A method for rapid automatic rotation of a transmission electron microscope (TEM) sample based on electron backscatter diffraction (TKD-EBSD) crystal orientation information

Abstract

This invention discloses a rapid and automatic sample rotation method for transmission electron microscopy (TEM) based on crystal orientation information obtained from electron backscatter diffraction (TKD-EBSD). The steps include: acquiring complete crystallographic information of each grain in the TEM sample; calculating the theoretical tilt angle parameters (α, β) required for the TEM sample stage; loading the TEM sample to be characterized into the TEM sample holder, and then transferring the sample holder into the TEM; making preliminary adjustments to the TEM parameters; controlling the tilt of the sample stage based on the theoretical tilt angle parameters (α, β); moving the target grain to the image center, and making secondary adjustments to the sample stage zone axis based on the alignment accuracy of the target zone axis; and completing the microstructure analysis of the target grain. This invention combines theoretical tilt angle analysis with the TEM sample stage tilting function, ultimately achieving precise and rapid tilting of the target zone axis of the grain of interest in the TEM, thus providing a reliable technical guarantee for efficient and accurate microscopic analysis.

Description

Technical Field

[0001] This invention relates to the field of electron microscopy and materials microstructure research, specifically a rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information. Background Technology

[0002] Transmission electron microscopy (TEM) is a key instrument for characterizing the microstructure of materials, especially CS-TEM (Cs-TEM) with spherical aberration correction systems. Its sub-angstrom-level ultra-high resolution imaging has revolutionized the study of atomic-scale material microstructures. However, precise alignment of the sample's zone axis (aligning a specific zone axis with the electron beam incident direction) is a prerequisite for acquiring atomic-scale microscopic images. Only when aligned with the appropriate zone axis can the atomic-scale structure and defects of the material be observed. Therefore, the efficiency and accuracy of the alignment directly affect the overall time cost and effectiveness of TEM characterization, especially in batch analysis scenarios involving multiple grains and regions. Thus, developing fast, accurate, and stable alignment methods is crucial for improving TEM-related research.

[0003] Currently, traditional / mainstream TEM rotation methods mainly rely on the identification of the Kikuchi zone and manual rotation. This involves obtaining the Kikuchi zone of the target grain through diffraction patterns, then tilting the sample rod accordingly until the target Kikuchi pole is at the center of the diffraction pattern, thus aligning the zone axis. The core bottlenecks and technical difficulties lie in the difficulty of crystal information analysis and the need for repeated adjustments during rotation, resulting in a lengthy overall process that fails to meet the demands of efficient characterization. Existing methods suffer from the following main problems:

[0004] 1) Existing methods follow the logic of "first analyzing crystal information, then gradually adjusting the tilt angle." The acquisition of crystal information is highly dependent on the quality of the Kikuchi zone signal. If the sample is too thin or too thick, the Kikuchi zone becomes blurred, making it difficult to identify the zone axis. Simultaneously, the rotation operation heavily relies on the operator's experience and crystallographic knowledge, and is limited by the mechanical tilt range of the sample holder. Operators often cannot quickly and accurately predict the position and accessibility of the target zone axis, easily leading to a process of repeated trial and error.

[0005] 2) Due to the lack of precise calculation data for the tilt angle, operators can only rely on repeated attempts based on the Kikuchi belt analysis results: tilting the sample stage in small steps, then collecting Kikuchi belt patterns, and comparing signal changes to determine the adjustment direction. This "tilt-collection-comparison" cycle relies entirely on manual experience and lacks quantitative guidance, resulting in dozens of repetitions for a single rotation, with poor repeatability between different personnel. Furthermore, for polycrystalline materials with fine grains, the image contrast changes rapidly during rotation, making accurate positioning difficult and further increasing the complexity of the rotation.

[0006] 3) Repeated electron beam irradiation (used to collect Kikuchi flower samples) and sample stage tilting during shaft rotation will exacerbate electron beam damage and contamination on the sample surface, and may even lead to damage to the crystal structure, amorphization and deposition contamination. This not only requires additional time to deal with sample contamination, but may also affect the authenticity of subsequent structural characterization data, further reducing characterization efficiency and increasing the difficulty of structural analysis.

[0007] In recent years, some newly developed crystal rotation methods and software have enabled rapid zone axis rotation based on Kikuchi zone or electron diffraction spectra combined with transmission electron microscopy (TEM) stage tilting. These methods have found wide application, particularly in nanomaterials and electron beam-sensitive materials. However, these methods require electron diffraction operations on individual crystal grains within the TEM to obtain Kikuchi zone or diffraction patterns, thus acquiring the current orientation information of the target crystal grain before further zone axis rotation. This approach demands that the operator be relatively familiar with the crystal information of the sample being analyzed, and each experiment can only complete the orientation analysis of a single target crystal grain. Therefore, it increases the technical difficulty and remains inefficient in terms of target grain finding and batch processing of multiple crystal grains. More importantly, current methods, whether traditional manual or software-assisted automatic, rely on on-site TEM experiments to determine subsequent zone axis rotation and related operations. They cannot pre-analyze the orientation of individual crystal grains in the sample, significantly reducing TEM characterization efficiency and increasing the difficulty and time required for post-analysis. This is undoubtedly a huge waste of scientific research resources for TEM, which often costs millions or even tens of millions of dollars, and it also causes a lot of problems such as tight machine time.

