JP2000249668A - Quantitative analysis device of nonuniform composite tissue sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately perform a quantitative analysis by performing calculation based on density and atom concentration corresponding to the element of each particle structure in a sample and the volume rate of each particle structure and rapidly measuring weight concentration. SOLUTION: First, for example an electron beam is scanned via an electronic scanning circuit 20 and a scanning coil 5 to obtain a reflection electron image or a secondary electron image on a sample surface. Then, based on it, the center of gravity of each particle structure in a sample is obtained, an electron beam is fixed to the position, and a quantitative analysis is executed by a quantitative analysis means 28. Also, the area of each particle structure in the sample is calculated by a volume rate calculation means 27, the volume rate in the sample of each particle structure is calculated based on it, the weight concentration of each particle structure is calculated by a weight concentration calculation means 29, and the quantitative value of the entire sample is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for quantitatively analyzing a heterogeneous composite tissue sample in which the weight concentration of each particle structure in the heterogeneous composite tissue sample is measured so that a quantitative value of the entire sample can be obtained with high accuracy. About.

[0002]

2. Description of the Related Art Conventionally, wavelength dispersion type X-ray spectrometer (WDS)
Alternatively, surface analysis equipment such as an electron probe microanalyzer (EPMA) using an energy dispersive X-ray spectrometer (EDS) detects a characteristic X-ray of a sample and performs quantitative analysis by comparing the X-ray intensity with a standard sample. Quantitative analysis of a minute area of a sample is performed with higher reliability than other analytical instruments. In addition, continuous analysis is possible by automatic control of the sample stage or electron beam controlled by a computer, and recently, particles such as inclusions are automatically detected by reflected electron images or secondary electron images. Thus, a system has been constructed which calculates the center of gravity, automatically moves and fixes the electron beam at the center of gravity, and can perform quantitative analysis. When quantitative analysis of elements contained in a sample is performed, generally, ZAF correction (Z: atomic number correction, A: absorption correction, F: fluorescence excitation correction) or a modified prz method is applied. Have been.

[0003]

By the way, as a sample to be quantitatively analyzed using a surface analysis device such as an EPMA, a sample having a heterogeneous composite structure containing a large number of inclusions, segregation and crystallized substances in a three-dimensional manner is used. There is. In the quantitative analysis of such a heterogeneous composite tissue sample, even if the analysis is performed by expanding the electron beam, the quantitative accuracy such as ZAF correction is reduced. This is because quantitative correction theory such as ZAF correction is constructed based on a homogeneous sample such as a solid solution.

On the other hand, Japanese Patent Application Laid-Open No. Hei 10-26593 discloses a technique for performing quantitative analysis in consideration of an area ratio and an element density. In this technique, the area ratio of an element distribution region of a sample is taken into consideration. However, since the distribution in the depth direction of the sample is not taken into account, high-precision quantitative analysis cannot be expected.

The present invention has been made to solve the above problems in quantitative analysis of a heterogeneous composite tissue sample. The present invention measures the weight concentration quickly even in a sample of a heterogeneous composite tissue and achieves high accuracy. An object of the present invention is to provide an apparatus for quantitatively analyzing a heterogeneous composite tissue sample which enables quantitative analysis.

[0006]

In order to solve the above problems, the present invention provides a sample surface observing means for observing a sample surface as an electronic image or an X-ray image, and a method for observing a sample obtained by the sample surface observing means. Means for calculating the volume fraction of each particle structure based on the area of each particle structure, means for performing quantitative analysis of each particle structure based on characteristic X-rays generated by an electron beam irradiated to the sample, and quantitative analysis means. Means for calculating the weight concentration based on the density and the atomic concentration corresponding to the element of each particle structure obtained and the volume ratio of each particle structure obtained by the volume ratio calculation means, quantitative analysis of the heterogeneous composite tissue sample It constitutes the device.

