Device and method for detecting the metalization transition of a substance under high pressure based on microwave technology

Abstract

The application relates to a detection device and method for the metallization transition of a substance under high pressure based on microwave technology. The detection device is composed of a microwave generator, a DAC detection unit and a parameter detection device. 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 group, an upper diamond and a lower diamond. The width of the lower microstrip line in the DAC detection unit is changed to measure an S parameter response simulation curve, and the position with the best experimental effect is found. The application realizes the detection of the metallization transition process of a substance under high pressure by adopting the mode of combining a microstrip antenna with a diamond anvil. The detection device has the advantages of simple and reliable structure, low power consumption, convenience and easy use, low experimental cost, simple and easy-to-operate experimental steps, convenient replacement of gaskets and samples to be detected, and the like. The application can be used for the research on the metallization or non-metallization transition process of a substance under high pressure.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure material physical property detection technology, specifically relating to a detection device and method for detecting the metallization transformation of materials under high pressure based on microwave technology. Background Technology

[0002] High-pressure physics is a discipline that studies the physical behavior and property changes of matter under extreme conditions of high or ultra-high pressure. Under high pressure, changes in the interaction forces between atoms alter the original basic structure of matter, resulting in many properties that the material does not possess. Therefore, high-pressure synthesis is an important channel for obtaining new materials. High-pressure physics has thus played a crucial role in advancing disciplines such as earth sciences, chemistry, condensed matter physics, materials science, and biological sciences.

[0003] Metallization transition refers to the phenomenon where the electrical conductivity of certain materials abruptly changes from an insulating state to a metallic conductive state when subjected to changes in external conditions such as temperature, pressure, electric field, or chemical doping, often accompanied by a structural phase transition. Currently, the most common method for detecting metallization transitions under high-voltage conditions in a diamond anvil cell (DAC) is the four-probe method. The four-probe method is crucial for measuring the resistivity and conductivity of materials, particularly in semiconductor and metallization transition research. This method works by placing four electrodes on the sample and applying current and measuring voltage to calculate the material's resistivity. Due to its high accuracy, wide applicability, and high reliability, it is widely used in the study of material electrical properties. However, in high-voltage electrical property research, the four-probe (four-terminal method) measurement technique requires etching metal electrodes onto the diamond anvil cell, which is a complex and difficult process; moreover, the electrodes are relatively fragile, limiting the application of higher pressures.

[0004] Over the past few decades, microwave technology has developed rapidly. Due to its advantages such as high frequency and wide bandwidth, it has become a research hotspot for technological applications. However, its application in the field of high-pressure science is currently limited. Existing technology discloses a microwave-based device for detecting the metallization transition of matter under high pressure, combining a microwave resonant cavity with a diamond anvil cell for detecting this transition. The detection principle utilizes the principle that when a microwave signal is transmitted into the resonant cavity, resonance occurs when the wavelength of the microwave signal matches the size of the resonant cavity, thus detecting the metallization transition process and determining the high-pressure transition point of the metal structure phase transition in the sample under test. However, the fabrication of the resonant cavity is complex and costly. Therefore, to improve traditional electromagnetic detection techniques under high pressure, there is an urgent need to develop a novel microwave-based device for detecting the metallization transition of matter under high pressure, effectively addressing the aforementioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a novel microwave-based device and method for detecting the metallization transition of substances under high pressure, combining microstrip lines with anvil cells to solve the problem of detecting changes in the electrical properties of substances under high pressure and assisting in the study of structural phase transitions.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A high-pressure metallization transformation detection device based on microwave technology comprises 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 realize signal transmission;

[0008] The DAC detection unit 3 mainly consists of a microstrip line assembly, 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 assembly; the DAC detection unit 3 also includes an upper support block 12 and a lower support block 13, which are located on the upper and lower sides of the upper diamond 15 and the lower diamond 16, respectively; the lower support block 13 has a conical observation window 11 at its bottom;

[0009] The microstrip line assembly consists of an upper microstrip line 7 and a lower microstrip line 9. The upper microstrip line 7 is mounted on an upper diamond 15, and the middle of the lower microstrip line 9 serves as a high-voltage DAC pad. A sample cavity 6 is located at the center of the pad, and the top of the upper diamond 15 contacts the sample cavity 6. Signal input terminals 10 and signal output terminals 8 are respectively located on both sides of the microstrip line assembly. The microwave generator 1 is connected to the signal input terminal 10 through a microwave transmission line 2, transmitting microwave signals to the microstrip line assembly for transmission. The parameter detection device 4 is connected to the signal output terminal 8 through the microwave transmission line 2, transmitting microwave signals to the parameter detection device 4 for detection.

