JP2573053B2 - Method for analyzing two-element compounds in microscopic X-ray analysis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an epoch-making method for analyzing a two-element compound in microscopic X-ray analysis.

<Conventional technology> For example, an electron microscope and a so-called EPMA (Electorn Probe X-ra)
Y analyzer), and more specifically, scans and irradiates an electron beam within a predetermined small area of the sample, and accordingly emits from a matrix-like detection point area within the predetermined area. In recent years, in the field of microscopic X-ray analysis in which each characteristic X-ray is measured and the sample is analyzed based on the measurement result of the characteristic X-ray, attempts to apply image processing technology to the analysis result by EPMA However, at present, the image processing function based on them is to simply image the results of peak separation, line analysis, surface analysis, etc., which were performed in the traditional EPMA analysis. Staying in range.

Therefore, in the image processing method in the microscopic X-ray analysis according to the prior art described above, while applying the image processing technology to the analysis result by EPMA, the type of element constituting the sample and its concentration (content ratio) ) [Elemental identification] was not out of the range of the traditional EPMA analysis.

Thus, the present inventors have conducted intensive studies and, as a result, applied a completely new image processing means to the analysis results by EPMA, thereby enabling a new analysis field which was not possible in the past, that is, the analysis of the elements constituting the sample. Image processing in micro-part X-ray analysis as a base that enables not only analysis of types and concentrations (content ratios) [element identification], but also analysis of the types and distribution of compounds composing samples (material identification) A method (which is prior art to the present invention) has been developed, which has already been proposed in a patent application filed on March 13, 1989.

That is, the image processing method in the microscopic X-ray analysis according to the prior art is as follows. In a minute part X-ray analysis for measuring each emitted characteristic X-ray and analyzing the sample based on the measurement result of the characteristic X-ray, a memory area corresponding to a matrix detection area within a predetermined range of the sample And storing each measurement result of the characteristic X-ray for each address in a memory having an address, converting each measurement result of the characteristic X-ray stored in the memory into a luminance value of image information, A value histogram is created, and each peak in the image luminance value histogram of the characteristic X-ray is multi-valued so that a foot portion between adjacent peaks does not interfere with each other. Only each peak multi-valued portion in the characteristic X-ray image luminance value histogram is represented by a different color or symbol on a matrix screen having the number of pixels and addresses corresponding to the matrix detection point area within a predetermined range of the sample. The image processing means of displaying the image is adopted.

FIG. 5 and FIG. 6 show a specific example of an analysis result using an image processing method in the microscopic X-ray analysis using dolomite ore as a sample. The dolomite ore as the sample is composed of three kinds of compounds, namely, dolomite [CaMg (CO ₃ ) ₂ ], dolomite [CaCO ₃ ], and limestone [Ca
CO ₃ · MgCO ₃ ].

First, similarly to the conventional method, an electron microscope and an EPMA are used to scan and irradiate an electron beam on a minute predetermined area of the sample, and accordingly, each of the matrix-like detection point areas within the predetermined area of the sample is irradiated. The energy intensity of characteristic X-rays (X-rays unique to each element) emitted from each detection point is measured.

Next, the measurement results of the energy intensities of the characteristic X-rays for each element obtained by the EPMA are respectively converted into a matrix detection point region (for example, 256 × 256) within a predetermined range of the sample.
In a memory having a memory area (65536 memory) corresponding to a pixel) and an address, the data is stored for each address.

Here, if the energy intensity measurement result of the characteristic X-ray stored in each memory is analyzed according to a method similar to the conventional method, the type of element contained in the sample (in this example, C
a, Mg, C, O) and the concentration (content ratio) are each analyzed, and the element identification of the sample can be performed.

