Sample table device of X-ray diffractometer

Abstract

The utility model provides a sample table device of an X-ray diffractometer, which comprises a sample table body provided with a sample groove; the groove opening of the sample groove is rectangular, the bottom surface of the sample groove is an arc surface, and the arc center of the arc surface is positioned above the groove opening; the length of the notch is larger than 20 mm and smaller than 60 mm. The length of the groove opening of the sample groove of the X-ray diffractometer is set to be larger than 20 mm, it can be guaranteed that X-rays can effectively irradiate on samples, diffraction intensity is guaranteed, meanwhile, impurity peaks can be reduced, and therefore measurement accuracy is guaranteed. The bottom face of the sample groove is arranged to be the arc face, compared with an existing sample groove with the bottom face being a plane, deeper samples can be filled in the middle of the sample groove, the requirement of high-angle measurement for the sample amount is met, the diffraction intensity of high-angle measurement is improved, the utilization rate of the samples can be improved to the maximum degree, and in other words, on the premise that the samples are limited, the measurement accuracy is improved. And high-quality detection data can also be obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of X-ray diffraction spectrum testing, in particular to an X-ray diffractometer sample stage device. Background Art

[0002] X-ray diffraction analysis is an important method for studying the chemical structure of positive electrode materials. It can conduct qualitative and quantitative analysis of material composition and microstructure, and is usually used to measure powders, polycrystalline metals or polymer bulk materials.

[0003] Research has found that the size of the slit of a commonly used polycrystalline X-ray diffractometer affects both the diffraction intensity and resolution when testing the X-ray diffraction spectrum. A large slit can obtain a larger diffraction intensity, but will reduce the resolution. A small slit can improve the resolution but lose the intensity. How to increase the irradiated area and depth, increase the number of grains involved in diffraction, and reduce the statistical error of intensity measurement under the premise of a certain divergence slit DS has become a technical problem that needs to be solved urgently. Utility Model Content

[0004] The utility model aims to provide an X-ray diffractometer sample stage device which can increase the irradiated area and depth, increase the number of crystal grains involved in diffraction, and reduce the statistical error of intensity measurement.

[0005] In order to achieve the above-mentioned purpose, the utility model provides an X-ray diffractometer sample stage device, including: a sample stage body, on which a sample slot is provided; the slot of the sample slot is rectangular, the bottom surface of the sample slot is an arc surface, and the center of the arc surface is located above the slot; the length of the slot is greater than 20 mm and less than 60 mm.

[0006] Optionally, the ratio of the length to the width of the slot is 2:1 to 4:1.

[0007] Optionally, the curvature radius of the arc surface ranges from 20 to 40 mm.

[0008] Optionally, the end of the sample groove has a minimum groove depth, which is 0.15mm-0.25mm; and / or the center of the groove of the sample groove has a maximum groove depth, which is 0.4mm-0.6mm.

[0009] Optionally, the minimum groove depth is 0.2 mm, the maximum groove depth is 0.5 mm, and the length of the arc surface is 47.1 mm.

[0010] Optionally, the ratio of the thickness of the sample stage body to the maximum groove depth is 3:1 to 4:1.

[0011] Optionally, the sample stage body is made of glass.

[0012] Optionally, the inner surface of the sample groove is provided with a frosted layer.

[0013] Optionally, a connecting portion is further provided on one side of the long side of the sample stage body, and the connecting portion can be used for installation in a diffractometer.

[0014] Optionally, the connecting portion is a cubic structure, the long side of the connecting portion extends along the long side direction of the sample stage body, and the wide side of the connecting portion extends along the wide side direction of the sample stage body.