[0010] Furthermore, the upper microstrip line 7 has holes that can be nested on the upper diamond 15.

[0011] Furthermore, the circular portion in the middle of the lower microstrip line 9 serves as a high-voltage DAC pad, with a microhole drilled in its center to serve as a sample cavity 6 for holding the sample to be tested, which is doped with ruby ​​powder.

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

[0013] Furthermore, the upper support block 12 and the lower support 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 support block 12 and the lower support block 13. Two bolts 5 are fastened to the nuts through the corresponding bolt holes to achieve support and limit of the upper support block 12 and the lower support 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 microstrip line assembly is composed of two strips, an upper one and a lower one, with a ring-shaped structure of unequal radius in the middle of each strip. The upper microstrip line 7 is a ring, and the lower microstrip line 9 is a perforated disk. Both strips are 6cm–8cm long, 2mm–7mm wide, and 0.2mm–1.1mm thick. The outer diameter of the center circle of the upper microstrip line is 15mm–25mm, and the inner diameter is 0.2mm–3.5mm. The outer diameter of the center circle of the lower microstrip line is 10mm–20mm, and the inner diameter is 0.05mm–0.7mm. The distance between the two microstrip lines is 1.5mm–3.5mm. Both ends of the microstrip line assembly are connected to SMA connectors and bonded and cured using solder or highly conductive silver adhesive.

[0016] Furthermore, the two microstrip lines are 6.32 cm long and 0.25 mm thick. The outer diameter of the center circle of the upper microstrip line is 18 mm, the inner diameter is 2.3 mm, and the length of the strip-shaped portion 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-shaped portion on both sides is 24.6 mm and the width is 2.8 mm. The distance between the two microstrip lines is 1.6 mm.

[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 material of the upper microstrip line 7 and the material of the lower microstrip line 9, which serves as a high-voltage DAC pad, 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 the metallization transformation of matter under high pressure based on microwave technology includes the following steps:

[0019] A. Prepare the sample to be tested and add ruby ​​powder; then place 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.

[0020] B. Place the upper microstrip line 7 on the upper diamond 15; place the lower microstrip line 9 between the anvils of the upper diamond 15 and the lower diamond 16, with the sample chamber 6 facing the diamond anvil; and fasten the upper support block 12 and the lower support block 13 with 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 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 transmitted to the parameter detection device 4.

[0022] D. Slowly tighten the two bolts on the upper diamond 15 and use the nuts to make the upper diamond 15 and the lower diamond 16 fit tightly together, continuously increasing the pressure on the sample. Detect the ruby ​​fluorescence spectrum in the sample cavity 6 through the observation window (11) to obtain the sample pressure in the sample cavity 6. At the same time, use the parameter detection device 4 to measure the S-parameters and record the characteristic peaks or valleys of the S-parameter curve and their corresponding frequencies.

[0023] E. Based on the real-time measurement of S-parameter curves under different pressures, obtain the S-amplitude and corresponding frequency value at the maximum extreme value of the real-time S-parameter curve; compare and calculate the difference ΔS or Δf between the extreme value of the S-parameter curve at this state and the initial state; the difference ΔS or Δf between the change of the S-value and corresponding frequency at the maximum extreme value of the S-parameter curve and the initial state; when the difference ΔS or Δf reaches or exceeds the preset threshold, it can be determined that the material has undergone metallization transformation.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention employs a combination of a microstrip antenna and a diamond anvil cell to detect the metallization transformation process of materials under high pressure. The detection device has a simple and reliable structure, low power consumption, and is easy to use. The detection method has low experimental cost and simple and easy-to-operate experimental steps. In this invention, the replacement of the gasket and the sample to be tested is also relatively convenient, and it can be used to study the metallization or non-metallization transformation process of materials under high pressure. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the overall structure of the metallization transition in microwave technology;

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

[0029] Figure 3 This is a diagram of the microstrip line structure. Figure 3 'a' represents the upper microstrip line. Figure 3 b represents the lower microstrip line;

[0030] Figure 4 The graph shows the relationship between the frequency difference Δf of metallization transition between metals and nonmetals and the microstrip linewidth w.

