JP3685422B2 - X-ray diffraction measurement method and X-ray diffraction apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray diffraction measurement method and apparatus for detecting X-ray diffraction generated from a sample by X-ray detection means when the sample is irradiated with X-rays.
[0002]
[Prior art]
In the conventional X-ray diffractometer, for example, as shown in FIG. 5, the sample S is rotated intermittently or continuously at a predetermined angular velocity around the sample axis ω, so-called θ rotation. At the same time, the light receiving slit 53, the scattered radiation restricting slit 54, and the X-ray counter 55 are rotated integrally or continuously at an angular velocity twice as large as θ rotation around the sample axis ω, so-called 2θ rotation. While the sample S rotates θ and the X-ray counter 55 and the like rotate 2θ, X-rays radiated from the X-ray source 51 are irradiated to the sample S by regulating the divergence angle by the divergence regulating slit 52. When so-called Bragg diffraction conditions are satisfied between the X-rays incident on the sample S and the crystal lattice plane of the sample S, X-ray diffraction occurs in the sample S, and the diffracted X-rays are generated by the X-ray counter 55. Detected.
[0003]
The above measurement method is effective when the sample S is solid, but cannot be used when the sample S is liquid. This is because if the sample S is a liquid, the sample S spills out of the case when the sample S is rotated by θ and measurement cannot be performed. When the liquid is used as a sample in this way, instead of rotating the sample S by θ rotation, the sample S is fixedly held in a horizontal state, the X-ray source 51 is rotated around the sample S in a certain direction at a predetermined angular velocity θ, The X-ray counter 55 and the like are rotated in the opposite direction around the sample S at the same angular velocity θ. As a result, the X-ray source 51 can be rotated by θ with respect to the sample S at an angular velocity θ, and at the same time, the X-ray counter 55 and the like can be rotated by 2θ with respect to the incident X-ray at an angular velocity 2θ that is twice θ.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional X-ray diffraction measurement method using a liquid as a sample, X-ray diffraction measurement is performed by irradiating the upper surface of the liquid sample with X-rays. However, it is difficult to maintain the upper surface of the liquid sample on a smooth plane, and therefore it is difficult to obtain highly reproducible measurement data. Further, since the liquid evaporates, the position of the upper surface thereof changes, and therefore, measurement for a long time is difficult.
[0005]
In addition, depending on the type of measurement, there is a measurement such as observing the behavior of powder and other foreign substances mixed in the liquid. For such measurement, it is necessary to stir the liquid during the measurement. . When such agitation is performed, there is a problem that the upper surface of the liquid is further oscillated and disturbed, and therefore the reliability of the measurement data is further reduced.
[0006]
The present invention has been made in view of the above-mentioned problems in the conventional X-ray diffraction measurement method, and an X-ray diffraction measurement method capable of stably obtaining a highly reliable measurement result for a liquid sample, and An object is to provide an X-ray diffractometer.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an X-ray diffraction measurement method according to the present invention detects X-ray diffraction generated from a sample by X-ray detection means when the sample is irradiated with X-rays. In the measurement method, a liquid sample is stored in a sample holder whose lower surface is made of a material that can transmit X-rays, and the liquid sample is irradiated with X-rays through the lower surface of the sample holder while the sample holder is horizontally supported. It is characterized by doing.
When a liquid is applied as a sample, the lower surface of the liquid sample always exists as a smooth plane at a fixed position even when the upper surface is disturbed. Therefore, according to the X-ray diffraction measurement method having the above-described configuration, highly reproducible X-ray diffraction measurement data can be stably obtained for the liquid sample.
[0008]
Depending on the type of measurement, there is a measurement aimed at observing the behavior of foreign substances mixed in the liquid. In such a measurement, it is necessary to stir the liquid sample from the upper surface. Thus, when the liquid sample is stirred from the upper surface, the upper surface is rocked and disturbed, but the lower surface on which the X-rays enter maintains a smooth flat state. Therefore, according to the present invention, highly reproducible X-ray diffraction measurement data can be stably obtained even when a liquid sample is stirred.
[0009]
An X-ray diffractometer according to the present invention is an X-ray diffractometer that detects diffracted X-rays generated from a sample when the sample is irradiated with X-rays by an X-ray detector, and the lower surface is the X-ray diffractometer. A sample holder that is formed of a material that can pass through the sample and stores the sample, a sample support that horizontally supports the sample holder, an X-ray tube arm that rotates about the sample axis and supports the X-ray tube, Have The X-ray tube is attached to the X-ray tube arm such that the attached power cable extends upward from the X-ray tube arm.