The apparatus for quantitatively analyzing a heterogeneous composite tissue sample constructed as described above includes means for calculating a volume ratio based on the area of each particle structure, and calculates the volume ratio of each particle structure to calculate each particle structure. Since the weight concentration is calculated in consideration of the average distribution in the depth direction, the weight concentration can be quickly measured even in a heterogeneous composite tissue sample, and quantitative analysis can be performed with high accuracy.

[0008]

Next, an embodiment will be described. FIG. 1 is a schematic configuration diagram showing an embodiment of a quantitative analysis apparatus for a heterogeneous composite tissue sample according to the present invention. This embodiment shows a case where the present invention is applied to EPMA. In FIG. 1, 1 is an electron gun, 2 is a condenser lens coil, 3 is an objective aperture, 4 is a Faraday cup, 5 is a scanning (deflection) coil, 6 is an astigmatism correction coil, 7 is an objective lens, and 8 is reflected electron detection. , 9 is a secondary electron detector, 10 is a sample, 11 is a sample stage, and 12 is a stage drive motor. Reference numeral 13 denotes an X-ray spectroscopy element, 14 denotes an X-ray detector, 15 denotes an X-ray spectroscopy element driving motor, and these constitute a WDS (Wavelength Dispersion X-ray Spectrometer) 16. 17 is an EDS (energy dispersive X-ray spectrometer), 18 is an optical microscope, 19 is an EDSX-ray signal data acquisition device, 20 is an electronic scanning circuit, 21 is a secondary electron signal data acquisition device, 22 is a reflected electron signal data acquisition. Device, 23 is a stage motor control circuit, 24 is a WDS X-ray signal data acquisition device, 25 is a central processing unit, 26 is a large capacity storage device, and in the central processing unit 25, secondary electron signal data or reflected electron signal data is used. Means 27 for determining the area of each particle structure in the sample based on the sample electronic image and calculating the volume ratio based on the area; EDSX-ray signal data or WDS
Means 28 for performing quantitative analysis based on X-ray signal data
And means 29 for calculating the weight concentration based on the density and atomic concentration corresponding to the element of each particle structure obtained by the quantitative analysis means and the volume ratio of each particle structure obtained by the volume ratio calculation means. Have.

Next, the operation of the apparatus for quantitatively analyzing a heterogeneous composite tissue sample configured as described above will be described. First, electron beam scanning through the electronic scanning circuit 20 and the scanning coil 5 or scanning of the sample stage 11 through the stage motor control circuit 23 and the stage motor 12 is performed, and reflected electrons or secondary electrons from the sample surface are scanned. Is detected by the reflected electron detector 8 or the secondary electron detector 9, and a reflected electron image or a secondary electron image of the sample surface is obtained via the reflected electron signal data acquisition device 22 or the secondary electron signal data acquisition device 21. .

Next, based on the reflected electron image or the secondary electron image of the sample surface, the center of gravity of each particle structure in the sample is obtained, and the sample stage 11 or the electron beam is sequentially moved to the position of the center of gravity of each particle to obtain the electron. Fix the beam, WDS16 or EDS
17 performs a quantitative analysis operation. And a WDSX-ray signal data acquisition device 24 or an EDSX-ray signal data acquisition device
Quantitative analysis is performed by quantitative analysis means 28 based on the analysis data taken in via 19. Further, the area ratio of each particle structure in the sample is calculated by the volume ratio calculating means 27 based on the electronic image of the sample surface, and the volume ratio of each particle structure in the sample is calculated based on the area. Next, the density and atomic concentration of the element in each particle structure obtained by the quantitative analysis unit 28 are derived from literatures and the like, and further, based on the volume ratio obtained by the volume ratio calculation unit 27, each weight concentration calculation unit 29 The weight concentration of the particle structure is calculated, and the quantitative value of the whole sample is calculated.

