JPH0735705A - Method and equipment for x-ray quantitative analysis - Google Patents

Abstract

PURPOSE:To allow the absorption measurement of mut and the measurement of intensity of diffracted light for a component to be inspected using a same X-ray analyzer when the quantitative analysis of a sample is conducted by absorptive diffraction method. CONSTITUTION:An unused filter and a filter adhered with a sample are weighed to determine the rhot of the sample. A standard sample 22 of poly-Si plate is then fixed to the sample stage 12 of an X-ray analyzer and the diffracted light therefrom is passed through the unused filter fixed to a sample holder 24a and the filter with adhered sample fixed to another sample holder 24b in order to detect the intensities thereof. mut of the sample is calculated based on the intensities thus detected. Subsequently, a pure sample 26 comprising only the component to be detected and a sample holder 24b fixed with the filter adhered with sample are fixed to the sample stage 12 and the intensity of each diffracted light is measured. The measurements are employed in the quantitative determination of specific component in the sample according to a specific formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray quantitative analysis method and apparatus for quantitatively analyzing a test sample composed of a plurality of components by utilizing X-ray diffraction.

[0002]

2. Description of the Related Art In quantitative analysis using X-ray diffraction,
The most common analysis condition is when a test sample containing N component is analyzed, and the test component and other components have different mass absorption coefficients. Under such general conditions, absorption diffraction method, internal standard method, and standard addition method are known as types of quantitative analysis methods. The absorption diffraction method is the average mass absorption coefficient (μ / ρ) of the test sample.
Is a method of actually measuring and utilizing this. The internal standard method is
This is a method of mixing a known amount of a known substance into a test sample.
The standard addition method is a method of adding a fixed amount of a pure substance of a test component to a test sample. The present invention relates to the absorption diffraction method.

In the absorption diffraction method, it is necessary to measure the average mass absorption coefficient (μ / ρ) of the sample to be measured, but since the mass absorption coefficient cannot be measured directly, in practice μt of the sample to be measured is actually measured. (However, μ is the average linear absorption coefficient of the test sample,
t is the thickness of the test sample in the X-ray transmission direction) and ρ of the test sample
(μ / ρ) is calculated by separately obtaining t (where ρ is the average density of the test sample and t is the thickness of the test sample in the X-ray transmission direction). In this case, to obtain μt of the test sample, the X-ray absorption rate of the test sample may be measured by the absorption method. To obtain ρt of the test sample, the weight of the test sample may be measured.

[0004]

By the way, in the conventional absorption diffraction method, in order to obtain μt of the test sample, the X-ray absorption method is used.
The X-ray diffractometer was used to obtain the diffraction line intensity of the test sample. That is, in addition to an X-ray diffractometer for quantitative analysis, an X-ray analyzer for absorption measurement for μt was required.

An object of the present invention is to perform the same X-ray measurement for the measurement of μt by the absorption measurement and the measurement of the diffraction line intensity of the test component when the quantitative analysis of the test sample is performed by using the absorption diffraction method. It is to be possible with an analyzer.

[0006]

[Means for Solving the Problems] According to the absorption diffraction method, a quantitative value A _J (% by weight) of a test component (J component) in a test sample is obtained.
Can be calculated by the following equation (1).

[0007]

## EQU1 ## A _J = (I _J / I _JP ) · ((μ / ρ) / (μ / ρ) _JP ) / (1-exp (-2 μt / sin θ _J )) (1) where I _J : Diffraction line intensity of J component (measured value) I _JP : Diffraction line intensity of pure substance of J component (measured value) (μ / ρ): Average mass absorption coefficient (measured value) of test sample (μ / ρ) _JP : Mass absorption coefficient of J component pure substance (calculated value) μ: Average mass absorption coefficient of test sample ρ: Average density of test sample t: Thickness of test sample θ _J : J component Half the diffraction line angle (2θ _J ) (calculated value)

Although (μ / ρ) cannot be measured directly, ρt and μt can be measured respectively, and (μ / ρ) = μ
It can be calculated by t / ρt. ρt can be calculated from the weight W of the sample to be tested and the area S by ρt = W / S. μt can be calculated by the following formula (2) from the amount of X-ray absorption.