Further, the result of measuring the energy intensity of the characteristic X-ray stored in each memory is converted into a luminance value (image density value) of image information (normalized to, for example, 0 to 255), and then each element is analyzed. The image brightness value histogram (the relationship between the image brightness value and the count number of pixels having the same image brightness value) is created. FIG. 5 is an example of the image brightness value histogram, which is a characteristic X-ray of Ca selected as an element contained in all three compounds constituting the sample (dolomite ore). And the image brightness value histogram H indicates that the three types of compounds have three peaks A, B, and C.

Here, data (65536 pieces of image luminance value data) in all areas of each peak A, B, and C in the image luminance value histogram H of the characteristic X-ray of Ca obtained as described above is
Assuming that the brightness is simply displayed on one matrix screen having the number of pixels (256 × 256 pixels) and addresses corresponding to the matrix detection point area within the predetermined range of the sample, all pixels on the screen are displayed. Since the image brightness changes only in a continuous plane (analog), the boundaries between the peaks A, B, and C cannot be grasped at all.

Therefore, as shown in FIG. 5, the peaks A, B, and C in the image luminance value histogram H of the characteristic X-rays of Ca are defined as the peaks adjacent to each other (A and B, B and C). Multi-valued so that the foot part does not interfere (divided into a, b, c parts)
And the multivalued parts (a, b, c) of each of the peaks A, B, C
As shown in FIG. 6, only one pixel is displayed on one matrix screen P (for example, CRT) having the number of pixels (256 × 256 pixels) and the address corresponding to the matrix detection point area within a predetermined range of the sample. Have different colors (eg, red, blue, yellow) or symbols (eg, ○, ×,
By providing a special means of displaying (mapping) by Δ), the area and each boundary occupied by each of the peaks A, B, and C, that is, the sample (dolomite ore) constituting The phases of the compounds can be clearly distinguished.

As described above, according to the image processing method in the microscopic X-ray analysis, in particular, an image luminance histogram of characteristic X-rays of the elements constituting the sample is created, and each peak in the image luminance value histogram is adjacent to each other. Multi-valued so that the foot portions of the peaks do not interfere with each other, and only the multi-valued portion of each peak in the image luminance value histogram is represented by the number of pixels corresponding to the matrix detection point area within a predetermined range of the sample and By adopting a unique image processing means of displaying different colors or symbols on a matrix screen having addresses,
The area and each boundary occupied by each of the peaks, that is,
The phases (distribution state) of the compounds constituting the sample can be clearly distinguished and grasped, and thus, a new analysis field which has not been possible in the past, that is, the types of elements constituting the sample Thus, the possibility of analyzing (identifying substances) the types and distributions of the compounds constituting the sample is not limited to the analysis of concentration (content ratio) (element identification).

<Problems to be Solved by the Invention> However, the following problems still remain in the prior art (image processing method in microscopic X-ray analysis) in which the very excellent advantages as described above can be expected. .

That is, in the case of using the image processing method in the microscopic X-ray analysis according to the above prior art, (a) Although the number and distribution state of the compounds constituting the sample can be analyzed, once for the compound, The only information that can be obtained from the analysis is that these compounds contain one selected element, and it is not necessary to specify only what kind of element they contain. In addition to the basic limitation that it is not possible, (a) the characteristic X of Ca selected as one element contained in the sample (dolomite ore) as in the above analysis example
The problem is that the number (3) of the peaks A, B, and C in the line image luminance value histogram H matches the number (3) of the compounds (e.g., dolomite, dolomite, and limestone) constituting the sample. However, the number of peaks in the image brightness histogram of the characteristic X-ray of one element selected in this manner does not always match the number of compounds constituting the sample. For example, in the image luminance value histogram of the characteristic X-ray of one selected element, even if a peak looks like one, the peak may actually be formed from an overlap of a plurality of peaks. However, there is a problem that a plurality of compounds are erroneously regarded as one compound, and a correct analysis cannot be performed.

