A pressure device for magnetic measurement

Abstract

The present invention discloses a pressure device for magnetic measurement, which relates to the technical field of high-pressure physical in-situ measurement. The pressure device comprises a top cap, a pressure piece, a main body and an extension piece. The main body has a sample cavity inside, the top end of the main body has a channel, the pressure piece can extend into the sample cavity, the bottom end of the pressure piece is used to apply pressure to a fluid medium, the top end of the top cap is fixedly connected to a sample drive rod of a magnetic measuring device, the top cap is fixedly sleeved on the top end of the main body, a pressing surface is provided inside the top cap, and the pressing surface can contact the top end of the pressure piece; the position of the top cap on the main body can be adjusted upward or downward; the pressure piece can move upward or downward relative to the main body before the top cap is fixed to the main body; the top end of the extension piece is used to be fixedly arranged on the bottom end of the main body when using an MPMS DC test; the present invention is applicable to MPMS, PPMS, Foner magnetometers and differential magnetometers.

Description

Technical Field

[0001] The present invention relates to the technical field of high-pressure physical in-situ measurement, in particular to a pressure device for magnetic measurement. Background Art

[0002] Magnetic measurement is the measurement of the magnetic properties of materials, mainly referring to the measurement of relevant magnetic quantities of magnetic materials under a magnetic field.

[0003] Currently, commonly used magnetic measurement equipment on the market includes MPMS (Magnetic Property Measurement System), PPMS (Physical Property Measurement System), Foner magnetometer (vibrating sample magnetometer), and differential magnetometer. In addition, high-pressure magnetic measurements require a pressure device to provide hydrostatic pressure and a mounting base for the sample. To ensure accurate sample testing, the sample must be placed in the center of the detection coil during the experiment. Among the above magnetic measurement equipment, the MPMS has a detection coil with a significantly different height and range from the other equipment. That is, the MPMS has a longer sample chamber and a lower detection coil position. However, currently, no single pressure device is suitable for all of the above magnetic measurement equipment. Summary of the Invention

[0004] The object of the present invention is to provide a pressure device for magnetic measurement to solve the problems existing in the above-mentioned prior art, and the pressure device can be applied to MPMS, PPMS, Foner magnetometer and differential magnetometer.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a pressure device for magnetic measurement, comprising a top cap, a pressure piece, a main body and an extension piece, wherein the main body has a sample chamber inside, the sample chamber is used to accommodate a fluid medium and a sample, the top end of the main body has a channel, the bottom of the channel is connected to the top of the sample chamber, the pressure piece can extend into the sample chamber, the bottom end of the pressure piece is used to apply pressure to the fluid medium, the top end of the top cap is used to be fixedly connected to a sample drive rod of a magnetic measuring device, the top cap is fixedly sleeved on the top end of the main body, the top cap has a pressing surface inside, the pressing surface can contact the top end of the pressure piece and press the pressure piece downward and fix it; the position of the top cap on the main body can be adjusted upward or downward to adjust the distance from the pressing surface to the sample chamber; the pressure piece can move upward or downward relative to the main body before the top cap is fixed to the main body; the top end of the extension piece is used to be fixedly arranged on the bottom end of the main body when using MPMS DC testing.

[0007] Preferably, it also includes a cylindrical sleeve, which is used to be fixedly mounted on the outside of the main body and the extension when using the MPMS DC test, the top end face of the cylindrical sleeve is placed below the bottom end face of the top cap, the bottom end face of the cylindrical sleeve is used to be flush with the bottom end face of the extension, and the outer side surface of the cylindrical sleeve is used to be flush with the outer side surface of the top cap.

[0008] Preferably, a lower plug is also included, which includes a connecting column and a supporting plate, the connecting column is placed above the supporting plate, the bottom end of the connecting column is fixedly connected to the top end of the supporting plate, the connecting column is used to be fixedly connected to the bottom end of the extension piece when using the DC test of MPMS, and the top end face of the supporting plate is used to fit with the bottom end face of the cylindrical sleeve.

