Device and method for detecting metallization transformation of substance under high pressure based on microwave technology

Abstract

The invention relates to a microwave technology-based detection device and method for metallization transformation of a substance under high voltage, the detection device is composed of a microwave generator, a DAC detection unit and a parameter detection device, and the DAC detection unit is connected with the microwave generator and the parameter detection device through microwave transmission lines to realize signal transmission. The DAC detection unit is mainly composed of a microstrip line set, an upper diamond and a lower diamond, and the position with the optimal experiment effect is found by changing the width of the lower microstrip line in the DAC detection unit to measure an S parameter response simulation curve. The mode of combining the microstrip antenna and the diamond anvil cell is adopted to detect the metallization transformation process of the substance under high pressure, the detection device is simple and reliable in structure, low in power consumption and convenient and easy to use, the detection method is low in experiment cost, and experiment steps are simple and easy to operate; the gasket and the to-be-tested sample are convenient to replace, and the device can be used for researching the high-pressure scientific material metallization or material non-gold transformation process.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-pressure material physical property detection, and specifically relates to a detection device and a detection method for metallization transformation of a material under high pressure based on microwave technology. Background Art

[0002] High-pressure physics is a discipline that studies the physical behavior and property changes of matter under extreme conditions of high pressure or ultra-high pressure. Under high-pressure conditions, the change in the interaction between the atoms of a substance causes the original basic structure of the substance to change, presenting many properties that the substance does not have. Therefore, high-pressure synthesis methods are an important channel for obtaining new materials. Therefore, high-pressure physics also plays an extremely important role in promoting disciplines such as earth science, chemistry, condensed matter physics, materials science, and biological science.

[0003] Metallization transition refers to the phenomenon that the electrical conductivity of certain materials changes from an insulating state to a metallic conductive state when they experience changes in external conditions such as temperature, pressure, electric field or chemical doping, and is often accompanied by a structural phase change. At present, the most common method for detecting the metallization transition of a material under high pressure conditions in a diamond anvil cell (DAC) is the four-probe method, which has important applications in measuring the resistivity and conductivity of materials, especially in the study of semiconductors and metallization transitions. This method works by placing four electrodes on the sample, applying current and measuring voltage to calculate the resistivity of the material. It is widely used in the study of the electrical properties of materials because of its advantages such as high precision, wide applicability and high reliability. However, in the study of high-voltage electrical properties, the four-probe (four-terminal method) measurement technology requires metal electrodes to be plated on the diamond of the anvil cell, which is a complex process and difficult to process; moreover, the electrodes are relatively fragile, which limits the application of higher pressures.

[0004] In the past few decades, microwave technology has developed rapidly. Because of its advantages such as high frequency and wide bandwidth, it has become a research hotspot for technology application. However, at present, microwave technology is less used in the field of high-pressure science. The prior art discloses a detection device for metallization transformation of materials under high pressure based on microwave technology, which combines a microwave resonant cavity with a diamond anvil to detect material transformation under high pressure. The detection principle is to use the principle that when the microwave signal is transmitted into the resonant cavity, resonance will occur when the wavelength of the microwave signal matches the size of the resonant cavity, detect the metallization transformation process of the material, and use this as a basis to determine the high-pressure transformation point of the metal structure phase change of the sample to be detected. However, the process of making the resonant cavity is relatively complicated and the cost is high. Based on this, in order to improve the traditional electromagnetic detection technology under high pressure, it is urgent to develop a new device based on microwave technology to detect the metallization transformation of materials under high pressure, so as to effectively solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a new device based on microwave technology for detecting the metallization transformation of a substance under high pressure and a method based on microwave technology for detecting the metallization transformation of a substance under high pressure, combining a microstrip line with a gold-stone anvil to solve the problem of detecting changes in the electrical properties of a substance under high pressure and assisting in the study of structural phase changes.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A detection device for metallization transformation of materials under high pressure based on microwave technology, comprising a microwave generator 1, a DAC detection unit 3 and a parameter detection device 4; the DAC detection unit 3 is connected to the microwave generator 1 and the parameter detection device 4 through a microwave transmission line 2 to achieve signal transmission;

