JPH10160690A - X-ray diffraction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce background from a sample holder, with an irradiation width of X-ray emitted on a sample surface kept constant regardless of θ axis rotation. SOLUTION: X-ray 9 from an X-ray tube 1 is cast on a sample 3 with an expansion α, and the X-ray diffracted with the sample 3 converges on a detection slit 4, to be detected with a detector 5. A divergence slit 2 is allowed to rotate freely with a rotation mechanism 6, and a rotation controller 10 so controls that relationship β=θ, where β is rotation angle of the divergence slit 2 and θ is rotation angle of the sample 3 on θ axis placed on the center of a goniometer, is kept, thereby, irradiation width of X-ray on the sample surface is kept constant at always.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray diffractometer, and more particularly to an X-ray diffractometer having an automatic divergence slit control mechanism.

[0002]

2. Description of the Related Art An X-ray diffractometer is a device for qualitatively and quantitatively analyzing a crystal component contained in a powder sample or the like. X-rays are detected at each diffraction angle by a detector mounted on the goniometer. As shown in FIG. 3 showing a conventional X-ray diffractometer, a powder sample 23 is usually 20 m long using a sample holder.
An X-ray 29 formed at a center of a goniometer on the θ-axis 27 on a θ-axis 27 and formed in a flat plate having a size of about m square, and a divergent slit having a predetermined installation position and a slit width for an X-ray 29 generated by a target of the X-ray tube 21. The surface of the sample 23 is irradiated with the spread thereof being restricted to about 1 to 3 ° by the surface 22. Diffracted X-rays emitted from the sample 23 are detected by the detection slit 24 and the detector 25 mounted on the 2θ axis 28 while rotating the 2θ axis 28. The area on the sample surface to be irradiated with X-rays, that is, the X-ray irradiation width is determined substantially by the slit width of the divergent slit 22 because the X-ray generation shape in the X-ray tube 21 is a point or a line. , Its width changes with the rotation of the θ-axis 27, and especially in a small angle region, the X extends beyond the original range of the sample to be analyzed and reaches the portion of the sample holder.
The line was being irradiated.

[0003]

As described above, in the conventional apparatus, since the divergence slit is fixedly installed, the sample holder is also irradiated with X-rays, especially at a low angle, and the background increases in the diffraction data. There was a problem.
Although there is a mechanism that automatically changes the divergence slit width, there is no mechanism that can continuously change the slit width. Can only set the width of the divergence slit at certain angular intervals according to the rotation of the θ-axis, and cannot always keep the X-ray irradiation width constant.

The present invention has been made in view of such circumstances, and continuously changes the width of the divergent slit in conjunction with the rotation of the θ-axis, so that a constant X-ray irradiation width is always maintained. It is an object to provide an obtained X-ray diffraction device.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a goniometer having a .theta. Axis for mounting a sample at its center and a 2.theta. Axis for mounting a detector, and irradiating the sample with a goniometer. In an X-ray diffractometer having an X-ray source for generating X-rays and a divergence slit for restricting the divergence angle of the X-ray from the X-ray source, the slit width of the divergence slit is continuously changed. Slit width control means is provided, and the irradiation width of the X-ray radiated on the sample surface placed at the center of the θ axis is made constant regardless of the rotation of the θ axis.

Since the X-ray irradiation width on the sample surface can be calculated by a simple calculation formula, the X-ray irradiation width is continuously changed by the slit width control means in conjunction with the rotation of the θ-axis. Can be kept constant regardless of the rotation of the θ axis.

[0007]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram of the X-ray diffraction apparatus viewed from a direction perpendicular to the rotation plane of the goniometer. The X-rays 9 generated in the target portion of the X-ray tube 1 pass through the window of the X-ray tube 1, and while the divergence angle is regulated by the divergence slit 2, the powdered substance is solidified in the sample holder into a flat shape. The irradiated sample 3 is irradiated. The X-ray diffracted by the sample 3 passes through the detection slit 4 and is detected by a detector 5 such as a scintillation counter. Goniometers are θ axis 7 and 2
The θ axis 8 is coaxially assembled, and each is independently rotated and driven by the rotation controller 10 via a pulse motor or the like. The sample 3 is placed so that the surface to be measured coincides with the central axis of the goniometer, and rotated by the θ-axis. On the other hand, the detection slit 4 and the detector 5 are mounted on the 2θ axis, and are rotated by driving the 2θ axis. Usually, the angle θ between the irradiation direction of the X-ray to the sample and the sample surface
And the angle 2θ between the direction of irradiation of the sample with the X-rays and the direction of the detection slit from the sample is rotated in conjunction with each other while maintaining the relationship of exactly twice. The distance between the center of the goniometer and the detection slit is called a goniometer radius. The X-ray tube 1 is installed so that the distance between the X-ray generation point in the X-ray tube 1 and the center of the goniometer also matches the goniometer radius. By doing so, the X-ray that has spread from the X-ray tube 1 and applied to the sample is reflected (diffracted) by the sample and converges again at the position of the detection slit.