[0008] In summary, existing TEM rotation methods suffer from high technical difficulty, high reliance on experience, difficulty in batch processing, and inability to perform pre-analysis. These factors greatly increase the difficulty of TEM experiments and data analysis, and to a large extent contribute to problems such as low TEM operational effectiveness and limited machine time. Summary of the Invention

[0009] The purpose of this invention is to provide a rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on crystal orientation information from electron backscatter diffraction (TKD-EBSD), comprising the following steps:

[0010] Step 1) Clamp the transmission sample to be characterized onto the TKD-EBSD sample holder, and then place the TKD-EBSD sample holder with the transmission sample onto a scanning electron microscope with an EBSD system.

[0011] Step 2) Perform transmission electron backscattering diffraction information acquisition on the region of interest or the entire region of the transmission sample to obtain complete crystallographic information of each grain in the transmission sample;

[0012] Step 3) Using the automatic axis-finding function of the automatic axis-tilting software, input the desired maximum zone axis index. Based on the complete crystallographic information of each grain given by TKD-EBSD, automatically obtain the zone axis and the corresponding theoretical tilt angle parameters (α, β) with tilt angles α and β in the range of [±25, ±25]. Wherein, α and β are the rotation angles of the transmission electron microscope sample stage in two orthogonal dimensions, respectively.

[0013] Step 4) Load the transmission sample to be characterized into the transmission electron microscope sample holder, and then transfer the sample holder into the transmission electron microscope;

[0014] Step 5) Make preliminary adjustments to the transmission electron microscope (TEM) parameters to ensure that the transmitted sample is within the TEM field of view;

[0015] Step 6) Control the sample stage to tilt based on the theoretical tilt angle parameters (α, β);

[0016] Step 7) Move the target grain to the center of the image. Based on the alignment accuracy of the target zone axis, make a second fine adjustment to the sample stage zone axis (using the α and β tilt buttons of the TEM) so that the Kikuchi zone is aligned with the center of the spot.

[0017] Step 8) Complete the microstructure analysis of the current band axis of the target grain; select the next band axis and repeat steps 6)-8) until the microstructure of all band axes to be analyzed is completed.

[0018] Furthermore, the methods for preparing the transmission samples to be characterized include focused ion beam micro / nano fabrication, electrolytic double-jet method, ion beam thinning method, and ultrathin sectioning method.

[0019] Furthermore, when collecting transmission electron backscatter diffraction information, the electron beam accelerating voltage ranges from 15kV to 30kV, the electron beam current ranges from 11nA to 44nA, and the sample tilt angle ranges from 25° to 35°.

[0020] Furthermore, before acquiring transmission electron backscatter diffraction information, the transmission sample to be characterized is also cleaned with low voltage to remove the amorphous layer, contaminants and damage layer on the sample surface.

[0021] Furthermore, the complete crystallographic information of each grain includes the phase, orientation Euler angles (φ1, Φ, φ2), and unit cell parameters of all grains in the region of interest or the entire region.

[0022] Furthermore, the transmission electron microscope sample holder has a bidirectional tilting function.

[0023] Furthermore, the clamping direction of the transmission sample to be characterized on the TKD-EBSD sample holder is consistent with the placement direction on the transmission electron microscope sample rod.

[0024] Furthermore, when the clamping direction of the transmission electron microscope sample to be characterized on the TKD-EBSD sample holder is inconsistent with the placement direction on the transmission electron microscope sample rod, before controlling the sample stage to tilt in step 6), the sample placement angle is updated. The update steps include:

[0025] Based on the rotational relationship between the magnetic rotation angle of different transmission electron microscopes and the ideal vertical tilt angle α and horizontal tilt angle β, the corresponding actual sample rod tilt angle is obtained from the software, and the horizontal angle of the sample is changed (generally, the difference here is mostly a large angle such as 90° or 180°, and precise measurement is not required here).

[0026] Furthermore, in step 6), the step of controlling the tilting of the sample stage includes:

[0027] Step 6.1) Determine whether the theoretical tilt angle parameters (α, β) are both within the range of [-20°, +20°]. If so, directly control the sample stage to tilt according to the theoretical tilt angle parameters (α, β) and end the control. Otherwise, proceed to step 6.2).

[0028] Step 6.2) Preset the tilt angle parameters (α, β) and the iteration step size (e.g., 0.2°) within the relatively safe angle range [-20°, +20°].

[0029] Step 6.3) To ensure equipment safety and to get as close as possible to the theoretical tilt angle parameters, the tilt angle parameters (α, β) of Step 6.2) are iterated step by step using the iteration step size, and the iteration results are used to control the tilting of the sample stage.

[0030] Furthermore, in step 7), the secondary adjustment of the sample stage belt shaft can be performed manually or automatically with the assistance of the belt shaft tilting software.

[0031] Manual operation refers to observing the center position of the Kikuchi belt by manipulating the α and β buttons, so that the center of the Kikuchi belt on the target index belt axis is directly aligned with the center of the light spot. Automatic belt axis tilting software assistance utilizes the SmartCam function, which allows double-clicking the center of the Kikuchi belt on the operation interface to automatically adjust α and β so that the center of the Kikuchi belt on the target index belt axis is directly aligned with the center of the light spot.