[0009] Preferably, the connecting column is used to be threadedly connected to the bottom end of the extension piece when using the MPMS DC test; the outer side surface of the supporting plate is used to be flush with the outer side surface of the cylindrical sleeve.

[0010] Preferably, the cross-section of the top cap, the cross-section of the pressure member, the cross-section of the main body, and the cross-section of the extension member are circular or annular.

[0011] Preferably, the extension piece is a hollow structure, and a groove is provided on the bottom end surface of the main body, and the groove is used to communicate with the interior of the extension piece.

[0012] Preferably, the top end of the top cap is used to be threadedly connected to the sample drive rod of the magnetic measuring equipment, the top end of the main body is threadedly connected to the top cap, and the bottom end of the main body is used to be threadedly connected to the top end of the extension piece when using the DC test of MPMS; the top cap has a regular hexagonal prism portion, and the outer surface of the regular hexagonal prism portion can be snapped into the wrench socket.

[0013] Preferably, it also includes a force transmission member, a through hole is opened between the top end face of the top cap and the pressing surface, the force transmission member is used to pass through the through hole before the top cap is fixed to the main body, the top end of the force transmission member is used to be fixedly connected to the pressure shaft of the pressure device, and the bottom end of the force transmission member is used to contact the top end face of the pressure member.

[0014] Preferably, a rubber stopper is fixedly provided at the bottom end of the pressure piece, and the outer side surface of the rubber stopper can be sealed and pressed against the inner side surface of the sample cavity, and the outer side surface of the rubber stopper can slide upward or downward along the inner side surface of the sample cavity; the diameter of the middle part of the pressure piece is larger than the diameter of the two ends of the pressure piece, and the outer side surface of the middle part of the pressure piece can contact the inner side surface of the sample cavity; the diameter of the channel is larger than the diameter of the sample cavity.

[0015] Preferably, the sample cavity is used to accommodate the standard pressure substance and the fluid medium, the standard pressure substance and the fluid medium are arranged in sequence from bottom to top, the outside of the sample is fixedly surrounded by a pressure-relieving material, and the sample and the pressure-relieving material are both placed in the fluid medium.

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

[0017] The pressure device for magnetic measurement provided by the present invention blocks the hydrostatic pressure of the fluid medium in the sample chamber through the cooperation of a top cap, a pressure piece and a main body. The position of the top cap on the main body can be adjusted upward or downward to adjust the distance from the pressing surface to the sample chamber, thereby realizing the downward pressing and fixing of the pressure piece at different positions, which can provide different hydrostatic pressure conditions for magnetic measurement, and the combination of the top cap, the pressure piece and the main body has the following adaptation characteristics: first, the structure is compact and can be compatible with the sample chamber size constraints of MPMS, PPMS, Foner magnetometers and differential magnetometers; for AC test mode, since the acquisition of induced electromotive force only requires periodic switching of current direction, the shape tolerance requirements of the pressure device are relatively wide, so the combination structure of the top cap, the pressure piece and the main body can adapt to the AC test requirements of the four types of magnetometers, namely MPMS, PPMS, Foner magnetometers and differential magnetometers; for DC test mode, since the accuracy threshold of PPMS, Foner magnetometers and differential magnetometers is lower than M The left-right symmetrical design of the combined structure of PMS, top cap, pressure piece and main body can meet the DC testing requirements of PPMS, Foner magnetometer and differential magnetometer. When performing DC testing of MPMS, the top of the extension piece is fixedly assembled on the bottom end of the main body. The longitudinal extension of the extension piece can adapt to the longer size of the MPMS sample chamber and the lower position layout of the detection coil. The extension piece makes the pressure device form a top-down symmetrical configuration to ensure that the sample is accurately positioned at the geometric center of the pressure device. This "left-right symmetry + top-down symmetry" dual symmetry characteristic not only optimizes the positioning and calibration accuracy of the sample, but also effectively suppresses the background noise during the DC testing process and significantly reduces parasitic signal interference. Therefore, the pressure device for magnetic measurement provided by the present invention realizes cross-platform compatibility with the entire series of MPMS, PPMS, Foner magnetometer and differential magnetometer equipment through modular structural design and multi-parameter adjustable mechanism, covering the full spectrum of magnetic measurement requirements of AC test mode and DC test mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of a pressure device for magnetic measurement provided by the present invention;

[0020] Figure 2 for Figure 1 Schematic diagram of the top hat in;

[0021] Figure 3 for Figure 1 A schematic diagram of a pressure member in FIG.