[0015] First, when the X-ray with fixed intensity is measured at a low angle, the spot irradiated on the sample surface is relatively wide, and some X-rays will irradiate the glass outside the sample, reducing the diffraction intensity and causing impurity peaks. The X-ray diffractometer sample stage device of the utility model sets the slot length of the sample slot to be greater than 20 mm, which can ensure that the X-rays can be effectively irradiated on the sample, ensure the diffraction intensity, and also reduce the appearance of impurity peaks, thereby ensuring the accuracy of the measurement;

[0016] Secondly, based on the X-rays of fixed intensity, when irradiating, the X-rays have a narrower spot and deeper penetration when measuring at high angles. In this application, the bottom surface of the sample slot is set as an arc surface. Compared with the existing sample slot bottom surface being a flat surface, a deeper sample can be loaded in the middle of the sample slot (i.e., corresponding to the high-angle measurement position), meeting the sample quantity requirements of high-angle measurement, thereby improving the diffraction intensity of high-angle measurement;

[0017] Finally, the setting of the curved bottom surface can gradually reduce the sample filling depth as the sample slot extends in the length direction, so that in low-angle measurement, a wider irradiation area can make up for the smaller irradiation depth, and in high-angle measurement, a deeper irradiation depth can make up for the narrower irradiation area. In other words, whether in high-angle measurement or low-angle measurement, a constant diffraction intensity can be guaranteed. At the same time, the utilization rate of the sample can be maximized, that is, high-quality detection data can be obtained under the premise of limited samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a goniometer in a specific implementation manner of the utility model.

[0019] Figure 2 It is a top view of the sample stage device of the X-ray diffractometer of the utility model.

[0020] Figure 3 It is a structural diagram of a sample stage device of an X-ray diffractometer of the utility model.

[0021] Figure 4 It is a cross-sectional view of a sample slot of a sample stage device of an X-ray diffractometer of the utility model.

[0022] In the figure: 1. sample stage body; 2. sample slot; 3. bottom surface; 4. notch; 5. connection part.

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0024] Since the discovery of X-rays in the late 19th century and X-ray crystal diffraction in the early 20th century, X-ray diffraction has made great progress in the application of material characterization, covering crystal structure, crystallinity, crystal defects, stress and other aspects.

[0025] X-ray diffraction analysis is an important method for studying the chemical structure of cathode materials. It can analyze the composition of materials qualitatively, quantitatively and microscopically. It is usually analyzed and measured using a polycrystalline X-ray diffractometer, and is usually used to measure powders, polycrystalline metals or polymer bulk materials, etc. It is mainly composed of four parts: 1. X-ray generator (device for generating X-rays); 2. Goniometer (device for measuring the angle 2θ); 3. X-ray detector (counting device for measuring X-ray intensity); 4. X-ray system control device (data acquisition system and various electrical systems, protection system, etc.).

[0026] Goniometer (including slit system), detector, etc. are all very critical components of X-ray diffractometer. Goniometer includes goniometer body (horizontal or vertical), sample stage, slit, monochromator, counter, protective cover, etc. Goniometer is the core component of powder X-ray diffractometer, mainly composed of Soller aperture, divergence slit, receiving slit, anti-scattering slit, sample holder and scintillation detector, etc. Goniometer schematic diagram is shown in the figure below. Figure 1 As shown. There are two coaxial turntables on the goniometer. The sample table H is installed in the center of the small turntable; the large turntable is equipped with a rocker arm E, a detector D and a receiving slit RS, and the receiving slit RS is fixed on the front end of the rocker arm. Both the large and small turntables can rotate around their common axis O, which is called the diffractometer axis.

[0027] Diffractometers usually use a divergent beam emitted by a line-focus X-ray source. In order to control the horizontal divergence, a divergent slit DS is installed in front of the X-ray tube window. The sample used is generally a flat sample made of powder filled in a special frame, placed in the center of the sample table, and the sample surface passes through the axis of the goniometer. The X-rays emitted from the line focus S, after passing through the divergent slit DS, become a fan-shaped beam that irradiates the flat sample. The diffraction rays enter the detector through the receiving slit RS and are then converted into electrical signals and recorded. Figure 1S1 and S2 are called Soller slits, which are composed of a group of parallel thin metal sheets at equal intervals. They limit the vertical divergence of incident X-rays and diffracted rays. In order to prevent scattered X-rays from entering the detector and reduce the background intensity, anti-scattering slits SS are also provided in the optical path. The height of each slit is roughly the same as the length of the line focus.

