Continuous temperature control transmission electron microscope sample rod without heating coil

Abstract

The invention relates to a continuous temperature control transmission electron microscope sample rod without a heating coil. The continuous temperature control transmission electron microscope sample rod comprises a rear-end low-temperature Dewar with an inner-outer double-layer structure; the inner end of the sample rod outer rod is connected with the rear-end low-temperature Dewar in a sealing manner, and the outer end of the sample rod outer rod extends outwards; the inner end of the inner rod of the sample rod extends into the rear-end low-temperature Dewar and realizes heat conduction with the rear-end low-temperature Dewar, and the outer end of the inner rod of the sample rod extends out of the outer rod of the sample rod along the axial direction; the sample rod front-end assembly comprises a front-end outer frame and a front-end metal block, the front-end outer frame is connected with the front end of the sample rod outer rod, the front-end metal block is connected with the sample rod inner rod, the front-end outer frame and the front-end metal block are fixed in a non-conductive mode, and a heating chip is fixedly placed on the front-end metal block. Compared with the prior art, a traditional heating coil is omitted, the sample pollution and temperature drift risks are reduced, and the stability, applicability and the like of an in-situ heating experiment of the transmission electron microscope are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission electron microscope sample holders and relates to a continuous temperature-controlled transmission electron microscope sample holder without a heating coil. Background Art

[0002] In-situ temperature-variable transmission electron microscopy (TEM) is a powerful tool for materials characterization. By adjusting the internal temperature of micro- and nanoscale samples in real time, it allows for simultaneous observation of multiple parameters, including material structure, morphology, and electromagnetic field distribution. TEM has extensive applications in fields such as materials science, semiconductors, microelectronics, energy, catalysis, chemistry, polymers, superconductivity, and ferromagnetism, exploring key physical issues such as alloy phase transitions, crystal growth, interfacial diffusion, thermal stability, structural evolution, and critical properties.

[0003] However, current in-situ temperature-variation technologies fall into two main categories: one involves continuous temperature variation from low temperature to room temperature, controlled by a low-temperature dewar, a heating resistor, and a closed-loop control system; the other involves continuous temperature variation from room temperature to high temperature, controlled by a ceramic high-temperature crucible, a resistance detector, and an open-loop control system. For example, CN201811649281.8 provides an in-situ cryogenic transmission electron microscope (TEM) sample holder suitable for high-frequency signal transmission. The device comprises a dewar, a transition chamber, a sample holder, a sample holder head, and a coaxial cable. The coaxial cable, comprised of four coaxial conductors, exits through the gap between the oxygen-free copper inner core and the outer rod and is connected to the outside through a flange and vacuum connector, enabling low-loss transmission of high-frequency signals in the 0-4 GHz range. A heating resistor is located at the front end of the inner core, and a temperature sensor is located near the sample holder. An external temperature controller provides closed-loop control of the sample temperature. However, this device cannot achieve high-temperature in-situ temperature variation. Furthermore, during the heating process, it is difficult to prevent the continuous volatilization of organic matter from the heating resistor, which can affect the electron microscope's vacuum system. In addition, both methods have certain limitations. First, many materials in research require continuous temperature change from low temperature to high temperature, which cannot be achieved by both methods. Second, the heating range of the heating crucible is too large, which can easily lead to large-scale temperature drift and affect the quality of data acquisition. Summary of the Invention

[0004] The purpose of the present invention is to provide a continuously temperature-controlled transmission electron microscope sample holder without a heating coil. Through a unique structural design, the low temperature is provided by the Dewar and transferred to the sample area through the heat-conducting structure, and the high temperature is heated by the micro-nano heating chip. In conjunction with the closed-loop PID temperature control system, precise temperature control from 95K to 800K is achieved.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A continuous temperature-controlled transmission electron microscope sample holder without a heating coil, comprising:

[0007] The rear end low temperature Dewar with an inner and outer double-layer structure;

[0008] The inner end of the sample rod outer rod is sealed with the rear low-temperature Dewar, and the outer end extends outward;

[0009] The inner end of the sample rod extends into the interior of the rear low-temperature Dewar and realizes heat conduction with the rear low-temperature Dewar, and the outer end extends axially out of the sample rod outer rod;

[0010] The front end assembly of the sample rod includes a front end outer frame and a front end metal block. The front end outer frame is connected to the front end of the outer rod of the sample rod, and the front end metal block is connected to the inner rod of the sample rod. The front end outer frame and the front end metal block are fixed in a non-conductive manner, and a heating chip is fixed on the front end metal block.

[0011] Furthermore, the shell of the rear low-temperature Dewar has an extension portion, on which an aviation plug is installed. The aviation plug is also electrically connected to the enameled wire. The enameled wire is arranged along the extension direction of the inner rod of the sample holder to the front metal block area, and is connected to the electrode of the heating chip through silver glue, forming a complete temperature control closed-loop circuit.

