JPH01270651A - Processing method of data in x-ray diffraction apparatus - Google Patents

Abstract

PURPOSE:To determine a position and the intensity of a diffraction peak, by a method wherein three or more measuring points are set within the distribution width of diffracted X-rays, the shape of the diffraction peak is adapted to a Gaussian error distribution curve, and an undetermined constant is calculated from the intensity of X-rays obtained. CONSTITUTION:In an X-ray detecting device 4, X-ray detectors 41, 42...418 are arranged in three arrays each comprising six of them. A sample being set on a goniometer 3, the center (the middle of the detectors 49 and 410) of the device 4 is made to coincide with an expected central position of a diffraction peak in an angular position whereat diffracted rays to be measured appear. A control device 6 integrates outputs of the detectors 41-418 for a prescribed time and takes in the result as measured data, and after the execution of sensitivity correction, it sends the data to a host computer 7 to be processed. First base line correction is executed to determine measured data Pi, a value of an angular position corresponding thereto is set as Xi, and the intensity P (Xi) of diffracted rays corresponding to the value Xi is determined by the application of a Gaussian distribution curve. Three constants in the distribution curve can be decided from a number of expressions of the intensity P (Xi) by a least squares method, for instance. 1: X-ray tube, 2,8: solar slit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a data processing method for measurement output for determining the peak center position, peak height, half width, etc. of diffracted X-rays in an X-ray diffraction apparatus.

(Prior Art) When measuring the stress composition of a material using an X-ray diffraction device, it is necessary to accurately measure the peak position and intensity of diffracted X-rays. Conventionally, in order to increase the measurement accuracy of the peak position 2 intensity of diffracted X-rays, a method was used in which the feed angle of one step of the angle feed of the diffractometer was set small.If the step feed angle was shifted small, the measurement accuracy could be improved. However, since the number of measurements required is large, the time required for measurement is very long (and although it can be carried out in the case of laboratory measurements, it is necessary to send the measurement data online to a postcomputer at the work site). ,
This method is not suitable for cases where data is processed and the results are fed back to the work site.

(Problems to be Solved by the Invention) The present invention aims to enable accurate measurement of the position and intensity of diffraction X-ray peaks in a short time. The object of the invention is to increase the fil11 constant accuracy while setting the value large.

(Another means to solve the problem) The measurement angle interval in the diffractometer is set to a value that allows the existence of three or more fixed points on two sides within the distribution width of diffracted X-rays, and the shape of the diffraction peak is Gaussian or Gaussian-L1. - As the lens error distribution curve, set the undetermined constant of the formula representing the error distribution curve to -1-
The position and intensity of the diffraction peak were determined by calculating from the X-ray intensities obtained at regular angle intervals.

(Action) Gauss'B1'! The difference distribution curve is P(x) − Kc, −・(γ − “)″, = (1)
It is expressed as In the above formula, X is the diffraction angle, 21°)
) is the undetermined number, P (x) is symmetrical around x = -), ), and x = b is the peak center position,
K is the peak intensity, and :1 is the flea corresponding to the half width of the peak. Now x=x1. ．． P(xl) at x2...
P (x2)...If a constant value of 41 is obtained, then D'
(xl,)=Ke-"('-63"P (x 2 >
Since a large number of equations such as = K e-"?-" can be obtained, it is possible to determine, for example, a, b by the method of least squares.

The determination of K, a, and b is not limited to the method of least squares; for example, take three values from the measured values P (xll, P (x2), etc.) and substitute them into equation (1) to calculate K , a, b The combination of three sets of measured values is colored /,
K, a + obtained in the case of husband//
The values of b may be averaged.

The conventional method applies smoothing processing to the measured values at multiple measurement points to obtain the peak curve of the diffraction X-ray. It has already been decided.

Since the present invention makes use of the fact that the peak profile of diffracted X-rays is a Gaussian distribution curve, it is easy to determine the three constants incorrectly, and multiple measurement results are used to determine the three constants. , even if the total measurement time is small,
As for the three constants, they are the same even if they take a long time.

For example, conventionally, the heights of nine points on the frill were determined based on the measured values of nine points, but with the present invention, it is only necessary to determine three constants, so three constants can be measured in the same measurement time. Accuracy is f
The shape of the peak profile is determined by these three constants, so the peak profile itself is J-3.
This will result in twice the precision. The above explanation was based on the fact that the peak profile shows the shape of the Gaussian error distribution, but if even higher precision is desired, the "Beakup I" file can be determined in the same way as in -1- based on the shape of the Gauss-Lawrence error distribution. .

(Embodiment) Figure 1 shows an embodiment of the present invention. This device is a multi-channel type X'!f1. diffraction device, in which 1 is an X-ray tube, 2 is a solar slit, and 2 is a goniometer at the sample surface. A parallel beam of X-rays is projected onto a long and narrow area along the center line. 3 is a goniometer, and a sample S is rotatably set in the goniometer (in the middle upper part of the goniometer). Reference numeral 4 is an X-ray detection device, which is mounted on an arm 5 whose rotation center is at the center of the goniometer.The sample S and the arm 5 are each driven by a pulse motor, and the angular position of the husband/7 on the goniometer is It is detected by the control device O.

