JP2902441B2 - X-ray diffractometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention irradiates a sample with X-rays radiated from an X-ray source, and measures the intensity of the diffracted X-ray diffracted by the sample using an X-ray detector. X-ray diffractometer.

[Prior Art] The above X-ray diffractometers are roughly classified into two types.

One is that the X-ray source is fixed, and the sample is rotated about the sample axis at every predetermined step angle and every predetermined step time (so-called θ rotation). The X-ray intensity measurement is performed by the X-ray detection device while rotating at a speed twice as large as the θ rotation (so-called 2θ rotation) about the axis.

In the other, the sample is fixed and the X-ray source and X-ray
The X-ray intensity measurement is performed by the X-ray detection device while rotating the X-ray detection device around the sample axis at a constant angle θ in opposite directions.

In any of the X-ray diffractometers described above, the sample is rotated by θ relative to the X-ray source, and the X-ray detector is rotated by 2θ relative to the X-ray source.

[Problems to be Solved by the Invention] In the X-ray diffraction apparatus as described above, the relationship between the incident angle of X-rays incident on a sample and the diffracted X-ray intensity with respect to the incident angle (that is, the X-ray diffraction pattern) is described. In order to obtain a high accuracy, the θ rotation of the sample and the 2θ rotation of the X-ray detection device must always be controlled with high accuracy.

In a conventional X-ray diffractometer, a pulse motor is used to drive an X-ray detector, and the number of pulses supplied to the pulse motor controls the θ rotation of the sample and the 2θ rotation of the X-ray detector. I was

However, such a control method cannot cope with the X-ray diffraction measurement that requires extremely high measurement results.

The present invention has been made in view of the above-described problems in the conventional apparatus, and has as its object to provide an X-ray diffraction apparatus capable of performing extremely accurate measurement.

[Means for Solving the Problems] To achieve the above object, an X-ray diffractometer according to the present invention comprises a sample rotating means for rotating a sample about a sample axis, and an X-ray source centered on the sample axis. Source rotation means for rotating the X-ray detector, the detector rotation means for rotating the X-ray detector about the sample axis, and the sample, the X-ray source, and the X-ray detector which are rotationally driven by the respective means. Rotation fluctuation detecting means for detecting at least one rotation angle fluctuation, and correcting the rotation angle of the sample rotation means, the source rotation means or the detection device rotation means based on the rotation angle fluctuation value detected by the rotation fluctuation detection means. And control means for performing the control.

In the above configuration, there is no particular limitation on which element of the rotation angle fluctuation is detected by the rotation fluctuation detecting means. However, it is preferable to detect fluctuations in the rotation angle of the X-ray source.

Regarding the rotation of the sample, the X-ray source, and the X-ray detection device with respect to each other, several modes are conceivable.

For example, each can be configured to rotate independently and independently of the other, that is, a three-axis independent rotation structure. In addition, the other 2
A rotating structure in which a structure for rotating the shaft is mounted can also be adopted.

[Operation] In the X-ray diffraction apparatus according to claim 1, the sample (5), X
When a rotation angle fluctuation occurs in any one of the three elements of the X-ray source (X-ray tube 19) and X-ray detector (17), the control means (11) controls at least one of the remaining two elements. The angle adjustment is performed for each of them, whereby the rotation angle fluctuation is corrected.

In the X-ray diffractometer according to the second aspect, an X-ray source whose weight is extremely large and for which it is difficult to control the rotation angle with high precision is selected as a target for detecting the rotation angle fluctuation.

Embodiment FIG. 1 shows an embodiment of the X-ray diffraction apparatus according to the present invention.

In the figure, a sample support 3 is fixed on a goniometer base 2 placed on a frame 1 and extends upward in the figure. On the upper part of the sample support 3, a substantially cylindrical sample stage 4 is mounted. At the tip of the sample stage 4,
As shown in FIG. 2, a sample holder 6 packed with a sample 5 to be measured is detachably attached.

As shown in FIG. 2, the sample stage 4 is integrated with a sample rotation shaft 7 that penetrates the sample support 3. Thus, the sample stage 4 is rotatable around the sample axis ω (a straight line passing through the surface of the sample 5) with respect to the sample support 3. At the rear end (the upper end in FIG. 2) of the sample rotation shaft 7,
A worm wheel 8 is fixedly mounted, and a worm 10 fixed to an output shaft of a sample pulse motor 9 is engaged with the worm wheel 8. The sample pulse motor 9 rotates based on a pulse signal sent from the control device 11.