[0022] Figure 4 for Figure 1 A schematic diagram of the subject in ;

[0023] Figure 5 for Figure 1 Schematic diagram of the extension piece in;

[0024] Figure 6 for Figure 1 Schematic diagram of the lower plug in;

[0025] In the figure: 1-top cap, 2-pressure member, 3-main body, 4-extension member, 5-sample chamber, 6-channel, 7-pressing surface, 8-cylindrical sleeve, 9-lower plug, 10-connecting column, 11-carrying plate, 12-groove, 13-regular hexagonal prism part, 14-through hole. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The object of the present invention is to provide a pressure device for magnetic measurement to solve the problems existing in the above-mentioned prior art, and the pressure device can be applied to MPMS, PPMS, Foner magnetometer and differential magnetometer.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1 to 6As shown, this embodiment provides a pressure device for magnetic measurement, including a top cap 1, a pressure piece 2, a main body 3 and an extension piece 4. The main body 3 has a sample chamber 5 inside, which is used to accommodate a fluid medium and a sample. The top of the main body 3 has a channel 6, the bottom of the channel 6 is connected to the top of the sample chamber 5, the pressure piece 2 can extend into the sample chamber 5, and the bottom end of the pressure piece 2 is used to apply pressure to the fluid medium. The top of the top cap 1 is used to be fixedly connected to the sample drive rod of the magnetic measurement device. The top cap 1 is fixedly sleeved on the top of the main body 3, and the top cap 1 has a pressing surface 7, which can contact the top of the pressure piece 2 and press the pressure piece 2 downward and fix it; the position of the top cap 1 on the main body 3 can be adjusted upward or downward to adjust the distance from the pressing surface 7 to the sample chamber 5; the pressure piece 2 can move upward or downward relative to the main body 3 before the top cap 1 is fixed to the main body 3; the top of the extension piece 4 is used to be fixedly arranged on the bottom end of the main body 3 when using MPMS DC testing.

[0030] The pressure device for magnetic measurement provided in this embodiment is a universal device for alternating current (AC) and direct current (DC) magnetic measurement. The hydrostatic pressure of the fluid medium inside the sample chamber 5 is blocked by the cooperation of the top cap 1, the pressure member 2 and the main body 3. The position of the top cap 1 on the main body 3 can be adjusted upward or downward to adjust the distance from the pressing surface 7 to the sample chamber 5, thereby realizing the downward pressing and fixing of the pressure member 2 at different positions, which can provide different hydrostatic pressure conditions for magnetic measurement. The combination of the top cap 1, the pressure member 2 and the main body 3 has the following advantages: Adaptability characteristics: First, the structure is compact and can be compatible with the sample chamber size constraints of MPMS, PPMS, Foner magnetometers and differential magnetometers; for AC test mode, since the acquisition of induced electromotive force only requires periodic switching of current direction, the shape tolerance requirements of the pressure device are relatively loose, so the combination structure of the top cap 1, pressure piece 2 and main body 3 can adapt to the AC test requirements of MPMS, PPMS, Foner magnetometers and differential magnetometers; for DC test mode, since PPMS, Foner magnetometers and differential magnetometers are The accuracy threshold of er magnetometer and differential magnetometer is lower than that of MPMS. The left-right symmetrical design of the combined structure of the top cap 1, the pressure piece 2 and the main body 3 can meet the DC test requirements of PPMS, Foner magnetometer and differential magnetometer. When performing DC testing of MPMS, the top of the extension piece 4 is fixedly assembled on the bottom end of the main body 3. The longitudinal extension of the extension piece 4 can adapt to the longer size of the MPMS sample chamber and the lower position layout of the detection coil. The extension piece 4 is used to make the pressure device form a top-down symmetrical configuration to ensure that the sample is accurately positioned at the geometric center of the pressure device. This "left-right symmetry + top-down symmetry" dual symmetry characteristic not only optimizes the positioning and calibration accuracy of the sample, but also can effectively suppress the background noise during the DC test process and significantly reduce parasitic signal interference. Therefore, the pressure device for magnetic measurement provided by the present invention realizes cross-platform compatibility with the full range of MPMS, PPMS, Foner magnetometer and differential magnetometer equipment through modular structural design and multi-parameter adjustable mechanism, covering the full spectrum of magnetic measurement requirements of AC test mode and DC test mode.