[0032] The technical effectiveness of this invention is undeniable. This invention utilizes the TKD-EBSD system to acquire crystal orientation information in TEM samples, combining theoretical tilt angle analysis with the TEM sample stage tilting function to ultimately achieve precise and rapid tilting of the target band axis of the grain of interest in the TEM, thus providing reliable technical support for efficient and accurate microscopic analysis. This method is the first to achieve high-precision pre-analysis of TEM band axis tilting, separating band axis tilting analysis from TEM operation, greatly improving TEM research efficiency and reducing the difficulty of TEM technology and data analysis.

[0033] Specifically, the beneficial effects of the present invention are as follows:

[0034] 1) Wide range of applications: It can be used for the microstructure characterization of crystals such as metals, ceramics, semiconductors, composites and nanomaterials. It is applicable to samples obtained by various sample preparation methods such as FIB processing, ion thinning, electrolytic double spraying and ultrathin sectioning. In general, this method is applicable to most transmission electron microscopy samples and has broad application prospects.

[0035] 2) Reduced technical difficulty and significantly improved efficiency: In terms of equipment operation, existing TEM rotation methods typically require operators to be relatively familiar with Kikuchi zones or electron diffraction patterns, resulting in significant technical difficulty. This new method, however, only requires the user to input the relevant crystal information and the target zone axis, enabling efficient and accurate rotation to the correct zone axis without requiring in-depth crystallographic training, thus greatly reducing technical difficulty. In terms of data analysis, traditional methods often involve obtaining experimental electron diffraction patterns and high-resolution images before data analysis. In many cases (especially with complex materials), researchers cannot accurately determine the specific zone axis of the sample during the experiment, making it difficult to efficiently assess the validity of the current experimental data and further increasing the difficulty of subsequent data analysis. However, in this invention, researchers can pre-plan the zone axes to be observed and the corresponding structural studies, improving the controllability of the experimental process and the reliability of the data, greatly reducing the difficulty of experimental operation and post-analysis.

[0036] 3) Innovative Transmission Electron Microscopy (TEM) Research Methods: Currently, conventional TEM research and band axis analysis methods are only applicable to the sample being observed. That is, band axis analysis and manipulation can only be performed after the sample is already in the TEM and has interacted with the electron beam to produce Kikuchi bands or diffraction patterns. This prevents pre-analysis of the observed sample, which not only reduces TEM testing efficiency but also contributes to the scarcity of valuable TEM resources. In this invention, we pioneered high-precision pre-analysis of TEM samples, breaking through the traditional integrated paradigm of "sample observation—band axis analysis—experimental operation—TEM analysis." By pre-acquiring a "wide range" of crystal information (phases, orientations, etc.) of the sample under study through TKD, and then performing TEM band axis pre-analysis on the grains of interest, the results are finally transferred to the TEM to achieve rapid and accurate acquisition of band axes and high-precision TEM analysis. This forms an innovative two-step method separating "sample observation—band axis pre-analysis" and "experimental operation—TEM analysis." This method, on the one hand, improves the efficiency of TEM research and reduces the difficulty of subsequent data analysis through pre-analysis, effectively increasing the utilization rate of TEM resources. On the other hand, it overcomes the limitation of traditional TEM, which only performs localized analysis on a few grains and lacks a holistic understanding of the material. It enables rapid analysis of multi-regional, large-area characteristic structures, thus effectively establishing a cross-scale microscopic research framework spanning "atomic-nano-micron-submillimeter," providing crucial support for elucidating the relationship between microstructure and macroscopic properties. In summary, this method is of great significance in pioneering high-precision TEM pre-analysis with axes, improving the efficiency of TEM research, and constructing efficient cross-scale microscopic research methods. Attached Figure Description

[0037] Figure 1 The figures show the sample loading method and its corresponding morphological characterization. Figure 1 (a) Schematic diagram of the focused ion beam (FIB) fixture loading; Figure 1 (b) is a schematic diagram of the sample rod loading of a transmission electron microscope (TEM).

[0038] Figure 2 This is a full-area sampling result diagram of the TKD of the MgAgSb transmission sample; Figure 2 (a) Band Contrast plot: clearly characterizes the grain boundary distribution, crystal integrity and thickness uniformity within the effective observation area of ​​the sample; Figure 2 (b) is a grain orientation distribution diagram: it visually presents the spatial orientation characteristics of each grain, providing basic crystal orientation data for subsequent calculation of the tilt angle of the target zone axis.

[0039] Figure 3This is a schematic diagram of the zone axis rotation data processing and angle calculation program and output results, corresponding to steps S4~S5 of the method of this invention. It shows the core module (parameter input module, data operation area, result output area) and output results of the self-designed Python program. The output results include the accurate tilt angles α and β after error correction, reflecting the program's adaptability to different crystal systems and its automated operation characteristics.

[0040] Figure 4 The image shows the crystal structure model and diffraction simulation results of MgAgSb material, illustrating the crystal structure model of MgAgSb material and the electron diffraction simulation results of the corresponding zone axes.

[0041] Figure 5 The image shows the verification results of the Spectra300 TEM shaft with spherical aberration correction.