In FIG. 2, a detector arm 12 extending from the rear of the sample table 4 is disposed on the left side of the sample table 4. on the other hand,
On the right side of the sample table 4, a source arm 13, which also extends from the rear of the sample table 4, is arranged. In the detector arm 12,
As shown in FIG. 1, the scattering prevention slit 14, the light receiving side solar slit 15, the light receiving slit 16, and the X-ray detector
17 are fixedly mounted respectively.

The source arm 13 has a divergent slit 18 and X
An X-ray tube 19 as a radiation source is attached.

In FIG. 2, a cylindrical sleeve 20 is formed on the detector arm 12 located on the back side (upper side in the figure) of the sample support 3, and the sleeve 20 is fitted outside the sample rotation shaft 7. Thus, the detector arm 12 can rotate about the sample axis ω independently of the sample rotation axis 7, that is, the sample 5. A worm wheel 21 is fixed to the rear end of the detector sleeve 20, and a worm wheel attached to the output shaft of the detector pulse motor 22.
23 meshes with the worm wheel 21. The detector pulse motor 22 operates based on a pulse signal sent from the control device 11, and drives the detector arm 12 to rotate.

On the source arm 13, a cylindrical sleeve 24 is formed on the back side of the sample support 3, and the sleeve 24 is fitted on the outer peripheral surface of the detector sleeve 20. Thus, the source arm 13 can rotate around the sample axis ω independently of both the sample rotation shaft 7 and the detector arm 12. A worm wheel 25 is attached to the rear end of the source sleeve 24, and a worm 27 fixed to the output shaft of the source pulse motor 26 meshes with the worm wheel 25. Pulse motor for source 26
Operates based on the pulse signal sent from the control device 11 to rotationally drive the source arm 13.

The source arm 13 is provided with an encoder 29 as rotation fluctuation detecting means via a belt 28 wrapped around the outer circumference of the source sleeve 24. When the source arm 13 is rotated by an appropriate angle by being driven by the source pulse motor 26, a pulse signal corresponding to the rotation angle is sent from the encoder 29 to the control device 11.

Hereinafter, the operation of the X-ray diffraction device having the above configuration will be described.

In this X-ray diffractometer, in principle, the source arm 13 is rotated counterclockwise by a predetermined step angle at predetermined step times while the sample holder 6 and thus the sample 5 are held in a horizontal state as shown in FIG. The detector arm 12 is rotated in the opposite direction (so-called θ rotation) at the same time at the same step time and at the same step angle, that is, rotated in the counterclockwise direction (θ rotation). Then, while the above-described θ rotation is being performed with respect to the source arm 13 and the detector arm 12, the target 30 provided in the X-ray tube 19 emits X-rays and irradiates the sample 5 with the sample. The intensity of the diffracted X-ray diffracted at 5 is measured by the X-ray detector 17 and the X-ray
The change in the diffracted X-ray intensity corresponding to the change in the line incident angle θ is examined.

In a predetermined data storage location in the control device 11 shown in FIG. 2, for example, in a ROM, a magnitude and a step time of a target step angle when the source arm 13 and the detector arm 12 are rotated by θ. Is previously stored. For example, the setting is such that the θ rotation is performed at a step angle interval of about 0.001 ° every step time of about 0.1 second.

The control device 11 sends a pulse signal to the source pulse motor 26 and the detector pulse motor 22 according to the set conditions, whereby the source arm 13 and the detector arm 12 rotate θ as described above.

When the source arm 13 rotates θ in the counterclockwise direction in FIG. 1, the rotation angle is sent to the control device 11 in the form of a pulse signal by the encoder 29 (FIG. 2). The control device 11 that has received the rotation angle signal for the source arm 13 from the encoder 29 compares the rotation angle with a preset target rotation angle. As a result of the comparison, when it is found that the actual rotation angle of the source arm 13 is out of the allowable range and deviated from the target rotation angle, the pulse motor 9 for sample is sent to the sample pulse motor 9 in order to correct the angle deviation. A pulse signal corresponding to the angle shift amount is output. As a result, the sample holder 6 mounted on the sample table 4 is angularly displaced by a very small angle, and the step angle shift generated on the source arm 13 is corrected.