[0031] Figure 5 The graph shows the relationship between the parameter difference ΔS in the metallization transformation between metals and nonmetals and the microstrip linewidth w.

[0032] Figure 6 A graph showing the relationship between the parameter difference ΔS in the metallization transformation between metals and nonmetals and the diameter difference ΔD between the upper and lower disks;

[0033] Figure 7 A graph showing the relationship between the frequency difference Δf of metallization transition between metals and nonmetals and the diameter difference ΔD between the upper and lower disks.

[0034] Figure 8 Simulation diagram of the S12 parameter response curves when the detection device detects metallic and non-metallic states.

[0035] In the diagram, 1. Microwave generator; 2. Microwave transmission line; 3. DAC detection unit; 4. Parameter detection device; 5. Bolt; 6. Sample chamber; 7. Upper microstrip line; 8. Signal output terminal; 9. Lower microstrip line; 10. Signal input terminal; 11. Observation window; 12. Upper support block; 13. Lower support block; 14. Stud; 15. Upper diamond; 16. Lower diamond; 17. Sample material. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments:

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0038] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] This invention employs a combination of experimentation and simulation. The HFSS finite element simulation software is used to simulate and solve the experimental test results. Through simulation, the influence of changes in the position of the DAC detection unit 3 relative to the diamond anvil and changes in 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 its central planar disk can be determined, thereby finding the spatial position of each component and the shape and size of the DAC detection unit 3 corresponding to the best experimental effect.

[0040] like Figure 1 As shown, the high-pressure metallization transformation detection device based on microwave technology of the present invention consists 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 microwave transmission lines 2 to realize signal transmission.

[0041] like Figure 2 As shown, the DAC detection unit 3 mainly consists of a microstrip line assembly, 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 assembly.

[0042] The microstrip line assembly consists of an upper microstrip line 7 and a lower microstrip line 9. The upper microstrip line 7 has holes that allow it to be nested onto the upper diamond 15. The lower microstrip line 9 has a circular portion in the middle (e.g., Figure 3 As shown in Figure b, the central circular component of the lower microstrip line 9 (excluding the two side strip-shaped portions) serves as a high-voltage DAC gasket, with a microhole drilled in its center serving as the sample cavity 6 for holding the test sample doped with ruby ​​powder. The top of the upper diamond 15 contacts 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, i.e., the optimal size of the microstrip line in the DAC detection unit, is found. Specifically, the size of the microstrip line and the size of the sample cavity, including the two side strip-shaped portions and the central circular portion, are changed. Figure 4 , Figure 5 The change is to the width of the strip section. Figure 6 , Figure 7 The dimensions of the middle circular section were modified. The optimal position for experimental results refers to the curve. Figure 8 The optimal detection location is where the lower microstrip line has the most suitable size, where the S-parameter frequency and amplitude changes most significantly, resulting in the highest sensitivity. By finding this optimal location, high detection sensitivity and accuracy can be achieved when a material undergoes a metallization transition.

[0043] The microstrip line assembly has a signal input terminal 10 and a signal output terminal 8 on both sides, and the signal input terminal 10 and the signal output terminal 8 are fixed to the microstrip line assembly by welding or by using conductive silver paste.

[0044] The microwave generator 1 is connected to the signal input terminal 10 via the microwave transmission line 2, and transmits the microwave signal to the microstrip line group through the signal input terminal 10. When the transmitted microwave wavelength 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 via a microwave transmission line 2, through which microwave signals are transmitted 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, both the upper support block 12 and the lower support block 13 are 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 to nuts to achieve support and limit of the upper support block 12 and the lower support block 13.

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

[0047] In this 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 mesh analyzer (VNA) can be used as both the microwave generator 1 and the parameter detection device 4 to detect the S-parameter response signal curve. A vector mesh analyzer is a high-precision testing instrument capable of measuring and analyzing parameters such as amplitude, phase, and frequency of radio frequency (RF) and microwave signals. In this invention, the vector mesh analyzer can be used as both the microwave generator 1 and the parameter detection device 4 to generate microwave signals and analyze the signals returned from the DAC detection unit 3. It can detect the system's S-parameter response curve, i.e., the relationship curve between the horizontal axis (frequency sweep) and the vertical axis (S-parameters).