[0008] X-ray irradiation width W on the surface of sample 3 to be measured
Is defined as α, the divergence angle of the X-ray is θ, the angle between the incident direction of the X-ray to the sample and the sample surface is θ, and the distance (goniometer radius) between the X-ray generation point and the sample is L. 3
), And the following equation (1) is obtained. W = W1 + W2 = L sin.alpha./sin(.theta.+.alpha.)+L sin.alpha./sin(.theta.-.alpha.) (1) This X-ray irradiation width W has a fixed slit width (that is, X-ray irradiation width .alpha.). Then, as shown by the curve A in FIG. 2, the diffraction angle θ rapidly increases as the diffraction angle θ decreases. Therefore, in the X-ray diffraction apparatus of the present invention, the straight line B in FIG.
As shown in the figure, the divergence angle α of X-ray (substantial slit width)
Is continuously changed in conjunction with the diffraction angle θ so that the X-ray irradiation width W is constant regardless of the rotation of the θ axis.

For this purpose, in the X-ray diffractometer shown in FIG. 1, the divergence slit 2 is formed by a rotation mechanism 6 having a rotation center on a line connecting the X-ray generation point and the center of the goniometer (the center of the surface of the sample 3). It can rotate.
The angle β between the line and the opening direction of the divergent slit is set to be equal to the angle θ between the direction of irradiation of the X-ray to the sample and the sample surface. That is, the rotation position of the divergence slit 2 is controlled by the rotation controller 10 so that β = θ (2) at all times in conjunction with the rotation of the goniometer θ-axis 7. For this interlock, the rotation controller 10 may separately drive the rotation mechanism 6 and the θ-axis 7 while maintaining the above relationship, or the rotation mechanism 6 and the θ-axis 7 may be driven via gears, pulleys, belts, and the like. May be mechanically coupled to rotate in a one-to-one relationship.

In the X-ray diffraction apparatus illustrated in FIG.
Since the rotation mechanism 6 for rotating the divergence slit 2 was used to keep the X-ray irradiation width W constant regardless of the rotation of the θ axis,
The width of the divergent slit can be substantially changed by a simple mechanism.
The line irradiation width W can be precisely controlled. However, the present invention is not limited to this example, and the opening direction of the slit is fixed in a direction perpendicular to the line connecting the X-ray generation point and the center of the goniometer, and the opening width is continuously adjusted according to the value of θ. May be changed. The way of changing the opening width of the slit at this time is as follows: assuming that the irradiation width W is a predetermined value in Equation (1), the divergence angle α is obtained as a function of the diffraction angle θ, and the difference between the X-ray generation point and the divergence slit is determined. The opening width of the divergence slit may be determined so that the divergence angle determined from the distance and the opening width of the divergence slit becomes the obtained value α.

The present invention includes an X-ray diffraction device having the following configuration. A goniometer having a θ-axis on which the sample is placed at its center and a 2θ-axis with a detector, an X-ray source for generating X-rays for irradiating the sample, and a divergence angle of X-rays from the X-ray source A divergence slit rotating means for rotating the divergence slit about the center of its opening as a center of rotation, and the divergence slit rotating means in conjunction with the rotation of the goniometer θ axis. Rotation control means for rotating the X-ray, the irradiation width of the X-ray radiated on the sample surface placed at the center of the
An X-ray diffraction apparatus characterized in that it is constant regardless of the rotation of the shaft.

[0012]

According to the present invention, the irradiation width of the X-ray radiated onto the sample surface is fixed irrespective of the rotation of the θ-axis. Is no longer irradiated with X-rays, and the background of the measured diffraction pattern is rarely increased. Therefore, it is possible to specify a component contained in the sample from the measured diffraction pattern and to quantify how much the component is contained in the sample with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing an X-ray diffraction apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an X-ray irradiation width on a sample surface.

FIG. 3 is a diagram showing a conventional X-ray diffraction apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... Divergence slit 3 ... Sample 4 ... Detection slit 5 ... Detector 6 ... Rotation mechanism 7 ... θ-axis 8 ... 2θ-axis 9 ... X-ray 10 ... Rotation controller 21 ... X-ray tube 22 ... Divergence slit 23 ... Sample 24 ... Detection slit 25 ... Detector 27 ... θ-axis 28 ... 2θ-axis

Claims (1)

[Claims] 1. A goniometer having a .theta. Axis on which a sample is placed at its center and a 2.theta. Axis on which a detector is mounted, an X-ray source for generating X-rays for irradiating the sample, and an X-ray source An X-ray diffractometer having a divergence slit for regulating a divergence angle of X-rays, comprising: a slit width control means for continuously changing a slit width of the divergence slit; An X-ray diffraction apparatus characterized in that the irradiation width of X-rays applied to the object is constant regardless of the rotation of the θ-axis.