[0008] The DAC detection unit 3 is mainly composed of a microstrip line group, an upper diamond 15 and a lower diamond 16; the upper diamond 15 and the lower diamond 16 are symmetrically distributed on the upper and lower sides of the microstrip line group; the DAC detection unit 3 also includes an upper support block 12 and a lower support block 13, and the upper support block 12 and the lower support block 13 are respectively located on the upper and lower sides of the upper diamond 15 and the lower diamond 16; the bottom of the lower support block 13 is provided with a conical observation window 11;

[0009] Among them, the microstrip line group consists of an upper microstrip line 7 and a lower microstrip line 9, the upper microstrip line 7 is installed on the upper diamond 15, the middle part of the lower microstrip line 9 is used as a high-voltage DAC gasket, a sample cavity 6 is provided in the center of the gasket, and the top of the upper diamond 15 is in contact with the sample cavity 6; a signal input terminal 10 and a signal output terminal 8 are provided on both sides of the microstrip line group respectively; the microwave generator 1 is connected to the signal input terminal 10 through a microwave transmission line 2, and the microwave signal is transmitted into the microstrip line group through the signal input terminal 10 for transmission; the parameter detection device 4 is connected to the signal output terminal 8 through the microwave transmission line 2, and the microwave signal is transmitted to the parameter detection device 4 by the microwave transmission line 2 for detection.

[0010] Furthermore, the upper microstrip line 7 has holes and can be embedded in the upper diamond 15 .

[0011] Furthermore, the middle circular portion of the lower microstrip line 9 is used as a high-voltage DAC gasket, and a microhole is drilled in the center thereof as a sample cavity 6 for containing the sample to be tested mixed with ruby ​​powder.

[0012] Furthermore, the signal input terminal 10 and the signal output terminal 8 are fixed to the microstrip line group by welding or using conductive silver glue.

[0013] Furthermore, the upper supporting block 12 and the lower supporting block 13 are fastened by two bolts 5 and two studs 14. Four bolt holes are symmetrically opened at the four corners of the upper supporting block 12 and the lower supporting block 13. Two bolts 5 pass through the corresponding bolt holes and are fastened with nuts to achieve support and limitation of the upper supporting block 12 and the lower supporting block 13.

[0014] Furthermore, the microwave generator 1 is a vector analyzer or a controllable microwave voltage-controlled oscillator (VCO); the parameter detection device 4 is a vector analyzer, a frequency meter or a detector.

[0015] Furthermore, the shape of the microstrip line group is two upper and lower strip lines, and a circular ring structure with unequal radius is provided in the middle of each strip line; wherein, the upper microstrip line 7 is a circular ring, and the lower microstrip line 9 is a circular disk with holes, the length of the two strip lines is 6cm to 8cm, the width is 2mm to 7mm, and the thickness is 0.2mm to 1.1mm. The outer diameter of the center circle of the upper microstrip line is 15mm to 25mm, and the inner diameter is 0.2mm to 3.5mm. The outer diameter of the center circle of the lower microstrip line is 10mm to 20mm, and the inner diameter is 0.05mm to 0.7mm. The distance between the two microstrip lines is 1.5mm to 3.5mm, and the two ends of the microstrip line group are connected to the SMA port and solidified by welding or high-conductivity silver glue.

[0016] Furthermore, the length of the two strip lines is 6.32cm, the thickness is 0.25mm, the outer diameter of the center circle of the upper microstrip line is 18mm, the inner diameter is 2.3mm, the length of the strip parts on both sides is 22.6mm, and the width is 3.09mm; the outer diameter of the center circle of the lower microstrip line is 14mm, the inner diameter is 0.46mm, the length of the strip parts on both sides is 24.6mm, the width is 2.8mm, and the distance between the two microstrip lines is 1.6mm.

[0017] Furthermore, the upper support block 12 and the lower support block 13 are both made of metal with a radius of 2.8 cm and a height of 1.4 cm; the anvil radius of the upper diamond 15 and the lower diamond 16 is 50 μm to 700 μm, and the anvil height is 2 mm to 5 mm; the upper microstrip line 7 material and the lower microstrip line 9 material serving as a high-voltage DAC gasket are made of metal materials such as steel, tungsten, copper or rhenium with a thickness of 0.2 mm to 1.1 mm.

