JP2004093500A - X-ray diffraction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure diffraction without lowering resolution by minimizing the effect of orientation even for a polycrystalline specimen with intense orientation. <P>SOLUTION: An incident side optical system 10 comprises an X-ray source 24, a paraboloid surface multi-layer film mirror 26, a solar slit 28 for vertical divergence limitation, and an outgoing width limiting slit 30. The paraboloid surface multi-layer film mirror 26 converts diverging X-ray beam 38 into parallel beam 40. A light receiving side optical system 14 comprises a solar slit 32 for lateral divergence limitation and an X-ray detector 36. A third rotating table 22 of a specimen holding device 12 is rotatable around the rotating center axis 18 thereof. A support table 44 is fixed to the third rotating table 22. A specimen table 46 is movable in vertical direction relative to the support table 44, and rotatable around a ϕ axis 48. A specimen 50 is rotated in a plane (ϕ rotation) and oscillated with an eccentricity of ω during the measurement (The surface of the specimen is oscillated at a position apart from a rotating centerline 18). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a parallel beam X-ray diffraction apparatus characterized by a sample driving mechanism.
[0002]
[Prior art]
In the technical field of X-ray diffraction, the following is known as a well-known technique closely related to the present invention. A first known technique is a sample swing in a concentrated method, which is disclosed in Japanese Patent No. 2940555 (hereinafter referred to as a first document). A second known technique is in-plane rotation of a sample in the parallel beam method, which is disclosed in Japanese Patent Application Laid-Open No. H7-159300 (hereinafter referred to as a second document). A third known technique is to use a parabolic multilayer mirror for the incident-side optical system of the parallel beam method, which is disclosed in Japanese Patent Application Laid-Open No. H11-287773 (hereinafter referred to as a third document).
[0003]
In the first document, in a concentrated X-ray diffraction optical system, the surface of a sample with respect to incident X-rays is independent of the relative motion (generally θ-2θ scanning) between the X-ray source and the X-ray detector. The sample is oscillated around a rotation center line parallel to the sample surface so that the angle to be formed changes (such oscillation is hereinafter referred to as ω oscillation). This makes it possible to increase the number of grains that contribute to diffraction when measuring powder samples that are inadequately mixed or individual grains are large, or when measuring metal whose grains are coarsened by heat treatment. it can.
[0004]
[Problems to be solved by the invention]
By the way, when the sample is swung by ω in the concentration method, the sample surface deviates from the measurement principle of the concentration method, and the resolution of the measurement result is reduced. In addition, it is known that the sample is rotated in the plane by the concentrated method. In this case, the measurement principle of the concentrated method does not deviate, but the crystal that contributes to diffraction is obtained only by the in-plane rotation of the sample. May not be enough to increase grain.
[0005]
On the other hand, in the parallel beam method, it is conceivable to move the sample during measurement so that the number of crystal grains contributing to diffraction increases. The above-mentioned second document discloses that in a parallel beam method, a sample is rotated in a plane during measurement. If the in-plane rotation of the sample is not sufficient, the sample may be oscillated by ω during the measurement. In the parallel beam method, since there is no principle limitation unlike the focusing method, even if the sample is oscillated by ω, there is no possibility that the resolution of the measurement result is reduced. However, in the parallel beam method, a specific device for realizing both in-plane rotation and ω swing of the sample during measurement is not known.
[0006]
The use of a parabolic multilayer mirror to obtain a parallel beam with a large X-ray intensity is known from the above-mentioned third document. In this third document, a mechanism for in-plane rotation and ω-oscillation of the sample is incorporated in the sample stage. However, the in-plane rotation and ω-oscillation are not performed during the measurement, but are performed during the measurement. This is for setting a suitable sample orientation and posture.
[0007]
An object of the present invention is to use a parallel beam having a high X-ray intensity and to devise a sample swinging mechanism which is superior to a simple combination of in-plane rotation and ω swing, so that a polycrystalline sample having a strong orientation can be obtained. An object of the present invention is to provide an X-ray diffractometer capable of performing diffraction measurement while minimizing the influence of orientation and reducing the resolution.
