JP3742200B2 - X-ray, neutron or electron diffraction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray, neutron beam or electron beam diffraction method and apparatus for non-destructive and non-contact inspection of an object such as various materials and devices.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, apparatuses using X-ray diffraction have been widely used as apparatuses for non-destructive and non-contact inspection of specimens such as various materials and devices. As this type of detector, semiconductor detectors, scintillation detectors, proportional counters, films, etc. have been used in the past. Recently, imaging plates (volatile phosphor sheets), position sensitive proportional counter detection And array type semiconductor detectors have been developed.
[0003]
Among these various detectors, the imaging plate has the advantage of being a high-definition two-dimensional detector with extremely high sensitivity, a wide dynamic range (the output is proportional even if the X-ray intensity changes by 5 digits). Have. Further, the imaging plate can convert the image data into two-dimensional digital data by an optical readout device, and therefore has an advantage that subsequent data processing is easy.
[0004]
[Problems to be solved by the invention]
However, the imaging plate does not have energy resolution. That is, when a diffracted X-ray image is formed using an imaging plate, the image data of each pixel on the imaging plate is observed as a collection of photons of various energies while scanning the subject over the entire scanning angle. Is done. The diffraction data obtained in this way can only be obtained as a simple summation. For this reason, it is impossible to separate from the diffraction X-rays the fluorescence caused by the constituent elements to be inspected and the noise caused by air, scattered X-rays from other apparatus members, inelastic scattering, etc. There is a problem that the S / N ratio is poor and the detection performance is remarkably lowered. As a specific example, when analyzing a specimen with a superconducting thin film supported on a substrate, not only information on the thin film originally necessary, but also information on fluorescence and diffraction from the substrate are detected together. It was not a good detection performance.
[0005]
The present invention has been made to solve the problems of the conventional diffraction apparatus using an imaging plate, and is non-destructive, non-contact even for a subject having a large generation amount of fluorescence and scattered X-rays, and The object is to provide a technique capable of analyzing with a high S / N ratio.
[0006]
[Means for Solving the Problems]
According to the present invention, in order to achieve the above object, an X-ray, neutron beam or electron beam diffraction method for analyzing a subject,
Irradiating a predetermined region of the subject with a beam of X-ray, neutron beam or electron beam with a beam axis directed in a certain direction to obtain a diffraction line;
The predetermined region irradiated with the X-ray, neutron beam, or electron beam is not substantially changed, and the beam axis of the X-ray, neutron beam, or electron beam is formed between the tangent plane of the predetermined region. Rotating the subject so as not to substantially change the angle;
Using an imaging plate, forming a diffraction line image from the subject for each rotation of the subject at a predetermined angular width;
Reading out data of an image formed on the imaging plate and obtaining output data for each rotation of the subject with a predetermined angular width;
There is provided an X-ray, neutron beam, or electron beam diffraction method characterized by comprising a process of calculating the output data to obtain required analysis information.
[0007]
A preferred embodiment of the X-ray, neutron beam or electron beam diffraction method of the present invention is as follows.
(1) The subject is rotated at a constant rotational speed over an angle of 0 to 180 degrees.
(2) The predetermined angular width is set to 10 degrees or less.
(3) The calculation process of the output data is a difference process of the output data for each predetermined angle width of the subject.
(4) The calculation process of the output data is an integration process of the output data for each predetermined angle width of the subject, including removing single crystal diffraction peak information.
(5) The subject is a single crystal.
(6) The subject is amorphous or polycrystalline.
[0008]
Further, according to the present invention, a predetermined region of the subject is irradiated with an X-ray, neutron beam, or electron beam having a beam axis directed in a certain direction, and the diffraction line is detected, thereby the subject. An X-ray, neutron or electron beam diffractometer for analyzing
The predetermined region irradiated with the X-ray, neutron beam, or electron beam is not substantially changed, and the beam axis of the X-ray, neutron beam, or electron beam is formed between the tangent plane of the predetermined region. Rotating means for rotating the subject so as not to substantially change the angle;
An imaging plate for forming an image of a diffraction line from the subject for each rotation of the subject at a predetermined angular width;
Data detection means for reading out data of an image formed on the imaging plate and obtaining output data for each rotation of the subject with a predetermined angular width;
An X-ray, neutron beam, or the like, comprising: an arithmetic processing unit that performs arithmetic processing on output data obtained from the data detection unit for each rotation of the subject with a predetermined angular width to obtain required analysis information An electron beam diffractometer is provided.
[0009]
A preferred embodiment of the X-ray, neutron beam or electron beam diffraction apparatus according to the present invention is as follows.
