JP2001116705A - Method for calibrating intensity of x-rays in x-ray diffraction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calibrate the intensity of X-rays with high accuracy for a short time in quantitative analysis by an X-ray diffraction method using a monochromator. SOLUTION: In an X-ray diffraction method wherein a sample 2 is irradiated with X-rays emitted from an X-ray source 1 and the intensity of diffracted X-rays reflected from the sample is detected by a detector 3 through a monochromator 5, a standardized sample containing at least the same element as the target of the X-ray source 1 is used to calibrate the intensity of diffracted X-rays in order to perform the quantitative analysis of the sample 2. Since the standardized sample containing at least the same element as the target of the X-ray source 1 is used, fluorescent X-rays of which the kind is same to that of characteristc X-rays generated in the target are also generated from the standardized sample. The fluorescent X-rays are incident on the detector 3 as they are without being removed by the monochromator 5 to be detected as a background. Therefore, the intensity of X-rays of sufficient magnitude required in calibration can be obtained and can be calibrated with high accuracy for a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of calibrating X-ray intensity in X-ray diffraction, and more particularly to a method of calibrating X-ray intensity in quantitative analysis by X-ray diffraction using a monochromator.

[0002]

2. Description of the Related Art In quantitative analysis of a sample by X-ray diffraction,
X-ray intensity calibration using a standardized sample is performed. That is, in the X-ray diffraction method, fluctuations in the irradiation X-ray intensity due to deterioration of the X-ray tube, temperature changes, and the like cannot be avoided. Therefore, the sample to be measured and the standardized sample are alternately arranged and arranged. From the X-ray intensity of the sample, the X-
The line intensity is calibrated.

For example, Japanese Patent Application Laid-Open No. 7-209215 discloses a method for quantitatively analyzing a sample using an optical X-ray diffractometer as shown in FIG. That is, the X-ray emitted from the X-ray source 1 is converted into the incident side slit 4a.
Irradiates the sample 2 through the detector 2, and diffracted X-rays reflected from the sample 2 are detected by the detector 3 through the light receiving side slit 4b. In order to perform quantitative analysis of a sample, X-ray diffraction measurement is performed by replacing Sample 2 with a standardized sample, and the X-ray intensity is calibrated.

[0004] In the invention disclosed in Japanese Patent Application Laid-Open No. 7-209215, stainless steel is used as a standardized sample, and although not specifically described in the publication, fluorescent X-rays emitted from the standardized sample are used. Calibration is performed by focusing on the intensity of. The intensity of the fluorescent X-rays appear in the background I _b portion as shown in FIG. 2 (b).

[0005]

According to the X-ray diffractometer of the optical system shown in FIG. 2A, the detection intensity of the sample to be measured is also reduced by the fluorescent X-rays emitted from the sample. The ground appears. Since this background is essentially a noise component, its presence causes a reduction in the S / N ratio.

Therefore, as shown in FIG. 3A, there is a case where the background is removed by monochromaticizing the X-rays from the sample 2 using the counter monochromator 5. The background can be removed by using the X-ray diffractometer having such a configuration.
The measurement accuracy can be improved by increasing the / N ratio.

However, FIG.
Since the background is removed as shown in (b), it takes a long time to calibrate the X-ray intensity, and it may not be possible to perform highly accurate calibration. That is, the calibration of the X-ray intensity using the standardized sample is performed while paying attention to the background.

The present invention has been made in view of such circumstances, and has as its object to realize highly accurate X-ray intensity calibration in a short time in quantitative analysis by an X-ray diffraction method using a monochromator. And

[0009]

In order to achieve the above-mentioned object, the present invention irradiates a sample with X-rays emitted from an X-ray source and measures the intensity of diffracted X-rays reflected from the sample through a monochromator. In the X-ray diffraction method for detecting with a detector, the intensity of diffracted X-rays is calibrated using a standardized sample containing the same element as the target of the X-ray source in order to perform quantitative analysis of the sample. I do.

As is well known, a monochromator is an optical member having the function of reflecting only characteristic X-rays generated from a target used as an X-ray source and monochromaticizing incident X-rays.
In the present invention, since a standardized sample containing the same element as the target of the X-ray source is used, fluorescent X-rays of the same type as characteristic X-rays generated in the target are also generated from the standardized sample. The fluorescent X-rays enter the detector without being removed by the monochromator and are detected as a background. Therefore, a sufficiently large X-ray intensity required for calibration can be obtained, and highly accurate X-ray intensity calibration can be performed in a short time.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a configuration diagram of an X-ray diffraction apparatus used in the present embodiment. The apparatus includes a counter monochromator 5, and irradiates the sample 2 with X-rays generated by the X-ray source 1 through a slit 4a.
The diffracted X-rays reflected by the sample 2 enter the detector 3 via the counter monochromator 5 and further through the slit 4b.

When the sample 2 is a sample to be measured, the fluorescent X-rays generated in the sample 2 are removed by the counter monochromator 5 and only the diffracted X-rays enter the detector 3. Therefore, the background is removed, and a good S / N ratio X
A line profile can be obtained.