[0042] The two columns are, in order: Column 2 Figure 5 (a)- Figure 5 (e)

[110] ,

[210] ,

[220] ,

[331] ,

[321] Kikuchi zone images of the target zone axis; the second column corresponds to the experimental electron diffraction pattern of the target zone axis. Detailed Implementation

[0043] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0044] Example 1:

[0045] See Figures 1 to 5 A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on crystal orientation information from electron backscatter diffraction (TKD-EBSD) includes the following steps:

[0046] Step 1) Clamp the transmission sample to be characterized onto the TKD-EBSD sample holder, and then place the TKD-EBSD sample holder with the transmission sample onto a scanning electron microscope with an EBSD system.

[0047] Step 2) Perform transmission electron backscattering diffraction information acquisition on the region of interest or the entire region of the transmission sample to obtain complete crystallographic information of each grain in the transmission sample;

[0048] Step 3) Using the automatic axis-finding function of the automatic axis-tilting software, input the desired maximum zone axis index. Based on the complete crystallographic information of each grain given by TKD-EBSD, automatically obtain the zone axis and the corresponding theoretical tilt angle parameters (α, β) with tilt angles α and β in the range of [±25, ±25]. Wherein, α and β are the rotation angles of the transmission electron microscope sample stage in two orthogonal dimensions, respectively.

[0049] Step 4) Load the transmission sample to be characterized into the transmission electron microscope sample holder, and then transfer the sample holder into the transmission electron microscope;

[0050] Step 5) Make preliminary adjustments to the transmission electron microscope (TEM) parameters to ensure that the transmitted sample is within the TEM field of view;

[0051] Step 6) Control the sample stage to tilt based on the theoretical tilt angle parameters (α, β);

[0052] Step 7) Move the target grain to the center of the image. Based on the alignment accuracy of the target zone axis, make a second fine adjustment to the sample stage zone axis (using the α and β tilt buttons of the TEM) so that the Kikuchi zone is aligned with the center of the spot.

[0053] Step 8) Complete the microstructure analysis of the current band axis of the target grain; select the next band axis and repeat steps 6)-8) until the microstructure of all band axes to be analyzed is completed.

[0054] Example 2:

[0055] A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information is provided. The technical content is the same as in Example 1. Furthermore, the preparation method of the transmission sample to be characterized includes focused ion beam micro / nano fabrication, electrolytic double-jet method, ion beam thinning method, and ultrathin sectioning method.

[0056] Example 3:

[0057] A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information is provided. The technical content is the same as any one of Examples 1-2. Furthermore, when acquiring transmission electron backscatter diffraction information, the electron beam accelerating voltage range is 15kV-30kV, the electron beam current range is 11nA-44nA, and the sample tilt angle range is 25-35°.

[0058] Example 4:

[0059] A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information is provided. The technical content is the same as any one of Examples 1-3. Furthermore, before acquiring transmission electron backscatter diffraction information, the transmission sample to be characterized is cleaned with low voltage to remove the amorphous layer, contaminants and damage layer on the sample surface.

[0060] Example 5:

[0061] A rapid automatic rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the same technical content as any one of Examples 1-4. Furthermore, the complete crystallographic information of each grain includes the phase, orientation Euler angles (φ1, Φ, φ2), and unit cell parameters of all grains in the region of interest or the entire region.

[0062] Example 6:

[0063] A rapid automatic rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information is provided. The technical content is the same as any one of Examples 1-5. Furthermore, the TEM sample rod has a bidirectional tilting function.

[0064] Example 7:

[0065] A rapid automatic rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the same technical content as any one of Examples 1-6, further wherein the clamping direction of the transmission sample to be characterized on the TKD-EBSD sample holder is consistent with the placement direction on the transmission electron microscopy sample rod.

[0066] Example 8:

[0067] A rapid automatic rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the same technical content as any one of Examples 1-7, further comprising the following steps: when the clamping direction of the transmission sample to be characterized on the TKD-EBSD sample holder is inconsistent with the placement direction on the TEM sample rod, before controlling the sample stage to tilt in step 6), the sample placement angle is updated. The update steps include:

[0068] Based on the rotational relationship between the magnetic rotation angle of different transmission electron microscopes and the ideal vertical tilt angle α and horizontal tilt angle β, the corresponding actual sample rod tilt angle is obtained from the software, and the horizontal angle of the sample is changed (generally, the difference here is mostly a large angle such as 90° or 180°, and precise measurement is not required here).

[0069] Example 9:

[0070] A rapid automatic sample rotation method for transmission electron microscopy (TEM) based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the same technical content as any one of Examples 1-8, further comprising, in step 6), controlling the tilting of the sample stage, including:

[0071] Step 6.1) Determine whether the theoretical tilt angle parameters (α, β) are both within the range of [-20°, +20°]. If so, directly control the sample stage to tilt according to the theoretical tilt angle parameters (α, β) and end the control. Otherwise, proceed to step 6.2).

[0072] Step 6.2) Preset the tilt angle parameters (α, β) and the iteration step size (e.g., 0.2°) within the relatively safe angle range [-20°, +20°].

[0073] Step 6.3) To ensure equipment safety and to get as close as possible to the theoretical tilt angle parameters, the tilt angle parameters (α, β) of Step 6.2) are iterated step by step using the iteration step size, and the iteration results are used to control the tilting of the sample stage.

[0074] Example 10:

[0075] A rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the same technical content as any one of Examples 1-9. Further, in step 7), the secondary adjustment of the sample stage axis includes manual or automatic axis tilting software assistance.

