JPH0668471B2 - Sample capsule for X-ray defractometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sample capsule for an X-ray defractometer (hereinafter referred to as a defractometer). More specifically, when measuring the crystallographic properties of powdery or plate-like polycrystals, single crystals or amorphous samples with a defractometer using the Bragg-Brentano concentration method, The present invention relates to a sample capsule capable of easily and highly accurately measuring a sample that is easily affected, a sample that dislikes oxygen and carbon dioxide in the air, and a sample that contains a volatile component (hereinafter referred to as an unstable sample).

2. Description of the Related Art Conventionally, the following method has been used for the measurement and experiment of X-ray diffraction of an unstable sample with a diffractometer.

1) Place the sample in a recess of a glass or aluminum sample plate and measure it as quickly as possible by the ordinary method.

2) When measuring a hygroscopic sample, put a desiccant such as silica gel in the sample chamber of the defractometer.

3) Cellophane adhesive tape, mylar film (EIdu Pont
A thin film such as a polyethylene terephthalate film manufactured by K.K.) having X-ray transmissivity is brought into close contact with the sample surface.

4) Store the sample plate in a closed container having a window that allows the transmission of X-rays.

5) Install the entire defractometer in an inert gas atmosphere.

Etc.

However, all of these methods have the following problems.

The method 1) cannot be applied when the sample changes rapidly compared to the measurement time.

In the method 2), the influence of water vapor in the air cannot be completely eliminated because the sample chamber containing silica gel or the like is not completely sealed. In addition, it cannot be applied to samples affected by oxygen and carbon dioxide in the air and samples containing volatile components.

In the method 3), the reflected X-rays of a thin film material such as a cellophane adhesive tape or a Mylar film and the like (equivalent to the diffracted X-rays, the same applies below) and the reflected X-rays of the sample to be measured are simultaneously incident on the detector. Therefore, the reflected X-ray from the sample may not be discriminated from the X-ray diffraction pattern.

In the method of 4), since the sample chamber of the goniometer of the ready-made defractometer is not sufficiently large, it is often difficult to manufacture the container to be stored therein, and the goniometer itself needs to be modified.

The method 5) has the drawback that the operation is troublesome and the cost is high because the entire apparatus is placed in an inert gas atmosphere.

OBJECT OF THE INVENTION The present invention has been made in order to solve the problems in the above-mentioned conventional method, and the object thereof is to accurately and simply reflect X-rays from an unstable sample without the need to modify a ready-made diffractometer. It is intended to provide a sample capsule that can be captured in

As a result of earnest research to achieve the above-mentioned object, the inventors of the present invention, instead of closely covering the sample surface with the thin film in the method of 3), set the position of the thin film at a certain distance or more from the sample surface. It has been found that the above-mentioned method can eliminate the drawbacks of the method 3). The present invention has been completed based on this finding.

The gist of the present invention is to measure water vapor, oxygen, carbon dioxide gas, when measuring crystallographic characterization of a sample by an X-ray defractometer using the Bragg-Brentano concentration method.
A thin film made of a material that has a low ability to pass volatile components or a replacement gas and has an ability to pass X-rays is used, and the size of the thin film does not cause the cut of incident X-rays and reflected X-rays. A sample capsule for an X-ray defractometer is characterized in that a thin film is separated from a sample surface by a predetermined distance t or more calculated by the following equation so as not to be detected by the above, and covers the sample.

(Where, t is the distance between the sample surface and the thin film, R is the goniometer radius, θ _B is the Bragg angle, φ is 1/2 the opening angle of the divergence slit, and S is 1/2 the opening angle of the scattering prevention slit.
Represents ) Reflection X when the thin film is placed at a sample surface position (hereinafter abbreviated as sample surface / sample surface position) passing through the center of rotation of the goniometer and when the thin film is placed above and apart from the sample surface.
The difference between the lines will be described with reference to FIGS. 1, 2 and 3. First
The figure is an illustration of the optical system of the defractometer, FIG. 2 is the X-ray diffraction pattern of the thin film measured by the defractometer, and FIG. 3 is the relationship diagram between the reflected X-rays and the slit.

Referring to FIG. 1, A: Diffraction of θ _B when a thin film that causes diffraction at the Bragg angle θ _B is placed on the sample surface, the same thin film as B: is separated from the sample surface by t Diffraction at time, S is focus of X-ray source, D is detector, C is goniometer circle, O is goniometer rotation center, R is goniometer radius, D ・ S is divergence slit, R ・ S is light receiving slit, S ・S is a scattering prevention slit (hereinafter referred to as a scattering slit), θ _B is a Bragg angle, α is a center line of a reflected X-ray from a thin film placed above the sample surface by t, and R · S−S · S. Is the angle between the sample and the center line, 4 is the sample surface, and t is the distance between the sample surface and the thin film.

