JPH03165243A - X-ray diffraction device - Google Patents

Abstract

PURPOSE:To always correct the angular error by the misalignment between a sample surface and the center of rotation of a goniometer and to analyze with high acuracy by providing a position detecting means which detects the misalignment between the sample surface and the center of rotation of th goniometer and a controller for the goniometer to which the output from this position detecting means is inputted. CONSTITUTION:The ultrasonic position sensor 9 is provided in the position where the X-ray passage in the direction perpendicular to the sample surface is not hindered. A displacement measuring part 10 is connected to this ultrasonic position sensor 9 and further, an angle error correcting part 11 is provided in this goniometer control part 8. The position of the sample 3 is detected by the ultrasonic position sensor 9 and the displacement quantity between the sample 3 and the center of rotation of th goniometer is measured by the displacement measuring part 10 from the detected value. The measured displacement quantity signal is inputted to the goniometer control part 8 and an theta axis and 2theta axis are so controlled by the angle error correcting part 11 as to attain the exact angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray diffraction apparatus, and particularly to control of a goniometer used in an X-ray diffraction apparatus.

[Prior Art] X-ray diffraction is an analytical method for obtaining information regarding the arrangement of atoms in crystals and the like. When X-rays are irradiated onto a crystal, they are reflected on the crystal lattice planes and interfere with each other, so that only the diffraction rays in directions that meet predetermined conditions increase in intensity, while the others cancel out and are not observed. The interplanar spacing that satisfies this predetermined condition is generally a value unique to a substance, and if several interplanar spacings of a single substance and the relative intensities of the corresponding diffraction X-rays can be observed, that substance can be identified.

A conventional X-ray diffraction apparatus using this X-ray diffraction method is explained with reference to FIG.
, a detector 5. A divergence slit 2 in front of the X-ray tube 1 is a slit that determines the X-ray irradiation width on the sample 3, and a detection slit 4 in front of the detector 5 is a slit that determines the resolution of diffraction angle measurement. Further, the θ-axis drive motor 6 and the θ-axis drive motor 7 coupled to this goniometer section are controlled by a goniometer control section 8.

To explain the operation of this X-ray diffraction device, X-rays of wavelength λ taken out from an X-ray tube 1 pass through a divergence slit 2 and are irradiated onto a sample 3. Then, the diffracted X-rays from the sample 3 pass through the detection slit 4 and enter the detector 5. The diffracted X-ray at this time is expressed by Bragg's formula nλ=
It is diffracted to a position that satisfies 2d sin θ. To detect this, it is necessary to maintain a relationship such that the angle θ between the incident X-ray and the sample and the angle θ between the sample 3 and the detector 5 are always the same, and to scan θ about 00 to 80 degrees. Therefore, the holding part for the sample 3 and the holding part for the detector 5 have separate drive shafts, and the goniometer control part 8 controls the θ-axis so that they are driven at a ratio of θ and 2θ, that is, 1:2. Drive motor 6.2θ axis drive motor 7 is controlled.

[Problems to be Solved by the Invention] In the conventional X-ray diffraction apparatus as described above, ensuring that the sample surface is at the center of rotation of the goniometer section relies on mechanical precision, and if the sample surface is flat, To some extent, the deviation from the center of rotation can be minimized due to the precision of the parts. However, when the sample surface is uneven or when the sample is collected on a filter, the deviation between the sample surface and the center of rotation becomes large, causing errors in measurement accuracy.

The present invention was devised to eliminate the drawbacks of the prior art as described above, and it constantly corrects the angular error caused by the misalignment between the sample surface and the rotation center of the goniometer, allowing highly accurate analysis and making it easier to operate. An object of the present invention is to provide an X-ray diffraction device that can improve the properties of the X-ray diffraction device.

[Means for Solving the Problems] In order to achieve the above object, the X-ray diffraction apparatus of the present invention includes a position detecting means for detecting a deviation between the sample surface and the rotation center of the goniometer, and an output of the position detecting means. and a goniometer control device to which the goniometer is input.