[0018] A method for detecting metallization transformation of a material under high pressure based on microwave technology comprises the following steps:

[0019] A. Prepare the sample to be tested and add ruby ​​powder; then put the sample to be tested into the microhole drilled in the center of the lower microstrip line 9, that is, the sample cavity 6, and ensure that it is filled;

[0020] B. Put the upper microstrip line 7 on the upper diamond 15; put the lower microstrip line 9 between the anvil surfaces of the upper diamond 15 and the lower diamond 16, and the sample cavity 6 faces the diamond anvil surface; fasten the upper support block 12 and the lower support block 13 by bolts 5 and studs 14 to fix the gasket part in the lower microstrip line;

[0021] C. Start the microwave generator 1, and input the microwave signal to the port 10 of the microstrip line group in the DAC detection unit 3 through the microwave transmission line 2; the microwave signal is transmitted in the microstrip line group; the microwave signal is output from the signal output port 8 through the microwave transmission line 2 and is transmitted to the parameter detection device 4;

[0022] D. Slowly tighten the two bolts on the upper diamond 15 and match them with the nuts so that the upper diamond 15 and the lower diamond 16 fit tightly together, continuously increase the pressure on the sample, and detect the ruby ​​fluorescence spectrum in the sample chamber 6 through the observation window (11), so as to obtain the size of the sample pressure in the sample chamber 6; at the same time, measure the S parameter with the parameter detection device 4, and record the characteristic peak or valley value and corresponding frequency of the S parameter curve;

[0023] E. Based on the real-time measurement of the S parameter curve under different pressures, the S amplitude and the corresponding frequency value at the maximum extreme value of the real-time S parameter curve are obtained; the difference ΔS or Δf between the S parameter amplitude or frequency f at the extreme value in this state and the initial state is compared and calculated; the change difference ΔS or Δf between the S value and the corresponding frequency at the maximum extreme value of the S parameter curve and the initial state; when the change difference ΔS or Δf reaches or exceeds the preset threshold, it can be determined that the material has undergone a metallization transition.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention adopts a combination of a microstrip antenna and a diamond anvil to realize the detection of the metallization transformation process of a material under high pressure. The detection device has a simple and reliable structure, low power consumption, and is convenient and easy to use. The detection method has a low experimental cost and the experimental steps are simple and easy to operate. In the present invention, the replacement of the gasket and the sample to be tested is also relatively convenient, and it can be used for the research on the metallization transformation process of a material or the non-metallization transformation process of a material in high-pressure science. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 The overall structural diagram of the metallization transformation for microwave technology;

[0028] Figure 2 It is the structural diagram of DAC detection unit;

[0029] Figure 3 is the microstrip line structure diagram, Figure 3 a is the upper microstrip line, Figure 3 b is the lower microstrip line;

[0030] Figure 4 The relationship between the frequency difference Δf of the metallization transition between metal and non-metal and the width w of the microstrip line is shown in the graph;

[0031] Figure 5 The relationship curve diagram is the relationship between the parameter difference ΔS of the metallization transition between metal and non-metal and the width w of the microstrip line;

[0032] Figure 6 It is a curve diagram showing the relationship between the parameter difference ΔS of the metallization transition between metal and non-metal and the difference ΔD between the upper and lower disk diameters;

[0033] Figure 7 The relationship curve between the frequency difference Δf of the metallization transition between metal and non-metal and the difference ΔD between the upper and lower disk diameters;

[0034] Figure 8 It is a simulation diagram of the S12 parameter response curve corresponding to the detection device detecting the metal state and the non-metal state.

[0035] In the figure, 1. microwave generator 2. microwave transmission line 3. DAC detection unit 4. parameter detection device 5. bolt 6. sample cavity 7. upper microstrip line 8. signal output end 9. lower microstrip line 10. signal input end 11. observation window 12. upper support block 13. lower support block 14. stud 15. upper diamond 16. lower diamond 17. sample material. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with embodiments:

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0038] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0039] The present invention adopts a combination of experiment and simulation, and uses HFSS finite element simulation software to simulate and solve the experimental detection results. Through simulation, the influence of the change of the position of the DAC detection unit 3 relative to the diamond anvil and the change of the size of the DAC detection unit 3 on the experimental results can be analyzed; the optimal values ​​of the width of the DAC detection unit 3 and the radius and position of the intermediate plane disk are obtained, and then the spatial positions of each component and the shape and size of the DAC detection unit 3 corresponding to the best experimental effect are found.