[0031] As a more preferred implementation of this embodiment, the pressure device for magnetic measurement provided in this embodiment also includes a cylindrical sleeve 8, which is used to be fixedly mounted on the outside of the main body 3 and the extension 4 when using the DC test of MPMS. The top end face of the cylindrical sleeve 8 is placed below the bottom end face of the top cap 1, and the bottom end face of the cylindrical sleeve 8 is used to be flush with the bottom end face of the extension 4. The outer side surface of the cylindrical sleeve 8 is used to be flush with the outer side surface of the top cap 1. The setting of the cylindrical sleeve 8 helps to simplify the overall shape of the device, so that the MPMS detection coil perceives the device as a whole as an approximate right cylinder, balances the magnetic measurement signal, greatly reduces the generation of magnetic background, and presents a lower magnetization background under the scanning of the detection coil. In actual tests, the cylindrical sleeve 8 cooperates with the extension 4 to enable the entire pressure device to maintain magnetic uniformity and a lower magnetic background signal during the DC oscillation test of MPMS.

[0032] As a more preferred implementation of this embodiment, the pressure device for magnetic measurement provided in this embodiment also includes a lower plug 9, which includes a connecting column 10 and a carrying plate 11. The connecting column 10 is placed above the carrying plate 11, and the bottom end of the connecting column 10 is fixedly connected to the top end of the carrying plate 11. The connecting column 10 is used to be fixedly connected to the bottom end of the extension member 4 when using the DC test of MPMS. The top end face of the carrying plate 11 is used to fit with the bottom end face of the cylindrical sleeve 8, which is convenient for supporting and locking the cylindrical sleeve 8 and facilitating upright operation.

[0033] As a more preferred implementation of this embodiment, the connecting column 10 is used to be threadedly connected to the bottom end of the extension piece 4 when using the MPMS DC test, which is convenient for installation and disassembly; the outer surface of the supporting plate 11 is used to be flush with the outer surface of the cylindrical sleeve 8, which helps to simplify the overall shape of the device and reduce the generation of magnetic backing.

[0034] As a more preferred implementation of this embodiment, the cross-section of the top cap 1, the cross-section of the pressure piece 2, the cross-section of the main body 3 and the cross-section of the extension piece 4 are circular or annular, which can effectively reduce the generation of magnetic background, well balance the magnetic background signal, and realize accurate magnetic measurement of the sample.

[0035] As a more preferred implementation of this embodiment, the extension piece 4 is a hollow structure, and a groove 12 is provided on the bottom end face of the main body 3. The groove 12 is used to communicate with the interior of the extension piece 4, which can balance the magnetic measurement signal, reduce the generation of magnetic background, and present a lower magnetization background under the scanning of the detection coil.

[0036] As a more preferred implementation manner of this embodiment, the top of the top cap 1 is used to be threadedly connected to the sample drive rod of the magnetic measuring equipment, the top of the main body 3 is threadedly connected to the top cap 1, and the bottom end of the main body 3 is used to be threadedly connected to the top of the extension piece 4 when using the DC test of MPMS, which is convenient for installation and disassembly; the top cap 1 has a regular hexagonal prism part 13, and the outer surface of the regular hexagonal prism part 13 can be snapped into the wrench bayonet, which is convenient for use with a wrench.