[0076] Manual operation refers to observing the center position of the Kikuchi belt by manipulating the α and β buttons, so that the center of the Kikuchi belt on the target index belt axis is directly aligned with the center of the light spot. Automatic belt axis tilting software assistance utilizes the SmartCam function, which allows double-clicking the center of the Kikuchi belt on the operation interface to automatically adjust α and β so that the center of the Kikuchi belt on the target index belt axis is directly aligned with the center of the light spot.

[0077] Example 11:

[0078] A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, with the technical content being the same as any one of Examples 1-10, further comprising the following steps for determining the theoretical tilt angle parameters (α, β):

[0079] Based on the correspondence between the sample's EBSD coordinate system and the FIB processing equipment coordinate system, the normal direction of the target crystal plane is constructed. or target crystal orientation ;

[0080] Construct the target orientation matrix based on the target crystal plane normal or target crystal orientation. This ensures that the target orientation satisfies the single-direction constraint.

[0081] Among them, the single orientation constraint is the alignment of the target crystal plane normal or the target crystal orientation with the sample normal;

[0082] Calculate the rotation matrix required for machining ;

[0083] The rotation matrix required for processing Decompose the rotation angle sequence of the FIB electron microscope processing equipment into the allowable external rotation tilt angle sequence, and determine the rotation angle of the FIB dual-beam electron microscope processing equipment;

[0084] Constructing the current orientation matrix of the crystal material The steps include:

[0085] The target region of the crystal material is scanned using an EBSD probe to obtain the current orientation parameters of the target region, denoted as ( ). ,ϕ, );

[0086] Construct a rotation matrix based on the current orientation parameters, that is:

[0087] = (1)

[0088] = (2)

[0089] = (3)

[0090] In the formula, , , It is a rotation matrix;

[0091] Step 1.3) Construct the current orientation matrix of the crystal material. .

[0092] Target crystal plane normal ; ;{ , , } represents the reciprocal basis vectors; (h, k, l) represents the target crystal plane indices;

[0093] Target crystal orientation ; ;{ , , } represents the direct basis vectors; [u, v, w] represents the target crystal orientation indices.

[0094] Construct the target orientation matrix The steps include:

[0095] The target crystal plane normal or the target crystal direction is aligned with the sample normal. Its single orientation constraint condition is expressed as follows: ;

[0096] Project the target crystal plane normal or target crystal direction onto a Cartesian orthogonal coordinate system and perform orthogonal normalization, then directly construct the target orientation moment using this column vector: = , This represents the three components of the target vector in a three-dimensional orthogonal coordinate system.

[0097] The rotation matrix required for processing The steps for decomposing the material into a sequence of external rotation tilt angles permissible by the FIB electron microscope processing equipment include:

[0098] Rotation matrix required for processing Perform a mirror transformation to obtain the mirror rotation matrix. =S S; S=diag(1,-1,1);

[0099] Mirror rotation matrix It is decomposed into a sequence of external rotation tilt angles allowed by the FIB electron microscope processing equipment.

[0100] Example 12:

[0101] A rapid automated axis-rotation method for transmission electron microscopy (TEM) samples based on crystal orientation information obtained through electron backscatter diffraction (TKD-EBSD) includes the following steps:

[0102] S1. Clamp the transmission sample to be characterized onto the TKD-EBSD sample holder, and then place the holder with the sample onto a scanning electron microscope equipped with an EBSD system.

[0103] S2. Perform transmission electron backscatter diffraction (TKD-EBSD) information acquisition on the region of interest (or the entire region) in the transmission sample to obtain complete crystallographic information of each grain in the sample;

[0104] S3. Using the self-developed crystal rotation software, import the original crystal information data of the target grain (including crystal phase, unit cell parameters and orientation Euler angle) obtained by TKD sampling in step S2 and the target zone axis (crystal plane index [hkl]) to be tilted. After confirming that the parameters are correct, perform rotation calculation to obtain the corresponding accurate tilt angle parameters (α, β) required for the transmission electron microscope sample stage, where α and β are the rotation angles of the sample stage in two orthogonal dimensions, respectively.

[0105] S4. Load the sample into the transmission electron microscope sample holder, ensuring that the loading direction of the sample is consistent with the loading (horizontal) direction of the TKD-EBSD test, and then transfer the sample holder into the transmission electron microscope.

[0106] S5. In the TEM, make preliminary adjustments to the electron microscope parameters, including finding the sample position and magnification. Then, in the sample stage control interface, input the theoretical tilt angles α and β calculated in step S3, and start the automatic tilting program of the sample stage (or manual tilting) to complete the precise tilting of the sample stage.

[0107] S6. After the initial tilting is completed, the target grain is moved to the center of the image. The alignment accuracy of the target grain axis is verified by observing its Kikuchi zone or electron diffraction pattern. The precise adjustment of the zone axis is completed through fine manual adjustments.

[0108] S7. After the axis tilting is completed, further microstructure analysis of the target grains (electron diffraction, high-resolution imaging, composition analysis, etc.) is performed as needed. Then, through steps S3, S5, and S6, the precise axis rotation and microstructure analysis of multiple grains are completed.

