JP3552333B2 - X-ray diffraction analysis method - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an X-ray diffraction analysis method, and particularly to a method for collecting measurement data in a powder X-ray diffraction apparatus.
[0002]
[Prior art]
In a powder X-ray diffractometer, a powdery sample is solidified into a plate or a polycrystalline sample is placed at the center of the goniometer (so-called θ axis), and a detector such as a scintillation detector for detecting diffracted X-rays is used. It is arranged so as to rotate around the sample (so-called 2θ axis). The characteristic X-rays emitted from the X-ray tube to the sample are reflected around the sample as diffracted X-rays. Therefore, the diffraction pattern is obtained by measuring the X-ray intensity while rotating the detector around the sample using a goniometer. Is measured and used as data for subsequent qualitative / quantitative analysis. In the actual measurement, the scanning range of the detector (2θ axis) is determined by inputting from a keyboard or the like, but conventionally, the entire scanning range that can be scanned by the goniometer is obtained so that necessary diffraction peak data can be obtained. It was set wider to cover. In addition, the scan range was not widened and partial diffraction patterns were obtained by specifying only the required angle range.However, conventionally, the scan angle range was specified to obtain the necessary peak data. Therefore, when the type of the X-ray tube is changed, the peak from the same reflection surface of the sample appears in a different angle range. Therefore, the angle range has to be set each time.
[0003]
[Problems to be solved by the invention]
If the scanning range of the detector is set to be wide, measurement omission of necessary data does not occur and it is reliable, but especially when the number of detected peaks is small, the angle range without peaks will be scanned uselessly. It was taking time. An object of the present invention is to reduce the measurement time by omitting scanning of a portion having no diffraction peak and scanning only a necessary portion. It is another object of the present invention to provide an X-ray diffraction analysis method that facilitates handling when the type of X-ray tube is changed and that does not require extra time for qualitative or quantitative analysis performed after collecting diffraction data. .
[0004]
[Means for Solving the Problems]
The present invention solves the above problem by irradiating a sample with characteristic X-rays from an X-ray tube and scanning an X-ray detector around the sample using a goniometer, thereby emitting the sample from the sample. In the X-ray diffraction analysis method for measuring diffracted X-rays, the wavelength of the characteristic X-ray and the plane spacing of one or more lattice planes to be measured of the sample are input, and the diffraction is performed by this lattice plane. The scanning range is determined so that the X-ray detector scans only near the angle where the diffracted X-rays appear, and the measurement data of each part obtained by this and the measurement data of the other angle ranges are obtained. The virtual data connecting between them is combined as data with the horizontal axis as the diffraction angle, and is used as data used for subsequent qualitative analysis or quantitative analysis.
[0005]
[Action]
Calculation formula λ = 2d sin θ from the lattice spacing d of the sample to be measured and the characteristic X-ray wavelength λ of the X-ray tube (1)
Can be used to calculate the diffraction angle θ at which the diffracted X-ray appears. Therefore, the detector is scanned only near the diffraction peak to measure the diffracted X-ray intensity. After all measurements are made for one or a plurality of lattice plane spacings d that have been input in advance, and data are arranged using the detector angle (2θ) as coordinates, all necessary diffraction peaks can be obtained. It can be used as data for quantitative analysis. Since the actual scanning is not performed in the angle range other than the necessary diffraction peak, the total measurement time can be shortened.
[0006]
【Example】
FIG. 1 is a flowchart showing an embodiment of the present invention, and FIG. 2 is a functional block diagram of an apparatus for realizing the method of the present invention. Each of the units 1 to 7 shown in FIG. 2 can be realized by software of a computer that controls the X-ray diffraction apparatus, but is not limited thereto.
[0007]
Prior to the measurement, the characteristic X-ray wavelength λ of the X-ray tube is input by the wavelength input means 1 (ST1), and the spacing d of the lattice plane required for the analysis of the sample is input by the d value input means 2 (ST2). The input of the d value may be one or plural depending on the characteristics of the crystal structure of the sample or the purpose of the analysis. The input of λ and d may be directly input from a keyboard or the like at the time of measurement, or may be stored in advance in the measurement condition storage means 7 as measurement conditions, and an appropriate one may be selected from the conditions stored at the time of measurement. You may make it. The scanning range calculating means 3 calculates the detector angle (2θ) where the diffraction peak appears based on the input λ and d using the equation (1), and scans the range before and after the detector angle so that the detector scans the range before and after the angle. Is calculated (ST3). In general, the calculated peak angle of about ± 1 degree is sufficient. However, depending on the type of sample, a slightly wider range of about ± 3 degrees may be appropriate, and a narrower range may be sufficient. Further, the scanning range is not uniform for all peaks, and may be set to be narrow according to the diffraction angle, for example, narrow at a small diffraction angle and wide at a large diffraction angle. Measurement conditions other than the scanning range, such as the scanning speed and the integration time, may be input on the spot or read out from the measurement condition storage means and set.