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

[0050] like Figure 3As shown, the microstrip line assembly consists of two strips, an upper one and a lower one, with a ring-shaped structure of unequal radius in the middle of each strip. The upper microstrip line 7 is a ring, and the lower microstrip line 9 is a perforated disk (the perforation is the sample chamber). Both strips are 6cm–8cm long, 2mm–7mm wide, and 0.2mm–1.1mm thick. The outer diameter of the center circle of the upper microstrip line is 15mm–25mm, and the inner diameter is 0.2mm–3.5mm. The outer diameter of the center circle of the lower microstrip line is 10mm–20mm, and the inner diameter (perforation) is 0.05mm–0.7mm. The distance between the two microstrip lines is 1.5mm–3.5mm. Both ends of the microstrip line assembly are connected to SMA connectors and bonded and cured using solder or highly conductive silver adhesive.

[0051] Preferably, the length is 6.32 cm, the thickness is 0.25 mm, the outer diameter of the center circle of the upper microstrip line is 18 mm, the inner diameter is 2.3 mm, and the length of the strip-shaped portions 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-shaped portions on both sides is 24.6 mm, and the width is 2.8 mm, with a distance of 1.6 mm between the two microstrip lines. This is the optimal position described above, i.e., 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 transition has occurred. The S-parameter frequency and amplitude changes are most significant at this location, resulting in the highest sensitivity.

[0052] Specifically, in the material selection for the DAC detection unit 3, both 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 materials for the upper microstrip line 7 and the lower microstrip line 9, which serves as a high-voltage DAC pad, 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 fluorescence wavelength of ruby ​​changes with pressure, ruby ​​powder needs to be incorporated into the sample to achieve real-time measurement of the pressure generated by the diamond anvil cell. Specific operating steps: Ruby powder and the test sample are placed together in sample cavity 6. The characteristic peaks of the fluorescence spectrum of the ruby ​​powder are used to calibrate the measurement pressure. Pre-compression is performed before the experiment to ensure the sample is compact and fills sample cavity 6. In this invention, a microhole, similar to a groove structure, is drilled in the center of the lower microstrip line 9. This microhole serves as sample cavity 6 to hold the sample to be tested. Installation of the detection device:

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

[0055] 2. Select an appropriate amount of 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 pads. Then, compact the sample material 17. Try to fill the sample cavity 6 completely with the sample material 17.

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

[0057] This invention utilizes a combination of microstrip lines and diamond anvil cells to detect the metallization transformation process of materials under high pressure. It offers advantages such as simple sample structure, low power consumption, and ease of use. Furthermore, the replacement of the gasket and the sample is convenient, making it suitable for studying the metallization or non-metallization transformation processes of materials under high pressure.

[0058] Metallization transformation detection principle:

[0059] Before the metallization transition, the lower microstrip line 9 is a metallic radiative patch with micropores. After the metallization transition occurs under high pressure, the lower microstrip line 9 is equivalent to a whole metallic radiative patch. Its radiation parameters can be measured using a vector analyzer to obtain the S-parameters. By judging whether the S-parameters have changed, it can be determined whether the material has undergone a metallization transition. Similarly, the transition of a material from a metallic state to a nonmetallic state under high pressure can also be detected.

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

[0061] I. S-parameter amplitude. During the metal-to-nonmetal transformation of a sample, the S-parameter value changes. Therefore, the change in S-parameter value at the maximum extreme value of the S-parameter curve can be used to determine whether a metallization transition has occurred. The parameter amplitude difference ΔS represents the transmission coefficient S before the metallization transition. 21 'Subtract the transmittance S after the metal transformation 21 The formula is expressed as ΔS = S 21 '-S 21 ".

[0062] II. Extreme Frequency. During the transformation of a sample from a metal to a nonmetal, the frequency f at the maximum extreme value will also change. The parameter difference Δf represents the frequency value before the metal transformation and f. 21 'Frequency value f after the metallic transformation occurs' 21 The difference between the two values. The formula is Δf = f 21 '-f 21 ".