(1) A slit having a structure in which a plurality of thin plates are radially arranged around the X-ray, neutron beam, or electron beam irradiation region of the subject at a certain angle between the subject and the imaging plate, The X-ray, neutron beam, or electron beam irradiation region of the subject is installed to be rotatable.
[0010]
Hereinafter, the present invention will be described in detail.
In the diffraction method of the present invention, analysis is performed by irradiating the subject with X-rays, neutron beams or electron beams.
[0011]
In the present invention, it is possible to use various shapes such as a spherical shape, a columnar shape, a bulk, a thin film, a powder, and the like as the specimen, and the diffraction method can be any of various conventionally known diffraction methods according to the specimen. it can.
A preferable subject to which the present invention is applied is a thin film supported on a substrate, and the thin film may be any of a single crystal thin film, an amorphous thin film, and a polycrystalline thin film.
[0012]
In the present invention, while rotating the subject, a predetermined region of the subject is irradiated with an X-ray, a neutron beam or an electron beam at a constant incident angle to obtain a diffraction line. In this case, the conditions for rotating the subject Is as follows.
(I) The predetermined region of the subject irradiated with X-rays, neutron beams, or electron beams is not substantially changed.
(Ii) The angle formed between the beam axis of the X-ray, neutron beam or electron beam and the tangent plane of the predetermined region of the subject is not substantially changed.
Here, when the subject is a thin film, the tangent plane of the predetermined region coincides with the surface of the thin film, but when the subject has a curved shape, the tangential plane is perpendicular to the radius of curvature of the curved surface and the curved surface. It becomes a plane in contact with
[0013]
Usually, the subject is preferably rotated over an angle range of 0 to 180 degrees. In this case, the rotation may be continuous rotation, or may be rotation at a certain angular width corresponding to image formation for each predetermined angular width. The rotational speed is preferably constant.
For rotation of the subject, a conventionally known rotating means that is commonly used in X-ray diffraction or the like can be used.
[0014]
In the present invention, an imaging plate is used as a detector for diffraction lines. Here, the imaging plate will be described.
The imaging plate is composed of a substrate in which fine crystals of a photostimulable phosphor (BaFBr: Eu ₂ + or the like) are uniformly applied. For example, when an X-ray, a neutron beam, or an electron beam is incident on the imaging plate, a metastable color center called an F center is generated in the phosphor. This F center disappears by irradiation with visible light, but simultaneously emits stimulable fluorescence. The emission intensity is proportional to the intensity of the incident X-ray, neutron beam or electron beam. The imaging plate is a two-dimensional integral X-ray, neutron beam, or electron beam detector constructed using such a phenomenon. The afterimage after reading is further erased by irradiating visible light, and can be used repeatedly.
The diffraction image irradiated on the imaging plate is accumulated as a density distribution of the F center, and forms a latent image. For example, a He-Ne laser (oscillation wavelength: 633 nm) is effective as an excitation light source for reading this latent image, and the photomultiplier tube is effective because the spectrum of the stimulable emission has a peak near 390 nm. Available to: That is, the imaging plate on which the diffraction image is formed is scanned two-dimensionally with a converged laser beam, the intensity of the stimulable emission spectrum emitted at that time is measured with a photomultiplier tube, and the analog data is converted into digital data. The data is converted and reconstructed into two-dimensional data by a computer.
[0015]
This imaging plate has excellent performance such as a detection sensitivity of 0.1 cps, a dynamic range of 10 ⁵ or more, and a spatial resolution of 80 μm square. However, as described above, since this imaging plate does not have energy resolution, for example, in the case of X-ray diffraction, for an object that generates a large amount of fluorescent X-rays, scattered X-rays, etc., these noise and diffraction X-rays Cannot be separated, the S / N ratio is small, and the detection performance is low.
Therefore, in the present invention, instead of forming an image of diffraction lines from the subject over the entire rotation angle on the imaging plate as in the past, the diffraction lines from the subject are rotated every rotation of the predetermined angular width of the subject. A method of forming an image on an imaging plate is adopted. A preferable value of the predetermined angle is 10 degrees or less, and for example, diffraction is performed in an angle range having a width such as 0 degrees to 5 degrees, 5 degrees to 10 degrees, and 10 degrees to 15 degrees.
[0016]
The image of the diffraction line formed on the imaging plate for each rotation of a predetermined angular width is rotated by a predetermined angular width from the subject by, for example, image reading using a laser beam as described above and signal detection by a photomultiplier tube. Output data (diffraction intensity in each two-dimensional pixel) is obtained.