[0109] In step S1, the methods for preparing the transmission sample include, but are not limited to: focused ion beam (FIB) micro-nano fabrication, electrolytic double-jet method, ion beam thinning method, and ultrathin slicing method. The prepared sample exhibits uniform thickness in the effective observation area and exhibits no significant stress damage. FIB sample preparation is recommended because its specially designed semi-circular comb-shaped stage facilitates the identification of sample placement orientation. Furthermore, FIB's point-to-point processing and pre-preparation orientation prediction functions make it easier and more efficient to locate the region of interest / target.

[0110] In step S1, the clamping direction of the transmission electron microscope (TEM) sample on the TKD fixture must be consistent with the sample placement direction on the subsequent TEM sample rod to reduce the difference between the actual tilt angle and the theoretical tilt angle. However, since different electron microscopes (scanning electron microscope, transmission electron microscope) may have different imaging directions, the horizontal direction of the sample placement on different devices may be reversed. However, the actual sample placement correspondence between the two devices can be determined through one experiment without repeated attempts.

[0111] In step S1, according to the requirement that the TKD and TEM sample orientations are consistent, the TEM sample or stage needs to have a clearly identifiable orientation. For FIB samples, the stage orientation is obvious, so it is only necessary to align the sample stage parallel to the TKD fixture and the TEM sample rod. For samples without obvious orientation, such as those used for ion thinning or electrolytic double-jet printing, a short horizontal line or other feature mark can be "etched" on the sample edge to indicate the sample loading orientation.

[0112] In step S2, the effective observation area thickness of the transmitted sample is generally 50nm-300nm; during TKD sampling, the electron beam accelerating voltage range is 15kV-30kV, generally 30kV is selected. If the sample is too thin, the Kikuchi band will not be obvious, so the voltage can be reduced; the electron beam current range is 11nA-44nA, generally 11nA is selected; the sample tilt angle range is 25-35° to ensure the intensity of the TKD signal and the acquisition resolution.

[0113] Before performing TKD sampling in step S2, it is recommended to perform low-voltage cleaning on the upper and lower surfaces of the TEM sample in the FIB system. Use low accelerating voltages of 5kV, 2kV, and 1kV in sequence, combined with a positive and negative oscillation mode of 4°-7° on the sample stage, to better remove the amorphous layer, contaminants, and damage layer on the sample surface, ensuring the accuracy of TKD sampling data and the high quality of the sample for subsequent TEM characterization.

[0114] In step S2, the sample crystal information obtained by TKD includes at least the phase composition and orientation Euler angles (φ1, Φ, φ2) of all grains in the analysis area, which are used for subsequent analysis of sample orientation and TEM sample rod tilt angle.

[0115] In step S3, the independently developed crystal software has been separately licensed for software copyright. Its core function is to calculate the corresponding (α (vertical tilt) and β (horizontal tilt) angles that the transmission electron microscope sample stage needs to be tilted under ideal conditions, based on the current orientation of the crystal obtained by TKD and the required tilt to obtain the target orientation.

[0116] In step S3, based on the theoretical tilt angle, it is possible to relatively accurately predict whether the sample can actually be tilted to the corresponding orientation. Generally, the tilt angle range of α and β of the transmission electron microscope sample stage does not exceed ±30° (i.e., -30° to +30°). Therefore, when at least one of the α or β angles exceeds ±25°, it is recommended to first preset a relatively safe angle and then gradually approach the theoretical angle to ensure equipment safety.

[0117] In step S4, when the sample is transferred to the transmission TEM sample rod, the sample placement position should be kept at the same level as during the TKD test to ensure sample positioning accuracy and reduce angular deviation during the rotation process. Under normal circumstances, the loading direction can be roughly judged by eye (generally the deviation does not exceed 10°), and it can be accurately adjusted to the positive axis in the subsequent belt axis fine adjustment (generally the adjustment angle does not exceed 5°).

[0118] In step S4, consistent with the situation in step S1, there may be a reversal of the horizontal image between different devices. Therefore, the positional relationship between two devices can be determined by one calibration. This relationship is a correspondence of three-dimensional physical positions and is unique. Therefore, the relationship can be used directly without recalibration, which greatly facilitates actual operation.

[0119] In step S5, the sample placement direction on the TEM sample holder is generally assumed to be consistent with the TKD fixture placement direction. However, due to the different magnetic rotation angles of different transmission electron microscopes, the imaging direction may differ after horizontal placement. Therefore, to ensure "horizontal and vertical alignment" for aesthetic purposes (i.e., ensuring the horizontal and vertical alignment of the sample and sample holder during placement; the magnetic rotation angle may differ for different brands and models of transmission electron microscopes, and the relative angle between the sample and sample holder during loading also needs to be adjusted according to the magnetic rotation angle), the sample placement (horizontal) angle can be appropriately changed. Then, by using the rotational relationship between the magnetic rotation angle and the ideal α (vertical tilt) and β (horizontal tilt) angles, the actual sample holder tilt angle corresponding to the changed sample placement angle can be calculated. This calibration result is of great significance for specific transmission electron microscopes, as it can ensure both rapid and accurate tilting of the sample shaft and aesthetically pleasing (horizontal and vertical alignment) imagery, facilitating data analysis and high-quality presentation.

[0120] In step S6, due to the orientation difference inside the crystal and the deviation of the artificial positioning direction of the sample loading, the crystal orientation obtained by the initial tilting in step S5 often deviates slightly from the target positive zone axis, generally not exceeding 3°. After a second fine adjustment, the ideal positive zone axis can be obtained quickly.