[0009]

[Mathematical formula-see original document] [mu] t = -ln (Tb / Ta) (2) where ln: natural logarithmic function Tb: X-ray intensity after measurement sample transmission (measured value) Ta: X-ray before transmission of test sample Strength (measured value)

When the sample is sufficiently thick, the above equation (1) can be simplified and approximated by the following equation (3).

[0011]

[Number 3] _{A J = (I J / I} JP) · ((μ / ρ) / (μ / ρ) JP) ... (3)

The present invention carries out the quantitative analysis of the test sample based on the above-mentioned principles, and these principles themselves are already known. The feature of the present invention is that the same X-ray analyzer is used to measure μt by absorption measurement.
Is to be able to carry out the measurement and the diffraction line intensity measurement.

The first invention is an X-ray quantitative analysis method for quantitatively analyzing a test sample composed of a plurality of components, and has the following steps. (A) A step of measuring ρt of the test sample (where ρ is the average density of the test sample and t is the thickness of the test sample in the X-ray transmission direction). (B) A step of measuring the intensity Ta when the X-ray from the X-ray source is reflected by a monochromator arranged at the center of the goniometer to make it monochromatic, and the reflected X-ray does not pass through the sample to be tested. (C) The intensity Tb after the monochromatic X-rays have passed through the test sample while the X-ray from the X-ray source is reflected by the monochromator to be monochromatic, and the test sample is moved within the plane. Measuring stage. (D) A step of obtaining μt of the test sample from Ta and Tb (where μ is the average linear absorption coefficient of the test sample, and t is the thickness of the test sample in the X-ray transmission direction). (E) A step of arranging a pure sample consisting only of the test component at the center of the goniometer, irradiating the pure sample with X-rays from the X-ray source, and measuring the intensity I _JP of the diffracted X-rays therefrom. (F) The test sample is placed in the center of the goniometer, the test sample is irradiated with X-rays from the X-ray source while the test sample is moved within the plane, and the intensity I of diffracted X-rays from the sample is irradiated. Measuring _J. (G) Based on the mass absorption coefficient (μ / ρ) _{JP of the} test component and the ρt, μt, I _JP , and I _J obtained thus far, the weight ratio A _{J of the} test component in the test sample The stage of seeking.

In the present invention, the ρt of the test sample is measured by weight measurement, the μt of the test sample is measured by absorption measurement, and the diffraction line intensities of the pure sample and the test sample are measured by diffraction measurement. However, the temporal context between these measurements is arbitrary. That is, the weight measurement, the absorption measurement, and the diffraction measurement may be performed in any order.

According to a second aspect of the invention, instead of the pure sample of the first aspect, a standard sample different from the components of the sample to be tested is used to measure the intensity I _S of the diffracted X-ray from the standard sample, Based on the mass absorption coefficient (μ / ρ) _{JP of the} test component, ρt, μt, I _S , and I _J obtained so far, and the correction coefficient due to the difference between the test component and the standard sample, The weight ratio A _J of the test component in the test sample is determined. That is, in this case, since the test component and the standard sample are different, the above formulas (1) and (3) cannot be used as they are. Therefore, the diffraction line intensity I _JP that would be obtained by using a pure sample and the diffraction line intensity I _S measured using the standard sample
It suffices to correct the ratio with the correction coefficient C _PS . For example, the above equation (3) is changed to the following equation (4).