[0010]
In general, in an X-ray diffractometer, its main part, that is, a goniometer, an X-ray tube, an X-ray detection means, and the like are installed on a table, and a power supply device for supplying high voltage and high current to the X-ray tube is below the table. It is arranged. For this reason, the power cable connecting the X-ray tube and the power supply device is generally arranged to extend downward from the X-ray tube. When applying a liquid as a sample in such a conventional apparatus, if X-rays are to be irradiated from the lower surface of the sample, the X-ray tube is disposed at a lower position than the sample, and the electric power is further moved to the lower position. There will be a cable. In addition, when a liquid sample is applied as a sample, the X-ray tube must be rotated by θ while the liquid sample is fixedly supported. In that case, the power cable attached to the X-ray tube follows the X-ray tube. It will move. However, this power cable is generally thick and difficult to bend, and a large installation space must be secured between the X-ray tube and the table in order to arrange it so that it can move. In the past, it was impossible to secure such a large installation space.
[0011]
On the other hand, if the X-ray tube is attached to the X-ray tube arm so that the power cable attached to the X-ray tube extends above the X-ray tube arm as in the X-ray diffraction apparatus according to the present invention. A sufficiently large space can be secured below the X-ray tube arm. Therefore, it is possible to irradiate the lower surface of the liquid sample with X-rays by installing the X-ray tube below the liquid sample. It was.
[0012]
As described above, according to the X-ray diffraction apparatus of the present invention, X-rays can be irradiated from the lower surface of the sample, but in some cases, it is desired to irradiate X-rays from the upper surface of the sample. In consideration of such cases, the power cable attached to the X-ray tube is positioned between the upper mounting position where the X-ray tube arm extends upward and the lower mounting position where the power cable extends below the X-ray tube arm. It is desirable to attach the X-ray tube to the X-ray tube arm so that the position can be changed.
[0013]
As such a position conversion mechanism, for example, a fixing member for fixing the X-ray tube is provided in advance, and by changing how the fixing member is attached to the X-ray tube arm, A mechanism is conceivable in which the X-ray tube mounting position is switched between the upper mounting position and the lower mounting position.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of an X-ray diffraction apparatus according to the present invention. The purpose of this X-ray diffractometer is to perform so-called radial distribution measurement of a liquid sample. When X-ray diffraction lines are measured with a gas, liquid, amorphous metal, or the like, a halo that attenuates as the angle increases is generally observed. This halo corresponds to the structure of a liquid or the like, and the halo is analyzed by calculating a radial distribution function. This radial distribution function represents a distribution of density of a spherical shell having a distance r from the center considering a sphere centered on a certain atom. For structural analysis of amorphous substances such as liquids, it is a common technique to obtain a radial distribution function from the measurement result of scattered X-ray intensity by X-rays, and this measurement method is called radial distribution measurement. Is.
[0015]
The X-ray diffractometer shown in FIG. 1 includes a goniometer 14 that includes a columnar sample support 11, an X-ray tube arm 12, and a detector arm 13. The sample support 11 supports the sample holder 15 in which the liquid sample S is accommodated in a fixed state, and the lower surface 15a of the sample holder 15 is made of a material that can transmit X-rays, such as a polymer film or aluminum. It is comprised with metal foil etc.
[0016]
The X-ray tube arm 12 extends from the side surface of the θ turntable 16 so as to be able to rotate up and down about a sample axis ω that is an axis passing through the lower surface of the liquid sample S. A fixing member 17 is fixed to the tip of the X-ray tube arm 12 with a screw or other fastener, and the X-ray tube 9 is fixed to the fixing member 17 with a screw or other fastener. The fixing member 17 is constituted by two portions 17a and 17b bent at an appropriate angle, and guide holes 8a and 8b are formed in these portions, respectively. In the state shown in the drawing, the guide hole 8 a provided in one fixing member portion 17 a is fitted into the guide pin 7 provided on the X-ray tube arm 12, whereby the position of the fixing member 17, and thus the X-ray tube 9. Is determined to be a fixed position. A divergence regulating slit 2 is provided on the X-ray tube arm 12 between the X-ray tube 9 and the sample S.
[0017]
As shown in FIG. 2, the X-ray tube 9 is configured by covering a cylindrical X-ray tube 20 with a cylindrical tube shield 18. Inside the X-ray tube 20, a filament 19 as a cathode and a target 21 as an anti-cathode are disposed. A power cable 22 is connected to the filament 19, a current is passed through the filament 19 through the power cable 22, and a high voltage is applied between the filament 19 and the target 21. The filament 19 is heated by energization to emit thermoelectrons, and the thermoelectrons are accelerated by the high voltage and collide with the target 21 at a high speed.