[0037] As a more preferred implementation of this embodiment, the pressure device for magnetic measurement provided in this embodiment also includes a force transmission member, and a through hole 14 is opened between the top end face of the top cap 1 and the pressing surface 7. The force transmission member is used to pass through the through hole 14 before the top cap 1 is fixed to the main body 3. The top end of the force transmission member is used to be fixedly connected to the pressure shaft of the pressure device, and the bottom end of the force transmission member is used to contact the top end face of the pressure member 2 to facilitate pressurizing the fluid medium.

[0038] As a more preferred implementation of this embodiment, a rubber plug is fixedly provided at the bottom end of the pressure piece 2, and the outer side surface of the rubber plug can be sealed and pressed on the inner side surface of the sample cavity 5, and the outer side surface of the rubber plug can slide up or down along the inner side surface of the sample cavity 5. The bottom end of the pressure piece 2 is provided with a mounting groove, and the mounting groove is used to fix the rubber plug; specifically, the top end surface of the pressure piece 2 can contact the pressing surface 7, the diameter of the middle part of the pressure piece 2 is larger than the diameter of the two ends of the pressure piece 2, the outer side surface of the middle part of the pressure piece 2 can contact the inner side surface of the sample cavity 5, and the middle section of the pressure piece 2 is thicker, which can effectively reduce the gap with the inner diameter of the sample cavity 5, prevent the pressure piece 2 from shaking, especially prevent the pressure piece 2 from shaking when pressure is applied, and avoid pressure caused by shaking of the pressure piece 2. Uneven or leaking; a mounting groove is provided at the bottom end of the pressure piece 2, and the narrow bottom end of the pressure piece 2 can make the thickness of the side wall of the mounting groove smaller, which can effectively reduce the contact area between the bottom end face of the pressure piece 2 and the rubber stopper before the rubber stopper is inserted into the mounting groove, thereby reducing the resistance of the bottom end face of the pressure piece 2 to the rubber stopper, so as to facilitate the insertion of the rubber stopper into the mounting groove. At the same time, on the premise of making the thickness of the side wall of the mounting groove smaller, on the basis of the narrow bottom end of the pressure piece 2, the diameter of the mounting groove is also smaller, that is, it can effectively reduce the diameter requirement of the rubber stopper so that the rubber stopper is firmly and firmly inserted into the mounting groove, thereby effectively avoiding the excessive resistance of the sample cavity 5 to the rubber stopper due to the rubber stopper being too large; the diameter of the channel 6 is larger than the diameter of the sample cavity 5, which facilitates the insertion of the pressure piece 2 through the channel 6.

[0039] As a more preferred implementation of this embodiment, the sample chamber 5 is used to accommodate a standard pressure substance and a fluid medium. The standard pressure substance and the fluid medium are arranged in sequence from bottom to top. The outside of the sample is fixedly surrounded by a pressure-relieving material. The sample and the pressure-relieving material are both placed in the fluid medium. The standard pressure substance is preferably selected from small pieces of lead particles or tin particles. The superconducting transition temperature at low temperature changes linearly with pressure. The internal pressure range can be known by testing the transition temperature. The fluid medium is preferably low-viscosity silicone oil. Low-viscosity silicone oil is a good pressure transmission medium. The pressure-relieving material is a non-magnetic material, and beryllium copper material is preferably selected. Its function is to wrap the sample down, which is convenient for roughly positioning the sample outside the device. At the same time, during a wide range of temperature changes, the pressure-relieving material helps balance the volume changes caused by the temperature change to ensure the accuracy of the pressure.