[0121] In step S6, minute deviations in sample orientation are obtained through electron diffraction or Kikuchi bands, and then, with the assistance of manual or automatic belt axis tilting software, the sample can be quickly and accurately rotated to the corresponding belt axis.

[0122] In step S7, on the one hand, band axis-dependent microscopic analysis such as electron diffraction and atomic-level imaging can be obtained based on the band axis tilting results and test characterization requirements; on the other hand, this method can quickly perform comprehensive and rapid analysis on multiple target grains of interest, which not only improves the efficiency and depth of microscopic analysis, but also provides a reliable methodology for the stability and statistical nature of microstructure analysis.

[0123] In steps S2, S5, and S6, although the TKD signal acquisition equipment and data analysis in this invention utilize the Oxford Instruments Symmetry S3 electron backscatter diffraction detector and Aztec Crystal analysis system mounted on a Helios 5 CX focused ion beam (FIB) microscope; and the TEM characterization is performed on instruments such as the Talos F200S field emission transmission electron microscope and the Spectra 300 aberration-corrected transmission electron microscope, the core of this method lies in the correspondence of the three-dimensional physical positions of the sample / grain between the two types of equipment. It is not limited to a specific brand of electron microscope equipment; this method is applicable to different electron microscope systems and has broad universality.

[0124] In step S3, the crystal orientation tilting software has built-in orientation conversion algorithms for various crystal systems (cubic, hexagonal, tetragonal, orthogonal, rhombohedral, monoclinic, triclinic), which can adapt to different crystal form samples. It also supports batch data import, export of calculation results, and error source analysis. The absolute error of the calculated tilt angles α and β is no greater than 2°.

[0125] In step S4, according to the requirement of high-precision rotating shaft, the TEM sample rod is required to have bidirectional tilting function. The sample rod can be a regular double-tilting sample rod or a double-tilting sample rod with in-situ heating / electricity, etc. The repeatability of the sample rod is better than 0.1° to meet the requirement of precise axis positioning.

[0126] Example 13:

[0127] This embodiment provides a method for rotating MgAgSb with an axis, the method comprising the following steps:

[0128] The prepared MgAgSb transmission sample is clamped parallel to the comb-shaped fixture of the FIB system, and then the fixture is placed into the FIB sample chamber. The sample stage is then adjusted to the initial horizontal position.

[0129] Before TKD sampling in step S2, the sample is cleaned in a segmented low-voltage manner: 5kV, 2kV and 1kV accelerating voltages are used in sequence, combined with the sample stage ±5° swing mode, and each voltage level is cleaned for 45s to remove the initial amorphous layer and contaminants on the sample surface, so as to ensure the accuracy of TKD sampling data.

[0130] TKD sampling parameters were set as follows: electron beam accelerating voltage 30kV, beam current 11nA; FIB sample stage tilt angle was adjusted to 10° to enhance backscattered signal intensity; full-area scanning sampling was performed on the 150nm thick effective observation area of ​​the sample; the sampling data was processed using the Aztec TKD analysis system to obtain complete crystal information of the sample, including grain size, grain orientation, Euler angles (φ1, Φ, φ2), and hexagonal crystal system parameters. The sampling results are as follows: Figure 1 As shown ( Figure 1 (a) is a BandContrast diagram, which clearly shows the grain boundaries and crystal integrity; Figure 1 (b) is an orientation distribution diagram, reflecting the spatial orientation of each grain.

[0131] A low Kv cleaning process was used to perform secondary surface purification on the samples, with process parameters consistent with those before sampling (5kV, 2kV, and 1kV staged cleaning, 45s per stage, with the sample stage oscillating ±5°). This thoroughly removed the ion-damaged layer and amorphous contaminants generated during TKD sampling. After treatment, the copper mesh supporting the sample was removed from the FIB system, maintaining its horizontal position, and transferred to the Talos F200S Cs-TEM sample chamber. The double-tilt sample holder was then mounted, and the sample stage calibration program was initiated to complete the initial position calibration.

[0132] The self-written Python data processing program was started. In the parameter input interface, the raw data of MgAgSb grains obtained by TKD (including Euler angles) were imported in batches. The cell parameters and the crystal plane indices [hkl] of the five target zone axes

[110] ,

[210] ,

[220] ,

[331] , and

[321] were entered sequentially. After confirming that the parameters were complete and error-free, the program was run. The program is based on the tetragonal crystal system orientation conversion model and the TEM double-tilt sample stage geometry model. It automatically completes the data calculation and system error correction, and outputs the accurate tilt angle parameters α and β of the sample stage corresponding to the five target zone axes (see Table 1 for specific results). The program interface and output results are shown in the figure. Figure 3 As shown, the entire process of parameter import, calculation, and result output is clearly presented.

[0133] Table 1. TEM Sample Stage Tilting Angle Parameters Corresponding to Target Zone Axis of MgAgSb Samples

[0134]

[0135] Table 1 shows the crystallographic data of the MgAgSb sample acquired by TKD. These data were calculated using a self-written Python program and include the sample stage tilt angles α and β corresponding to each target zone axis, providing direct parameter basis for precise TEM rotation operation.