The present invention has been made as a result of further research in view of such circumstances, and its main purpose is to focus on two elements contained in a sample, thereby reducing the number of compounds constituting the sample. It is necessary to develop a method for the analysis of two-element compounds in microscopic X-ray analysis, which can easily and accurately analyze X-rays and obtain more detailed information on those compounds (can identify the two types of contained elements). Is to do.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a method for scanning and irradiating a small predetermined range in a sample with an electron beam, and accordingly, a matrix-like detection point in the predetermined range. The characteristic X-rays of the two elements respectively emitted from the region are measured, and the characteristics of the two elements are stored in two memories having a memory area and an address corresponding to a matrix detection point area within a predetermined range of the sample. X-ray measurement results are stored for each address,
By forming a plurality of data groups where the ratios of the image luminance values of the two elements are substantially equal using the measurement results of the specific X-rays of the two elements stored in the two memories,
On the two-dimensional matrix screen of the CRT, make an image brightness value correlation diagram of those two elements, and include at least the two elements in the sample based on the number of the data group appearing in the image brightness value correlation diagram of the two elements The number of compounds is identified, and
A method for determining a content ratio of at least the two elements in each of the specified compounds from a two-dimensional position of each of the data groups. is there.

<Operation> The operation exhibited by adopting such a characteristic means is as follows.

That is, in the method of analyzing a two-element compound in the microscopic X-ray analysis according to the present invention, only one element contained in the sample is used as in the image processing method in the microscopic X-ray analysis according to the prior art. Rather than focusing on, by selecting two elements, by using a measurement result of the characteristic X-rays of the two elements, by forming a plurality of data groups where the ratio of the image luminance value of the two elements is substantially equal, On the two-dimensional matrix screen of the CRT, make an image brightness value correlation diagram of those two elements, based on the number and position of the data group appearing in the image brightness value correlation diagram, the number of compounds containing both elements and By determining the content ratio of both elements in each compound, as will become clearer from the description of the examples described below, even if the image luminance value histogram for each element Even if the peaks are slightly overlapped in each other, it is possible to accurately analyze the number of compounds constituting the sample without error, and further, to determine the content ratio of those compounds, It can be carried out very easily, and more detailed and reliable information on the compounds containing the above two elements can be obtained in one analysis operation.

<Example> Hereinafter, as a specific example of the image processing method in the microscopic X-ray analysis according to the present invention, an analysis result using a meteorite as a sample will be described.

First, in the same manner as in the conventional method, using an electron microscope and EPMA, a microscopic predetermined area of the sample is scanned and irradiated with an electron beam. The energy intensity of characteristic X-rays (X-rays unique to each element) emitted from each detection point is measured.

Next, the measurement results of the energy intensities of the characteristic X-rays for each element obtained by the EPMA are respectively converted into a matrix detection point region (for example, 256 × 256) within a predetermined range of the sample.
In a memory having a memory area (65536 memory) corresponding to a pixel) and an address, the data is stored for each address.

Here, if the energy intensity measurement result of the characteristic X-ray stored in each memory is analyzed according to a method similar to the conventional method, the type of element contained in the sample (in this example, C
a, Mg, etc.) and the concentration (content ratio) are each analyzed, and the element identification of the sample can be performed.

Further, the result of measuring the energy intensity of the characteristic X-ray stored in each memory is converted into a luminance value (image density value) of image information (normalized to, for example, 0 to 255), and then each element is measured. , An image brightness value histogram (a relationship between the image brightness value and the count number of pixels having the same image brightness value) is created. FIG. 1 and FIG.
6 is an example of the image luminance value histogram, wherein the characteristic X-ray image luminance value histogram of the first element (Ca) and the second element (Mg) selected from the elements contained in the sample (meteorite) H1 and H2 are shown respectively.

Among these, the image luminance value histogram H1 of the characteristic X-ray of Ca shown in FIG. 1 has two peaks A1 and B1 in this example, and the image luminance of the characteristic X-ray of Mg shown in FIG. It can be seen that the value histogram H2 also has two peaks A2 and B2 in this example.