[0008]
[Means for Solving the Problems]
The X-ray diffraction apparatus of the present invention has the following configuration. (A) an incident-side optic comprising an X-ray source, a parabolic multilayer mirror for converting X-rays emitted from the X-ray source into a parallel beam, and a vertical divergence limiting means for limiting the vertical divergence of the parallel beam; system. (B) a light receiving side optics comprising: a lateral divergence limiting means for limiting the lateral divergence of the diffracted X-rays coming out of the sample; and an X-ray detector for detecting the intensity of the diffracted X-rays passing through the lateral divergence limiting means. system. (C) A sample holding device for holding a sample, wherein an in-plane rotation mechanism that enables in-plane rotation of the sample during measurement, and an ω swing mechanism that enables eccentric ω swing of the sample surface during measurement A sample holding device comprising:
[0009]
The ω-oscillation of the sample is independent of the relative movement between the X-ray source and the X-ray detector in the diffraction measurement, and is a rotation parallel to the sample surface such that the angle formed by the sample surface with respect to the incident X-ray changes. This refers to the motion of swinging the sample around the center line. The eccentric ω swing of the sample surface refers to ω swing such that the sample surface is separated from the rotation center line of the ω swing.
[0010]
The present invention further has the following features. (D) The sample holding device includes a support table swingable about a rotation center line, and a sample table movable and rotatable with respect to the support table. (E) The eccentric ω swing can be performed by the swing of the support base. (F) The sample stage is movable in a direction perpendicular to the rotation center line, and by this movement, the distance between the sample surface and the rotation center line can be adjusted. (G) The sample stage is rotatable around a φ axis perpendicular to the rotation center line, and the rotation enables the in-plane rotation.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a perspective view of one embodiment of the present invention. This X-ray diffractometer employs an optical system of the parallel beam method, and includes an optical system 10 on the incident side, a sample holding device 12, and an optical system 14 on the light receiving side. The optical system 10 on the incident side is mounted on a first turntable 16, and the first turntable 16 is rotatable around a horizontal rotation center line 18. The optical system 14 on the light receiving side is mounted on a second turntable 20, and the second turntable 20 is rotatable around the same rotation center line 18. The sample holding device 12 is fixed to a third turntable 22, and the third turntable 22 can also swing around the same rotation center line 18.
[0012]
The optical system 10 on the incident side includes an X-ray source 24, a parabolic multilayer mirror 26, a solar slit 28 for limiting vertical divergence, and an emission width limiting slit 30. Although the X-ray source 24 shows only a linear X-ray focal point in FIG. 1, an X-ray tube including such an X-ray focal point is actually mounted on the first turntable 16. The parabolic multilayer mirror 26 has a parabolic reflection surface, and converts a linear divergent X-ray beam 38 emitted from the X-ray source 24 into a parallel beam 40. An X-ray source 24 is arranged at the focal point of the paraboloid. Such a parabolic multilayer mirror 26 is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-287773, and can produce a parallel beam having a large X-ray intensity. The solar slit 28 for restricting vertical divergence limits the divergence (longitudinal divergence) of X-rays in a direction perpendicular to a diffraction plane (a plane including an incident X-ray beam and a diffracted X-ray beam). The emission width limiting slit 30 is a slit for setting the beam width (beam width in the diffraction plane) and the beam position of the parallel beam 40 incident on the sample to a desired width and position.
[0013]
The optical system 14 on the light receiving side includes a solar slit 32 for limiting lateral divergence, a light receiving width limiting slit 34, and an X-ray detector 36 (scintillation counter in this embodiment). The solar slit 32 for limiting lateral divergence limits the divergence (lateral divergence) of X-rays of the diffracted X-rays 42 coming out of the sample within the diffraction plane. In the embodiment, the length of the foil (length in the optical axis direction) of the solar slit is 100 mm (or 200 mm), and the interval between the foils is 100 μm. At this time, the divergence angle of the lateral divergence is 0.114 °. (Or 0.057 °).
[0014]
The light receiving width limiting slit 34 is a slit for defining a beam width (beam width in a diffraction plane) of the diffracted X-rays incident on the X-ray detector 36, and has a function of cutting scattered rays that become noise.
