A coupling two-axis piezoelectric displacement stage for transmission electron microscope

Abstract

This invention discloses a coupled biaxial piezoelectric displacement stage for transmission electron microscopy, comprising a mechanical displacement stage, a biaxial piezoelectric displacement stage, and a sample clamping end. The biaxial piezoelectric displacement stage includes an X-axis base, an X-axis piezoelectric displacement stage, a Y-axis base, and a Y-axis piezoelectric displacement stage. The X-axis output end of the mechanical displacement stage is connected to the X-axis base. The X-axis base is connected to the X-axis piezoelectric displacement stage via an X-axis piezoelectric stack and an X-axis flexible hinge structure. The X-axis piezoelectric displacement stage is connected to the Y-axis base. The Y-axis base is connected to the sample clamping end via a Y-axis piezoelectric stack and a Y-axis flexible hinge structure. The X-axis piezoelectric stack generates a driving force on the X-axis flexible hinge structure, causing the biaxial piezoelectric displacement stage to move the sample in the X-axis direction through the sample clamping end. The Y-axis piezoelectric stack generates a driving force on the Y-axis flexible hinge structure, causing the biaxial piezoelectric displacement stage to move the sample in the Y-axis direction through the sample clamping end. The displacement stage provided by this invention can achieve stable displacement at the nanometer level, with large holding force and long stroke.

Description

[0001] This invention claims priority to Chinese Patent Application No. 2026112599295, filed on August 19, 2026, entitled "A Coupled Biaxial Piezoelectric Displacement Stage for Transmission Electron Microscopy", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention discloses a coupled biaxial piezoelectric displacement stage for transmission electron microscopes, belonging to the technical field of electron microscope sample support devices. Background Technology

[0003] The sample stage of a transmission electron microscope (TEM) is a precise and multifunctional displacement stage, an extremely critical and delicate component. The sample itself must be located within an extremely narrow space (usually a vacuum) inside the microscope cylinder, and all operations on the sample (movement, tilting, heating, cooling, etc.) are performed through this stage. It needs to translate in the X and Y directions with a precision typically at the nanometer level to ensure the sample remains on the focal plane of the objective lens; any minute vibration or drift will result in image blurring. Furthermore, the displacement stage must possess sufficient holding force and a sufficient displacement stroke.

[0004] Mechanical displacement stages are limited by transmission accuracy and other factors, making it difficult to achieve high-precision and stable displacement at the nanometer level. Piezoelectrically driven displacement stages, on the other hand, can achieve precise displacement at the nanometer level, but this type of displacement stage has two problems: large holding force but small displacement stroke and large displacement stroke but small holding force.

[0005] CN120048710A discloses a displacement stage, whose sample stage coupling assembly includes a static sample stage and an in-situ tensile stage. It only realizes the coupling of two sample stages, overcoming the lack of a suitable tensile stage in conventional electron microscopes, but neither of them solves the problem of nanometer-level motion accuracy of the sample stage.

[0006] The purpose of this invention is to provide a displacement stage that achieves stable displacement at the nanometer level and has a strong holding force. Summary of the Invention

[0007] To achieve the above objectives, the present invention first provides a coupled biaxial piezoelectric displacement stage for a transmission electron microscope (TEM). The coupled biaxial piezoelectric displacement stage for the TEM includes a mechanical displacement stage and a biaxial piezoelectric displacement stage between the X-axis output end and the sample clamping end of the mechanical displacement stage. The biaxial piezoelectric displacement stage includes an X-axis base, an X-axis piezoelectric displacement stage located on the X-axis base, a Y-axis base, and a Y-axis piezoelectric displacement stage located on the Y-axis base. The X-axis output end of the mechanical displacement stage is connected to the X-axis base. The X-axis base is connected via an X-axis piezoelectric stack and an X-axis piezoelectric displacement stage arranged thereon. The flexible hinge structure is connected to the X-axis piezoelectric displacement stage, which is connected to the Y-axis base. The Y-axis base is connected to the sample clamping end via a Y-axis piezoelectric stack and a Y-axis flexible hinge structure arranged thereon. When the coupled biaxial piezoelectric displacement stage for transmission electron microscope is working, the driving force generated by the X-axis piezoelectric stack on the X-axis flexible hinge structure causes the biaxial piezoelectric displacement stage to move the sample in the X-axis direction through the sample clamping end, and the driving force generated by the Y-axis piezoelectric stack on the Y-axis flexible hinge structure causes the biaxial piezoelectric displacement stage to move the sample in the Y-axis direction through the sample clamping end.