Then, the image luminance value histogram of these two characteristic X-rays
As far as H1 and H2 are concerned, this sample (meteorite) is composed of Ca and Mg
It is presumed to be composed of two compounds including

However, as shown in FIG. 3, a diagram showing the correlation between the image luminance value of the characteristic X-ray of Ca and the image luminance value of the characteristic X-ray of Mg is shown in FIG.
(56x256 pixels), you can see that the above estimation is incorrect.

That is, in the image luminance value correlation diagram shown in FIG.
The horizontal axis (x-axis) represents the image luminance value of the characteristic X-ray of Ca (0 to 25).
5) The vertical axis (y-axis) is the image characteristic value (0 to 2) of the characteristic X-ray of Mg.
55), and each point shown on this xy screen is
(The image luminance value of Ca and the image luminance value of Mg) are determined by the number of data having the same combination as the luminance of the image information (image density: 0, for example).
256 tones of 255). For example, x = 20
And the number of data that satisfies y = 40 is counted with reference to the original data, and the number is displayed at the pixel located at (x, y) = (20, 40) with the luminance corresponding to the number. It is to let. In this example, if the above operation is performed for each of x and y in 256 units, one point at a time, the number of operations is 256 ² = 65536.

As is clear from the above-described image brightness value correlation diagram, in this example, the data groups (three data groups G1 in this example) are located where the ratio of the image brightness values of the two elements Ca and Mg is substantially equal. , G2, G3) are formed. Therefore, from this, that is, from the number (3) of the data groups G1, G2, G3 appearing in the image brightness value correlation diagram, Ca and Mg
It can be seen that there are actually three compounds, not the two compounds estimated from FIGS. 1 and 2 described above. Further, the content ratio of Ca and Mg in each compound can be read from the positions (x coordinate, y coordinate) of each data group G1, G2, G3.

By the way, in the image luminance value histogram H1 of the characteristic X-ray of Ca shown in FIG. 1, the two data groups G1 and G2 are one peak A1, and the image of the characteristic X-ray of Mg shown in FIG. It can be understood from the image brightness value correlation diagram that the two data groups G2 and G3 appeared as one peak B2 in the brightness value histogram H2.

Further, as shown by, for example, square window marks a ', b', and c 'in FIG.
1, G2, and G3 are extracted (that is, multivalued), and data corresponding to the multivalued portions a ', b', and c 'of the data groups G1, G2, and G3 are converted to the Ca or It is extracted from the characteristic intensity measurement result of the characteristic X-ray stored in the memory of Mg and converted into an image luminance value (image density value) (for example, normalized to 0 to 255). Although omitted, the number of pixels corresponding to a matrix-like detection point area within a predetermined range of the sample (256 × 256 pixels)
And one matrix screen with addresses (eg,
Different colors for each data group (e.g. CRT)
By displaying (mapping) with red (red, blue, yellow) or symbols (for example, ○, ×, Δ), the sixth
As shown in the figure, the region occupied by each of the three types of compounds constituting the sample (meteorite) and each boundary, that is, the phases of these three types of compounds can be clearly distinguished and captured. It is also possible to read the content ratio of each type of compound. The data groups G1, G2,
If the method of taking the multivalued portion (a ', b', c ') of G3 is too narrow, the background portion on the matrix screen becomes too large, and the boundary of each region becomes unclear. , These multi-valued parts (a ′, b ′, c ′)
It is desirable to adopt as wide a range as possible without deviating from each data group G1, G2, G3.

In the above-described embodiment, when the image luminance value correlation diagram is created, the image luminance value of the characteristic X-ray of the first element and the image luminance value of the characteristic X-ray of the second element are plotted on the horizontal axis (x
Axis) and vertical axis (y axis), this xy screen
Although the number of data having the same combination of the (image luminance value of the first element and the image luminance value of the second element) is represented by the luminance of the image information, the so-called luminance display method has been described. As schematically shown in the drawing, the horizontal axis (x-axis) and the vertical axis (y-axis) take the image luminance value of the characteristic X-ray of the first element and the image luminance value of the characteristic X-ray of the second element, A so-called three-dimensional coordinate system in which the number of data having the same combination of the (image luminance value of the first element and the image luminance value of the second element) is taken on the vertical axis (z-axis) may be adopted.