[0040] As a more preferred implementation of this embodiment, the top cap 1, the pressure piece 2, the main body 3, the extension piece 4, the cylindrical sleeve 8 and the lower plug 9 are all made of non-magnetic materials and are longitudinally coaxially arranged. The top cap 1, the pressure piece 2, the main body 3, the extension piece 4, the cylindrical sleeve 8 and the lower plug 9 are preferably made of hardened BeCu or NiCrAl alloy materials; when in use, the top cap 1, the pressure piece 2 and the main body 3 are assembled, and the overall outer diameter is 4.00 mm, the total length is about 50 mm, and the top cap 1, the pressure piece 2 and the main body 3 are assembled. The same hydrostatic pressure corresponds to different screwing lengths of the top cap 1 and the main body 3. The diameter of the sample cavity 5 is 1.40 mm, and the diameter of the channel 6 is 1.45 mm, which is convenient for the axial movement and limitation of the pressure piece 2. The bottom end of the pressure piece 2 is designed with a mounting groove with a depth of 2.50 mm and a diameter of 1.35 mm, which is used to fix the rubber stopper. When the top cap 1, pressure piece 2, main body 3, extension piece 4, cylindrical sleeve 8 and lower plug 9 are assembled, the overall outer diameter is 5.00 mm and the length is 100 mm.

[0041] As a more preferred implementation of this embodiment, it is necessary to prepare a sample first. The shape of the sample is preferably set to be cylindrical as a whole. Preferably, a cylindrical barrel is made of tin foil. The diameter of the barrel cannot be larger than the diameter of the cavity of the main body 3. After the sample is loaded into the cylindrical barrel, the barrel is sealed to prevent the sample from leaking out. Subsequently, a standard pressure substance is added to the sample cavity 5 of the main body 3, and then a fluid medium is added to the sample cavity 5 of the main body 3. Then, a pressure-relieving material, a cylindrical barrel containing the sample, a second piece of pressure-relieving material are sequentially placed, and finally a cylindrical rubber is cut. Rubber plug, embed the rubber plug into the installation groove at the bottom end of the pressure piece 2 and prevent it from falling off, then slowly push the pressure piece 2 and the rubber plug at the bottom end of the pressure piece 2 into the sample chamber 5. Resistance will appear during the operation, proving that the fluid medium and the pressure piece 2 and the rubber plug at the bottom end of the pressure piece 2 are well sealed, and then cover the top cap 1 and tighten it; when applying pressure, first pass the force transmitting piece through the through hole 14, use a hydraulic press to give pressure to the force transmitting piece, and then tighten the top cap 1 with a wrench to fix the generated hydrostatic pressure and realize a continuously controllable non-magnetic hydrostatic pressure test environment.

[0042] As a preferred embodiment of this embodiment, when using PPMS, Foner magnetometer or differential magnetometer, the top of the top cap 1 is fixedly connected to the sample drive rod of the magnetic measuring device, and the sample position is adjusted to obtain the maximum signal response. Under pressure conditions, the measurement error does not exceed (3~5)×10 -5 cm 3 / g; In MPMS magnetic measurement, the extension 4 must be tightly connected to the main body 3 and ensure that the sample is in the center position. During the center alignment process, the signal of the sample inside and outside the pressure device should be consistent, and the signal measurement error should not exceed 1×10 -7 cm 3 / g.

[0043] All of the above embodiments comprehensively consider various commonly used magnetometer systems currently available, and consider various factors such as the length of the pressure device under different measurement methods, magnetic uniformity, coupling effect with the measurement coil, and positioning of the sample in the pressure device, so as to facilitate accurate magnetic measurement of the sample in the sample chamber 5 and realize the design concept of a universal device. It can provide and withstand a hydrostatic pressure of 1.2 GPa and a variable temperature environment in the range of 2K to 350K. It has a simple and reliable structure, a convenient and labor-saving pressurization process, and is applicable to both DC and AC measurements, meeting the high-precision requirements of DC and AC.