[0136] In the sample stage control interface of Thermo Fisher Spectra 300, input the tilt angle parameters in Table 1 to start the automatic tilting program of the sample stage. The sample stage completes precise tilting and positioning according to the preset α and β angles. After each zone axis tilt is completed, it is left to stand for 2 minutes to eliminate the influence of mechanical vibration.

[0137] Switch Cs-TEM to STEM mode and acquire images of the Kikuchi zone corresponding to the zone axis and selected area electron diffraction patterns (results are shown in Figure 1). Figure 5 As shown), the actual diffraction pattern is compared with... Figure 4 Simulated diffraction patterns in Figure 4 (a)- Figure 4 (e) Comparison and verification were performed for each of the five target zone axes. The results show that the actual diffraction spot positions and Kikuchi line clarity are in high agreement with the simulation results.

[0138] Then, keeping the samples in the same relative positions, place them in the Talos electron microscope and perform the same axis rotation operation. The results are as follows. Figure 5 As shown, when only the physical position is considered and the actual imaging position is ignored, the image orientation only has a certain magnetic rotation angle; further calculations can be made to consider the aesthetics of the image. It is evident that the rotation axis information obtained using this method is independent of the electron microscope itself and can be adapted to various electron microscopes.

Claims

1. A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, characterized in that, Includes the following steps: Step 1) Clamp the transmission sample to be characterized onto the TKD-EBSD sample holder, and then place the TKD-EBSD sample holder with the transmission sample onto a scanning electron microscope with an EBSD system. Step 2) Perform transmission electron backscattering diffraction information acquisition on the region of interest or the entire region of the transmission sample to obtain complete crystallographic information of each grain in the transmission sample; Step 3) Input the desired maximum zone axis index. Based on the complete crystallographic information of each grain given by TKD-EBSD, automatically obtain the zone axis and the corresponding theoretical tilt angle parameters (α, β) with tilt angles α and β in the range of [±25, ±25]. Wherein, α and β are the rotation angles of the transmission electron microscope sample stage in two orthogonal dimensions, respectively. Step 4) Load the transmission sample to be characterized into the transmission electron microscope sample holder, and then transfer the sample holder into the transmission electron microscope; Step 5) Make preliminary adjustments to the transmission electron microscope (TEM) parameters to ensure that the transmitted sample is within the TEM field of view; Step 6) Control the sample stage to tilt based on the theoretical tilt angle parameters (α, β); Step 7) Move the target grain to the center of the image. Based on the alignment accuracy of the target zone axis, make a second fine adjustment to the sample stage zone axis so that the Kikuchi zone is aligned with the center of the spot. Step 8) Complete the microstructure analysis of the current band axis of the target grain; select the next band axis and repeat steps 6)-8) until the microstructure of all band axes to be analyzed is completed.

2. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information as described in claim 1, characterized in that, Methods for preparing transmission samples to be characterized include focused ion beam micro / nano fabrication, electrolytic double-jet method, ion beam thinning method, and ultrathin sectioning method.

3. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information as described in claim 1, characterized in that, When collecting transmission electron backscatter diffraction information, the electron beam accelerating voltage ranges from 15kV to 30kV, the electron beam current ranges from 11nA to 44nA, and the sample tilt angle ranges from 25° to 35°.

4. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, Before acquiring transmission electron backscatter diffraction information, the transmission sample to be characterized is also cleaned with low voltage to remove the amorphous layer, contaminants and damage layer on the sample surface.

5. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, The complete crystallographic information of each grain includes the phase, orientation Euler angles (φ1, Φ, φ2), and unit cell parameters of all grains in the region of interest or the entire region.

6. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, The transmission electron microscope sample holder has a bidirectional tilting function.

7. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, The clamping direction of the transmission electron microscope sample to be characterized on the TKD-EBSD sample holder is consistent with the placement direction on the transmission electron microscope sample rod.

8. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, When the clamping direction of the transmission electron microscope sample to be characterized on the TKD-EBSD sample holder is inconsistent with the placement direction on the transmission electron microscope sample rod, before controlling the sample stage to tilt in step 6), the sample placement angle is updated. The update steps include: Based on the rotational relationship between the magnetic rotation angle of different transmission electron microscopes and the ideal vertical tilt angle α and horizontal tilt angle β, the corresponding actual sample rod tilt angle is obtained from the software, and the horizontal angle of the sample is changed.

9. The rapid automatic axis rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information according to claim 1, characterized in that, Step 6) involves controlling the tilting of the sample stage, including: Step 6.1) Determine whether the theoretical tilt angle parameters (α, β) are both within the range of [-20°, +20°]. If so, directly control the sample stage to tilt according to the theoretical tilt angle parameters (α, β) and end the control. Otherwise, proceed to step 6.2). Step 6.2) Preset the tilt angle parameters (α, β) and the iteration step size (e.g., 0.2°) within the relatively safe angle range [-20°, +20°]. Step 6.3) To ensure equipment safety and to get as close as possible to the theoretical tilt angle parameters, the tilt angle parameters (α, β) of Step 6.2) are iterated step by step using the iteration step size, and the iteration results are used to control the tilting of the sample stage.

10. A rapid automatic axis-rotation method for transmission electron microscopy (TEM) samples based on electron backscatter diffraction (TKD-EBSD) crystal orientation information, as described in claim 1, is characterized in that... In step 7), the secondary adjustment of the sample stage belt shaft can be performed manually or automatically with the assistance of the belt shaft tilting software.

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