[0063] contrast Figure 4 , Figure 5, Figure 6 , Figure 7 It can be observed that in this invention, when the microstrip line has suitable dimensions (microstrip line width w is 2.8 mm and the difference in diameter between the upper and lower disks ΔD is 4 mm), the changes in the parameter amplitude difference ΔS and the frequency difference Δf are quite significant. Therefore, appropriate S-parameter difference ΔS and frequency difference Δf can be used as detection thresholds S. t and f t The S-parameters or frequency thresholds are used to determine whether a metallization transition has occurred. These thresholds can be empirical values; under high pressure, if the S-parameters or frequency change exceeds the threshold, a metallization transition can be considered to have occurred.

[0064] This invention provides a method for detecting the metallization transition of matter under high pressure using 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, i.e. the sample cavity 6, and ensure that it is filled.

[0066] 2. Place the upper microstrip line 7 onto the upper diamond 15; place the lower microstrip line 9 between the anvils of the upper diamond 15 and the lower diamond 16, with the sample chamber 6 facing the diamond anvil. Secure the upper support block 12 and the lower support block 13 with bolts 5 and studs 14 to fix the gasket portion in the lower microstrip line.

[0067] 3. Start the microwave generator 1, and input the microwave signal to 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 transmitted to the parameter detection device 4.

[0068] 4. Slowly tighten the two bolts on the upper diamond 15 and the nuts to ensure a tight fit between the upper diamond 15 and the lower diamond 16, continuously increasing the pressure on the sample. Observe the ruby ​​fluorescence spectrum within the sample cavity 6 through the observation window 11 to obtain the sample pressure within the sample cavity 6. Simultaneously, use the parameter detection device 4 to measure the S-parameters and record the characteristic peaks or valleys (extreme values) of the S-parameter curve and their corresponding frequencies.

[0069] 5. Based on real-time measurements of the S-parameter curves under different pressures, obtain the amplitude and corresponding frequency values ​​at the maximum extreme values ​​of the real-time S-parameter curves. Compare and calculate the difference ΔS or Δf between the amplitude or frequency f at the extreme values ​​of the S-parameter curves at this state and the initial state (no pressure applied, pressure is 0). Calculate the difference ΔS or Δf between the change in the S-parameter value and the corresponding frequency at the maximum extreme value of the S-parameter curve and the initial state. When the difference ΔS or Δf reaches or exceeds a preset threshold, it can be determined that the material has undergone a metallization transition.

[0070] Example 1

[0071] A high-pressure metallization transformation detection device based on microwave technology comprises 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 compressor parameter detection mechanism.

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

[0073] By using HFSS software for simulation on a PC, the optimal dimensions of the microstrip line were determined as follows: total length 6.32 cm, thickness 0.25 mm, outer diameter of the upper microstrip line's center circle 18 mm, inner diameter 2.3 mm, and strip length of 22.6 mm and width of 3.09 mm on both sides; outer diameter of the lower microstrip line's center circle 14 mm, inner diameter 0.46 mm, and strip length of 24.6 mm and width of 2.8 mm on both sides. The most significant change was observed at the extreme values ​​of the S-parameter curve during the metallization transition when the distance between the two microstrip lines was 1.6 mm. Figure 8 As shown in the figure. During the simulation, the initial state is set to non-metallic, and the material inside the sample cavity is a non-metallic material; after the metallization transition, the material inside the sample cavity is set to a metallic material.

[0074] Depend on Figure 8 It can be seen that the maximum extreme value of the S-parameter curve during the metallization transition is in the range of 26.872 GHz to 27.214 GHz, with S-parameter and frequency changes of ΔS = 5.546 dB and Δf = 0.342 GHz, respectively. These two values ​​can be used as a reference 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 description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A device for detecting the metallization transformation of matter under high pressure based on microwave technology, characterized in that: It consists 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 realize signal transmission; The DAC detection unit (3) is mainly composed of a microstrip line assembly, 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 assembly; 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) being located on the upper and lower sides of the upper diamond (15) and the lower diamond (16), respectively; the lower support block (13) has a conical observation window (11) at its bottom; The microstrip line group consists of an upper microstrip line (7) and a lower microstrip line (9). The upper microstrip line (7) is mounted on an upper diamond (15). The middle part of the lower microstrip line (9) serves as a high-voltage DAC pad. A sample cavity (6) is provided in the center of the pad. The top of the upper diamond (15) contacts the sample cavity (6). The two sides of the microstrip line group are respectively provided with a signal input terminal (10) and a signal output terminal (8). The microwave generator (1) is connected to the signal input terminal (10) through a microwave transmission line (2) and transmits the microwave signal to the microstrip line group through the port of the signal input terminal (10). The parameter detection device (4) is connected to the signal output terminal (8) through the microwave transmission line (2) and transmits the microwave signal to the parameter detection device (4) for detection.