[0016]

## EQU4 ## A _J = (I _J / (C _PS I _S )) · (μt / ρt) / (μ / ρ) _JP (4) However, in C _PS, the test component and the standard sample are different. Correction coefficient by

A third invention is an X-ray quantitative analyzer for quantitatively analyzing a test sample composed of a plurality of components, which has the following constitution. (A) An X-ray diffraction measurement system capable of measuring the intensity of diffracted X-rays from a sample placed on the sample stage by changing the relative positional relationship among the X-ray source, the sample stage and the X-ray detector. (B) A monochromator that can be attached to and detached from the sample table. (C) An absorption measuring table arranged between the sample table and the X-ray detector. (D) A sample holder that can be attached to and detached from both the sample table and the absorption measurement table. (E) A sample movement mechanism that can move the test sample attached to the sample holder within the plane of the sample holder, whether it is attached to the sample table or the absorption measurement table.

[0018]

The present invention uses the X-ray diffractive optical system for measuring the intensity of the diffracted rays of the component to be measured so that the μt of the sample to be measured can also be measured. Both measurements can be performed with the same X-ray analyzer. The actual procedure is to measure the ρt of the test sample by weighing.
Then, the μt of the test sample is determined by absorption measurement, the diffraction line intensity of a pure sample of the test component is determined by diffraction measurement, and the diffraction line intensity from the test component in the test sample is determined by diffraction measurement, Finally, the weight ratio of the test component in the test sample is calculated based on these measurement data. At that time, in the absorption measurement, an ordinary X-ray diffraction measurement optical system is used, and a monochromator is arranged on the sample stage in the center of the goniometer, and the test object is placed between the monochromator and the X-ray detector. The sample is placed and the absorption is measured. When performing the diffraction measurement, a pure sample or a test sample is placed on the sample table.

As for the apparatus configuration, an absorption measurement table is provided between the sample table and the X-ray detector, and the sample holder attached to the sample holder can be mounted on either the sample table or the absorption measurement table. So that it can be moved within that plane. As a result, in absorption measurement and diffraction measurement, the test sample can be rotationally or translationally reciprocally moved in the plane during the measurement, and the X-ray irradiation region of the test sample is averaged to obtain reliable measurement results. It is increasing the nature.

[0020]

EXAMPLES Next, examples of the present invention will be described by taking as an example the quantitative analysis of deposits attached to a filter for filtering wastewater of a nuclear reactor. In order to quantitatively analyze this adhered substance (hereinafter referred to as a test sample), it is necessary to know in advance what component the test sample contains. This test component may be already known, but if it is not known, it is necessary to identify the test component by qualitative analysis in advance. In this example, the test sample contains four types of test components as shown in Table 1.

[0021]

[Table 1] Test component Diffraction angle (2θ _J ) Mass absorption coefficient (μ / ρ) _JP [cm ² / g] Fe ₃ O ₄ 35.4 ° 226.0 γFeOOH 14.1 ° 197.8 αFeOOH 21. 2 ° 197.8 Fe ₂ O ₃ 24.2 ° 218.9

The mass absorption coefficient (μ / ρ) _JP depends on the wavelength of X-rays, but Table 1 shows values when CuKα rays are used. The mass absorption coefficient of each element is known, and
The mass absorption coefficient of a compound can be easily obtained from a known calculation formula using the mass absorption coefficient of an element.

Next, a method of determining ρt of the test sample will be described. Ρt of the test sample can be obtained by the following equation (5). The weight of the filter is measured with a balance.

[0024]

[Mathematical formula-see original document] [rho] t = (Wb-Wa) / S (5) Here, [rho]: average density of test sample t: thickness of test sample Wb: weight of filter to which test sample adheres Wa : Weight of filter without test sample attached S: Area of filter part with test sample attached

Next, the basic structure of the X-ray quantitative analyzer will be described. FIG. 1 is a plan view showing a procedure from absorption measurement to diffraction measurement after determination of ρt in the X-ray quantitative analysis method of this example.