[0017]
In the present invention, calculation processing is performed on output data for each rotation of the subject with a predetermined angular width to obtain necessary information, and typical processing includes the following.
(I) Differential processing (including differentiation processing) is performed on output data for each rotation of the subject with a predetermined angular width. Thereby, diffraction pattern data having a large S / N ratio can be obtained.
(Ii) Integration processing of output data for each rotation of the subject with a predetermined angular width. By including removal (smoothing process) of diffraction pattern data caused by a single crystal in this integration process, for example, only data from a polycrystalline or amorphous sample can be obtained.
[0018]
In the present invention, a rotary slit can be disposed between the subject and the imaging plate. This rotary slit has a structure in which a plurality of thin plates are radially arranged at a certain angle centered on an X-ray, neutron beam, or electron beam irradiation region of a subject, and these are arranged on the subject's X-ray, neutron beam. Or it arrange | positions rotatably around an electron beam irradiation area | region. As the material of the thin plate, iron or stainless steel can be used for X-ray. The reason why the slit is rotated is to eliminate a portion where the X-ray, neutron beam or electron beam is not irradiated by the slit.
By installing this rotary slit, it is possible to reduce the influence of fluorescent X-rays and scattered X-rays, and in combination with the method of the present invention, it becomes possible to further increase the S / N ratio.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. In the illustrated embodiment, the case of X-ray diffraction will be described. Needless to say, the present invention can also be applied to neutron diffraction and electron diffraction.
FIG. 1 is an external perspective view showing a schematic configuration of an X-ray diffraction apparatus using an X-ray Weissenberg camera according to an embodiment of the present invention.
In FIG. 1, 1 is an X-ray generator, 2 is a spectrometer, 3 is an X-ray beam, 4 is a sample rotating mechanism, 5 is a sample, 6 is an imaging plate mounted on an X-ray Weissenberg camera (not shown), and 7 is rotated. 8 is an image processing device for reading a diffracted X-ray image formed on the imaging plate 6, 9 is a data processing device, and 10 is a storage device. Here, as the sample 5, a BaCuO ₂ thin film grown on a SrTiO ₃ substrate was used. Further, MoKα was used as the X-ray generation source of the X-ray generator 1.
[0020]
X-rays radiated from the X-ray generator 1 become an X-ray beam 3 having good parallelism and a small wavelength width by the spectrometer 2. The X-ray beam 3 was irradiated to the surface of the sample 5 at a constant incident angle (α = 6 degrees), and an image of the diffraction line was formed on the imaging plate 6. Here, the sample rotation mechanism 4 substantially changes the angle formed by the beam axis of the X-ray beam 3 and the surface of the sample 4 so as not to substantially change the irradiation region of the sample 5 irradiated with the X-ray beam 3. The sample 5 was adjusted so that it could be rotated. Sample 5 was irradiated with X-rays over 180 degrees while rotating at a rotational speed of 2 degrees / minute for each angular width of 5 degrees around the X-ray irradiation area in the in-plane direction of the thin film.
Between the sample 5 and the imaging plate 6, 30 thin stainless steel plates are installed every 5 degrees, and a rotary slit 7 is arranged so as to be radial centering on the X-ray irradiation region of the sample 5, The rotary slit 7 was reciprocated at a rotational speed of 5 degrees / second to reduce the influence of scattered X-rays and fluorescent X-rays.
When the rotating X-ray diffraction image having the predetermined angular width is formed on the imaging plate 6, another prepared imaging plate 6 is exchanged to obtain an X-ray diffraction image. The plate 6 used the above-described method using a laser beam by the image processing device 8 to obtain a count value for each pixel when the imaging plate 6 was divided into a large number of pixels, and two-dimensional diffraction data was obtained. This operation was repeated. The two-dimensional diffraction data was sent to the data processing device 9 and the arithmetic processing shown in FIG. 2 was performed.
[0021]
Here, calculation processing by the data processing device 9 will be described.
Differential processing {(ΔPh (φ) = Ph (φn) −Ph (φm)} is performed on the image (photograph) Ph (φ) (step 200) formed on the imaging plate 6 while rotating the crystal (step 201). ), Background noise such as fluorescent X-rays and scattered X-rays caused by air or the like is removed (step 203), and only diffracted X-rays can be detected (step 204).