[0008] In a preferred embodiment, the X-axis output end of the mechanical displacement stage is connected to the cylindrical surface and stepped surface of the X-axis base through an inner circular hole, screw holes on the end face and side face of the inner circular hole, and the inner circular hole of the mechanical displacement stage and the cylindrical surface of the X-axis base are coaxially fitted through a shaft hole. The end face of the inner circular hole of the mechanical displacement stage and the stepped surface of the X-axis base define the X-axis axial position, and the screw holes on the side face of the inner circular hole of the mechanical displacement stage lock the cylindrical surface of the X-axis base.

[0009] In a preferred embodiment, the X-axis piezoelectric displacement stage is connected to the cylindrical surface, stepped surface, and pin groove of the Y-axis base along the X-axis direction via an inner hole, an inner hole end face, a pin, and a set screw. The inner hole of the X-axis piezoelectric displacement stage and the cylindrical surface of the Y-axis base are coaxially fitted through a shaft hole. The inner hole end face and the stepped surface define the X-axis position, the side pin groove and the inner hole side pin define the circumferential position, and the set screw locks the cylindrical surface of the Y-axis base through the threaded hole on the inner hole side.

[0010] In a preferred embodiment, a piezoelectric stack and a flexible hinge structure are respectively provided on the X-axis base and the Y-axis base from the proximal end to the distal end. The proximal end of the flexible hinge is connected to the piezoelectric stack, and the distal end is connected to the biaxial piezoelectric displacement stage. In this invention, "proximal end" refers to the direction near the mechanical displacement stage, and "distal end" refers to the direction near the sample clamping end.

[0011] In a more preferred embodiment, a displacement sensor is mounted on the side of the piezoelectric stack to provide real-time feedback on the displacement of the displacement platform, thus forming a closed-loop control.

[0012] In a preferred embodiment, the bottom of the X-axis piezoelectric displacement stage is provided with a guide groove and a guide block fixed on the X-axis base, and an elastic roller is provided above the X-axis piezoelectric displacement stage to press its upper surface, so that the X-axis piezoelectric displacement stage moves along the X-axis direction.

[0013] In a preferred embodiment, the X-axis flexible hinge structure and the Y-axis flexible hinge structure are thin-walled structures, in the form of six symmetrically distributed cuboids. The connections with the base and the piezoelectric displacement platform are rounded. Under the thrust of the piezoelectric ceramic, the flexible hinge structure undergoes elastic deformation, and the base and the piezoelectric displacement platform generate a relative displacement within the micrometer level. After the piezoelectric ceramic is de-energized and returns to its initial state, the base and the piezoelectric displacement platform return to their initial positions under the elastic deformation force of the flexible hinge structure.

[0014] In a preferred embodiment, the flexible hinge structure is made of a copper alloy with a beryllium content of 1.8% to 2.0%.

[0015] In a preferred embodiment, the X-axis piezoelectric stack has dimensions of 3.5×3.5×7mm, a stroke of 9μm, and an X-axis thrust of 800N; the Y-axis piezoelectric stack has dimensions of 2×3×5mm, a stroke of 5μm, and a Y-axis thrust of 300N.

[0016] Secondly, the present invention provides a method for controlling the displacement of the observed sample using the coupled biaxial piezoelectric displacement stage for transmission electron microscopy, the method comprising the following steps: (1) When searching for samples of interest over a wide range at low magnification, use a mechanical stage to move the sample with a precision of more than 100 nm; (2) When locking onto the sample of interest and magnifying it for observation, use a piezoelectric displacement stage to move the sample with a precision of less than 100 nm.