In FIG. 1A, the sample stage 12 and the X-ray detector 14 are mounted on a goniometer so that they can rotate at an angle ratio of 1: 2. The X-ray from the X-ray source 10 passes through the divergence slit 16 and is applied to the sample on the sample stage 12, and the diffracted X-ray from there passes through the light-receiving slit 18 and is detected by the X-ray detector 14. It That is, this X-ray quantitative analyzer is equipped with a basic diffraction measurement optical system. Further, an absorption measuring table 20 is arranged between the sample table 12 and the X-ray detector 14. The absorption measuring table 20, the light receiving slit 18, and the X-ray detector 14 are mounted on the same 2θ rotating table. As the X-ray source 10, a Cu target X-ray tube is used.

Next, the procedure for determining μt of the test sample will be described. First, the standard sample 22 made of a polycrystalline Si plate is attached to the sample table 12. Then, the sample stage 12 and the X-ray detector 14 are arranged so that the diffraction line from the Si (422) plane can be detected.
Set the angle of. The standard sample 22 in this case serves as a monochromator for converting the X-ray into a single color. The sample holder 24a to which the unused filter is attached is attached to the absorption measurement table 20. X-ray source 10
The X-ray emitted from the sample is diffracted by the standard sample 22 to be monochromatic into an X-ray (CuKα ray) of a specific wavelength, and this diffracted ray passes through an unused filter and is detected by the X-ray detector 14. It In addition, the diffraction line from the standard sample 22 is the absorption measurement table 2
The through hole 21 of the absorption measuring table 20 without touching 0
You can pass through.

Next, in FIG. 1B, the sample holder 24b to which the used filter (filter to which the sample to be tested is attached) is attached is attached to the absorption measuring table 20.
Then, the same measurement as that in FIG. In this case, the diffraction line from the standard sample 22 is detected by the X-ray detector 14 after passing through the filter and the test sample attached to the filter. The detection intensity at this time is Tb.

Based on the above Ta and Tb, the following equation (2)
Sample to be tested (that is, only deposits excluding filter)
Of μt is calculated.

[0030]

[Mathematical formula-see original document] .mu.t = -ln (Tb / Ta) (2) where ln: natural logarithmic function

Based on ρt and μt thus obtained, (μ / ρ) of the test sample can be calculated by μt / ρt.

Next, the diffraction line intensity I _JP of a pure sample containing only the test component is measured as follows. As shown in FIG. 1C, first, the powder of the pure sample 26 is packed in a sample holder, which is attached to the sample table 12, and the diffraction line intensity I _JP at that time is measured. In this case, nothing is attached to the absorption measurement table 20 and the diffraction line is allowed to pass through.

Next, the diffraction line intensity I _J from the test component in the test sample is measured as follows under the same conditions as possible when the diffraction line intensity I _JP is measured. Figure 1
As shown in (D), a sample holder 24 to which a used filter (filter to which a test sample is attached) is attached.
b is attached to the sample table 12, and the diffraction line intensity I at that time
Measure _J. Nothing is attached to the absorption measurement table 20 as in the case of FIG.

To measure the diffraction line intensities I _JP and I _J , the diffraction line angle 2θ _J is adjusted according to the component to be tested. For example,
When the component to be detected is Fe ₃ O ₄ , it is set to 2θ _J = 35.4 °. Then, angle scan near the angle of this diffraction line,
The diffraction peak is measured, and the integrated intensity is calculated and used as the diffraction line intensity.

As described above, ρt, μt, (μ /
ρ), I _JP , and I _J are obtained, and these are shown in Table 1 above.
(Μ / ρ) _JP and θ _J shown in Equation (1) above are used.
The quantitative value A _J is calculated by When the thickness of the test sample is sufficiently thick, the quantitative value can be calculated using the above formula (3).

In this way, all quantitative values of the four types of test components can be obtained. In addition, ρ of the test sample
The determination of t, the determination of μt of the test sample, and the calculation of (μ / ρ) are common when determining the quantitative values of the four types of test components, and therefore need only be performed once. Therefore, only the diffraction line intensities I _JP and I _J are measured for each of the four types of test components.