[0012] Furthermore, the connection between the extension portion and the outer rod of the sample rod is sealed by a flange and a sealing rubber ring.

[0013] Furthermore, the rear end low-temperature Dewar is made of aluminum alloy, the inner and outer double-layer structures are sealed, and a needle valve is reserved as an exhaust hole for vacuuming or filling with liquid nitrogen.

[0014] Furthermore, the inner rod of the sample holder and the outer rod of the sample holder are coaxially arranged without contact between them.

[0015] Furthermore, the outer end of the sample holder outer rod is connected to the front end outer frame by a copper alloy screw;

[0016] The outer end of the inner rod of the sample rod is softly connected to the front end metal block by welding copper wire.

[0017] Furthermore, a groove is processed on the front end metal block, the heating chip is embedded in the groove, and is pressed and fixed by a metal pressing sheet.

[0018] Furthermore, the front end outer frame and the front end metal block are connected by screws made of polytetrafluoroethylene.

[0019] Furthermore, the outer rod of the sample holder is provided with a guide pin and a positioning pin to facilitate matching with an electron microscope.

[0020] Furthermore, the heating chip is a planar resistive structure, and its temperature resistance can reach at least 800K.

[0021] The key to this invention's ability to achieve continuous temperature control from low temperatures (95K) to high temperatures (800K), overcoming the limitations of existing technologies that cannot accommodate both low and high temperature in-situ temperature changes, lies in two core innovations in its structural design and temperature control mechanism: 1. A dewar-chip dual heat source structure: a decoupled design of low-temperature heat conduction and high-temperature point heat sources. Existing temperature control systems typically rely on a single heat source (such as an integral heating filament or ceramic heating crucible), making it difficult to maintain the small-scale nature of the temperature control area and vacuum stability at high temperatures. The present invention cleverly introduces a "cold source-heat source separation" mechanism: the low temperature is provided by a liquid nitrogen cold source through the rear-end dewar, and the low temperature is effectively transferred to the sample area using an inner and outer double-layer structure and a heat-conducting inner rod, ensuring a low-temperature environment starting from 95K; the high temperature is completed by a locally embedded micro-nano heating chip. The chip is small in size, has a fast temperature control response, a localized heating area, and controlled heat diffusion, which can effectively support high-temperature requirements up to 800K. Through this structural separation method, thermal drift and system instability caused by large-scale heating are effectively avoided, while ensuring the reliability of high-temperature in-situ experiments in the high vacuum environment of the transmission electron microscope. ② The heating coil is eliminated and an embedded micro-nano heating chip + closed-loop PID control system is used. The traditional heating wire method is prone to organic volatilization and contamination of the vacuum system during the heating process, and the heating response speed is slow and the energy distribution is uneven. The present invention uses a planar resistive micro-nano heating chip instead, which has the following key advantages: small package size: it can be embedded in the micro-groove of the front metal block, with a compact structure and a precise heating area; fast heating and high resolution: the response speed is better than that of traditional heating wires, and it can be combined with temperature sensors to achieve fine control; closed-loop temperature control: through silver glue connection and closed-loop linkage with the external PID temperature control system, a highly responsive and stable temperature control system is formed; strong high-temperature resistance: the chip used can withstand temperatures up to 800K, far exceeding the upper temperature limit of traditional sample rod heating elements.

[0022] In summary, the present invention introduces the three-in-one structure of "low-temperature Dewar + thermally conductive inner rod + micro-nano heating chip", combines inorganic material connection, vacuum-compatible component design and closed-loop PID temperature control system, and completely breaks through the bottleneck of existing technology in "in-situ high-temperature temperature change" from three dimensions: temperature control principle, structural layout and material compatibility. It realizes wide, continuous and precise temperature control capability from low temperature to high temperature, and adapts to a wider range of in-situ characterization needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the in-situ sample holder for transmission electron microscopy;

[0024] Figure 2 Schematic diagram of the front end structure of the sample rod;

[0025] Figure 3 Schematic diagram of the temperature distribution of the heating chip;

[0026] Figure 4 This is a schematic diagram of temperature control logic;

[0027] Description of the marks in the figure:

[0028] 1-Evacuation hole; 2-Rear-end cryogenic dewar; 3-Reserved hole for plug; 4-Outer rod of sample holder; 5-Inner rod of sample holder; 6-Front end of sample holder; 7-Front end outer frame; 8-Front end metal block; 9-Groove; 10-Observation window; 11-PTFE screw. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0030] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] In the following embodiments or examples, any functional components or structures not specifically described, such as a heating chip (a commercially available product), are conventional components or structures used in the art to achieve corresponding functions.