[0008]
Next, the X-ray intensity is measured by the measuring means 4 while actually scanning the set scanning range (ST4), and the data of each range is temporarily stored in the storage device (ST5). At this time, the storage is not necessarily a permanent storage such as a hard disk, but may be a temporary storage such as a RAM of a computer. When the measurement of all the set scan ranges is completed (ST6), the data of all the scan ranges measured so far are virtually arranged one-dimensionally with the horizontal axis as the angle 2θ and the vertical axis as the X-ray intensity. The data is synthesized by the data synthesizing means 5 as if all of the data were obtained in each scan (ST7), and stored in a permanent storage device such as a hard disk by the data storage means 6 (ST8). At this time, the data of the range that is not actually measured is stored as zero, or the data that connects the end values of the measured data on the left and right sides of the range that is not measured is connected with a straight line. You may.
[0009]
FIG. 3 shows an example of the data thus obtained. The horizontal axis represents the detector angle 2θ, and the vertical axis represents the X-ray intensity. The angle ranges represented by a, b, and c in the figure are regions calculated from the input λ and d, and the respective diffraction peaks are obtained as a result of measuring the X-ray intensity while scanning the detector. . In the other angle range, the X-ray was not measured and the goniometer was fast-forwarded, and all the data was set to zero or a straight line was connected between the measured data as indicated by the dotted line in the figure. Is temporary data. S in the figure is a virtual scan (measurement) start point, and E is a virtual scan end point. In the example of this figure, the data from S to a has the same value as the data at the left end of a, and the data from c to E has the same value as the data at the right end of c. By setting the start and end points of the virtual scanning and storing the data from S to E in the storage device in this manner, the interpretation and display of the data can be made easier at the time of qualitative or quantitative analysis performed later. Can be improved.
[0010]
【The invention's effect】
The method of the present invention is particularly effective when the components of the sample are known to some extent. In such a case, when performing quantitative analysis of the concentration of the component, the objective can be achieved by measuring only a few necessary peaks, so there is no need to measure the other 2θ range, and the measurement time is greatly reduced. can do.
[0011]
In addition, instead of inputting the 2θ range of the measurement itself as the measurement condition, the lattice spacing d and the X-ray wavelength λ are input. Therefore, even when the type of the X-ray tube is changed, the value of the X-ray wavelength λ is changed. Correcting only the above can provide an excellent effect that the target diffraction peak can be measured, so that the correspondence is simple.
[0012]
Furthermore, since the data obtained only near the peaks are combined and stored using the diffraction angle as the horizontal axis, there is no need to re-synthesize the data during subsequent qualitative analysis or quantitative analysis, and quick data is saved. Processing can be performed.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment of the present invention.
FIG. 2 is a functional block diagram of an apparatus for implementing the method of the present invention.
FIG. 3 is an example of diffraction data obtained by the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wavelength input means 2 ... d value input means 3 ... Scan range calculation means 4 ... Measurement means 5 ... Data synthesis means 6 ... Data storage means 7 ... Measurement condition storage means

Claims (1)

An X-ray diffraction analysis method for measuring a diffracted X-ray radiated from a sample by irradiating the sample with characteristic X-rays from an X-ray tube and scanning an X-ray detector around the sample using a goniometer. In the above, by inputting the wavelength of the characteristic X-ray and the spacing between one or more lattice planes of the sample to be measured, a predetermined angular range around the angle at which the diffracted X-ray diffracted by this lattice plane appears Only the scanning range is determined so that the X-ray detector scans only the data, and the measurement data obtained for each portion obtained by the scanning range and virtual data connecting the measured data in other angle ranges are obtained. Are synthesized as data having a horizontal axis as a diffraction angle, and used as data for subsequent qualitative or quantitative analysis.

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