[0040] like Figure 1 As shown, the metallization transformation detection device of a material under high pressure based on microwave technology of the present invention is composed of a microwave generator 1, a DAC detection unit 3 and a parameter detection device 4. The DAC detection unit 3 is connected to the microwave generator 1 and the parameter detection device 4 through a microwave transmission line 2 to realize signal transmission.

[0041] like Figure 2 As shown, the DAC detection unit 3 is mainly composed of a microstrip line group, an upper diamond 15 and a lower diamond 16. The upper diamond 15 and the lower diamond 16 are symmetrically distributed on the upper and lower sides of the microstrip line group.

[0042] The microstrip line group is composed of an upper microstrip line 7 and a lower microstrip line 9. The upper microstrip line 7 has a hole and can be embedded in the upper diamond 15. The middle circular part of the lower microstrip line 9 (such as Figure 3 As shown in Fig. 1b, the middle circular part of the lower microstrip line 9 (excluding the strip-shaped parts on both sides) is used as a high-voltage DAC gasket, and a microhole is drilled in the center thereof as a sample cavity 6 for holding the sample to be tested mixed with ruby ​​powder. The top of the upper diamond 15 is in contact with the sample cavity 6. By changing the width of the lower microstrip line 9 in the DAC detection unit 3 and measuring the S parameter response simulation curve, the position with the best experimental effect is found, that is, the microstrip line in the DAC detection unit reaches the optimal size. Specifically, the size of the microstrip line and the size of the sample cavity are changed, including the strip-shaped parts on both sides and the middle circular part. Figure 4 , Figure 5 What is changed is the width of the strip part. Figure 6 , Figure 7 The best experimental result is the position where the curve Figure 8 The best detection effect position is where the lower microstrip line has the most suitable size, where the S parameter frequency and amplitude change most obviously and the sensitivity is the highest. By finding the best position, the detection sensitivity is high when the material undergoes metallization transformation, and the detection accuracy is improved.

[0043] A signal input terminal 10 and a signal output terminal 8 are respectively disposed on both sides of the microstrip line group. The signal input terminal 10 and the signal output terminal 8 are fixed to the microstrip line group by welding or using conductive silver glue.

[0044] The microwave generator 1 is connected to the signal input terminal 10 through the microwave transmission line 2, and transmits the microwave signal to the microstrip line group through the signal input terminal 10 for transmission. When the wavelength of the transmitted microwave matches the parameters such as the size and shape of the microstrip line, the S parameter curve of the microstrip line group will have obvious extreme values ​​(peaks or valleys), and the amplitude of the S parameter at the maximum extreme value and its corresponding frequency value f can be obtained.

[0045] The parameter detection device 4 is connected to the signal output terminal 8 through a microwave transmission line 2, and the microwave transmission line 2 transmits the microwave signal to the parameter detection device 4 for detection. The DAC detection unit 3 also includes an upper support block 12 and a lower support block 13. The upper support block 12 and the lower support block 13 are fastened by two bolts 5 and two studs 14. Specifically, the upper support block 12 and the lower support block 13 are both made of metal, and four bolt holes are symmetrically opened at the four corners of the upper support block 12 and the lower support block 13. Two bolts 5 are passed through the corresponding bolt holes and fastened with nuts to achieve support and limit of the upper support block 12 and the lower support block 13.

[0046] In the present invention, in order to further observe the upper diamond 15 , the lower diamond 16 , the sample material 17 and the fluorescence spectrum detection, a conical observation window 11 is opened at the bottom of the lower support block 13 .

[0047] In the present invention, the microwave generator 1 is a vector analyzer or a controllable microwave voltage controlled oscillator (VCO). The parameter detection device 4 is a vector analyzer, a frequency meter or a detector.

[0048] For example, a vector grid analyzer (VNA) can be used as a microwave generator 1 and a parameter detection device 4 to detect the S parameter response signal curve. A vector network analyzer is a high-precision test instrument that can measure and analyze the amplitude, phase, frequency and other parameters of radio frequency (RF) and microwave signals. In the present invention, a vector grid analyzer can be used as a microwave generator 1 and a parameter detection device 4 to generate a microwave signal and analyze the signal transmitted back from the DAC detection unit 3. The S parameter response curve of the system can be detected, that is, the relationship curve between the horizontal axis frequency sweep and the vertical axis S parameter.