On the other hand, integration processing is performed on the image (photograph) Ph (φ) (step 200) formed on the imaging plate 6 while rotating the crystal (step 202). That is, the images (photographs) Ph (φn) and Ph (φm) at angles φn and φm are compared. Assuming that the intensity of the pixel (p, q) in the image (photograph) is I (p, q), when | In (p, q) −Im (p, q) |> ε, the surrounding pixel data is used. Smoothing is performed, and when | In (p, q) −Im (p, q) | <ε, the data is not changed. When this processing is integrated for all images (photographs) (information of all spaces (over 180 degrees) is integrated and averaged), the diffracted X-rays from the single crystal with high intensity are removed (step 205), and the polycrystalline Only X-rays from the amorphous sample can be detected (step 206).
[0022]
According to the X-ray diffractometer, since the sample 5 rotates at a constant speed, X-ray intensities at all X-ray diffraction points can be obtained by rotating 0 to 180 degrees. FIG. 3 shows a conventional Weissenberg photograph (X-ray diffraction pattern photograph) and an X-ray intensity distribution result, and FIG. 4 is a schematic diagram of the Weissenberg photograph (X-ray diffraction pattern photograph) obtained by the embodiment of the present invention. The X-ray intensity distribution result is shown.
3 and 4, (a) and (b) show the X-ray intensity distribution results on the AA ′ line shown in the Weissenberg photograph of FIG. (B) The black spot portion XP in the schematic diagram of the Weissenberg photograph in the figure is an X-ray diffraction spot, and the black spot indicates that the X-ray intensity is higher. A black dot in the pattern corresponds to the peak of the X-ray intensity in FIG.
[0023]
3 and 4, when the apparatus according to the embodiment of the present invention is used, the background noise due to fluorescence / scattering clearly disappears and only the X-ray diffraction points from the thin film are extracted as compared with the conventional apparatus. It can be seen that the S / N ratio is improved. In the case of FIG. 4, the S / N ratio is improved by three orders of magnitude or more compared to the case of FIG.
[0024]
【The invention's effect】
According to the present invention, since the above-described configuration is adopted, the drawbacks of the imaging plate can be eliminated, and X-ray, neutron beam, or electron beam diffraction using the imaging plate can be performed with a high S / N ratio.
In addition, the present invention can be suitably applied to non-contact and non-destructive inspection of various materials, devices, products composed of these, and the like.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing a schematic configuration of an X-ray diffraction apparatus using an X-ray Weissenberg camera according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a calculation processing procedure in the embodiment of the present invention.
FIG. 3 is a schematic diagram of a Weissenberg photograph (X-ray diffraction pattern photograph) and an X-ray intensity distribution when MoKα is used as an X-ray source (conventional example).
FIG. 4 is a schematic diagram of a Weissenberg photograph (X-ray diffraction pattern photograph) and an X-ray intensity distribution when MoKα is used as an X-ray source (embodiment of the present invention).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 X-ray generator 2 Spectrometer 3 X-ray beam 4 Sample rotation mechanism 5 Sample 6 Imaging plate 7 Rotary slit 8 Image processing device 9 Data processing device 10 Memory | storage device

Claims (2)

An X-ray, neutron or electron beam diffraction method for analyzing an object,
Irradiating a predetermined region of the subject with a beam of X-ray, neutron beam or electron beam with a beam axis directed in a certain direction to obtain a diffraction line;
A beam axis of the X-ray, neutron beam or electron beam and a tangential plane of the predetermined region so as not to substantially change the predetermined region irradiated with the X-ray, neutron beam or electron beam. Rotating the subject so as not to substantially change the angle formed by:
Using an imaging plate, forming a diffraction line image from the subject for each rotation of the subject at a predetermined angular width;
Reading out data of an image formed on the imaging plate and obtaining output data for each rotation of the subject with a predetermined angular width;
X-rays and neutrons characterized in that the output data is processed to obtain required analysis information, and the subject is rotated at a constant rotation speed over an angle of 0 to 180 degrees. X-ray or electron diffraction method. An X-ray, neutron or electron beam diffraction method for analyzing an object,
Irradiating a predetermined region of the subject with a beam of X-ray, neutron beam or electron beam with a beam axis directed in a certain direction to obtain a diffraction line;
A beam axis of the X-ray, neutron beam or electron beam and a tangential plane of the predetermined region so as not to substantially change the predetermined region irradiated with the X-ray, neutron beam or electron beam. Rotating the subject so as not to substantially change the angle formed by:
Using an imaging plate, forming a diffraction line image from the subject for each rotation of the subject at a predetermined angular width;
Reading out data of an image formed on the imaging plate and obtaining output data for each rotation of the subject with a predetermined angular width;
An X-ray, neutron beam, or electron beam diffraction method , comprising: a step of calculating the output data to obtain required analysis information; and the subject is a single crystal .

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