The X-ray detection device 4 includes a large number of X-ray detectors 41, 42...4
18 are arranged in three rows of six rows. - The rows of X-ray detectors are spaced 2.1 degrees apart from each other with respect to the center of the goniometer, and these rows are arranged in three rows with a 0.7 degree offset between the rows. . A solar slit 8 is provided on the front surface of each X-ray detector in a direction perpendicular to the rotation center of the goniometer. Therefore, a total range of 11.9 degrees can be measured at once at intervals of 0.7 degrees.

The measurement operation is performed as follows. & (Let the sample be removed, and place the
Move the arm 5 so that the center of the diffraction peak, specifically the middle between the detectors 49 and 410, coincides with the expected center position of the diffraction peak,
After that, the control device 6 integrates the output of each X-ray detector 41 to 418 for a certain period of time and takes in the result as measurement data.
The value obtained by multiplying the measurement data of each detector by the sensitivity correction coefficient of each detector is sent to the post computer 7 together with the angle data of the goniometer corresponding to each measurement data, and the data is processed by the host computer. It goes without saying that the data processing may be performed by the control device 6 at any location.

'' In the double measurement operation, the sensitivity correction of each detector 41 to 418 is performed as follows. Set any sample, rotate arm 5 so that all X451 detectors 41-418 pass through one diffraction line peak of the sample, and record the output of each X-ray detector as a function of the angular position of arm 5. do. This record is a record of one diffraction line profile, so if the sensitivity of each detector is the same, the peak heights in each record are all equal, and the difference in peak height in each record is due to the difference in peak height between each detector. represents the difference in sensitivity. Therefore, the correction coefficient is a value whose numerator is the average peak height of each record and the denominator is the peak height of each detector record, and the correction coefficient obtained by such measurements is sent to the control device 6. Let it be remembered.

Next, data processing for two series of sensitivity-corrected measurement data will be explained. The measurement data is the measurement data of the profile angle of one diffraction peak in 0.7° increments. Baseline correction is first performed from these data. The angular range that the X-ray detector 4 can measure at one time is approximately ±5°.
Therefore, some detectors near both ends of the detected wave Ff4 are located outside the tail of the diffraction line peak. Therefore, X
Using the measurement data of six line detectors 41 to 43 and 416 to 418, -calculate the quadratic curve,
What is subtracted from the data of each detector 44-415 by using this as a baseline is baseline-corrected measurement data. For data processing, these measurement data and data on the angular position of each XI detector providing the respective measurement data are used. The above baseline-corrected measurement data is P
Let the data of the angular position corresponding to i be Xi. Now, assuming that a and b are correctly determined for each constant in equation (1) above, the correct intensity of the diffracted X-ray at the angular position Xi is p < x 1> :== K oQ'X"l') ”
and Δ1=Pi−P(Xi) is the measurement error of X &'1 intensity at angular position X1. The method of least squares determines a and b so that S-Σ(Δ1)1 is minimized.

Therefore, if we partially differentiate the expression for the bipedal S with respect to a and b and set each as O, we will have three expressions for K, a, and b, so from this we can calculate I, a, and b. do it. Since exponent operations are troublesome, we take the logarithms of both sides of equation (1) and calculate e ogP (X i ) −f! ogK-a
(X i -b) - (2), and a and b are obtained from the three equations obtained by logarithmically transforming each measurement data Pi.

In the above embodiment, the X-ray diffraction angle is measured at 0.7° intervals, so the required accuracy is ±0.035° to ±0.07°.
° can be accommodated. If you want to increase the measurement accuracy by twice as much, place the detector 4 in one angular position, wait for the output data of each detector to be = 9, then move the arm 5 by 0635 degrees and repeat Just take the same measurements at different times.

In the above example, a multi-channel diffraction device was used.
It goes without saying that the present invention can also be applied to the case where measurements are performed sequentially at necessary angular jumps using a single detector device.

(Effect of the invention) Since the present invention determines three constants from multiple measurements, it means that for a given number, more measurement results are averaged than in the past, so if the same amount of time is spent, The accuracy is further improved, and when the same accuracy is obtained, the measurement time can be shortened, and the measurement efficiency can be significantly improved.

[Brief explanation of the drawing]

The drawing is a perspective view of an apparatus according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... X-ray tube, 2... Solar slit, 3... Goniometer, 4... X-ray detection device, 5... Arm, 6...
...Control device, 7...Host computer, S...
sample. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] The measurement angle interval is set so that three or more measurement points are included in the angular range where the diffracted X-rays to be measured are distributed in the X-ray diffractometer, and the peak waveform of the diffracted X-rays is determined by Gauss or Gauss-Lawrence. X-ray diffraction characterized in that the diffraction angle, intensity, half-value width, etc. of diffracted X-rays are determined by calculating constants that determine the error distribution curve from the measured values at each of the positions as the error distribution curve. Data processing method in the device.