In the above examples, the diffraction line intensities I _JP were measured using the pure samples corresponding to the different test components, but the diffraction line intensities of a plurality of pure samples were measured each time the quantitative measurement was performed. It is complicated to measure. In order to solve this, there is a method of using one specific standard sample instead of using each pure sample, and this method will be described below. As a standard sample, FIGS. 1 (A) and 1 (B)
The standard sample 22 made of a polycrystalline Si plate used as the monochromator can be used. That is, this standard sample is attached to the sample table, and the diffraction line intensity I _S of Si (111) is detected. Then, the ratio of the diffraction line intensity I _JP from the pure sample consisting of only the test component and the diffraction line intensity I _S from Si (111), that is, the correction coefficient C _PS is measured in advance only once, and this correction is performed. Using the coefficient C _PS , the diffraction line intensity I _JP of the pure sample is calculated as I _JP = C _PS × I _S. This saves the labor of measuring the diffraction line intensity of the pure sample for each quantitative measurement. In this case, changes in various conditions for each quantitative measurement can be reflected in the diffraction line intensity I _S of the standard sample. Thus, instead of measuring the diffraction line intensities of the pure samples corresponding to each of the four types of test components, the diffraction line intensities of the standard sample are measured only once, and the measurement is simplified. You can

Next, the sample holder used in this embodiment will be described. FIG. 2 is a sectional view of the sample holder. The sample holder comprises a circular holder body 28 and a circular cover 30. The holder body 28 has a circular opening 32 that is wide enough to allow the complete passage of X-rays.
A sufficiently wide circular opening 34 is also formed in the cover 30. Further, four elastic claws 36 are formed on the outer periphery of the cover 30 at equal intervals. The used or unused filter 38 is sandwiched between the cover 30 and the holder body 28 and mounted on the sample holder. When the filter 38 is attached to the sample holder, the elastic claw 36 is opened outward. The holder body 28 is a magnet and can be attracted to the rotary table 40 provided on the sample table. A sufficiently wide circular opening 41 and a circular concave portion 42 are formed in the circular rotary table 40, and the holder main body 28 enters the circular concave portion 42 and is positioned.

FIG. 3A is a front view showing the movement of the filter 38. The filter 38 is attached to the sample holder as described above, and the sample holder is attached to the rotary table of the sample table. Therefore, the filter 38 is
When attached to the sample table, it rotates around its center. The X-ray irradiation shape 43 on the filter 38 is
In this embodiment, the filter 3 has an elongated line shape.
The rotation of 8 spreads the X-ray irradiation region over the entire circular region 44. As a result, the local variations in the intensity of the diffracted rays from the test sample are averaged by this rotational movement.

The absorption measuring table 20 of FIG. 1 is also provided with a rotary table similar to that shown in FIG. 2, and the sample holder can be adsorbed to this rotary table. Therefore, the filter can be rotated also in the absorption measurement for determining the μt of the test sample.

FIG. 3B shows an example in which the filter is moved in translation and reciprocation instead of being rotated. in this case,
The filter 38 is capable of translational reciprocating motions to the left and right, and has a rectangular area 4 with respect to the linear X-ray irradiation shape 43.
The X-ray irradiation area spreads over the entire area 6. In order to make the filter 38 reciprocate in translation, a translation reciprocating mechanism may be provided on the sample stage and the absorption measuring stage.

The present invention is not limited to the above embodiment, but the following modifications are possible. (1) In order to make the filter rotate or reciprocate reciprocally, in the above-mentioned embodiment, the sample stage and the absorption measuring stage are provided with the revolving mechanism or the reciprocating reciprocating mechanism, respectively. In addition, it is also possible to provide these movement mechanisms on the side of the sample holder and to omit the movement mechanisms on the sample table and the absorption measurement table.

(2) In the above-mentioned embodiment, the quantitative analysis method is explained by taking the deposit on the drainage filter of the nuclear reactor as an example, but the present invention can quantitatively analyze any sample.
For example, a plate-shaped sample or a powder-shaped sample may be used, and quantitative analysis is possible if a sample holder is prepared accordingly.