When a thin film is placed on the surface of the sample, as shown in FIG. 1, the thin film having a reflectivity for X-rays has a Bragg angle θ.
When the incident X-rays are reflected by the _B, X-rays are reflected in the angular direction of the incident X-ray and 2 [Theta] _B, incident on the detector via the receiving slit (R · S) · Scattering slit (S · S).

The X-ray diffraction pattern in this case is as shown in FIG. 2a. A Mylar film was used as the thin film, and CuKα rays were used as the X-ray source. (Even in the following measurements, all X-ray sources are CuK
α rays were used. ) From this figure, the Mylar film has a strong diffraction peak near 2θ (actual defractometer reading angle) = 26 °. Therefore, when a thin mylar is brought into close contact with the sample surface, small reflected X-rays near this angle due to the sample are hidden by the reflected X-rays of the mylar film.

The diffractometer used for this measurement was a goniometer radius: 173 mm, X-ray source: Cu-filled tube, detector: NaI (Tl)
A scintillation counter. As a measuring condition, the opening angle of divergence and scattering slit: both 1/2, receiving slit (K _B line cutting Ni with filter) of opening width: 0.3 m
m, X-ray tube voltage: 30 kV, X-ray tube current: 10 mA, goniometer speed: 2 ° / min, time constant: 1 second, recording speed: 2 cm / min.

On the other hand, as shown in FIG. 1B, when the thin film is separated from the position on the sample surface by t, the reflection X by the thin film at this position is reflected.
The condition of the optical system for the rays to pass through the light-receiving slit (R / S) is that the X-ray source and the detector are rotated by a certain angle α toward the high angle side and are incident on the center of the thin film at a position separated by t. Do X
This is the case when the irradiation angle of the line is equal to θ _B. (Note that
Most of the actual defractometers have a fixed incident X-ray direction, and the structure is such that the sample surface and the detection unit rotate at a ratio of 1: 2, but here, the sample surface is fixed and the X-ray source and The model was a sample horizontal diffractometer in which the detectors were rotated in opposite directions in a one-to-one relationship. Both are completely equivalent in principle. ) Α is obtained from the following equation using θ _B and t and the goniometer radius R.

This means that the reflected X-rays from the thin film located away from the surface of the sample apparently shift to the high angle side and are observed at the position of θ _B + α (2θ _B + 2α when 2θ _B is the measured value). Means

However, in reality, the reflected X-rays are partially or wholly shielded by the scattering slit.

Next, that point will be described.

As shown in FIG. 3, in the diffractometer, the reflected X-ray from the center of the sample surface is received by the light receiving slit (R / S).
Both slits are installed at a position (A ′) that passes through the center of the scattering slits (S · S). On the other hand, the center of the reflected X-ray from the thin film away from the sample surface passes through the light-receiving slit (R / S) with an angle of α with Equation 1 (B '), so part or all of it scatters. Slit (S /
It is shielded by S). C is a scattering slit (SS)
2 shows X-rays reflected from a thin film shielded by.

In the present invention, the position of the thin film is separated from the sample surface so that the reflected X-rays from the thin film do not enter the detector D. For that purpose, it is necessary to completely shield the reflected X-rays from the thin film located away from the sample surface by the scattering slit (S · S). Whether or not this can be completely shielded depends on the distance t between the sample surface and the thin film, and the minimum value of t for completely shielding is that of the divergence slit (DS) and the scattering slit (SS). Once the opening angle is determined, it can be approximately calculated as follows.

Generally, the reflected X-ray that passes through the light receiving slit (R / S) is
It is considered that it has an opening angle almost equal to the opening angle of the divergence slit (DS). The opening angle of the divergence slit is 2φ,
If the opening angle of the scattering slit is 2S, the minimum value of α for completely blocking the reflected X-rays from the thin film away from the sample surface is α = φ + S.

From Equation 1 Equation 2, the minimum value of t is (However, φ, S: radian).

That is, if the thin film is set apart from the sample surface by t or more obtained by the equation 3, the reflected X-ray from the thin film cannot be detected.

Mylar film is used as a thin film material and CuK is used as an X-ray source.
Since θ _B ≅13 ° using α rays, when the goniometer radius is 173 mm and the opening angles of the divergence slit and the scattering slit are both 1/2 °, the value of t is 1.55 mm according to equation 3.