[0049] Specifically, when a vector grid analyzer is used as the microwave generator 1, the microwave transmission line 2 uses a coplanar stripline for transmission; the input and output ends use SMA conversion connectors; and the parameter detection device 4 is also a vector grid analyzer.

[0050] like Figure 3As shown, the shape of the microstrip line group is two upper and lower strip lines, and a circular ring structure with unequal radius is provided in the middle of each strip line. Among them, the upper microstrip line 7 is a circular ring, and the lower microstrip line 9 is a disc with holes (the hole is a sample cavity). The length of the two strip lines is 6cm to 8cm, the width is 2mm to 7mm, and the thickness is 0.2mm to 1.1mm. The outer diameter of the center circle of the upper microstrip line is 15mm to 25mm, and the inner diameter is 0.2mm to 3.5mm. The outer diameter of the center circle of the lower microstrip line is 10mm to 20mm, and the inner diameter (aperture) is 0.05mm to 0.7mm. The distance between the two microstrip lines is 1.5mm to 3.5mm. The two ends of the microstrip line group are connected to the SMA port and solidified by welding or high-conductivity silver glue.

[0051] Preferably, the length is 6.32cm, the thickness is 0.25mm, the outer diameter of the center circle of the upper microstrip line is 18mm, the inner diameter is 2.3mm, the length of the strip parts on both sides is 22.6mm, and the width is 3.09mm; the outer diameter of the center circle of the lower microstrip line is 14mm, the inner diameter is 0.46mm, the length of the strip parts on both sides is 24.6mm, the width is 2.8mm, and the distance between the two microstrip lines is 1.6mm. The above is the optimal position mentioned above, that is, the component size at which the system monitoring achieves the best effect. The curve reflected by this size can better observe whether a metallization phase change has occurred. The S parameter frequency and amplitude changes are most obvious here, and the sensitivity is the greatest.

[0052] Specifically, in the material selection of the DAC detection unit 3 of the present invention, the upper support block 12 and the lower support block 13 are made of metal with a radius of 2.8 cm and a height of 1.4 cm. The anvil radius of the upper diamond 15 and the lower diamond 16 is 50 μm to 700 μm, and the anvil height is 2 mm to 5 mm. The material of the upper microstrip line 7 and the material of the lower microstrip line 9 as the high-voltage DAC gasket are made of metal materials such as steel, tungsten, copper or rhenium with a thickness of 0.2 mm to 1.1 mm.

[0053] Because the wavelength of ruby's fluorescence line will change with the change of pressure, it is necessary to add ruby ​​powder to the sample to achieve the purpose of real-time measurement of the pressure generated by the diamond anvil. Specific operation steps: Put the ruby ​​powder and the test sample into the sample cavity 6 together, and use the characteristic peak of the fluorescence spectrum of the ruby ​​powder to calibrate the measurement pressure. Pre-press before the experiment to make the sample tight and fill the sample cavity 6. In the present invention, a microhole is drilled in the center of the lower microstrip line 9, which is similar to a groove structure. The microhole serves as the sample cavity 6 for holding the sample to be tested. Installation of the detection device:

[0054] 1. Place the lower microstrip line 9, which serves as a high-voltage DAC gasket, in the gap between the upper diamond 15 and the lower diamond 16 so that the gasket is tightly fixed on the two anvils.

[0055] 2. Select an appropriate amount of the sample material 17 to be tested and place it in the sample cavity 6 located between the upper diamond 15 and the lower diamond 16 gaskets, and then compact the sample material 17. Try to fill the sample cavity 6 with the sample material 17 to be tested.

[0056] 3. Slowly tighten the two bolts 5 on the upper diamond 15 and fit the nuts, so that the upper diamond 15 and the lower diamond 16 fit tightly together and the lower microstrip antenna 9 is located between the upper diamond 15 and the lower diamond 16.

[0057] The present invention uses a combination of microstrip line and diamond anvil to detect the metallization transformation process of a material under high pressure, and has the advantages of simple sample structure, low power consumption, convenience and ease of use, etc. In addition, the replacement of the gasket and the sample to be tested is also relatively convenient, and can be used for the study of the metallization or non-metallization transformation process of a material under high pressure science.