[0015]
By using the optical systems on the incident side and the light receiving side as described above, even in the parallel beam method, it is possible to perform diffraction measurement with the same high resolution as the focusing method.
[0016]
FIG. 2 is a perspective view of the sample holding device 12. The third turntable 22 is swingable about a horizontal rotation center line 18. A support 44 (almost horizontal) is fixed perpendicular to the surface of the third turntable 22. The oscillating movement of the third turntable 22 oscillating about the rotation center line 18 is referred to as ω oscillation. A sample table 46 is provided on the support table 44. The sample 50 is set on the surface of the sample table 46. The sample table 46 is vertically movable with respect to the support table 44. By this vertical movement, the distance between the surface of the sample 50 and the rotation center line 18 (the distance d in FIG. 3) can be adjusted. The sample table 46 is rotatable around a φ axis 48. The φ axis 48 is perpendicular to the rotation center line 18. The rotation around the φ axis 48 is driven by an electric motor.
[0017]
FIG. 3 is a front view showing the movement of the sample holding device 12. The surface of the sample 50 is separated from the rotation center line 18 by a distance d downward. When the third turntable 22 swings around the rotation centerline 18 within a predetermined angle range (that is, when swinging by ω), the sample 50 also swings. At this time, since the surface of the sample 50 is separated from the rotation center line 18 by the distance d, the X-ray incident angle α with respect to the sample surface changes, and the X-ray irradiation area on the sample also shifts. This will be described later. The maximum possible value of the distance d is determined by the condition that the parallel beam 40 does not deviate from the sample when the sample surface is eccentrically oscillated. For example, assuming that the diameter of the sample stage 46 is 25 mm, the line width of the parallel beam 40 at the sample position is 20 mm, and the beam width of the parallel beam 40 is 0.7 mm, the maximum possible value of d is about 0.3 mm. .
[0018]
The sample stage 46 rotates φ while performing the above-described ω swing. Along with the ω swing, the φ axis 48 naturally also swings. In the embodiment, the rotation speed of the φ rotation is 50 to 60 rpm, and the period of the ω swing is about 4 seconds. The speed of these rotations and swings can be changed by controlling each electric motor.
[0019]
FIG. 4 is an elevational view of the ω swing mechanism, as viewed from the rear side in FIG. 1. In FIG. 1, the third turntable 22 is fixed to a hollow shaft 52, and the hollow shaft 52 has a casing (not shown) for accommodating a rotation drive mechanism for the first turntable 16 and the second turntable 20. ) Protruding to the back side. At the rear end of the hollow shaft 52, as shown in FIG.
[0020]
In FIG. 4, a swing plate 54 is fixed to the hollow shaft 52. The swing plate 54 can swing around the rotation center line 18 integrally with the hollow shaft 52. The upper end of a tension coil spring 58 is hooked on a pin 56 at the right end of the swing plate 54. The lower end of the tension coil spring 58 is hooked on the pin 60. The pin 60 is fixed to the above-mentioned casing. Therefore, the swinging plate 54 is always provided with the rotational moment 62 in the clockwise direction in FIG. On the other hand, a roller 64 is rotatably mounted on a line connecting the rotation center line 18 and the pin 56 on the rocking plate 54. The outer peripheral surface of the roller 64 is in contact with the outer peripheral surface of the eccentric cam 66. The outer periphery of the eccentric cam 66 is circular, and the rotation shaft 68 of the eccentric cam 66 is located at a position eccentric to the outer periphery. The rotation shaft 68 is connected to the output shaft of the electric motor.
[0021]
When the eccentric cam 66 rotates around the rotation shaft 68 at a constant speed as shown by an arrow 70, the roller 64 in contact with the eccentric cam 66 follows the eccentric cam 66 while rotating freely. As a result, the swing plate 54 swings within a predetermined angle range. When the oscillating plate 54 is horizontal, the sample surface is just horizontal, at which time ω = 0 °. In this embodiment, the swing plate 54 swings within the range of ω = ± 10 °.