[Operation] The X-ray diffraction apparatus configured as described above detects the deviation between the sample surface to be measured and the rotation center of the goniometer using the position detection means, and inputs the detected deviation to the goniometer control device. The error in the measurement angle due to the shift is calculated, and the drive signals for the θ-axis and 2θ-axis of the goniometer are corrected.

[Example] An example will be described with reference to the drawings. In FIG. 1, an X-ray tube 1, a diverging slit 2, a sample 3, a detection slit 4, a detector 5, a θ-axis drive motor 62, a θ-axis drive motor 7,
The goniometer control section 8 is the same as that shown in FIG. A displacement measuring section 10 is connected. Furthermore, the goniometer control section 8 is provided with an angular error correction section 11.

To explain the operation of the X-ray diffraction apparatus of the present invention, the position of the sample 3 is detected by the ultrasonic position sensor 9, and the amount of displacement between the sample 3 and the rotation center of the goniometer is measured by the displacement measurement unit 10 based on the detected value. .

Then, this displacement measurement signal is input to the goniometer control unit 8, and the angle error correction unit 11 calculates a correction value due to the deviation between the sample 3 and the rotation center of the goniometer. Control the axis.

An example of calculation in the angle error correction section will be explained with reference to FIG.
In FIG. 2, X is the irradiation position of X-rays from the X-ray tube, S is the sample surface, and 0 is the rotation center of the goniometer.

When the angle between the X-ray irradiation direction and the rotation center plane of the goniometer is θ, the displacement between the rotation center and the sample surface is D, the goniometer radius is L, and the angular error is Δθ, the following equation holds true.

Δθ=sin-(a/L)... (1) a=D cos
(θ−Δθ) = D(cosθ′cosΔθ+sinθ.

sinΔθ) ... (2) However, a=
L sin Δθ.

At this time, since 80 is extremely small, cosΔθ≠1, s
Since inΔθ≠Δθ holds true, the above equation (2) becomes aiD (cosθ+Δθ·sinθ). Also, from equation (1), Δθ well a/L, so Δθ=D(cosθ+Δθ·sinθ)/L. Therefore, when the displacement is in the positive direction, Δθ=Dcosθ/ (
L Ds in θ) When the displacement is in the negative direction, Δθ=D cos θ/ (L+Ds in θ), and by measuring the displacement ff1D with the displacement measuring section 10, θ
It is possible to find the angular error at each θ value during scanning.

Therefore, this correction value Δ obtained by the angle error correction section 11
θ is input to the goniometer control section 8, and the θ-axis drive motor 6
．． By correcting the drive signal to the 2θ-axis drive motor 7, highly accurate analysis can be performed.

In the above embodiment, an ultrasonic sensor was used as the position detector, but other position detectors such as optical sensors can also be used as long as they are non-contact and do not obstruct the passage of X-rays. .

[Effects of the Invention] As explained above, the present invention detects the deviation between the sample surface and the center of rotation and constantly corrects the angular error, so that highly accurate analysis can be performed. Furthermore, setting the sample at the center of rotation can be done more roughly than in conventional goniometers, and the operability of the analyzer can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the X-ray diffraction device of the present invention, FIG. 2 is a diagram for explaining the calculation method of the angular error correction value, and FIG. 3 is a diagram showing the conventional X-ray diffraction device.・X-ray tube, 2...
Divergence slit, 3. Sample, 4. Detection slit, 5.
・Detector, 6.. θ-axis drive motor, 7.. 2θ-axis drive motor, 8.. Goniometer control section, 9.. Ultrasonic position sensor, 10.. Displacement measurement section, 11.. Angle error correction section.

Claims (1)

[Claims] (1) Each has a goniometer, a position detection means for detecting a deviation between the sample surface to be measured and the rotation center of the goniometer, and a goniometer control means to which the output of the position detection means is input, and An X-ray diffraction apparatus characterized in that an error in a measurement angle due to a deviation from a rotation center of a goniometer is corrected.