[0044] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A pressure device for magnetic measurement, characterized in that: The invention comprises a top cap, a pressure piece, a main body and an extension piece, wherein the interior of the main body is provided with a sample cavity, and the sample cavity is used to accommodate a fluid medium and a sample, the top end of the main body is provided with a channel, the bottom of the channel is connected to the top of the sample cavity, the pressure piece can extend into the sample cavity, the bottom end of the pressure piece is used to apply pressure to the fluid medium, the top end of the top cap is used to be fixedly connected to the sample drive rod of the magnetic measuring device, the top cap is fixedly sleeved on the top end of the main body, the top cap has a pressing surface inside, the pressing surface can contact with the top end of the pressure piece and press the pressure piece downward and fix it; the position of the top cap on the main body can be adjusted upward or downward to adjust the distance from the pressing surface to the sample cavity; the pressure piece Before the top cap is fixed to the main body, it can move upward or downward relative to the main body; the top end of the extension piece is used to be fixed on the bottom end of the main body when using MPMS for DC testing; a rubber plug is fixed to the bottom end of the pressure piece, and the outer side surface of the rubber plug can be sealed and pressed on the inner side surface of the sample cavity, and the outer side surface of the rubber plug can slide upward or downward along the inner side surface of the sample cavity, and the rubber plug is used to directly contact the fluid medium and apply pressure to the fluid medium; the diameter of the middle part of the pressure piece is larger than the diameter of the two ends of the pressure piece, and the outer side surface of the middle part of the pressure piece can contact the inner side surface of the sample cavity, and the bottom end of the pressure piece is provided with a mounting groove, and the mounting groove is used to fix the rubber plug.

2. The pressure device for magnetic measurement according to claim 1, characterized in that: It also includes a cylindrical sleeve, which is used to be fixedly mounted on the outside of the main body and the extension when using MPMS for DC testing. The top end face of the cylindrical sleeve is placed below the bottom end face of the top cap, the bottom end face of the cylindrical sleeve is used to be flush with the bottom end face of the extension, and the outer side surface of the cylindrical sleeve is used to be flush with the outer side surface of the top cap.

3. The pressure device for magnetic measurement according to claim 2, characterized in that: It also includes a lower plug, which includes a connecting column and a supporting plate. The connecting column is placed above the supporting plate, and the bottom end of the connecting column is fixedly connected to the top end of the supporting plate. The connecting column is used to be fixedly connected to the bottom end of the extension piece when using MPMS DC testing, and the top end face of the supporting plate is used to fit with the bottom end face of the cylindrical sleeve.

4. The pressure device for magnetic measurement according to claim 3, characterized in that: The connecting column is used to be threadedly connected to the bottom end of the extension piece when using the MPMS DC test; the outer side surface of the carrying plate is used to be flush with the outer side surface of the cylindrical sleeve.

5. The pressure device for magnetic measurement according to claim 1, characterized in that: The cross-sections of the top cap, the pressure member, the main body and the extension member are circular or annular.

6. The pressure device for magnetic measurement according to claim 1, characterized in that: The extension piece is a hollow structure, and a groove is provided on the bottom end surface of the main body, and the groove is used to communicate with the interior of the extension piece.

7. The pressure device for magnetic measurement according to claim 1, characterized in that: The top end of the top cap is used to be threadedly connected to the sample drive rod of the magnetic measuring equipment, the top end of the main body is threadedly connected to the top cap, and the bottom end of the main body is used to be threadedly connected to the top end of the extension piece when using the MPMS DC test; the top cap has a regular hexagonal prism portion, and the outer surface of the regular hexagonal prism portion can be snapped into the wrench socket.

8. The pressure device for magnetic measurement according to claim 1, characterized in that: It also includes a force transmission member, a through hole is opened between the top end face of the top cap and the pressing surface, the force transmission member is used to pass through the through hole before the top cap is fixed to the main body, the top end of the force transmission member is used to be fixedly connected to the pressure shaft of the pressure device, and the bottom end of the force transmission member is used to contact the top end face of the pressure member.

9. The pressure device for magnetic measurement according to claim 8, characterized in that: The diameter of the channel is larger than the diameter of the sample cavity.

10. The pressure device for magnetic measurement according to claim 1, characterized in that: The sample cavity is used to accommodate the standard pressure substance and the fluid medium, which are arranged in sequence from bottom to top. The outside of the sample is fixedly surrounded by a pressure-discharging material, and the sample and the pressure-discharging material are both placed in the fluid medium.

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