[0017] This invention provides a coupled biaxial piezoelectric displacement stage for transmission electron microscopy, solving two types of technical problems in sample displacement in existing technologies: the difficulty of achieving stable nanometer-level displacement with mechanical displacement stages; and the problems of large holding force but small stroke, and large stroke but small holding force with piezoelectric displacement stages. This invention adds a piezoelectric displacement stage based on a flexible hinge structure to the moving end of the mechanical displacement stage, employing a coupled motion scheme. That is, for displacements above the nanometer level, the mechanical displacement stage is used to perform the displacement requirements; for displacements below the nanometer level, the piezoelectric displacement stage based on the flexible hinge structure is used to perform the displacement requirements. The technical solution of this invention combines the advantages of both mechanical and piezoelectric displacement stages, effectively solving the technical problems of the difficulty of achieving stable sub-nanometer displacement with mechanical displacement stages, and the problems of large holding force but small stroke, and large stroke but small holding force with piezoelectric displacement stages. Attached Figure Description

[0018] Figure 1 Overall assembly view of the mechanical displacement stage and the biaxial piezoelectric displacement stage along the X-axis; Figure 2 View of the connection point between the X-axis of the mechanical stage and the X-axis of the biaxial piezoelectric displacement stage; Figure 3 View showing the connection relationships between the X-axis mechanical stage, the X-axis piezoelectric displacement stage, and the Y-axis piezoelectric displacement stage; Figure 4 X-axis base and bottom structure view of X-axis piezoelectric displacement stage; Figure 5 Schematic diagram of the fit between the guide groove, guide block, and elastic roller; Figure 6 Y-axis base structure view; Figure 7 Schematic diagram of the X-axis piezoelectric stack; Figure 8 Schematic diagram of the Y-axis piezoelectric stack; Figure 9 Schematic diagram of the connections between the components of the biaxial piezoelectric displacement stage; Figure 10 Schematic diagram of the motion direction of the biaxial piezoelectric displacement stage; Figure 11 Cross-sectional view of a biaxial piezoelectric displacement stage.

[0019] In the picture: 1-X-axis output end of mechanical displacement stage; 2-X-axis of biaxial piezoelectric displacement stage; 3-Y-axis of biaxial piezoelectric displacement stage; 4-Spring backlash-free bearing; 5-Elastic roller; 6. X-axis piezoelectric stack; 7. X-axis base; 8. X-axis flexible hinge structure; 9. X-axis displacement platform; 10. Guide block; 11. Guide groove; 12. Y-axis displacement platform; 13. Y-axis piezoelectric stack; 14. Y-axis base; 15. Y-axis flexible hinge structure; 16. Pin slot. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result of the description. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of protection defined by the claims of the present invention.

[0021] The mechanical displacement stage of this invention has five axes, wherein the X-axis extends and retracts along the inner wall of the vacuum tube. A sealed ball joint is located at the end of the X-axis vacuum tube near the sample chamber. Using this ball joint as the origin, the Y, Z, and R axes can all drive the X-axis vacuum tube away from the sample chamber. This invention adds a biaxial piezoelectric displacement stage based on a flexible hinge structure between the end of the X-axis movement and the sample clamping end of the mechanical displacement stage.

[0022] Figure 1 An overall assembly view of the mechanical displacement stage X-axis output end and the biaxial piezoelectric displacement stage X-axis in the coupled biaxial piezoelectric displacement stage of the present invention is given; it can be seen that the mechanical displacement stage X-axis output end 1 and the biaxial piezoelectric displacement stage X-axis 2 are sleeved together to form a long rod-shaped structure and are equipped with a protective shell.

[0023] Figure 2 A view of the connection between the X-axis output end of the mechanical stage and the X-axis of the biaxial piezoelectric displacement stage is given. As can be seen from the figure, the X-axis 2 of the biaxial piezoelectric displacement stage includes an X-axis base 7, an X-axis piezoelectric stack 6, an X-axis flexible hinge structure 8, an X-axis displacement platform 9 located on the X-axis base 7, and a spring-backlash-free bearing 4 located at the X-axis output end of the mechanical stage.