[0028] The design principle of the goniometer is the Bragg-Brentano focusing method. The standard Bragg-Brentano focusing method must meet the following two conditions: ① The distance between the X-ray source and the goniometer rotation center O must be equal to the distance between the goniometer rotation center O and the receiving slit RS. This distance is the goniometer circle radius, usually 185mm; ② The flat sample is mounted on the sample holder so that the sample surface is tangent to the focusing circle. The focusing circle is an imaginary circle passing through the X-ray source, the goniometer rotation center, and the receiving slit. Its radius changes with the rotation angle 2θ.

[0029] In order to keep the sample surface tangent to the focusing circle, the ratio of the incident angle to the diffraction angle 2θ should always maintain a relationship of 1:2. To satisfy this relationship, the counter must rotate 2° for every 1° rotation of the sample, that is, rotate at a speed ratio of 1:2.

[0030] In the experiment, the width of the divergence slit DS determines the divergence angle α of the incident X-ray beam on the scanning plane. Its function is to control the energy and divergence of the incident ray, and therefore also limits the irradiation area of ​​the incident ray on the sample. It is set between the Sollar slit and the sample. The purpose of the divergence slit DS is to limit the X-ray beam from irradiating outside the sample to avoid causing a large amount of additional scattering. When the irradiation width does not exceed the width of the sample, the wider the width of the divergence slit DS, the stronger the intensity of the X-ray. Usually, a fixed divergence slit with an aperture angle of 1° is used. Usually, the sample scanning range is 5°-80° (2θ). At this time, for the range from the initial angle to 17°, part of the beam irradiates the sample holder outside the sample area, and the diffraction caused by contaminants or other materials (such as transparent tape) stuck to the frame of the sample holder will be superimposed on the diffraction pattern, increasing the peak background and covering some weaker peaks, thereby affecting the peak intensity. If the sample has many diffraction peaks below 20°, a divergence slit DS with a width of 1 / 2 can be used. However, based on the above content, it can be known that the size of the divergent slit DS has an impact on both the diffraction intensity and the resolution. A large slit can obtain a larger diffraction intensity, but it will reduce the resolution. A small slit can improve the resolution but lose the intensity. How to increase the irradiated area and depth, increase the number of grains involved in diffraction, and reduce the statistical error of intensity measurement under the premise of determining the width of the divergent slit DS is the main purpose of this application.

[0031] As mentioned above, according to the requirements of the focusing conditions, the sample surface should always maintain the same curvature as the focusing circle. However, since the radius of curvature of the focusing circle changes continuously during the measurement process, the sample surface cannot achieve this. Therefore, only an approximate treatment can be made, using a flat sample so that the sample surface is always tangent to the focusing circle, that is, the center of the focusing circle is always located on the normal line of the sample surface. Since the powder polycrystal diffractometer always detects those diffraction surfaces parallel to the sample surface, in order to make the counter always in the diffraction direction of the sample surface (that is, the HKL diffraction surface equal to the sample surface), the sample surface and the counter must rotate in the same direction around the central axis of the goniometer at the same time, and maintain an angular velocity relationship of 1:2. That is, when the sample surface is at an angle θ with the incident angle, the counter is exactly at an angle 2θ.