In the quantitative analysis by the X-ray diffraction method, a calibration curve is prepared using a standard sample, and a sample 2 is prepared based on the calibration curve.
The X-ray intensity detected for (the sample to be measured) is quantified. In addition, the X-ray intensity is calibrated (standardized) using a standardized sample with respect to the fluctuation of the X-ray intensity caused by the fluctuation of the irradiation X-ray intensity due to the deterioration of the X-ray tube, the temperature change, and the like. These X
Regarding the quantitative analysis and the calibration (standardization) of the X-ray intensity by the line diffraction method, since a well-known general method is used in the present embodiment, a detailed description thereof will be omitted.

In the present embodiment, a material composed of the same element as the target of the X-ray source 1 or a material containing the same element is used as a standardized sample used for calibrating the X-ray intensity. The X-ray source 1 is a device that causes thermal electrons emitted from an electron gun to collide with a target (also called an anti-cathode) and emits X-rays from the surface of the target, and emits characteristic X-rays corresponding to the target material. Is done. For example, from the X-ray source 1 in which the target is formed of Cu (copper), CuΚ
A characteristic X-ray called α is emitted.

By using a material made of the same element as the target or a material containing the same element as the standardized sample, when the standardized sample is irradiated with X-rays from the X-ray source 1, the target surface X-rays of the same type as characteristic X-rays emitted from the standardized sample can be generated in the standardized sample. For example, as described above, if the standardized sample is also formed of Cu or a metal material containing Cu with respect to the Cu target, the standardized sample generates fluorescent X-rays of CuΚα.

The counter monochromator 5 has a function of selecting and reflecting only the characteristic X-rays according to the type of the characteristic X-rays radiated from the target of the X-ray source 1. As the spectral crystal used in the monochromator, for example, there are graphite, Ge, Si, SiO ₂ , LiF, and the like, and these can be properly used depending on applications such as required accuracy. In general, graphite having a large integral intensity is often used although the spectral accuracy is slightly inferior.

In the counter monochromator 5, the diffracted X-ray (CuΚα) reflected by the sample 2 (standardized sample) and the fluorescent X-ray (CuΚα) generated by the sample are both reflected to the detector 3. Therefore, X-ray intensity detected by the detector 3 relates standardization sample, becomes of high strength containing background I _b by X-ray fluorescence, as shown in FIG. 1 (b). Since the calibration of the X-ray intensity is performed focusing on the background _Ib , it can be performed in a short time and with high accuracy.

The present invention is not limited to the above embodiment. For example, as the target material of the X-ray source, there are various materials other than Cu, and it goes without saying that the standardized sample should be formed of a material corresponding to the target material. The largest generation of the same fluorescent X-rays as the characteristic X-rays emitted from the target occurs when a standardized sample is formed of a material composed of the same element as the target. However, if the same element as that of the target is contained, such fluorescent X-rays are generated from the standard sample to a considerable extent, so that the object of the present invention can be achieved.

Further, the method of the present invention can be applied to various quantitative analyzes by the X-ray diffraction method. As examples to which the present invention can be applied, for example, quantitative analysis of free lime (CaO) in cement clinker, CaCO ₃ , Ca
It can be used for standardization of the analysis of crystalline phases such as (OH) ₂ . Further, the method of the present invention provides a method for preparing cementite (Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ),
Crystal phase such as wustite (FeO), CaS in sintered ash
Crystal phase such as O ₃ , CaSO ₄ , CaS, CaO, CaCO ₃ , Ca (OH) ₂ , 2CaO · S in steel slag
crystalline phase such as iO ₂ , free silicic acid (SiO ₂ ) in dust,
It can be used for standardization in quantitative analysis of asbestos and the like. The method of the present invention can also be performed unattended by adding an automatic calibration mechanism to the device.

[0020]

As described above, according to the present invention, highly accurate X-ray intensity calibration can be realized in a short time in quantitative analysis by X-ray diffraction using a monochromator.

[Brief description of the drawings]

FIG. 1A is a configuration diagram of an X-ray diffraction apparatus used in an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of X-ray detection intensity for a standardized sample used in the embodiment.

FIG. 2A is a configuration diagram of an X-ray diffractometer that does not use a monochromator, and FIG. 2B is a schematic diagram illustrating X-ray detection intensities of a conventional standardized sample using the same device.

FIG. 3A is a configuration diagram of an X-ray diffraction apparatus provided with a monochromator, and FIG. 3B is a schematic diagram showing an X-ray detection intensity of a conventional standardized sample using the same.

[Explanation of symbols]

 1: X-ray tube 2: Sample (sample to be measured or standardized sample) 3: Detector 4a, 4b: Slit 5: Counter monochromator

Claims (2)

[Claims] An X-ray diffraction method for irradiating a sample with X-rays emitted from an X-ray source and detecting the intensity of diffracted X-rays reflected from the sample with a detector via a monochromator, A method for calibrating the X-ray intensity in the X-ray diffraction method, wherein the intensity of the diffracted X-ray is calibrated using a standardized sample containing at least the same element as the target of the X-ray source in order to perform the analysis. 2. The method according to claim 1, wherein a standardized sample made of the same material as the target of the X-ray source is used.