[0024] Figure 3 The connection relationship of the mechanical displacement stage X-axis output end 1, the biaxial piezoelectric displacement stage X-axis 2, and the biaxial piezoelectric displacement stage Y-axis 3 of the present invention is given. The mechanical displacement stage X-axis output end 1 and the biaxial piezoelectric displacement stage X-axis 2 are connected in the X-axis direction. The bottom of the biaxial piezoelectric displacement stage X-axis 2 has a guide groove 11 and a guide block 10 fixed on the X-axis base. An elastic roller 5 is located above the biaxial piezoelectric displacement stage X-axis 2 to press its upper surface, so that the biaxial piezoelectric displacement stage X-axis 2 can move stably along the X-axis direction. The elastic roller 5 presses against the upper plane of the X-axis 2 of the biaxial piezoelectric displacement stage. The guide groove 11 is located at the bottom of the X-axis 2 structure, meaning the elastic roller 5 and the guide groove 11 (or guide block 10) are positioned opposite each other. The elastic roller 5 presses the X-axis 2 towards the guide groove 11, thus preventing the guide block 10 from disengaging from the guide groove 11 and ensuring that the guide block 10 remains within the guide groove 11. This ensures that the X-axis 2 of the biaxial piezoelectric displacement stage can move stably along the X-axis direction. Specifically, the elastic roller 5 presses against the X-axis displacement platform 9, and the guide groove 11 is formed on the X-axis displacement platform 9. The X-axis 2 of the biaxial piezoelectric displacement stage is connected to the perpendicular side of the Y-axis 3 of the biaxial piezoelectric displacement stage, allowing the Y-axis to move in the Y-axis direction perpendicular to the X-axis.

[0025] Figure 4 A structural view of the bottom of the X-axis of the biaxial piezoelectric displacement stage of the present invention is provided. It can be seen that the X-axis piezoelectric stack 6, the X-axis flexible hinge structure 8, the X-axis displacement platform 9, the guide groove 11 at the bottom of the X-axis structure of the biaxial piezoelectric displacement stage 2 are arranged along the X-axis direction on the X-axis base 7, and the guide block 10 that cooperates with it to move the X-axis of the biaxial piezoelectric displacement stage 2 along the X-axis direction. The guide block 10 is fixed on the X-axis base 7, and an elastic roller 5 is provided on the other side of the X-axis structure of the biaxial piezoelectric displacement stage 2.

[0026] Figure 4The inner circular hole at the end of the X-axis piezoelectric displacement stage can also be seen. The inner circular hole is used to connect with the cylindrical surface of the Y-axis base 14, which is perpendicular to the extension direction, through a shaft hole, so as to transmit the movement of the X-axis of the biaxial piezoelectric displacement stage to the Y-axis base.

[0027] Figure 5 and Figure 11 A schematic diagram of the guide groove, guide block, and elastic roller is provided. It can be seen that an elastic roller 5 is provided at the top of the X-axis displacement platform 9, and a guide groove 11 is provided at the bottom of the X-axis displacement platform 9. The guide groove 11 cooperates with the guide block 10 on the X-axis base. The elastic roller 5 presses against the upper plane of the X-axis displacement platform 9, so that the X-axis 2 of the biaxial piezoelectric displacement stage can move stably along the X-axis direction.

[0028] Figure 6 A structural view of the Y-axis of the biaxial piezoelectric displacement stage is provided. The Y-axis is a horizontally lying T-shaped structure. The laterally protruding portion connects with the inner circular hole at the end of the X-axis piezoelectric displacement stage via a shaft hole. A pin slot 16 is used to fix the connection between the Y-axis and X-axis of the biaxial piezoelectric displacement stage using a pin and locking it with a set screw. The main body of the Y-axis forms a Y-axis base. On the Y-axis base 14, a Y-axis piezoelectric stack 13, a Y-axis flexible hinge structure 15, and a Y-axis displacement platform 12 located on the Y-axis base 14 are arranged along the Y-axis direction. Through this structure and configuration, the Y-axis base is fixed, and the Y-axis displacement platform 12 can move along the Y-axis under the action of the piezoelectric stack.

