JPH0146822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a micro-area X-ray diffractometer that can obtain an X-ray diffraction image of a micro-area of a sample consisting of a large number of crystal grains.

[Prior Art] Conventionally, an X-ray diffraction apparatus has been used for structural analysis of substances, particularly for determining the structure of substances consisting of a large number of crystal grains. When performing such X-ray diffraction, it is often necessary to obtain only information on a minute region with a diameter of 100 μm or less. When the analysis or measurement area becomes minute in this way, the number of crystal grains present in the X-ray irradiation area becomes relatively small. Therefore, if the sample 7 is fixed or rotates only around the φ axis, the probability that a Bragg reflection will occur due to crystal grains in the irradiated area is small. Furthermore, even if Bragg reflection occurs, the probability that the reflected X-rays will enter the band-shaped detection area surrounding the sample is even smaller. Therefore, in conventional cases like this, when X-rays are irradiated to a minute area of a sample made up of many crystal grains, diffraction without any missed detections is obtained when the sample is irradiated with thick X-rays. It was not possible to obtain a spectrum. In particular, if there is a bias in the directional distribution of the crystal lattice planes of crystal grains in the sample, the possibility of this detection failure becomes even greater, making it even more difficult to perform satisfactory measurements.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points. The object of the present invention is to provide a micro-area X-ray diffractometer that can be used in a relatively short period of time without causing problems.

[Means for Solving the Problems] Therefore, the present invention provides a sample consisting of a large number of crystal grains, an X-ray source, and collimating the X-rays from the X-ray source to irradiate a minute area on the sample. an optical microscope for observing the X-ray irradiation position on the sample; a position-sensitive X-ray detector disposed in the detector, an adjustment mechanism for finely adjusting the position of the sample in order to position a desired micro region of the sample at a measurement position using the optical microscope; A circuit for processing a signal to obtain position information, a means for cumulatively storing this signal for a certain period of time, and a rotating shaft (φ) for holding the sample at its tip during the measurement period for storing the signal cumulatively. a sample drive mechanism for continuously rotating the sample and continuously rotating the sample around a χ axis perpendicular to the rotation axis (φ);
It is characterized by comprising means for reading out and displaying the stored signal.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic diagram showing one embodiment of the present invention.
is a fine focus X-ray source. This X-ray source is composed of an electron gun 2, focusing lenses 3 and 4, and a target 5, and generates X-rays by colliding an electron beam focused to a minute focus of, for example, several tens of micrometers with the target. . The X-rays are made into a fine bundle by a collimator 6, and are irradiated onto a sample 7, which is made up of a large number of crystal grains, with a spot having a diameter of, for example, about 100 μm. As can be seen from FIG. 2, a mirror 8 is provided between the sample 7 and the collimator 6 so that it can be inserted and removed. The mirror 8 is held by a holder 10, and the holder 10 is connected to a rotating shaft 12 having a knob 11. By rotating the knob 11, the mirror 8 can be easily inserted and removed from the X-ray optical axis. be able to. Only when positioning the sample, as shown in FIG. 2, the mirror 8 is arranged so as to form an angle of 45 degrees with the optical path of the X-rays from the collimator 6 to the sample 7. Although not shown, a sample position fine adjustment mechanism for positioning the sample is provided, and the sample surface is observed with an optical microscope 9 through the mirror 8, and the cross position of the crosshair provided in the microscope is Measurement positioning is performed using the adjustment mechanism so that the minute regions of the sample to be measured overlap and the optical microscope image is clear. This alignment position remains unchanged even when the sample is rotated around the φ axis and the χ axis, which will be described later.
As shown in FIG. 3, 13 is a position-sensitive X-ray detector in the form of a belt or line and arranged in a semicircle around the sample 7, and its output is sent to the processing circuit 14. is sent, becomes a position information signal, and is stored in the memory 15.
is memorized. This stored signal is read out and displayed on the display device 16.