[0033] In order to achieve precise temperature control from 95K to 800K and reduce the risk of sample contamination and temperature drift, the present invention provides a continuous temperature control transmission electron microscope sample holder without a heating coil. Figure 1 and Figure 2 As shown, including:

[0034] The rear end low temperature Dewar 2 has an inner and outer double layer structure;

[0035] The sample holder outer rod 4 has an inner end sealedly connected to the rear low-temperature Dewar 2 and an outer end extending outward;

[0036] The inner end of the sample holder inner rod 5 extends into the interior of the rear low-temperature Dewar 2 and realizes heat conduction with the rear low-temperature Dewar 2, and the outer end extends axially out of the sample holder outer rod 4;

[0037] The front end 6 component of the sample rod includes a front end outer frame 7 and a front end metal block 8. The front end outer frame 7 is connected to the front end of the sample rod outer rod 4, and the front end metal block 8 is connected to the sample rod inner rod 5. The front end outer frame 7 and the front end metal block 8 are fixed in a non-conductive manner, and a heating chip is fixed on the front end metal block 8.

[0038] Here, in the present invention, the “inner end” refers to the end close to the rear low-temperature Dewar 2 , and the “outer end” refers to the end away from the rear low-temperature Dewar 2 .

[0039] In some specific embodiments, the housing of the rear low-temperature dewar 2 has an extension with a reserved plug hole 3. This hole 3 allows for the installation of an aviation plug. The aviation plug is also electrically connected to an enameled wire, which extends along the inner rod 5 of the sample holder to the region of the front metal block 8 and is connected to the electrodes of the heater chip via silver glue. The aviation plug is connected to an external DC power supply, the power of which is controlled by a computer, forming a complete temperature-controlled closed-loop circuit.

[0040] In a more specific embodiment, the connection between the extension portion and the sample holder outer rod 4 is sealed by a flange and a sealing rubber ring.

[0041] In a more specific embodiment, the enameled wire is closely attached to the inner rod 5 of the sample rod and does not contact the outer rod 4 of the sample rod.

[0042] In some specific embodiments, the rear low-temperature Dewar 2 is made of aluminum alloy, the inner and outer double-layer structures are sealed, and a needle valve is reserved as the exhaust hole 1 for vacuuming or filling with liquid nitrogen.

[0043] In some specific embodiments, the sample rod inner rod 5 and the sample rod outer rod 4 are coaxially arranged without contact between them.

[0044] In some specific embodiments, the outer end of the sample holder outer rod 4 is connected to the front end outer frame 7 by a copper alloy screw;

[0045] The outer end of the sample rod inner rod 5 is softly connected to the front end metal block 8 by welding copper wire to ensure heat conduction from the inner end of the sample rod inner rod 5 to the front end metal block 8.

[0046] In some specific embodiments, a groove 9 is processed on the front metal block 8, and the heating chip is embedded in the groove 9 and is pressed and fixed by a metal pressing sheet.

[0047] In some specific embodiments, the front outer frame 7 and the front metal block 8 are connected by screws made of polytetrafluoroethylene.

[0048] In some specific embodiments, the sample holder outer rod 4 is further provided with a guide pin and a positioning pin to facilitate mechanical cooperation with the electron microscope.

[0049] In some specific embodiments, the heating chip is a planar resistive structure, and its temperature resistance can reach at least 800K.

[0050] The above embodiments may be implemented individually or in any combination of two or more.

[0051] The above implementation is described in more detail below with reference to specific examples.

[0052] Example 1:

[0053] like Figures 1 to 4 As shown, the present invention provides a continuous temperature-controlled transmission electron microscope sample holder without a heating coil, comprising a rear low-temperature Dewar 2, a sample holder outer rod 4, a sample holder inner rod 5, a sample holder front end 6, and a heating chip.

[0054] The rear end cryogenic Dewar 2 is a double-layer aluminum alloy structure with inner and outer layers sealed by annular welding and equipped with a needle-shaped evacuation hole 1 for vacuuming or filling with liquid nitrogen. This structure has excellent low temperature maintenance performance.

[0055] One end of the sample rod inner rod 5 is inserted into the low-temperature Dewar and firmly connected to it by welding to achieve low-temperature conduction; the other end passes through the entire sample rod and extends to the front end area, and is welded to the front end metal block 8 by copper wire soft connection for heat transfer.

[0056] The sample holder outer rod 4 and the sample holder inner rod 5 are coaxially distributed and do not touch each other. Guide pins and positioning pins are provided on the sample holder outer rod 4 to facilitate matching and installation with the transmission electron microscope.

