are connected in parallel to form a separation stage, and then the plurality of separation stages are connected in series, so that the target isotope abundance can be gradually increased, and the required product abundance can be finally achieved; the parallel connection of a plurality of gas diffusion separation devices can increase the flow rate of a single stage to achieve the output required for industrial production. In the process of connecting the above-mentioned gas diffusion separation devices in parallel, each gas diffusion separation device is not interfered with by other machines in the same separation stage in terms of hydraulic parameters, so that it is convenient to carry out a scaled-up design in production in principle.

Each gas diffusion separation device performs separation based on the isotope separation effect of SiH ₄ passing through a porous organic membrane. FIG2 is a schematic diagram of the principle of gas passing through a membrane in a single-stage single separator according to an embodiment of the utility model.

In some preferred embodiments, the silane-based total separation coefficient of the gas diffusion separation device measured through a four-stage total reflux diffusion cascade experiment is 1.009 to 1.011.

In some particularly preferred embodiments, the gas diffusion cascade is composed of a gas diffusion separation device with a silane basic total separation coefficient of 1.009 to 1.011 obtained by measuring a four-stage full reflux diffusion cascade experiment: multiple gas diffusion separation devices are connected in parallel to form a separation stage, and then multiple of the separation stages are connected in series.

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 gas diffusion cascade of the utility model, the silane-based total separation coefficient obtained by the four-stage full reflux diffusion cascade experiment is preferably not less than 1.010.

In the present invention, the four-stage total reflux diffusion cascade experiment is performed to measure the basic total separation coefficient of silane by a mass spectrometry method commonly used in the art, and the specific implementation method is not limited. The basic total separation coefficient is defined as the separation coefficient corresponding to the difference in unit molar mass.

In the present invention, there is no particular restriction on the total number of gas diffusion cascades, which can be appropriately adjusted according to actual needs. In some preferred embodiments, the total number of gas diffusion cascades can be 200 to 600, and the total number of gas diffusion cascades is more preferably 280 to 300.

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, the feed stage is located at a position 5 to 50 stages away from the heavy fraction end, further preferably, the feed stage is located at a position 5 to 30 stages away from the heavy fraction end.

In the present invention, there is no particular restriction on the light fraction flow rate of the gas diffusion cascade, which 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.

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

In some preferred embodiments, the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade has a silicon-28 isotope abundance of less than 92.1%, and further, the heavy fraction contains a silicon-30 isotope byproduct.

In some preferred embodiments, the purity of natural abundance silane gas is greater than 99.9%.Natural abundance silane gas can be commercially available.

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 for use under negative pressure conditions described in CN209510664U (the contents of this patent are incorporated herein by reference in their entirety).

In addition, there may be one or more (eg, 2 to 4) high-speed magnetic levitation compressors before each gas diffusion separation device.

In 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, or even as high as above 5.0, for example, 5.2.

The following is a detailed description of the gas diffusion cascade for preparing high-abundance silicon-28 isotopes using silane as a medium provided by the utility model with reference to FIG. 5 and in combination with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the utility model and should not be regarded as limiting the scope of the utility model. If no specific conditions are specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

Silane with a chemical purity higher than 99.9% of natural abundance is fed into a 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. Based on the isotope separation effect of SiH ₄ passing through a porous organic membrane, a high-speed magnetically suspended gas compressor is used to achieve effective compression of SiH ₄ gas, and the production and preparation of silicon-28 isotope is carried out by gas diffusion method. Specific embodiments are as follows.

FIG. 3 is a diagram of a double-pipeline 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.

The gas diffusion cascade is composed of gas diffusion separation devices with a silane-based total separation coefficient of 1.010 connected in series and in parallel, with a total number of 291 stages, wherein the feed stage is located 10 stages away from the heavy fraction end.

The light fraction flow rate of the gas diffusion cascade is 0.0366 times the feed flow rate, the total gas diffusion cascade flow rate 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 isotopes at each stage in the gas diffusion cascade is shown in Figure 5.

It can be seen from the above embodiments that the gas diffusion cascade provided by the utility model for preparing high-abundance silicon-28 isotopes using silane as a medium has the advantages of large flow, high efficiency and low cost, and can be used to prepare silicon-28 isotopes with an abundance of more than 99%. At the same time, the gas diffusion separation process is a physical separation process, and no other impurities are introduced, and the prepared high-abundance silicon-28 isotope has a high chemical purity. The gas diffusion cascade is used for the preparation of high-abundance silicon-28 isotopes, which is suitable for industrial applications.

The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (9)

1. A gas diffusion cascade for preparing silicon-28 isotope with an abundance of more than 99% using silane as a medium, characterized in that it comprises: a plurality of gas diffusion separation devices, and a high-speed magnetically suspended gas compressor located before each of the gas diffusion separation devices in the flow direction of the silane gas; From the light fraction end of the gas diffusion cascade, silicon-28 isotope with an abundance of more than 99% is obtained, which is prepared using natural abundance silane as a medium. 2. The gas diffusion cascade according to claim 1 is characterized in that the gas diffusion cascade is composed of a gas diffusion separation device with a silane basic total separation coefficient of 1.009 to 1.011 obtained by measuring a four-stage full 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 gas diffusion cascade according to claim 2 is characterized in that the silane basic total separation coefficient obtained by measuring the four-stage full reflux diffusion cascade experiment is not less than 1.010. 4 . The gas diffusion cascade according to claim 1 , wherein the total number of stages of the gas diffusion cascade is 200 to 600. 5 . The gas diffusion cascade according to claim 4 , wherein the total number of stages of the gas diffusion cascade is 280 to 300. 6. The gas diffusion cascade according to any one of claims 1 to 3, characterized in that the feed stage of the gas diffusion cascade is located 3 to 100 stages away from the heavy fraction end, the light fraction flow rate 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. 7. The gas diffusion cascade according to claim 6, characterized in that the feed stage of the gas diffusion cascade is located 5 to 50 stages away from the heavy fraction end. 8. The gas diffusion cascade according to any one of claims 1 to 3, characterized in that the heavy fraction obtained from the heavy fraction end of the gas diffusion cascade has a silicon-28 isotope abundance of less than 92.1%, and the heavy fraction contains a silicon-30 isotope byproduct. 9. A gas diffusion cascade according to any one of claims 1 to 3, characterised in that the purity of the natural abundance silane gas is higher than 99.9%.