2. The microwave-based high-pressure metallization transformation detection device according to claim 1, characterized in that: The upper microstrip line (7) has holes and can be nested on the upper diamond (15).

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

4. The microwave-based high-pressure metallization transformation detection device according to claim 1, characterized in that: The signal input terminal (10) and the signal output terminal (8) are fixed to the microstrip line assembly by welding or by using conductive silver paste.

5. The microwave-based high-pressure metallization transformation detection device according to claim 1, characterized in that: The upper support block (12) and the lower support block (13) are fastened by two bolts (5) and two studs (14). 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 fastened to the studs through the corresponding bolt holes to achieve support and limit of the upper support block (12) and the lower support block (13).

6. The microwave-based high-pressure metallization transformation detection device 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 microwave-based high-pressure metallization transformation detection device according to claim 1, characterized in that: in, The upper microstrip line (7) is a ring, and the lower microstrip line (9) is a perforated disk. The length of the upper microstrip line (7) and the lower microstrip line (9) are both 6cm to 8cm, the width is both 2mm to 7mm, and the thickness is 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. 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 upper microstrip line (7) and the lower microstrip line (9) is 1.5mm to 3.5mm. The two ends of the microstrip line assembly are connected to the SMA port and bonded and cured by welding or high conductivity silver paste.

8. The microwave-based high-pressure metallization transformation detection device according to claim 7, characterized in that: The upper microstrip line (7) and the lower microstrip line (9) are 6.32 cm long and 0.25 mm thick. The outer diameter of the center circle of the upper microstrip line (7) is 18 mm and the inner diameter is 2.3 mm. The length of the strip-shaped part 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 and the inner diameter is 0.46 mm. The length of the strip-shaped part on both sides is 24.6 mm and the width is 2.8 mm. The distance between the upper microstrip line (7) and the lower microstrip line (9) is 1.6 mm.

9. The microwave-based high-pressure metallization transformation detection device according to claim 1, characterized in that: The upper support block (12) and 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 material of the upper microstrip line (7) and the material of the lower microstrip line (9) which serves as a high-voltage DAC pad are made of steel, tungsten, copper or rhenium metal with a thickness of 0.2 mm to 1.1 mm.

10. A method for detecting the metallization transformation of matter under high pressure based on microwave technology, characterized in that, Includes the following steps: 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 make sure it is filled; B. Place the upper microstrip line (7) onto the upper diamond (15); The lower microstrip line (9) is placed between the anvils of the upper diamond (15) and the lower diamond (16), and the sample chamber (6) is directly facing the diamond anvil. 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) and input the microwave signal to the signal input terminal (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 terminal (8) through the microwave transmission line (2) and transmitted to the parameter detection device (4). D. Slowly tighten the two bolts on the upper diamond (15) and the stud to make the upper diamond (15) and the lower diamond (16) fit tightly together, continuously increasing the pressure on the sample. Observe the ruby ​​fluorescence spectrum in the sample cavity (6) through the observation window (11) to obtain the magnitude of the sample pressure in the sample cavity (6); at the same time, use the parameter detection device (4) to measure the S-parameters and record the characteristic peaks or valleys of the S-parameter curves and their corresponding frequencies. E. Based on the real-time measurement of S-parameter curves under different pressures, obtain the S-amplitude and corresponding frequency value at the maximum extreme value of the real-time S-parameter curve; compare and calculate the difference ΔS or Δf between the S-parameter amplitude or frequency f at the extreme value when the real-time state is different from that when the initial state is different from that when the difference ΔS or Δf reaches or exceeds the preset threshold, it can be determined that the material has undergone metallization transformation.

Images