The detector 13 and processing circuit will be described in detail with reference to FIGS. 3 and 4. The detector 13 has an X-ray entrance window 18 in an outer cylinder 17, and a drift electric field setting cathode 19 made of tungsten or stainless steel wire, and a grid 2 in the direction along this entrance window.
A large number of reading cathodes 22a, 22b, . . . , 22n are provided at regular intervals in a direction perpendicular to these electrodes. Each of the cathodes 22a, 22b, . Said outer cylinder 1
A predetermined reaction gas is introduced into the chamber 7 through an inlet 24 and discharged through an outlet 25 . now,
When X-rays enter through the window 18, gas molecules are ionized, and electrons generated by this initial ionization are accelerated by the electrostatic field between the electrodes, reach the vicinity of the anode 21, cause a local avalanche phenomenon, and are captured by the anode. be done. When this avalanche occurs, a positive pulse voltage is induced in the adjacent readout cathode, and the signal is extracted from both ends of the delay line 23. However, if the positions where the avalanche occurs, that is, the X-ray incident positions are not equal from both ends of the delay line 23, the signals from both ends of the delay line will be extracted with a time lag. This signal is transmitted to the amplifier 26a,
The signal is sent to the waveform shaping circuits 27a and 27b via the signal line 26b, where it is shaped into a signal showing a sharp rise, and then sent to the time difference intensity conversion circuit 28 as a start or stop signal. This circuit 28
The output of A has an intensity corresponding to the time difference between the signals from both circuits 27a and 27b, and this signal is
- It is digitized by the D converter 29 and stored in the memory 30 as a position signal. If the A-D converted signals have the same strength, the memory integrates and stores them at the same address.
Therefore, if a large number of X-ray photons are incident on the same point on the X-ray detector 13, the integrated signal is stored in the memory 30 according to the number of X-ray photons. After the measurement is completed, the signal in this memory is read out and sent to the computer and/or to the display device 31, where it is displayed as a spectrum.

In FIGS. 5 and 6, 34 is a rotating shaft corresponding to the rotating shaft (φ), and a sample is held at the tip of the shaft 34. In order to rotate the sample 7 also around an axis χ perpendicular to the axis 34, the slider 33 supporting the axis 34 can rotate along an annular guide 32.
3 is designed to be able to rotate continuously within a certain angle range while changing the direction of rotation, as shown by the arrow in FIG. 5, during the measurement period in which the signals from the detector 13 are stored cumulatively .

In such a configuration, the sample 7 rotates continuously during the measurement period during which the shaft 34 and the sliding body 33 accumulate the signals from the detector 13.

Now, in FIG. 5, the rotation angle φ around the φ axis is considered with the plane of paper as the first reference plane, and the rotation angle φ around the χ axis is considered as the second reference plane perpendicular to the plane of paper including the detector 13. Considering the angle χ, the state of the sample 7 can be expressed using a set (φ, χ) of the angles φ and χ. Now, in a certain state (φa, χa) where φ becomes a certain angle φa and χ becomes a certain angle χa,
Based on the X-rays incident on the sample 7 perpendicularly to the plane of the paper, a blurred reflection occurs by a certain crystal grain in the irradiation area, and this reflected X-ray contains the incident X-rays and forms an angle α with the second reference plane. If the reflected X-rays travel along the plane formed by the ) Since the above rotation is performed, the state (φa, χa−α) also occurs while the rotations about the φ and χ axes are repeated during a relatively short measurement period. In this state, the X-rays travel within the second reference plane where the detector 13 is present, so they pass through the detection window and are detected by the detector 13. In this way, when the probability of Bragg reflection is increased by rotation around the φ axis and the probability of occurrence of Bragg reflection X-rays is increased, the reflected X-rays do not proceed into the plane where the detector 13 is present. By rotating the sample 7 around the χ axis, the probability that the reflected X-rays will be detected by the detector 13 can be considerably increased. As a result, although only a relatively small number of crystal grains exist in the X-ray irradiated area of the sample, a large number of crystal grains with a random directional distribution are found in the X-ray irradiated area throughout the measurement period. Therefore, the detector 13
The signal obtained by accumulating the signals becomes a continuous diffraction spectrum signal with no missing peaks as would be obtained in that case. Therefore, by displaying this signal, X-ray diffraction analysis can be performed satisfactorily in a minute region of a sample consisting of many crystal grains. In particular, even if there is a bias in the directional distribution of the crystal lattice planes of crystal grains within a microscopic region, the rotation around the φ and χ axes can greatly improve the occurrence of missed detection due to this bias. Therefore, sufficient measurement is possible.