[0058] Metallization transition detection principle:

[0059] Before the metallization transformation occurs, the lower microstrip line 9 is a metal radiation patch with microholes. After the material undergoes metallization transformation under high pressure, the lower microstrip line 9 is equivalent to a whole metal radiation patch. The radiation parameters can be measured by a vector analyzer to obtain S parameters; the S parameters can be used to determine whether a change has occurred to determine whether the material has undergone metallization transformation. Similarly, the transformation of a material from a metallic state to a non-metallic state under high pressure can also be detected.

[0060] The device of the present invention has two parameters that can be used as a basis for detection:

[0061] 1. S parameter amplitude. The S parameter value will change during the process of the sample transforming from metal to non-metal, so the change in the S parameter value at the maximum extreme value of the S parameter curve can be used to determine whether the metallization transformation has occurred. The parameter amplitude difference ΔS is the transmission coefficient value S before the metal transformation occurs. 21 'Subtract the transmission coefficient S after the metal transition 21 ". The formula is ΔS=S 21 '-S 21 ".

[0062] 2. Extreme frequency. When the sample is transformed from metal to non-metal, the frequency f at the maximum extreme value will also change. The parameter difference Δf is the frequency value before the metal transformation and f 21 'Frequency value f after metal transformation occurs 21 "The formula is Δf=f 21 '-f 21 ".

[0063] contrast Figure 4 , Figure 5, Figure 6 , Figure 7 It can be found that in the present invention, when the microstrip line has a suitable size (the microstrip line width w is 2.8 mm and the difference ΔD between the upper and lower disk diameters is 4 mm), the change in the parameter amplitude difference ΔS and the frequency difference Δf are both significantly changed, so the appropriate S parameter difference ΔS and the frequency difference Δf can be used as the detection threshold S t and f t , to determine whether metallization transition occurs. The S parameter or frequency threshold can actually be an experimental experience value. Under high voltage conditions, if the S parameter or frequency change exceeds the threshold, it can be determined that metallization transition occurs.

[0064] The present invention provides a method for detecting the metallization transformation of a substance under high pressure based on microwave technology, comprising the following steps:

[0065] 1. Prepare the sample to be tested and add ruby ​​powder; then put the sample to be tested into the microhole drilled in the center of the lower microstrip line 9, that is, the sample cavity 6, and ensure that it is filled.

[0066] 2. Put the upper microstrip line 7 on the upper diamond 15; put the lower microstrip line 9 between the upper diamond 15 and the anvil surface of the lower diamond 16, and the sample cavity 6 faces the diamond anvil surface. Fasten the upper support block 12 and the lower support block 13 with the bolts 5 and the studs 14 to fix the gasket part in the lower microstrip line.

[0067] 3. Start the microwave generator 1, and input the microwave signal to the port 10 of the microstrip line group in the DAC detection unit 3 through the microwave transmission line 2; the microwave signal is transmitted in the microstrip line group. The microwave signal is output from the signal output port 8 through the microwave transmission line 2 and is transmitted to the parameter detection device 4.

[0068] 4. Slowly turn the two bolts on the upper diamond 15 and match the nuts to make the upper diamond 15 fit tightly with the lower diamond 16, continuously increase the pressure on the sample, and detect the ruby ​​fluorescence spectrum in the sample chamber 6 through the observation window 11, so as to obtain the size of the sample pressure in the sample chamber 6. At the same time, use the parameter detection device 4 to measure the S parameter, and record the characteristic peak or valley value (extreme value) and the corresponding frequency of the S parameter curve.

[0069] 5. According to the real-time measurement of the S parameter curve under different pressures, the S amplitude and corresponding frequency value at the maximum extreme value of the real-time S parameter curve are obtained. Compare and calculate the difference ΔS or Δf of the S parameter amplitude or frequency f at the extreme value in this state and the initial state (no pressure is applied, the pressure is 0). The change difference ΔS or Δf between the S value and the corresponding frequency at the maximum extreme value of the S parameter curve and the initial state. When the change difference ΔS or Δf reaches or exceeds the preset threshold, it can be judged that the material has undergone a metallization transition.

[0070] Example 1

[0071] A device for detecting metallization transformation of materials under high pressure based on microwave technology is composed of a microwave generator 1, a microwave transmission line 2, a DAC detection unit 3 and a parameter detection device 4. The DAC detection unit 3 adopts a four-column DAC press parameter detection mechanism.