Thus, according to the present device, the source arm 13, and thus X
When the tube 19 is rotated by θ with respect to the sample 5, the step angle can be controlled very accurately, and therefore, a highly accurate X-ray diffraction measurement can be performed.

Generally, the X-ray tube 19 is connected to vacuum equipment such as an evacuation pump, and many auxiliary devices such as a high-voltage connector. Therefore, its weight becomes very large. When a rotary target is used as the target 30, the weight is further increased. It is very difficult to accurately rotate the heavy X-ray tube 19 by θ, and the rotation angle tends to fluctuate.
However, in the present embodiment, even when such an angle variation occurs, the sample pulse motor 9 is operated to operate the sample 5.
By changing the holding angle, the angle fluctuation is canceled to always obtain the target step angle. Therefore, highly accurate X-ray diffraction measurement can be performed.

Further, even if the rotation angle of the X-ray tube 19 fluctuates, the fluctuation is compensated for by the angle control of the sample 5. Therefore, the structure of the rotation drive system for the X-ray tube 19 must be highly accurate. However, high-precision X-ray diffraction measurement can be performed. For example, even when the accuracy of the source worm wheel 25 is low or when the backlash between the worm wheel 25 and the worm 27 is large, high-precision measurement can be performed. Until now, a great deal of effort has been made on how to rotate the heavy X-ray tube 19 by θ with high precision, but according to the present embodiment, such a concern has been eliminated.

 FIG. 3 shows another embodiment.

In this embodiment, a goniometer support 31 is fixed slightly above the center of the goniometer base 2 in the same manner as the sample support 3 in FIG. Extending. The front end of the gonio rotating shaft 32 penetrating the gonio support 31 (the lower end in the figure)
, A goniometer frame 33 is fixed.

In the embodiment shown in FIG. 2, the sample support 3 holding the sample rotating shaft 7 is directly fixed to the goniometer base 2, but in this embodiment, as shown in FIG. The body 3 is fixed to the bottom 33 a of the goniometer frame 33 instead of the goniometer base 2. The source arm 13 is not rotatably mounted on the sample rotation shaft 7 but is fixedly mounted on the goniometer frame 33. The detector arm 12 is rotatably mounted on the sample rotation shaft 7 in the same manner as in the embodiment of FIG.

As can be understood from the above description, considering the goniometer frame 33 as a reference, the X-ray tube 19 is fixed to the X-ray tube 19 and is stationary, and the sample 5 is driven by the sample pulse motor 9 to rotate, And the detector arm
12 is driven and rotated by the detector pulse motor 12. In other words, the X-ray tube 19, the sample 5, the X-ray detector 17, and other components provided on the goniometer frame 33 constitute a well-known X-ray diffraction device by themselves. I have. In the case of the embodiment, a so-called vertical goniometer in which the sample 5 is arranged horizontally and the X-ray tube 19 and the X-ray detector 17 are rotated by θ or 2θ in a vertical plane about the sample axis ω is constituted. Have been.

A worm wheel 25 for rotationally driving the entire goniometer frame 33 is fixedly attached to the rear end (upper end in the figure) of the goniometer rotation shaft 32 that rotatably supports the goniometer frame 33. A worm 27 fixed to the output shaft of the source pulse motor 26 meshes with the worm wheel 25. When the source pulse motor 26 operates, the entire goniometer frame 33 rotates around the sample axis ω. Thereby, the X-ray tube 19,
The sample 5 and the X-ray detector 17 rotate accordingly about the sample axis ω.

The gonio rotating shaft 32 is connected to an encoder 29 via a belt 28.
The pulse output of the encoder 29 is supplied to the control device 11 in the same manner as in the embodiment shown in FIG.
To be sent to

When X-ray diffraction measurement is performed in the present embodiment,
The X-ray tube 19 is driven by the source pulse motor 26 to rotate in the counterclockwise direction in FIG. The sample 5 is driven by the sample pulse motor 9 and rotates θ in the counterclockwise direction at a step angle θ. Then, the X-ray detector 17 is driven by the detector pulse motor 22 to rotate in the counterclockwise direction by θ at a step angle 2θ (twice θ).

As a result, when this X-ray diffractometer is viewed from the outside,
The sample 5 is held in a horizontal state, the X-ray tube 19 rotates counterclockwise about the sample axis ω by θ at a step angle θ, and the X-ray detector 17 rotates the clockwise about the sample axis ω. In this case, X-ray diffraction measurement is performed in exactly the same manner as in the embodiment of FIG.