[0057] An aviation plug is provided at the extension of the rear low-temperature Dewar 2. The inside of the aviation plug is electrically connected to the enameled wire. The enameled wire is arranged along the inner rod 5 of the sample holder to the area where the heating chip is located at the front end, and is connected to the electrode of the heating chip through silver glue, forming a complete temperature control closed-loop circuit.

[0058] The front end structure of the sample rod is as follows Figure 2 As shown, it includes a front outer frame 7 and a front metal block 8. The front outer frame 7 is connected to the sample holder outer rod 4 using copper alloy screws; the front metal block 8 is connected to the sample holder inner rod 5 by copper wire welding. Both are secured together with a non-conductive polytetrafluoroethylene screw 11 to prevent current leakage and thermal short circuits.

[0059] A micro-nano-sized heater chip is embedded in a groove 9 of the front metal block 8 and secured with a metal pressing plate. The chip features a planar resistive structure that can withstand temperatures of at least 800K, offering advantages such as rapid heating, sensitive response, and high space efficiency. Furthermore, the front metal block 8 includes an observation window 10 adjacent to the groove 9 for observation during TEM experiments.

[0060] In actual use, users can secure the sample to the center of the chip using ion beam micromachining (FIB) and insert the entire sample holder into the transmission electron microscope chamber. After startup, low temperature is provided by the rear liquid nitrogen dewar and transmitted to the front area through the inner rod of the sample holder; high temperature is achieved by energizing the heating chip. The system detects temperature through the resistance feedback changes of the heating chip and uses a PID control system for closed-loop regulation, achieving continuous and stable temperature variation between 95K and 800K. This avoids large-scale temperature increases in the heating resistor or heating crucible, while achieving rapid temperature control at the low temperature end.

[0061] The temperature control circuit of the sample rod of this embodiment is as follows Figure 4 As shown, the resistance signal is detected, amplified, and then fed into the controller. The PID controller then generates a heating current regulation signal, achieving precise temperature control. The entire process offers fast temperature response and high stability, making it particularly suitable for in-situ research on heat-sensitive nanomaterials.

[0062] Furthermore, before implementing temperature control, the temperature-resistance curve of the heating chip was tested and fitted. Three data points were obtained, measuring the resistance at liquid nitrogen temperature (73K), the resistance in an ice-water mixture environment (273K), and the resistance at boiling water temperature (373K). Based on the temperature-resistance characteristics of the electrode material, a complete curve was derived. During the actual power-on process, the resistance change of the heating resistor was monitored in real time to determine the actual temperature at the sample. Using the resistor's feedback, a PID control system was established to achieve continuous variable temperature control.

[0063] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A continuous temperature controlled transmission electron microscope sample holder without a heating coil, characterized in that: include: The rear end low temperature Dewar with an inner and outer double layer structure; The inner end of the sample rod outer rod is sealed with the rear low-temperature Dewar, and the outer end extends outward; The inner end of the sample rod extends into the interior of the rear low-temperature Dewar and realizes heat conduction with the rear low-temperature Dewar, and the outer end extends axially out of the sample rod outer rod; The front end assembly of the sample rod includes a front end outer frame and a front end metal block. The front end outer frame is connected to the front end of the outer rod of the sample rod, and the front end metal block is connected to the inner rod of the sample rod. The front end outer frame and the front end metal block are fixed in a non-conductive manner, and a heating chip is fixed on the front end metal block.

2. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The shell of the rear low-temperature Dewar has an extension portion, on which an aviation plug is installed. The aviation plug is also electrically connected to the enameled wire. The enameled wire is arranged along the extension direction of the inner rod of the sample holder to the front metal block area and is connected to the electrodes of the heating chip through silver glue, forming a complete temperature control closed-loop circuit.

3. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 2, characterized in that: The connection between the extension part and the outer rod of the sample rod is sealed by a flange and a sealing rubber ring.

4. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The rear end low temperature Dewar is made of aluminum alloy, and the inner and outer double-layer structures are sealed, and a needle valve is reserved as an exhaust hole for vacuuming or filling with liquid nitrogen.

5. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The inner rod of the sample holder and the outer rod of the sample holder are coaxially arranged without contact between them.

6. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The outer end of the sample holder outer rod is connected to the front end outer frame by a copper alloy screw; The outer end of the inner rod of the sample rod is softly connected to the front end metal block by welding copper wire.

7. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: A groove is processed on the front metal block, the heating chip is embedded in the groove, and is pressed and fixed by a metal pressing sheet.

8. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The front end outer frame and the front end metal block are connected by screws made of polytetrafluoroethylene.

9. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The outer rod of the sample holder is also provided with a guide pin and a positioning pin to facilitate matching with the electron microscope.

10. The continuous temperature-controlled transmission electron microscope sample holder without a heating coil according to claim 1, characterized in that: The heating chip is a planar resistive structure with a temperature resistance of at least 800K.

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