Fig. 2b shows the Mylar membrane without 1.
The X-ray diffraction pattern when measured at a distance of 6 mm from the sample surface is shown. The position of this peak is 2θ = 1.0 as compared with FIG. 2a measured by placing the Mylar film at the position of the sample surface.
Deviated to the high angle side by ゜.

When a scattering slit having an opening angle equal to that of the divergence slit is inserted under the same condition, the reflected X-ray of the Mylar film disappears completely as shown in FIG. 2c.

One embodiment of the sample capsule of the present invention is shown in FIG. In the figure, 1 is a sample filling plate, 2 is a window frame, and 3 is a thin film. The sample filling plate 1 has basically the same structure as a sample plate in a normal measurement method, and has sufficient surface accuracy for measurement and a dent for filling a sample. The material is made of an inorganic compound, an organic compound, or a metal, and can be molded into a plate shape. The size of the sample filling plate can be inserted into the sample chamber of the goniometer to be used, and the window frame 2 described below needs to be attached.

The window frame 2 is used to attach the thin film 3 by raising the thickness of the thin film 3 from the position on the surface of the sample to t or more obtained by the formula 3. The thin film 3 and the window frame 2 may be integrated, and if they are not integrated, it is desirable to sufficiently bond them. It is not necessary to keep the thin film 3 flat, but it is desirable to make the space between the thin film and the sample surface as small as possible within the above range. When the irradiation angle θ on the sample surface is small, the incident X-rays and the reflected X-rays may be cut by the window frame 2. To avoid this,
It is desirable that the length of one side of the window of the window frame 2 that is orthogonal to the rotation axis of the goniometer be larger than the length of that side of the sample surface.

FIG. 5 is an explanatory diagram showing the required window size. In order not to cut incident X-rays and reflected X-rays, the minimum value of the length L of one side of the window orthogonal to the rotation axis of the goniometer is: the minimum irradiation angle is θm, the raised height of the thin film is t, and the goniometer radius is R, when the opening angle of the divergence slit is 2φ, L = 2t · cot (θm + φ) + R · sinφ {cosec (θm + φ) + cosec (θm−φ)} ... Equation 4

If the window is smaller than this, some or all of the incident X-rays and the reflected X-rays are shielded by the window frame near the irradiation angle θm.
The observation intensity of reflected X-rays is reduced. It is desirable that the dimension of one side of this window, which is perpendicular to one side, is equal to or larger than the length of the sample surface in the same direction, but even if it is slightly smaller than that, the observation intensity of reflected X-rays has a great influence. Do not receive

Further, each part of the sample capsule does not have to be rectangular.

The thin film material may be an organic compound / inorganic compound or a metal, as long as it has a low ability to pass water vapor, oxygen, carbon dioxide, a volatile component or a replacement gas and has an ability to transmit X-rays. When a material having a diffraction peak at an extremely high angle is used as the thin film material, θ _B in Expression 3 becomes large, so that the required height t of the thin film is increased. This means that, as can be seen from Equation 4, the size of the window required to measure a low angle becomes large. Therefore, in order to reduce the size of the sample capsule, it is desirable to use a thin film material having a diffraction peak at a lower angle.

The sample capsule is used by filling the sample filling plate 1 with the sample 4 and installing the window frame 2 on which the thin film 4 is attached on the sample filling plate 1. At this time, the replacement gas, the volatile component, the water vapor, the oxygen, and the carbon dioxide gas are bonded to each other with an adhesive, grease or the like so as not to flow out or flow in between the window frame 2 and the sample filling plate 1. If the sample is extremely unstable and cannot be handled in the air, it is necessary to perform these operations in a glove box or the like in a vacuum or an inert gas atmosphere.

Example 1. As shown in FIG. 6, a glass plate having a thickness of 1.8 mm as a sample filling plate 1 having a recess of 0.6 mm in depth and a size of 20 × 17 mm on one side, and a window frame 2 having a thickness of 1.6 mm. A 55 × 32 mm acrylic resin plate with a window of 45 × 17 mm, and the thin film 3 was a Mylar film having a thickness of 30 μm. Thin film 3
Was adhered to the window frame 2 with an epoxy resin adhesive. Α-alumina powder was used as a sample. Since α-alumina is stable in air, it can be measured by a normal measurement glass sample plate, but in order to compare and examine the measurement according to the present invention and the normal measurement, the diffraction peak of the Mylar film Α-alumina having a diffraction peak in the vicinity was selected.
The measurement result was as shown in FIG.

a is a measurement of α-alumina using only a normal glass sample plate for measurement, b is a measurement of a Mylar film adhered on the surface of α-alumina, and c is the sample capsule of the present invention. Measured using, d is JCPDS (Joint Committee on Powder Diffraction S
tandards) data file of powder defraction file (hereinafter referred to as JCPDS data card) 10-173 α-alumina diffraction line 2θ
The indicated diffraction angles and relative intensities are shown for reference.