[0032] Considering that the selection of the divergent aperture slit width is based on the principle that the projection area of ​​the incident ray does not exceed the working surface of the sample, when the aperture size remains unchanged, as the 2θ angle increases, the irradiated width (area) gradually decreases, while the irradiation depth increases. When the 2θ angle is smaller, the incident ray irradiation width is larger. That is, the width of the divergent slit is selected based on the diffraction peak with the smallest 2θ angle within the measurement range. For example, precursors, layered sodium electrodes and new materials have diffraction peaks at low angles. The small irradiated area and small number of particles lead to high background and low peak intensity. Therefore, the existing sample holder cannot meet wider test conditions. During the test process, it cannot be guaranteed that the same diffraction intensity is obtained even at different 2θ angles, so there is a certain measurement error.

[0033] In view of the problems existing in the above-mentioned prior art, this embodiment provides an X-ray diffractometer sample stage device and an X-ray diffractometer having the sample stage device.

[0034] See also Figures 2 to 4 The X-ray diffractometer sample stage device of this embodiment includes a sample stage body 1 with a roughly cubic structure and a connecting portion 5 formed by horizontally extending the side of the sample stage body 1 and having a cubic structure for installation in the diffractometer. The volume of the connecting portion 5 is smaller than the volume of the sample stage body 1. The sample stage body 1 is provided with a sample slot 2 for placing the sample to be tested. The sample stage body 1 is 80 mm long, 30 mm wide, and 1 mm thick; the connecting portion 5 is 35 mm long and 20 mm wide.

[0035] Specifically, the connection part 5 is located on one side of the long side of the sample stage body 1, the long side of the connection part 5 extends along the long side direction of the sample stage body 1, and the wide side of the connection part 5 extends along the wide side direction of the sample stage body 1. The connection part 5 is used to connect the diffractometer, and the connection part 5 is a cubic structure. The reason why the utility model additionally sets a connection part 5 that is smaller than the sample stage body 1 is that the lengthening of the sample slot 2 makes the size of the sample stage body 1 longer, and it cannot be directly inserted into the existing diffractometer for testing, so an additional connection part 5 that is compatible with the diffractometer socket is set for installation.

[0036] The sample slot 2 is a groove opened on the upper surface of the sample stage body 1. The slot 4 of the groove is rectangular, the length of the slot 4 is greater than 20mm and less than 60mm, and the ratio of the length to the width of the slot is 2:1-4:1; different from the general slot length of 20mm in the prior art, the slot length of the sample slot 2 of the utility model is set to be greater than 20mm, which can obtain a larger diffraction intensity. In addition, the maximum size of the sample slot is calculated to be 60mm according to the diffraction angle, so a larger diffraction intensity can be obtained within the range of 20mm-60mm. Within the specified range, the larger the length of the slot, the greater the diffraction intensity that can be obtained. Based on the above theory, the preferred slot length of this embodiment is 60mm, and the ratio of the slot length to the slot width is 3:1, that is, the slot width is 20mm.

[0037] Since part of the beam in the range from the initial angle to 17° is irradiated onto the frame of the sample holder, the low-angle peak intensity is affected. The selection of the divergent aperture slit width is based on the principle that the projection area of ​​the incident ray does not exceed the working surface of the sample. When the aperture size remains unchanged, as the 2θ angle increases, the irradiated width (area) gradually decreases, while the irradiation depth increases. When the 2θ angle is smaller, the irradiation width of the incident ray is larger, so the width of the divergent slit is selected based on the diffraction peak with the smallest 2θ angle within the measurement range. According to the relationship between the irradiated width A of the sample surface, the aperture divergence angle β and the diffraction angle θ, the sample size required for irradiating the sample with 5°-80° (2θ) diffraction rays is calculated, that is, 60mm-5mm. This size can meet most test conditions. This application ensures that the diffraction intensity of high and low angle samples is normal by extending the sample pool length and longitudinal depth (that is, the bottom surface 3 is a curved surface), and the diffraction peak measurement is more accurate, thereby improving the stability of material structure testing. Therefore, in this embodiment, the sample slot 2 is configured as a U-shaped groove with a bottom surface 3 being an arc surface, and the arc center of the arc surface is located above the slot 4, specifically above the center of the slot 4; the length of the slot 4 is greater than 20 mm and less than 60 mm. The ratio of the length to the width of the slot 4 is 2:1 to 4:1. The range of the curvature radius of the arc surface is 20-40 mm, preferably 30 mm, and this range, especially the point value of 30 mm, can meet the sample size required for 5°-80° (2θ) diffraction line irradiation samples;