FIG. 7 is for explaining another example of the installation of the position-sensitive X-ray detector 13.
It is not limited to the case where it is placed on the side of the sample as shown in FIG.
It can also be used with a linear detector instead of a semicircular one.

[Effects of the Invention] As described in detail above, in the present invention, a sample consisting of a large number of crystal grains, a microfocus X-ray source, and a microfocus on the sample by collimating the X-rays from the X-ray source are provided. means for irradiating a region, an optical microscope for observing an X-ray irradiation position on the sample, and a desired angular range of X-rays diffracted by the sample in a plane containing the optical path of the X-rays. a position-sensitive X-ray detector arranged to cover the sample; an adjustment mechanism for finely adjusting the position of the sample in order to position a desired minute region of the sample at a measurement position using the optical microscope; A circuit for processing signals from the detector to obtain position information, means for cumulatively storing this signal for a certain period of time, and a rotating shaft that holds the sample at its tip during the measurement period for storing the signal cumulatively. (φ) and the sample drive mechanism for continuously rotating the sample around a χ axis perpendicular to the rotation axis (φ), and reading and displaying the stored signal. Since the means is provided, the directional distribution of the crystal lattice planes of crystal grains within the X-ray irradiated micro region can be sufficiently randomized within a relatively short measurement period, and the Despite the presence of only a small number of grains, the signal obtained by accumulating the detector signal is similar to that obtained when a large number of grains with a random directional distribution are present in the X-ray irradiation area. This results in a continuous diffraction spectrum signal with no missing peaks. Therefore, X-ray diffraction analysis of a minute region of a sample consisting of a large number of crystal grains can be performed satisfactorily in a relatively short time. In particular, even if there is a bias in the distribution of the crystal lattice plane directions of the crystal grains, the rotation around the φ and χ axes can greatly reduce the occurrence of detection errors due to this bias, and this is sufficient. Measurement becomes possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram of FIG. 1 viewed from the right, and FIG. 3 is a diagram showing one embodiment of the present invention.
Figure 4 showing an example of the detector used in Figure 4.
The figure also shows an example of the signal processing circuit, Figures 5 and 6 are diagrams showing an example of the sample drive device of the apparatus in Figure 1, and Figure 7 is a diagram for explaining the arrangement of the detector. be. 1: Microfocus X-ray source, 2: Electron gun, 3, 4: Focusing lens, 5: Target, 6: Collimator,
7: Sample, 8: Mirror, 9: Optical microscope, 10:
Mirror holder, 11: Knob, 12: Rotation shaft, 1
3: Position sensitive X-ray detector, 14: Processing circuit, 1
5: Memory, 16: Display device.

Claims (1)

[Claims] 1 A sample consisting of a large number of crystal grains, an X-ray source, a means for collimating the X-rays from the X-ray source and irradiating a minute area on the sample, and a means for determining the X-ray irradiation position on the sample. an optical microscope for observation; a position-sensitive X-ray detector arranged to cover a desired angular range of X-rays diffracted by the sample in a plane including the optical path of the X-rays; an adjustment mechanism for finely adjusting the position of the sample in order to locate a desired micro region of the sample at a measurement position using an optical microscope; a circuit for processing the signal from the detector to obtain position information; and a circuit for processing the signal from the detector to obtain position information. means for cumulatively storing the signal for a certain period of time; and during the measurement period for cumulatively storing the signal, a rotating shaft (φ) that holds the sample at its tip is continuously rotated, and the sample is held on the rotating shaft (φ). ) is a micro-area X-ray diffractometer characterized by comprising a sample drive mechanism for continuously rotating the sample around a vertical χ axis, and means for reading and displaying the stored signal.