[0018]
X-rays are generated from the target 21 by the collision of the thermal electrons, and the X-rays are taken out through the X-ray window 23 provided on the side surface of the X-ray tube 20 and the X-ray window 24 provided on the side surface of the tube shield. . Reference numeral 26 denotes an X-ray shutter that opens and closes the X-ray window 24. In general, the X-ray tube 20 is provided with a cooling water passage for cooling the target 21 that generates heat, which is omitted in the drawing. A region of the target 21 that generates X-rays is generally called an X-ray focal point, and in FIG. In the present embodiment, as shown in FIG. 1, the X-ray tube 9 is interposed via the fixing member 17 so that the main body portion of the X-ray tube 9 and the power cable 22 extend above the X-ray tube arm 12. It is fixed to the arm 12.
[0019]
In FIG. 1, the detector arm 13 extends from the side surface of the 2θ rotating table 27 so that it can be rotated up and down about the sample axis ω of the liquid sample S. At the tip of the detector arm 13, a light receiving slit 3, a scattered radiation regulating slit 4, and an X-ray counter 5 as an X-ray detecting means are fixed.
[0020]
The θ-rotation table 16 that supports the X-ray tube arm 12 is driven intermittently or continuously by being driven by a θ-rotation drive system 28, whereby the X-ray tube arm 12 is intermittently rotated at an angular velocity θ about the sample axis ω. Or it rotates continuously. On the other hand, the 2θ rotating table 27 is driven intermittently or continuously by being driven by a 2θ rotation drive system 29, so that the detector arm 13 is rotated at the same angular velocity θ as the X-ray tube arm 12 around the sample axis ω. It rotates intermittently or continuously in the opposite direction to the tube arm 12. The X-ray tube arm 12 and the detector arm 13 rotate at the same angular velocity θ in the opposite directions at the same time. As a result, the detector arm 13 rotates with respect to the X-ray tube arm 12 at an angular velocity 2θ that is twice the angular velocity θ. To do. The θ rotation drive system 28 and the 2θ rotation drive system 29 can be configured by using an arbitrary mechanism. For example, a driving force from a power source such as a motor is transmitted to a θ rotation table via a power transmission system having a worm and a worm wheel. It can be configured by a mechanism that transmits to the 16 or 2θ turntable 27.
[0021]
The X-ray counter 5 outputs a signal according to the amount of X-rays taken therein, and the counting device 31 counts the X-ray intensity based on the output signal. The counted X-ray intensity is sent from the counting device 31 to the control arithmetic device 32. The control arithmetic unit 32 is configured by using a computer, controls the operation of the θ rotation drive system 28 according to a predetermined program, rotates the X-ray tube arm 12 by θ, and further controls the operation of the 2θ rotation drive system 29. Then, the detector arm 13 is rotated by 2θ. Then, the relationship between the X-ray intensity signal sent from the counting device 31 and the diffraction angle 2θ is calculated, the change of the diffraction X-ray intensity with respect to the change of the diffraction angle 2θ is calculated, and the calculation result of the X-ray intensity is further calculated. Based on this, the radial distribution function is calculated, and the result is displayed as an image on the CRT display 33 or printed on a printing material such as paper by the printer 34.
[0022]
Although not particularly shown in FIG. 1, in some cases, in order to improve the measurement accuracy, a monochromator for monochromatic X-rays is provided between the X-ray focal point F and the divergence regulating slit 2 or scattered rays. It may be installed in the middle of the X-ray optical path between the restriction slit 4 and the X-ray counter 5.
[0023]
Since the X-ray diffraction apparatus of the present embodiment is configured as described above, each of the X-ray tube arm 12 and the detector arm 13 rotates in the downward direction of the liquid sample S at an equal angular velocity θ. Then, X-rays emitted from the X-ray tube 9 supported by the X-ray tube arm 12 and rotating by θ rotate to the lower surface of the liquid sample 2 through the bottom surface 15a of the sample holder 15 while the divergence angle is limited by the divergence restriction slit 2. Irradiated. Then, scattered X-rays, that is, diffracted X-rays are generated from the liquid sample 2 in accordance with the internal structure of the sample, and the scattered X-rays are detected by the X-ray counter 5 through the light receiving slit 3 and the scattered radiation regulating slit 4. Is done.