Next, as a specific example, as shown in FIG.
Carbon and iron weight concentrations C _C , C when 1 cm ³ of carbon (graphite) 32 is contained in ³ cm ³ of pure iron 31
_Fe is represented by the following equations (1) and (2), where ρ _C and ρ _Fe are the densities of carbon and iron. C _C = _{^{[1 3 × ρ C / {1}} 3 × ρ C + (2 3 -1 3) × ρ Fe} ] × 100 = [(1 × 2.25) / (1 × 2.25 + 7 × 7.86) ] × 100 = 3.9 (%) ·········· (1 ) C Fe = [(2 3 -1 3) × ρ Fe / {1 3 × ρ C + (2 3 -1 3) × ρ Fe ｝] X 100 = [7 x 7.86 / (1 x 2.25 + 7 x 7.86)] x 100 = 96.1 (%) ... (2)

In general, the total area of a sample is S, and the tissue in the sample is
Is the area of element A_A, Matrix (maternal) dense
Degree ρ_M, The density of element A is ρ_A, Atomic concentration of matrix
Degree c_M, The atomic concentration of element A is c_AThen the organization (ex
Weight concentration C of element A)_AIs represented by the following equation (3). C_A= (S_A ^3/2× ρ_A× c_A) / ｛(S^3/2-S_A ^3/2) × ρ_M× c_M+ S_A ^3/2× ρ_A× c_A｝ ・ ・ ・ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ ３ (2)
Weight concentration C of the structure (element A) in the case_AIs given by the following equation (4).
expressed. Note that the area of the element B is S_B, Density ρ _B,original
The child concentration is c_BAnd C_A= (S_A ^3/2× ρ_A× c_A) / ｛(S^3/2-S_A ^3/2-S_B ^3/2) × ρ_M× c_M+ (S_A ^3/2× ρ_A× c_A) + (S_B ^3/2× ρ_B× c_B(4) The same applies to the weight concentration of element B and the weight concentration in the case of three or more elements.
Is requested in a similar manner.

In the above embodiment, the volume ratio is calculated by calculating the area of each tissue on the sample surface based on the secondary electron image or the backscattered electron image. The volume ratio may be calculated based on the image.

[0014]

As described above with reference to the embodiments, according to the present invention, the volume ratio of each particle structure is determined based on the area of each particle structure in the sample obtained by an electron image or an X-ray image. Since the weight concentration is calculated in consideration of the distribution in the depth direction of each particle structure, a quantitative result of the entire sample can be quickly and accurately obtained even in a heterogeneous composite tissue sample.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a quantitative analysis device for a heterogeneous composite tissue sample according to the present invention.

FIG. 2 is a diagram schematically illustrating a mode of calculating a weight concentration when pure iron contains carbon.

[Explanation of symbols]

 Reference Signs List 1 electron gun 2 condenser lens coil 3 objective aperture 4 Faraday cup 5 scanning (deflection) coil 6 astigmatism correction coil 7 objective lens 8 backscattered electron detector 9 secondary electron detector 10 sample 11 sample stage 12 stage drive motor 13 X-ray Spectroscopic element 14 X-ray detector 15 Motor for driving X-ray spectroscopic element 16 WDS 17 EDS 18 Optical microscope 19 EDSX X-ray signal data acquisition device 20 Electronic scanning circuit 21 Secondary electron signal data acquisition device 22 Reflected electron signal data acquisition device 23 Stage Motor control circuit 24 WDS X-ray signal data acquisition device 25 Central processing unit 26 Mass storage device 27 Volume ratio calculation means 28 Quantitative analysis means 29 Weight concentration calculation means

Claims (1)

[Claims] 1. A sample surface observation means for observing a sample surface as an electronic image or an X-ray image, and a volume ratio of each particle structure is calculated based on an area of each particle structure in the sample obtained by the sample surface observation means. Means for performing quantitative analysis of each particle structure based on characteristic X-rays generated by an electron beam irradiated on the sample; density and atomic concentration corresponding to the element of each particle structure obtained by the quantitative analysis means; Means for calculating a weight concentration based on the volume ratio of each particle structure obtained by the volume ratio calculating means.