As this result shows, the method according to the present invention is not inferior to that of a, and both d are within the experimental error range and are in good agreement.

The defractometer used was a Philips goniometer with a radius of 173 mm, manufactured by Philips, an X-ray source was a sealed bulb having a copper anticathode, and the detector was a NaI (Tl) -scintillation counter to detect X-rays.

The measurement conditions are: divergence slit / scattering slit: opening angle 1/2 °, receiving slit with Kβ-ray cutting Ni filter: opening width 0.3 mm, X-ray tube voltage: 30 kV, X-ray tube current: 10 mA, goniometer Speed: 2 ° / min, time constant: 1 second, recording paper speed: 2 cm / min. The sample α-alumina used was Kanto Chemical Co., Ltd. reagent grade 1 heated at 1100 ° C. for 4 hours.

Example 2 A powder of phosphorus pentoxide was measured. Phosphorus pentoxide has a high hygroscopic property, and it is a sample that cannot be normally measured in the atmosphere.

For phosphorus pentoxide, the first-grade reagent made by Wako Pure Chemical Industries, Ltd. is used as it is, and this is quickly packed in a glass sample filling plate in the air, and the window frame with the mylar membrane attached is a sample filling plate with an epoxy resin adhesive. Glued on.

The same equipment as in Example 1 was used for the deflactometer, slits, and sample capsule. The measurement conditions were as follows: X-ray tube voltage: 40 kV, X-ray tube current: 20 mA, goniometer speed: 1 ° / min, time constant: 2 seconds, recording paper speed: 1 cm / min.

The room where the defractometer was installed was a room without humidity adjustment.

The measurement result was as shown in FIG. Figure 8b is JC
The diffraction angle (2θ) and the relative intensity of the diffraction line of phosphorus pentoxide obtained from PDS data cards 23-1303 and 23-1303A are shown. As the result shows, the two agree well.

EFFECTS OF THE INVENTION By using the sample capsule of the present invention, an accurate X-ray diffraction pattern can be easily obtained even for an unstable sample, and the sample capsule is easy and inexpensive to manufacture, and can be used as a ready-made diffractometer. It has an excellent effect that it can be easily attached and measured by a usual measuring method.

[Brief description of drawings]

FIG. 1 is an explanatory view of an optical system of a diffractometer, FIG. 2 is an X-ray diffraction pattern of a Mylar film, FIG. 3 is a relationship diagram of a reflected X-ray and a slit, and FIG. 4 is an outline of a sample capsule of the present invention. Figure,
FIG. 5 is a geometrical diagram for determining the size of the window, FIG. 6 is an exploded view of the sample capsule of the present invention, FIG. 7 is an X-ray diffraction pattern of α-alumina powder, and FIG. 8 is a phosphorus pentoxide powder. An X-ray diffraction pattern is shown. S: Focus of X-ray source, D: Detector, C: Goniometer circle, O: Goniometer rotation center, R: Goniometer radius, D / S: Divergence slit, R / S: Receiving slit, S / S: Scattering slit , Θ _B : Bragg angle, t: Distance between sample surface and thin film, 2φ: Divergence slit opening angle, 2S: Scattering slit opening angle, 1: Sample filling plate, 2: Window frame, 3: Thin film, 4: Sample .

Claims (1)

[Claims] 1. X using the Bragg-Brentano concentration method
When measuring crystallographic characterization of a sample with a line diffractometer, use a thin film made of a material that has a low ability to pass water vapor, oxygen, carbon dioxide, a volatile component or a replacement gas and has X-ray permeability. In order to prevent reflected X-rays due to the thin film from being detected by the detector, the thin film should be separated from the sample surface by a certain distance t or more calculated by the following equation, so that the incident X-rays and the reflected X-rays are not cut. A sample capsule for an X-ray defractometer, which is configured to cover a sample. (However, t is the distance between the sample surface and the thin film, R is the goniometer radius, θ _B is the Bragg angle, φ is the opening angle of the divergence slit, and S is the opening angle of the scattering prevention slit.
Represents )