[0029] Figure 7 A schematic diagram of the X-axis piezoelectric stack is provided. Figure 8A schematic diagram of the Y-axis piezoelectric stack is provided. The X-axis piezoelectric stack is placed in the X-axis piezoelectric stack slot, and the Y-axis piezoelectric stack is placed in the Y-axis piezoelectric stack slot. The piezoelectric stack described in this invention, also commonly referred to as a piezoelectric stack or piezoelectric ceramic stack, is a high-performance actuator that utilizes the piezoelectric effect to directly convert electrical energy into mechanical energy, achieving high precision, high frequency response, and small displacement motion. Essentially, it is a drive source. This invention integrates a precision motion platform for two piezoelectric stack actuators through flexible hinge connection technology, converting the linear motion of the two stacks into translational motion of the platform in two directions. This enables nanometer-level precision motion in two orthogonal directions (typically the X and Y axes). Therefore, the coupled biaxial piezoelectric displacement stage for transmission electron microscopy provided by this invention is essentially a two-dimensional piezoelectric micro / nano positioning platform. The X-axis piezoelectric stack has dimensions of 3.5×3.5×7mm, and the Y-axis piezoelectric stack has dimensions of 2×3×5mm. Its characteristics include small displacement stroke (9μm for X-axis, 5μm for Y-axis) and large holding force (800N thrust for X-axis, 300N thrust for Y-axis). Specifically, the biaxial piezoelectric displacement stage X-axis 2 is connected to the X-axis output end 1 of the mechanical displacement stage, and the biaxial piezoelectric displacement stage Y-axis 3 is connected to the biaxial piezoelectric displacement stage X-axis 2. Both the biaxial piezoelectric displacement stages X-axis 2 and Y-axis 3 have flexible hinge structures, and the piezoelectric stacks are fixed within the flexible hinge structure slots by set screws. Figure 9 and Figure 10 A schematic diagram of the connection of each component of the biaxial piezoelectric displacement stage and a schematic diagram of the motion direction under working conditions are given. Based on... Figure 9 The X-axis piezoelectric stack 6 is placed in the X-axis piezoelectric stack slot, and the Y-axis piezoelectric stack 13 is placed in the Y-axis piezoelectric stack slot, with the piezoelectric stacks pre-tightened by set screws. The X-axis flexible hinge structure 8 is placed in the X-axis flexible hinge structure slot, and the Y-axis flexible hinge structure 15 is placed in the Y-axis flexible hinge structure slot.

[0030] The flexible hinge structure is connected to and driven by the piezoelectric stack. Each axis has six flexible hinge segments. Figure 9 The X-axis flexible hinge structure 8 and Y-axis flexible hinge structure 15 are both three segments of a flexible hinge structure, stacked together with the other three segments, symmetrically distributed on both sides between the moving platform and the base. The connection between the piezoelectric stack and the flexible hinge structure is located between the base and the moving platform. The flexible hinge connection described in this invention refers to a platform supported by an integral flexible mechanism, with two piezoelectric stacks placed horizontally within the platform base. Each stack acts on a precise flexible hinge mechanism via push rods, utilizing the elastic deformation of the material to achieve frictionless and gapless movement. When the X-axis stack extends, it causes the platform to translate purely in the X direction through the flexible mechanism; the same applies to the Y-axis.

[0031] With the above configuration, the X-axis output end 1 of the mechanical displacement stage is connected to the X-axis base 7 of the biaxial piezoelectric displacement stage. The piezoelectric stack on the X-axis base 7 is connected to a flexible hinge structure, and then connected to the X-axis displacement platform 9 through the flexible hinge structure. The X-axis displacement platform 9 is connected to the Y-axis base 14. Similarly, the piezoelectric stack on the Y-axis base 14 is connected to a flexible hinge structure, and then connected to the Y-axis displacement platform 12 through the flexible hinge structure. Finally, the Y-axis displacement platform 12 is connected to the sample clamping end. This achieves the connection from the X-axis output end 1 of the mechanical displacement stage to the sample clamping end. In this invention, the connection direction is from the proximal end to the distal end.

[0032] like Figure 10 As shown, during sample viewing, the sample is loaded onto the sample clamping end, which is fixed to the Y-axis displacement platform. When the sample needs to perform precise displacement in the Y-axis direction, the Y-axis piezoelectric stack directly drives the sample to perform precise displacement along the Y-axis. When the sample needs to perform precise displacement along the X-axis direction, the X-axis piezoelectric stack directly drives the X-axis displacement platform to move along the X-axis, thereby causing the entire Y-axis piezoelectric module to perform precise displacement along the X-axis, and thus causing the sample to perform precise displacement along the X-axis.