[0022]
Next, the effect of the ω swing on the sample surface will be described. FIG. 5 is an elevation view illustrating an X-ray irradiation area on the sample surface 72 when the sample surface 72 is located on the rotation center line 18. When the sample surface 72 is in a horizontal state (ω = 0 °), the incident parallel beam 40 impinges on a region from point A to point B on the sample surface 72. The X-ray irradiation area is indicated by hatching. Since the parallel beam 40 is a linear beam in a direction perpendicular to the plane of the drawing, points A and B extend in a direction perpendicular to the plane of the drawing.
[0023]
Next, when the sample surface 72 is rotated counterclockwise in FIG. 5 by 10 °, the above-mentioned points A and B on the sample move to points A1 and B1. At this time, the parallel beam 40 hits the region from point C to point D on the sample. Conversely, when the sample surface 72 is rotated clockwise in FIG. 5 by 10 ° from the horizontal state, the above-mentioned points A and B on the sample move to points A2 and B2. At this time, the parallel beam 40 hits the region from point E to point F on the sample.
[0024]
As described above, when the sample is oscillated by ω, the incident angle of the parallel beam 40 with respect to the sample surface 72 changes variously, and the crystal grains contributing to diffraction increase. In addition, the X-ray irradiation area on the sample surface also changes, and the irradiation area contributing to diffraction becomes wider as compared with the case where the ω swing does not occur.
[0025]
Next, the eccentric ω swing will be described. FIG. 6 is a drawing similar to FIG. 5 in the case where the sample surface 72 is located at a position separated from the rotation center line 18 by a distance d below. The parallel beam 40 is at the same position with respect to the rotation center line 18 as in FIG. When the sample surface 72 is in a horizontal state (ω = 0 °), the incident parallel beam 40 impinges on a region from point A to point B on the sample surface 72.
[0026]
Next, when the sample surface 72 is swung counterclockwise in FIG. 6 by 10 °, the above-mentioned points A and B on the sample move to points A1 and B1. At this time, the parallel beam 40 hits the region from point C to point D on the sample. 5 is different from FIG. 5 in that points C and D are narrowed inward almost symmetrically with respect to points A1 and B1, whereas FIG. 6 is an intermediate point between points C and D. Is shifted to the right side of the intermediate point between the points A1 and B1.
[0027]
Conversely, when the sample surface 72 is swung clockwise in FIG. 6 by 10 ° from the horizontal state, the above-mentioned points A and B on the sample move to points A2 and B2. At this time, the parallel beam 40 hits the region from point E to point F on the sample. Also in this case, the intermediate point between the points E and F is shifted to the right more than the intermediate point between the points A2 and B2.
[0028]
As described above, when the sample surface 72 is away from the rotation center line 18, when the sample is oscillated by ω, the irradiation area on the sample surface 72 is shifted with the ω swing. For example, in FIG. 5, the distance from point B2 to point F is L1, but in FIG. 6, the distance from point B2 to point F is L2. L2 is larger than L1. Therefore, when the sample surface 72 oscillates eccentrically, the X-ray irradiation area on the sample surface becomes wider than in the case of normal ω swing. As a result, the eccentric ω swing of the sample surface has the same effect as translating the sample within the sample surface (moving the X-ray irradiation area), and the present invention utilizes biaxial rotational movement. By itself, an effect such as a combination of biaxial rotation and translation is produced.
[0029]
Next, a method of using the X-ray diffraction apparatus of FIG. 1 will be described. By changing the angle of the optical system 14 on the light receiving side relative to the optical system 10 on the incident side (corresponding to the diffraction angle 2θ), the X-ray detector 36 measures the X-ray intensity, and records the diffraction pattern. can do. Since this X-ray diffractometer employs the parallel beam method, there is no special restriction on the angle between the optical system on the incident side and the light receiving side and the sample surface. Therefore, in order to change the above-mentioned diffraction angle 2θ, (1) the incident-side optical system 10 is stationary and the light-receiving-side optical system 14 is rotated 2θ, and (2) the incident-side optical system 10 is rotated 2θ. (3) the optical system 10 on the light-receiving side and the optical system 14 on the light-receiving side are rotated left and right symmetrically by θ in opposite directions to each other. In the measurement results described below, a left-right symmetric θ rotation scan is executed.