In the above-described embodiment, the energy intensity of the characteristic X-ray of each element measured by an electron microscope and EPMA is directly converted into a luminance value (image density) of image information (for example, 0%).
In the example above, the value is normalized to ~ 255)
Characteristic X-ray energy intensity is expressed by weight concentration (or atomic%)
And then use it as the luminance value of the image information (image density value)
(For example, normalized to 0 to 100).

<Effects of the Invention> As is clear from the details described above, according to the method for analyzing a two-element compound in the microscopic X-ray analysis according to the present invention, particularly, the sample is contained in the sample as in the prior art. Instead of focusing on only one element, select two elements and use the measurement results of the characteristic X-rays of the two elements to form a plurality of data groups where the ratio of the image luminance values of the two elements is substantially equal. By forming, on the two-dimensional matrix screen of the CRT, an image brightness value correlation diagram of those two elements is created, and based on the number of data groups and each position appearing in the image brightness value correlation diagram, the two elements are compared. By calculating the number of compounds contained and the content ratio of both elements in the compound, even if the peaks are slightly overlapped in the image luminance value histogram for each element Even so, the number of compounds constituting the sample and their content ratio can be analyzed very easily and accurately, and it is said that these compounds contain the above two elements. This makes it possible to obtain more detailed and reliable information in one analysis operation, thereby solving the problems (a) and (b) in the prior art as described above. The effect is exhibited.

[Brief description of the drawings]

FIGS. 1 to 4 are for explaining a specific embodiment of a method for analyzing a two-element compound in a microscopic X-ray analysis according to the present invention, and FIG. 1 shows a case where a meteorite is used as a sample. 2 is an image luminance value histogram of the characteristic X-ray of Ca, FIG. 2 is an image luminance value histogram of the characteristic X-ray of Mg, and FIG. 3 is a (Ca-Mg) image luminance value correlation diagram expressed by the luminance display method. , And FIG. 4 is represented by a three-dimensional coordinate system (Ca
-Mg) shows an image luminance value correlation diagram. 5 and 6 are for explaining the technical background of the present invention and the problems in the prior art, and FIG. 5 is a diagram showing the image processing in the microscopic X-ray analysis according to the prior art. In the method, a luminance histogram of characteristic X-rays of Ca when a dolomite ore is used as a sample and an explanatory diagram of a multi-value conversion method are shown, and FIG. 6 is a schematic explanatory diagram of a matrix screen displaying a distribution state of Ca. Is shown. H1 ... Ca image brightness value histogram, H2 ... Mg image brightness value histogram, peaks ... A1, B1, A2, B2, G1, G2, G3
...... Data group.

Claims (1)

(57) [Claims] An electron beam is scanned and irradiated on a minute predetermined range of a sample, and characteristic X-rays of two elements respectively emitted from a matrix-like detection point area within the predetermined range are measured. In two memories having a memory area and an address corresponding to a matrix detection point area within a predetermined range of the sample, the measurement results of the characteristic X-rays relating to the two elements are respectively stored for each address, By forming a plurality of data groups where the ratio of the image luminance values of the two elements is substantially equal using the measurement results of the characteristic X-rays of the two elements stored in the memory,
On the two-dimensional matrix screen of the CRT, create an image brightness value correlation diagram of those two elements, and include at least the two elements in the sample based on the number of the data groups appearing in the image brightness value correlation diagram of the two elements The number of compounds is specified, and the content ratio of at least the two elements in each of the specified compounds is determined from the two-dimensional position of each of the data groups. Elemental compound analysis method.