Claims

1. A coupled biaxial piezoelectric displacement stage for transmission electron microscopy, characterized in that, The coupled biaxial piezoelectric displacement stage for transmission electron microscopy includes a mechanical displacement stage and a biaxial piezoelectric displacement stage between the X-axis output end and the sample clamping end of the mechanical displacement stage. The biaxial piezoelectric displacement stage includes an X-axis base, an X-axis piezoelectric displacement stage located on the X-axis base, a Y-axis base, and a Y-axis piezoelectric displacement stage located on the Y-axis base. The X-axis output end of the mechanical displacement stage is connected to the X-axis base, and the X-axis base is connected to the X-axis piezoelectric displacement stage via an X-axis piezoelectric stack and an X-axis flexible hinge structure arranged thereon. The X-axis piezoelectric displacement stage is connected to the Y-axis base. The Y-axis base is connected to the sample clamping end via a Y-axis piezoelectric stack and a Y-axis flexible hinge structure arranged thereon. When the coupled biaxial piezoelectric displacement stage for transmission electron microscope is working, the X-axis piezoelectric stack generates a driving force on the X-axis flexible hinge structure, causing the biaxial piezoelectric displacement stage to move the sample in the X-axis direction through the sample clamping end. The Y-axis piezoelectric stack generates a driving force on the Y-axis flexible hinge structure, causing the biaxial piezoelectric displacement stage to move the sample in the Y-axis direction through the sample clamping end. The bottom of the X-axis piezoelectric displacement stage is provided with a guide groove and a guide block fixed on the X-axis base. An elastic roller is provided above the X-axis piezoelectric displacement stage to press the upper surface of the X-axis piezoelectric displacement stage, so that the X-axis piezoelectric displacement stage moves along the X-axis direction.

2. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 1, characterized in that, The X-axis output end of the mechanical displacement stage is connected to the cylindrical surface and stepped surface of the X-axis base through an inner circular hole, screw holes on the end face and side face of the inner circular hole. The inner circular hole of the mechanical displacement stage and the cylindrical surface of the X-axis base are coaxially fitted through a shaft hole. The end face of the inner circular hole of the mechanical displacement stage and the stepped surface of the X-axis base define the X-axis position. The screw holes on the side face of the inner circular hole of the mechanical displacement stage lock the cylindrical surface of the X-axis base.

3. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 1, characterized in that, The X-axis piezoelectric displacement stage is connected to the cylindrical surface, stepped surface, and pin groove of the Y-axis base along the X-axis direction through an inner hole, the end face of the inner hole, a pin, and a set screw. The inner hole of the X-axis piezoelectric displacement stage and the cylindrical surface of the Y-axis base are coaxially fitted through a shaft hole. The end face of the inner hole and the stepped surface define the X-axis position, and the side pin groove and the side pin of the inner hole define the circumferential position. The set screw locks the cylindrical surface of the Y-axis base through the threaded hole on the side of the inner hole.

4. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 1, characterized in that, A piezoelectric stack and a flexible hinge structure are respectively arranged on the X-axis base and the Y-axis base from the proximal end to the distal end. The proximal end of the flexible hinge is connected to the piezoelectric stack, and the distal end is connected to the biaxial piezoelectric displacement stage.

5. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 4, characterized in that, The piezoelectric stack is equipped with a displacement sensor on its side, which provides real-time feedback on the displacement of the displacement platform to form a closed-loop control.

6. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 1, characterized in that, The X-axis and Y-axis flexible hinge structures are thin-walled structures, consisting of six symmetrically distributed cuboids. The connections to the base and piezoelectric displacement platform are rounded. Under the thrust of the piezoelectric ceramic, the flexible hinge structures undergo elastic deformation, resulting in a relative displacement of less than micrometers between the base and the piezoelectric displacement platform. After the piezoelectric ceramic is de-energized and returns to its initial state, the base and piezoelectric displacement platform return to their initial positions under the elastic deformation force of the flexible hinge structure.

7. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 6, characterized in that, The flexible hinge structure is made of a copper alloy with a beryllium content of 1.8% to 2.0%.

8. The coupled biaxial piezoelectric displacement stage for transmission electron microscopy according to claim 1, characterized in that, The X-axis piezoelectric stack has dimensions of 3.5×3.5×7mm, a stroke of 9μm, and a thrust of 800N. The Y-axis piezoelectric stack has dimensions of 2×3×5mm, a stroke of 5μm, and a thrust of 300N.

9. A method for controlling the displacement of an observed sample using a coupled biaxial piezoelectric displacement stage for transmission electron microscopy as described in any one of claims 1-8, characterized in that, The method includes the following steps: (1) When searching for samples of interest over a wide range at low magnification, use a mechanical stage to move the sample with a precision of more than 100 nm; (2) When locking onto the sample of interest and magnifying it for observation, a piezoelectric displacement stage is used to move the sample with a precision of less than 100 nm.

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