(3) An embodiment is described in which one standard sample is used instead of using each pure sample corresponding to four kinds of test components. In this case, a monochromator may be used as the standard sample. A usable polycrystalline Si plate is used. However, the standard sample for obtaining the diffraction line intensity may be another substance. For example, a pure sample corresponding to a specific test component may be used as a standard sample. In this case, for example, the quantitative value is calculated using the above-mentioned formula (3) for the test component, and the above-mentioned formula (4) is used for the other test components (that is, using the correction coefficient). ) The quantitative value should be calculated.

[0045]

According to the present invention, the same X-ray analyzer can be used to perform the measurement of μt by the absorption measurement and the measurement of the diffraction line intensity by the diffraction measurement, so that an efficient quantitative analysis can be performed. It will be possible.

[Brief description of drawings]

FIG. 1 is a plan view showing a procedure from absorption measurement to diffraction line intensity measurement in one embodiment of the present invention.

FIG. 2 is a sectional view of a sample holder.

FIG. 3 is a front view showing the movement of the test sample.

[Explanation of symbols]

 10 ... X-ray source 12 ... Sample stand 14 ... X-ray detector 16 ... Divergence slit 18 ... Receiving slit 20 ... Absorption measuring stand 22 ... Standard sample 24a ... Sample holder with unused filter 24b ... Used filter attached Sample holder 26 ... Pure sample

Claims (3)

[Claims] 1. An X-ray quantitative analysis method for quantitatively analyzing a test sample composed of a plurality of components, which comprises the following steps. (A) A step of measuring ρt of the test sample (where ρ is the average density of the test sample and t is the thickness of the test sample in the X-ray transmission direction). (B) A step of measuring the intensity Ta when the X-ray from the X-ray source is reflected by a monochromator arranged at the center of the goniometer to make it monochromatic, and the reflected X-ray does not pass through the sample to be tested. (C) The intensity Tb after the monochromatic X-rays have passed through the test sample while the X-ray from the X-ray source is reflected by the monochromator to be monochromatic, and the test sample is moved within the plane. Measuring stage. (D) A step of obtaining μt of the test sample from Ta and Tb (where μ is the average linear absorption coefficient of the test sample, and t is the thickness of the test sample in the X-ray transmission direction). (E) A step of arranging a pure sample consisting only of the test component at the center of the goniometer, irradiating the pure sample with X-rays from the X-ray source, and measuring the intensity I _JP of the diffracted X-rays therefrom. (F) The test sample is placed in the center of the goniometer, the test sample is irradiated with X-rays from the X-ray source while the test sample is moved within the plane, and the intensity I of diffracted X-rays from the sample is irradiated. Measuring _J. (G) Based on the mass absorption coefficient (μ / ρ) _{JP of the} test component and the ρt, μt, I _JP , and I _J obtained thus far, the weight ratio A _{J of the} test component in the test sample The stage of seeking. 2. Diffraction X from a standard sample using, instead of the pure sample, a standard sample different from the components of the sample to be tested.
The intensity I _S of the line is measured and the mass absorption coefficient (μ /
ρ) _JP and ρt, μt, I _S , and I _J obtained so far,
A step of obtaining the weight ratio A _J of the test component in the test sample based on the correction coefficient due to the difference between the test component and the standard sample. 3. An X-ray quantitative analysis apparatus for quantitatively analyzing a test sample composed of a plurality of components, which has the following configuration. (A) An X-ray diffraction measurement system capable of measuring the intensity of diffracted X-rays from a sample placed on the sample stage by changing the relative positional relationship among the X-ray source, the sample stage and the X-ray detector. (B) A monochromator that can be attached to and detached from the sample table. (C) An absorption measuring table arranged between the sample table and the X-ray detector. (D) A sample holder that can be attached to and detached from both the sample table and the absorption measurement table. (E) A sample movement mechanism that can move the test sample attached to the sample holder within the plane of the sample holder, whether it is attached to the sample table or the absorption measurement table.