[0024]
The X-ray counter 5 outputs a signal to the counting device 31 corresponding to the detected amount of scattered X-rays. The counting device 31 calculates the X-ray intensity based on the signal, and the calculation result is used as a control calculation device 32. Send to. The control calculation device 32 calculates an X-ray diffraction pattern as shown in FIG. 3 by associating the sent X-ray intensity signal with the diffraction angle 2θ. Further, the control calculation device 32 calculates a radial distribution function based on the X-ray diffraction pattern, and displays the result on the CRT display 33 or prints it by the printer 34. The measurer observes the displayed radial distribution function to analyze the structure of a liquid sample that does not have a specific atomic arrangement unlike single crystal materials and polycrystalline materials.
[0025]
In the X-ray diffractometer of this embodiment, scattered X-ray information is collected not from the upper surface of the liquid sample S but from its lower surface. Since the lower surface of the liquid sample S is accurately held in a stable and smooth plane state by the holder bottom surface 15a even when the upper surface fluctuates irregularly, stable measurement data with high reproducibility can be obtained. In the present embodiment, as shown in FIG. 1, the main body portion of the X-ray tube 9 and the power cable 22 are disposed so as to extend above the X-ray tube arm 12. A wide space is formed, and therefore, the X-ray focal point F of the X-ray tube 9 can be rotated downward at a large angle, and as a result, the lower surface of the liquid sample S is irradiated with X-rays. Could be realized.
[0026]
Depending on the type of measurement, the behavior of the liquid sample S containing a foreign substance, such as powder, in the liquid such as the powder may be measured. In such measurement, it is necessary to perform measurement while stirring the liquid sample S. When performing such measurement using this embodiment, the lower surface of the liquid sample S is irradiated with X-rays while stirring the liquid sample S from the upper surface in FIG. When the liquid sample S is stirred from the upper surface, the upper surface is vigorously shaken and disturbed, but the lower surface is accurately held in a stable and smooth flat state by the holder bottom surface 15a. Therefore, stable measurement data with high reproducibility can be obtained.
[0027]
The above is a description of the measurement performed by irradiating the lower surface of the sample S with X-rays. However, when the sample S is not a liquid but a solid, it is not always necessary to irradiate the lower surface of the sample S with X-rays. In some cases, it may be desirable to irradiate the upper surface of the sample S with X-rays. In such a case, in FIG. 1, the fixing member 17 is removed from the X-ray tube arm 12, and, as shown in FIG. Is in a state of extending downward. Then, the guide hole 8b in the other fixing member portion 17b is fitted into the guide pin 7 of the X-ray tube arm 12 to position the X-ray tube 9, and in this state, the fixing member 17 is fixed to the X-ray tube with screws or other fasteners. Fix to the tube arm 12.
[0028]
When irradiating the upper surface of the sample S with X-rays from the X-ray focal point F, the X-ray tube arm 12 rotates θ upward from the sample S. Therefore, the X-ray tube 9 and the power cable 22 are moved. It is not necessary to prepare a large space for securing at a position below the sample S. Therefore, even when the power cable 22 extends below the sample S as shown in FIG. 4, X-ray diffraction measurement can be performed without any trouble.
[0029]
The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and various modifications can be made within the technical scope described in the claims.
For example, the present invention includes not only the case where a liquid sample is irradiated with X-rays from its lower surface, but also the case where X-ray diffraction measurement is performed while irradiating a solid sample with X-rays from its lower surface. In addition, when a solid sample is used as a measurement target in such a manner, unlike the liquid sample, diffracted X-rays with high intensity can be obtained, and analysis is performed by a method different from the radial distribution.
[0030]
In the embodiment shown in FIG. 1, the fixing member 17 is once removed from the X-ray tube arm 12, and after the posture of the X-ray tube 9 is corrected, the fixing member 17 is reattached to the X-ray tube arm 12. The mounting state of the X-ray tube 9 was switched. However, it is also possible to provide a rotation mechanism in the X-ray tube arm 12 in place of the fixing member 17, support the X-ray tube 9 by the rotation mechanism, and switch the mounting state of the X-ray tube 9 by the rotation operation of the rotation mechanism. . Further, without providing a mechanism for switching the mounting state of the X-ray tube 9, the X-ray tube 9 is fixed in a state where the power cable 22 of the X-ray tube 9 extends upward as shown in FIG. It can also be fixed and installed directly on the X-ray tube arm 12 without an intervening member such as the member 17 or the like.
[0031]
In the embodiment shown in FIG. 1, as a method of positioning the fixing member 17, a method of fitting the circular guide pin 7 into the circular guide hole 8a or 8b is adopted. However, it goes without saying that any other positioning method can be adopted.
[0032]
【The invention's effect】
According to the X-ray diffraction measurement method of the first aspect, since the lower surface of the sample is irradiated with X-rays, when a liquid is applied as the sample, the upper surface of the liquid sample is oscillated and disturbed. Even at times, the lower surface of the sample on which X-rays are incident always exists as a smooth flat surface at a certain position, and therefore, highly reproducible X-ray diffraction measurement data can be stably obtained.