[0072] In the four-column DAC press parameter detection mechanism, the upper support block 12 and the lower support block 13 are respectively made of steel material with a thickness of 1.4 cm and a radius of 2.8 cm. The upper diamond 15 and the lower diamond 16 with anvil radius of 100 μm are selected. The lower microstrip line 9 is made of a metal material with certain toughness and ductility, and tungsten is selected in this embodiment.

[0073] By using HFSS software to simulate and solve on the PC side, the optimal dimensions of the microstrip line are: total length is 6.32cm, thickness is 0.25mm, the outer diameter of the center circle of the upper microstrip line is 18mm, the inner diameter is 2.3mm, the length of the strip parts on both sides is 22.6mm, and the width is 3.09mm; the outer diameter of the center circle of the lower microstrip line is 14mm, the inner diameter is 0.46mm, the length of the strip parts on both sides is 24.6mm, and the width is 2.8mm. When the distance between the two microstrip lines is 1.6mm, the change at the extreme value of the S parameter curve when the metallization transition occurs is the most obvious, such as Figure 8 During the simulation, the initial state is set to be non-metallic, and the substance in the sample cavity is non-metallic material; after the metallization transformation occurs, the substance in the sample cavity is set to be metallic material.

[0074] Depend on Figure 8 It can be seen that the maximum extreme value of the S parameter curve during metallization transition is in the range of 26.872GHz to 27.214GHz, and the S parameter and frequency changes are ΔS = 5.546dB and Δf = 0.342GHz. These two values ​​can be used as references for the detection threshold; the detection threshold S t and f t It can be set to 5.4dB and 0.32GHz (the actual value may be slightly smaller than the simulation value), that is, when the amplitude of S decreases by about ΔS≥5.4dB, or the frequency f decreases by about Δf≥0.32GHz, the material undergoes a metallization transition.

[0075] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A device for detecting metallization transformation of materials under high pressure based on microwave technology, characterized in that: The device is composed of a microwave generator (1), a DAC detection unit (3) and a parameter detection device (4); the DAC detection unit (3) is connected to the microwave generator (1) and the parameter detection device (4) respectively through a microwave transmission line (2) to achieve signal transmission; The DAC detection unit (3) is mainly composed of a microstrip line group, an upper diamond (15) and a lower diamond (16); the upper diamond (15) and the lower diamond (16) are symmetrically distributed on the upper and lower sides of the microstrip line group; the DAC detection unit (3) also includes an upper support block (12) and a lower support block (13), the upper support block (12) and the lower support block (13) are respectively located on the upper and lower sides of the upper diamond (15) and the lower diamond (16); the bottom of the lower support block (13) is provided with a conical observation window (11); The microstrip line group is composed of an upper microstrip line (7) and a lower microstrip line (9), the upper microstrip line (7) is installed on an upper diamond (15), the middle of the lower microstrip line (9) serves as a high-voltage DAC gasket, a sample cavity (6) is provided at the center of the gasket, and the top of the upper diamond (15) is in contact with the sample cavity (6); a signal input end (10) and a signal output end (8) are provided on both sides of the microstrip line group; the microwave generator (1) is connected to the signal input end (10) through a microwave transmission line (2), and transmits a microwave signal through the signal input end (10) into the microstrip line group for transmission; the parameter detection device (4) is connected to the signal output end (8) through a microwave transmission line (2), and the microwave transmission line (2) transmits the microwave signal into the parameter detection device (4) for detection.

2. According to claim 1, a device for detecting metallization transformation of materials under high pressure based on microwave technology, characterized in that: The upper microstrip line (7) has holes and can be embedded in the upper diamond (15).

3. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 1, characterized in that: The middle circular part of the lower microstrip line (9) serves as a high-voltage DAC gasket, and a microhole is drilled in the center thereof as a sample cavity (6) for containing a sample to be tested mixed with ruby ​​powder.

4. The device for detecting metallization transition of a substance under high pressure based on microwave technology according to claim 1, characterized in that: The signal input end (10) and the signal output end (8) are fixed to the microstrip line group by welding or using conductive silver glue.

5. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 1, characterized in that: The upper supporting block (12) and the lower supporting block (13) are fastened by two bolts (5) and two studs (14). Four bolt holes are symmetrically opened at the four corners of the upper supporting block (12) and the lower supporting block (13). The two bolts (5) pass through the corresponding bolt holes and are fastened with nuts to achieve support and position limiting of the upper supporting block (12) and the lower supporting block (13).

6. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 1, characterized in that: The microwave generator (1) is a vector analyzer or a controllable microwave voltage-controlled oscillator (VCO); the parameter detection device (4) is a vector analyzer, a frequency meter or a detector.

7. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 1, characterized in that: The microstrip line group is in the shape of two upper and lower strip lines, and a circular ring structure with unequal radius is respectively arranged in the middle of the strip lines; wherein the upper microstrip line (7) is a circular ring, and the lower microstrip line (9) is a circular disk with holes, the lengths of the two strip lines are both 6cm to 8cm, the widths are both 2mm to 7mm, and the thicknesses are both 0.2mm to 1.1mm, the outer diameter of the center circle of the upper microstrip line (7) is 15mm to 25mm, and the inner diameter is 0.2mm to 3.5mm, and the outer diameter of the center circle of the lower microstrip line is 10mm to 20mm, and the inner diameter is 0.05mm to 0.7mm. The distance between the two microstrip lines is 1.5mm to 3.5mm, and the two ends of the microstrip line group are connected to the SMA port and solidified by welding or high-conductivity silver glue.

8. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 7, characterized in that: The length of the two strip lines is 6.32 cm and the thickness is 0.25 mm. The outer diameter of the center circle of the upper microstrip line (7) is 18 mm, the inner diameter is 2.3 mm, the length of the strip parts on both sides is 22.6 mm, and the width is 3.09 mm. The outer diameter of the center circle of the lower microstrip line is 14 mm, the inner diameter is 0.46 mm, the length of the strip parts on both sides is 24.6 mm, the width is 2.8 mm, and the distance between the two microstrip lines is 1.6 mm.

9. The device for detecting metallization transformation of materials under high pressure based on microwave technology according to claim 1, characterized in that: The upper support block (12) and the lower support block (13) are both made of metal with a radius of 2.8 cm and a height of 1.4 cm; the anvil surface radius of the upper diamond (15) and the lower diamond (16) is 50 μm to 700 μm, and the anvil height is 2 mm to 5 mm; the upper microstrip line (7) material and the lower microstrip line (9) material used as a high-voltage DAC gasket are made of steel, tungsten, copper or rhenium metal material with a thickness of 0.2 mm to 1.1 mm.

10. A method for detecting metallization transformation of a substance under high pressure based on microwave technology, characterized in that: The following steps are involved: A. Prepare the sample to be tested and add ruby ​​powder; then put the sample to be tested into the microhole drilled in the center of the lower microstrip line (9), i.e., the sample cavity (6), and ensure that it is filled; B. The upper microstrip line (7) is placed on the upper diamond (15); the lower microstrip line (9) is placed between the anvil surfaces of the upper diamond (15) and the lower diamond (16), and the sample cavity (6) is directly opposite to the diamond anvil surface; the upper support block (12) and the lower support block (13) are fastened by bolts (5) and studs (14) to fix the gasket part in the lower microstrip line; C. Start the microwave generator (1), input the microwave signal to the port (10) of the microstrip line group in the DAC detection unit (3) through the microwave transmission line (2); the microwave signal is transmitted in the microstrip line group; the microwave signal is output from the signal output port (8) through the microwave transmission line (2) and input to the parameter detection device (4); D. Slowly tighten the two bolts on the upper diamond (15) and fit the nuts together so that the upper diamond (15) and the lower diamond (16) fit tightly together, continuously increase the pressure on the sample, and detect the ruby ​​fluorescence spectrum in the sample cavity (6) through the observation window (11), thereby obtaining the size of the sample pressure in the sample cavity (6); at the same time, measure the S parameter with the parameter detection device (4), and record the characteristic peak or valley value and the corresponding frequency of the S parameter curve; E. Based on the real-time measurement of the S parameter curve under different pressures, the S amplitude and the corresponding frequency value at the maximum extreme value of the real-time S parameter curve are obtained; the difference ΔS or Δf between the S parameter amplitude or frequency f at the extreme value in this state and the initial state is compared and calculated; the change difference ΔS or Δf between the S value and the corresponding frequency at the maximum extreme value of the S parameter curve and the initial state; when the change difference ΔS or Δf reaches or exceeds the preset threshold, it can be determined that the material has undergone a metallization transition.

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