When the rotation angle fluctuation occurs in the whole of the X-ray tube 19 and thus the goniometer frame 33, the fluctuation is detected by the encoder 29, and the pulse sent from the control device 11 to the sample pulse motor 9 based on the detection result. The signal is modified. Thus, the rotation angle fluctuation of the X-ray tube 19 is corrected by adjusting the rotation angle of the sample 5.

As described above, the present invention has been described based on the embodiment shown in the drawings, but the present invention is not limited to the embodiment.

For example, in the above embodiment, the step angle fluctuation generated in the X-ray tube 19 is corrected by changing only the holding angle of the sample 5. (FIGS. 2 and 3
By controlling the θ rotation of the detector arm 12 and thus the X-ray detector 17 by correcting the pulse signal sent to FIG. . As a result, more accurate measurement can be performed.

As described above, considering that the weight of the X-ray tube 19 becomes extremely large, as in each of the above embodiments, a change in the step angle of the X-ray tube 19 is detected, and the holding angle of the sample 5 and the like are determined. Can be said to be the most effective. However, by detecting the step angle fluctuation of the detector arm 12 and changing the holding angle of the sample 5 or the step angle of the X-ray tube 19 in accordance with the angle fluctuation, the angle fluctuation caused by the detector arm 12 is corrected. It is also possible to perform control for correction.

[Effects of the Invention] According to the present invention, the rotation angle fluctuation generated in the X-ray source or the X-ray detection device at the time of X-ray diffraction measurement is corrected by controlling the angle of the sample or the like. The step angle of the X-ray source or the like that rotates by θ can be maintained with extremely high accuracy, and therefore, it becomes possible to perform high-accuracy X-ray diffraction measurement.

The X-ray source is much heavier than other components in the X-ray diffractometer. The X-ray source includes
Heavy equipment such as high-voltage lines will be added. Therefore,
In particular, the rotation angle of the X-ray source is likely to fluctuate. According to the second aspect of the present invention, it is possible to reliably correct the rotation angle fluctuation generated for the X-ray source in this way, and to ensure high-accuracy measurement.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the X-ray diffraction apparatus according to the present invention, FIG. 2 is a partially cutaway plan view taken along the line II of FIG. 1, and FIG. It is a partially broken plan view which shows another Example of a line diffraction device. 5 ... sample, 6 ... sample holder, 8 ... worm wheel, 9 ... sample pulse motor, 10 ... worm, 11 ...
... Control device, 17 ... X-ray detector, 19 ... X-ray tube, 21 ...
… Warm wheel, 22 …… Pulse motor for detector, 23
… Worm, 25… worm wheel, 26… pulse motor for radiation source, 27… worm, 28… belt, 29…
Encoder, 33 ... Goniometer frame

Claims (4)

(57) [Claims] An X-ray diffractometer for irradiating a sample with X-rays emitted from an X-ray source and measuring the intensity of diffracted X-rays diffracted by the sample with an X-ray detector, wherein the sample is mounted on a sample axis. A sample rotating means for rotating the X-ray source about the sample axis; a detecting means rotating means for rotating an X-ray detecting apparatus about the sample axis; Rotation fluctuation detecting means for detecting a rotation angle fluctuation of at least one of a sample, an X-ray source, and an X-ray detection device which are rotationally driven by each of the above means; and a rotation angle fluctuation detected by the rotation fluctuation detecting means. An X-ray diffraction apparatus comprising: a control unit that corrects a rotation angle of a sample rotation unit, a source rotation unit, or a detection unit rotation unit based on a value. 2. An X-ray diffraction apparatus according to claim 1, wherein said rotation fluctuation detecting means detects a rotation angle fluctuation of an X-ray source, and said control means includes a sample rotating means and a sample rotation means. An X-ray diffraction apparatus for correcting at least one rotation angle of a detection device rotation unit. 3. The X-ray diffraction apparatus according to claim 1, wherein the sample rotating means, the source rotating means and the detecting apparatus rotating means independently rotate the sample, the X-ray source and the X-ray detecting apparatus. An X-ray diffraction apparatus, comprising: 4. The X-ray diffraction apparatus according to claim 1, wherein the sample rotating means and the detecting apparatus rotating means are driven to rotate about the sample axis together with the X-ray source by the source rotating means. X-ray diffractometer.