[0033]
When the liquid sample is stirred as in the X-ray diffraction measurement method according to claim 3, the upper surface of the liquid sample is particularly vigorously shaken. Therefore, in the conventional method of irradiating the upper surface of the sample with X-rays, Stable X-ray diffraction measurements are almost impossible. On the other hand, according to the present invention in which the lower surface of the sample is irradiated with X-rays, stable measurement can always be performed even when the sample is stirred from the upper surface.
[0034]
According to the X-ray diffraction apparatus of the fourth aspect, since the X-ray tube is attached to the X-ray tube arm so that the power cable extends above the X-ray tube arm, a sufficiently wide space is provided below the X-ray tube arm. As a result, the X-ray tube can be rotated θ to the lower side of the sample to a large angle, so that the lower surface of the sample can be irradiated with X-rays.
[0035]
According to the X-ray diffraction apparatus of the fifth aspect, the measurement of irradiating the lower surface of the sample with X-rays and the measurement of irradiating the upper surface of the sample with X-rays can be freely switched and executed.
[0036]
According to the X-ray diffraction apparatus of the sixth aspect, switching of the measurement conditions as in the fifth aspect can be realized with a very simple configuration.
[0037]
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of an X-ray diffraction apparatus according to the present invention and a block diagram of an electric control system.
FIG. 2 is a front sectional view showing an example of an X-ray tube.
FIG. 3 is a diagram showing an X-ray diffraction pattern which is an example of a measurement result.
4 is a front view showing a state in which the mounting state of the X-ray tube is switched with respect to the X-ray diffraction apparatus shown in FIG.
FIG. 5 is a diagram schematically showing a conventional X-ray diffraction measurement.
[Explanation of symbols]
2 Divergence regulating slit 3 Light receiving slit 4 Scattered ray regulating slit 5 X-ray counter (X-ray detection means)
7 Guide pin 8a, 8b Guide hole 9 X-ray tube 11 Sample support stand 12 X-ray tube arm 13 Detector arm 14 Goniometer 15 Sample holder 16 θ turntable 17 Fixed member 22 Power cable 26 X-ray shutter 27 2θ turntable F X Line focus S Sample ω Sample axis

Claims (6)

In the X-ray diffraction measurement method in which the X-ray detection means detects the diffracted X-rays generated from the sample when the sample is irradiated with X-rays,
A liquid sample is stored in a sample holder whose lower surface is made of a material that can transmit X-rays,
An X-ray diffraction measurement method comprising irradiating the liquid sample with X-rays through a lower surface of the sample holder in a state where the sample holder is horizontally supported . 2. The X-ray diffraction measurement method according to claim 1, wherein the lower surface of the sample holder is formed of a polymer film or aluminum . In X-ray diffraction measuring method according to claim 1 or claim 2 wherein, said in a liquid sample impurities are mixed and irradiated with X-rays to the lower surface of the liquid sample while stirring the liquid sample from the upper surface X-ray diffraction measurement method characterized by the above. In an X-ray diffractometer that detects diffracted X-rays generated from a sample when the sample is irradiated with X-rays by an X-ray detector,
A sample holder whose lower surface is made of a material capable of transmitting X-rays and stores a liquid sample;
A sample holder for supporting the sample holder horizontally,
An X-ray tube arm that rotates below the sample holder about the sample axis and supports the X-ray tube;
The X-ray tube, X-rays diffraction apparatus characterized by the supplied power cable is attached to the X-ray tube arm so as to extend upwardly of the X-ray tube arm. In an X-ray diffractometer that detects X-ray diffracted X-rays generated from a sample when the sample is irradiated with X-rays,
A sample holder whose lower surface is made of a material capable of transmitting X-rays and stores a liquid sample;
A sample holder for supporting the sample holder horizontally,
An X-ray tube arm that rotates below the sample holder about the sample axis and supports the X-ray tube;
The X-ray tube, characterized in that it positions convert between the upper mounting position of the supplied power cable extends upwardly of the X-ray tube arm, a lower mounting position in which the power cable extends downwardly of the X-ray tube arm X-ray diffractometer. In X-ray diffraction apparatus according to claim 5, the fixing member for fixing the X-ray tube is provided, by changing the mounting way of the X-ray tube arm of the fixing member, wherein with respect to the X-ray tube arm X-ray diffraction and wherein the switching between the mounted position of the X-ray tube and the upper attachment position and the lower mounting position.

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