[0030]
In addition to the above-described 2θ scanning, in the present invention, the sample is rotated in-plane (φ rotation) and eccentric ω rotation of the sample surface is performed during measurement. As a result, even for a sample having a strong orientation, the number of crystal grains contributing to diffraction can be increased, and a measurement result close to an ideal powder diffraction pattern can be obtained.
[0031]
Actually, when measuring a polycrystalline sample with a strong orientation (for example, Portland cement, which is a sample that has a strong cleavage property and is difficult to grind), a conventional X-ray diffractometer (sample by the concentrated method) was used. (In which the sample was rotated in the plane or the sample was rotated in the plane by the parallel beam method), it was possible to obtain a diffraction pattern with less influence of the orientation. Even when the sample was refilled and re-measured, the diffraction pattern did not change much compared with the measurement result obtained by the conventional X-ray diffractometer, and it was confirmed that the reproducibility was excellent.
[0032]
The present invention is not limited to the above embodiment, but can be modified as follows.
[0033]
(1) In the above embodiment, as shown in FIG. 3, the eccentric ω rocks while the surface of the sample 50 is separated from the rotation center line 18 downward. The effect is the same even if eccentric ω swings so that the surface of 50 is separated upward from the rotation center line 18.
[0034]
(2) In the above embodiment, a long solar slit is used as the lateral divergence limiting means on the light receiving side. Instead, an analyzer crystal (a planar artificial multilayer film made of germanium or silicon) or a radiation slit is used. It is also possible to use an object-surface multilayer mirror (used in the opposite direction to the incident side; that is, to input a parallel beam diffracted from the sample to obtain a focused X-ray beam).
[0035]
【The invention's effect】
Since the X-ray diffractometer of the present invention combines the in-plane rotation of the sample and the eccentric ω swing of the sample surface during measurement in the parallel beam method, the influence of the orientation can be obtained even for a sample with a strong orientation. And high-resolution diffraction measurement with good reproducibility.
[Brief description of the drawings]
FIG. 1 is a perspective view of one embodiment of the present invention.
FIG. 2 is a perspective view of a sample holding device.
FIG. 3 is a front view showing the movement of the sample holding device.
FIG. 4 is an elevation view of the ω swing mechanism.
FIG. 5 is an elevation view illustrating an X-ray irradiation area on the sample surface when the sample surface is located on the rotation center line.
FIG. 6 is an explanatory diagram similar to FIG. 5, when the sample surface is located at a position away from the rotation center line.
[Explanation of symbols]
Reference Signs List 10 Optical system 12 on the incident side 12 Sample holding device 14 Optical system 16 on the light receiving side 16 First turntable 18 Center of rotation 20 Second turntable 22 Third turntable 24 X-ray source 26 Parabolic multilayer mirror 28 Vertical divergence limit Solar slit 30 for emitting light Slit 32 for limiting the emission width Solar slit 34 for limiting lateral divergence Slit for limiting the light receiving width 36 X-ray detector 44 Support table 46 Sample table 48 φ axis

Claims (2)

An X-ray diffraction apparatus having the following configuration.
(A) an incident-side optic comprising an X-ray source, a parabolic multilayer mirror for converting X-rays emitted from the X-ray source into a parallel beam, and a vertical divergence limiting means for limiting the vertical divergence of the parallel beam; system.
(B) a light receiving side optics comprising: a lateral divergence limiting means for limiting the lateral divergence of the diffracted X-rays coming out of the sample; and an X-ray detector for detecting the intensity of the diffracted X-rays passing through the lateral divergence limiting means. system.
(C) A sample holding device for holding a sample, wherein an in-plane rotation mechanism that enables in-plane rotation of the sample during measurement, and an ω swing mechanism that enables eccentric ω swing of the sample surface during measurement A sample holding device comprising: The X-ray diffraction apparatus according to claim 1, comprising the following features.
(D) The sample holding device includes a support table swingable about a rotation center line, and a sample table movable and rotatable with respect to the support table.
(E) The eccentric ω swing can be performed by the swing of the support base.
(F) The sample stage is movable in a direction perpendicular to the rotation center line, and by this movement, the distance between the sample surface and the rotation center line can be adjusted.
(G) The sample stage is rotatable around a φ axis perpendicular to the rotation center line, and the rotation enables the in-plane rotation.

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