JP3593478B2 - Calibration method of X-ray intensity in X-ray diffraction method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for calibrating X-ray intensity in X-ray diffraction, and more particularly, to a method for calibrating X-ray intensity in quantitative analysis by X-ray diffraction using a monochromator.
[0002]
[Prior art]
In quantitative analysis of a sample by the X-ray diffraction method, 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. The X-ray intensity of the sample to be measured is calibrated from the X-ray intensity of the sample.
[0003]
For example, Japanese Patent Application Laid-Open No. 7-209215 discloses a method of performing a quantitative analysis of a sample using an X-ray diffractometer having an optical system as shown in FIG. That is, the sample 2 is irradiated with the X-rays emitted from the X-ray source 1 through the incident side slit 4a, and the detector 3 detects the diffracted X-rays reflected from the sample 2 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 JP-A-7-209215, stainless steel is used as a standardized sample, and although not specifically described in the publication, the intensity of fluorescent X-rays emitted from the standardized sample is reduced. Attention is paid to calibration. The intensity of the fluorescent X-rays appear in the background I _b portion as shown in FIG. 2 (b).
[0005]
[Problems to be solved by the invention]
Now, according to the X-ray diffractometer of the optical system as shown in FIG. 2A, the background due to the fluorescent X-rays emitted from the sample to be measured also appears in the detection intensity of the sample to be measured. Since the background is essentially a noise component, its presence causes a reduction in the S / N ratio.
[0006]
Therefore, as shown in FIG. 3A, a configuration may be adopted in which the X-rays from the sample 2 are made monochromatic to remove the background by using the counter monochromator 5. By using the X-ray diffractometer having such a configuration, the background can be removed. Therefore, the S / N ratio can be increased for the sample to be measured, and the measurement accuracy can be improved.
[0007]
However, since the background is also removed from the standardized sample as shown in FIG. 3B, it takes a long time to calibrate the X-ray intensity, and high-precision calibration may not be performed. That is, the calibration of the X-ray intensity using the standardized sample is performed while paying attention to the background.
[0008]
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.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides 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. The method is characterized in that in order to perform a quantitative analysis of the sample, the intensity of the diffracted X-ray is calibrated using a standardized sample containing the same element as the target of the X-ray source.
[0010]
As is well known, a monochromator is an optical member having a function of reflecting only characteristic X-rays generated from a target used in an X-ray source to monochromatic 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 by the target are also generated from the standardized sample. This fluorescent X-ray enters the detector as it is without being removed by the monochromator, and is 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]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described 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 through the counter monochromator 5 and further through the slit 4b.
[0012]
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 an X-ray profile with a good S / N ratio can be obtained.
[0013]
In the quantitative analysis by the X-ray diffraction method, a calibration curve is created using a standard sample, and the X-ray intensity detected for the sample 2 (measured sample) is quantified based on the calibration curve. Further, 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. Regarding the quantitative analysis and the calibration (standardization) of the X-ray intensity by the X-ray diffraction method, since a well-known general method is used in the present embodiment, a detailed description thereof will be omitted.
[0014]
In the present embodiment, a material made 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, the X-ray source 1 in which the target is formed of Cu (copper) emits a characteristic X-ray of CuΚα.
[0015]
By using a material composed 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 standardized sample is emitted from the surface of the target. X-rays of the same type as the characteristic X-rays 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.
[0016]
The counter monochromator 5 has a function of selecting and reflecting only the characteristic X-rays according to the type of characteristic X-rays emitted 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 with a large integral intensity is often used although the spectral accuracy is slightly inferior.
[0017]
In the counter monochromator 5, both the diffracted X-rays (CuΚα) reflected by the sample 2 (standardized sample) and the fluorescent X-rays (CuΚα) generated by the sample are 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.
[0018]
Note that the present invention is not limited to the embodiment described above. 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 greatest amount of fluorescent X-rays that are the same as the characteristic X-rays emitted from the target are generated when a standardized sample is formed from a material composed of the same element as the target. However, if the same element as that of the target is contained, not a small amount of such fluorescent X-rays are generated from the standard sample, so that the object of the present invention can be achieved.
[0019]
Further, the method of the present invention can be applied to various quantitative analyzes by the X-ray diffraction method.
As an example to which the present invention can be applied, for example, the present invention can be used for the quantitative analysis of free lime (CaO) in cement clinker and the standardization of the analysis of crystal phases such as CaCO ₃ and Ca (OH) ₂ .
Furthermore, the method of the present invention can be applied to crystal phases such as cementite (Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ), and wustite (FeO) in sintered ore, and CaSO ₃ , CaSO ₄ , and CaS _{4 in} sintered ash. To be used for standardization in the quantitative analysis of crystalline phases such as, for example, CaO, CaCO ₃ , Ca (OH) ₂ in steel slag, crystalline phases such as 2CaO · SiO ₂ , free silicic acid (SiO ₂ ) in dust, and asbestos. Can be.
The method of the present invention can also be performed unattended by adding an automatic calibration mechanism to the device.
[0020]
【The invention's effect】
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 an X-ray diffraction method 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 showing an example of X-ray detection intensity for a standardized sample used in the embodiment.
2A is a configuration diagram of an X-ray diffraction apparatus that does not use a monochromator, and FIG. 2B is a schematic view illustrating the X-ray detection intensity of a conventional standardized sample using the same apparatus.
3A is a configuration diagram of an X-ray diffraction apparatus provided with a monochromator, and FIG. 3B is a schematic diagram illustrating X-ray detection intensities 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: detectors 4a, 4b: slit 5: counter monochromator

Claims (2)

In an X-ray diffraction method in which a sample is irradiated with X-rays emitted from an X-ray source and the intensity of diffracted X-rays reflected from the sample is detected by a detector via a monochromator,
In order to perform quantitative analysis of the sample, the intensity of the diffracted X-rays is calibrated using a standardized sample containing at least the same element as the target of the X-ray source. Calibration method. The method of claim 1, wherein
A method for calibrating X-ray intensity in an X-ray diffraction method, comprising using a standardized sample made of the same material as a target of an X-ray source.

Images