[0038] Furthermore, the end of the sample groove 2 in the length direction has a minimum groove depth, which is 0.15mm-0.25mm, preferably 0.2mm; the center of the notch 4 of the sample groove 2 has a maximum groove depth, which is 0.4mm-0.6mm, which can meet the needs of most materials, and the ratio of the minimum groove depth to the maximum groove depth on the longitudinal section of the sample groove is in the range of 0.25-0.65mm. Preferably, the maximum groove depth of the sample groove 2 is 0.5mm; the arc length of the bottom surface 3 is 47.1mm.

[0039] Furthermore, the ratio of the thickness of the sample stage body 1 to the maximum depth of the sample slot 2 is 3:1 to 4:1; because when the thickness of the sample stage body 1 is 1.5mm-2mm, the appropriate depth of the sample slot 2 can increase the irradiation area and ensure high-angle sample penetration capability, and this thickness can meet the needs of all samples.

[0040] Furthermore, the material of the sample stage body 1 is glass, and the inner surface of the sample groove 2 is provided with a frosted layer, the purpose of which is to increase friction and prevent material flow and affect crystal diffraction.

[0041] In summary, the X-ray diffractometer sample stage device of this embodiment not only satisfies a wider irradiation area at a small angle but also satisfies a deeper irradiation volume at a high angle, thereby improving the measurement of diffraction intensity.

[0042] Another embodiment of the utility model further provides an X-ray diffractometer having the sample stage device.

[0043] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An X-ray diffractometer sample stage device, characterized in that include: A sample stage body, wherein a sample slot is provided on the sample stage body; the slot of the sample slot is rectangular, the bottom surface of the sample slot is an arc surface, and the arc center of the arc surface is located above the slot; The length of the notch is greater than 20 mm and less than 60 mm.

2. The X-ray diffractometer sample stage device according to claim 1, characterized in that: The ratio of the length to the width of the notch is 2:1 to 4:

1.

3. The X-ray diffractometer sample stage device according to claim 1 or 2, characterized in that: The curvature radius of the arc surface ranges from 20 to 40 mm.

4. The X-ray diffractometer sample stage device according to claim 3, characterized in that: The end of the sample groove has a minimum groove depth, which is 0.15mm-0.25mm; and / or the center of the groove of the sample groove has a maximum groove depth, which is 0.4mm-0.6mm.

5. The X-ray diffractometer sample stage device according to claim 4, characterized in that: The minimum groove depth is 0.2 mm, the maximum groove depth is 0.5 mm, and the length of the arc surface is 47.1 mm.

6. The X-ray diffractometer sample stage device according to claim 4, characterized in that: The ratio of the thickness of the sample stage body to the maximum groove depth is 3:1 to 4:

1.

7. The X-ray diffractometer sample stage device according to claim 1 or 2, characterized in that: The sample stage body is made of glass.

8. The X-ray diffractometer sample stage device according to claim 7, characterized in that: The inner surface of the sample groove is provided with a frosted layer.

9. The X-ray diffractometer sample stage device according to claim 1 or 2, characterized in that: A connecting portion is also provided on one side of the long side of the sample stage body, and the connecting portion can be used to be installed in a diffractometer.

10. The X-ray diffractometer sample stage device according to claim 9, characterized in that: The connecting portion is a cubic structure, the long side of the connecting portion extends along the long side direction of the sample stage body, and the wide side of the connecting portion extends along the wide side direction of the sample stage body.

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