Electronic probe quantitative analysis method for trace fluorine element in iron-containing sample

Abstract

The invention provides an electronic probe quantitative analysis method for trace fluorine elements in an iron-containing sample. According to the quantitative analysis method, during quantitative analysis, the TAPL light splitting crystal is used, the TAPL light splitting crystal has a larger diffraction area, and the obtained count is higher; the interference of the light splitting crystal Fe of the LDE1L is difficult to process; therefore, the TAPL light splitting crystal is used for replacing the LDE1L light splitting crystal and the TAP light splitting crystal; the quantitative analysis conditions are as follows: the acceleration voltage is 15 kV, the beam current is 300 nA, and the beam spot is 20 microns; a TAPL light splitting crystal is adopted, the F content detection limit is 76 ppm (3 sigma), and a TAP light splitting crystal is adopted, the F content detection limit is 195 ppm (3 sigma); when the TAPL spectroscopic crystal is used for testing the trace fluorine element in the iron-containing sample, the detection limit is lower, the detection value is closer to the reference value, and the accuracy is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of F element micro-area in-situ testing, and in particular to an electron probe quantitative analysis method for trace fluorine element in an iron-containing sample. Background Art

[0002] When the electron probe analyzes the F element, the F element X-ray has a long wavelength and low energy, and is easily absorbed by the sample, spectroscopic crystal, and detector window, so the actual received X-ray signal is low. The earliest spectroscopic crystal used to analyze the F element was the TAP spectroscopic crystal. The LDE1 spectroscopic crystal can provide a much higher count rate than the TAP spectroscopic crystal, greatly improving the accuracy and detection limit of the F element, which improves the accuracy of the analysis of Fe-free minerals such as apatite. Spectral peak interference is the main factor affecting the accuracy of F element analysis. The use of LDE1 spectroscopic crystals can obtain high counting rates. Most of the current research on F element electron probe analysis methods uses LDE1 spectroscopic crystals, and the research focuses on how to solve the problem of spectral peak interference. Existing studies have shown that when using LDE1 spectroscopic crystals to analyze Fe-containing minerals and glass, the Fe element will interfere with the F element analysis. The existing technology provides a method of quantifying interference using a calibration curve. This method uses eight FeO T The Fe Lα–F Kα interference is corrected using a Fe-free mineral standard (primarily olivine and pyroxene) ranging from 0 to 29.77 wt% and an Fe-free glass standard. This method is based on the linear relationship between the Fe content of the F-free mineral and the F Kα peak position counts in the same F-free mineral. Based on this relationship, the Fe Lα interference can be corrected based on the FeO content of the sample. T The F Kα counts are then deduced and quantified using a calibration curve. However, due to structural differences between different minerals and glasses, the calibration curve for minerals may not be suitable for all samples and requires a large amount of standard samples, which is cumbersome to operate.

[0003] In summary, the analysis of trace fluorine in iron-containing samples has the problems of difficult correction of element interference, low precision, and large errors. The core issue of electron probe analysis of trace fluorine in iron-containing samples is to improve the precision and accuracy of electron probe analysis of F elements, which requires consideration of factors such as signal changes caused by analysis beam damage, spectral peak interference, and background correction methods.

[0004] Based on the shortcomings of the current analysis of trace fluorine in iron-containing samples, it is necessary to improve it. Summary of the Invention

[0005] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide an electron probe quantitative analysis method for trace fluorine in iron-containing samples to improve the precision and accuracy of electron probe analysis of F elements.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides an electron probe quantitative analysis method for trace fluorine in an iron-containing sample, comprising the following steps:

[0008] The iron-containing sample is prepared into a sample suitable for electron probe analysis;

[0009] Spray-coating a carbon conductive film on the sample to be tested;

[0010] The sample to be tested, which is coated with a carbon conductive film, is placed on the sample stage of an electron probe microanalyzer, and the peak position and background position of the F element to be tested are searched and determined in the sample using an X-ray spectrum.

[0011] Measuring the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested;

[0012] Compare and analyze the F counting intensity in the standard sample and the F counting intensity in the sample to be tested, and obtain the fluorine content in the sample to be tested through matrix correction;

[0013] In the quantitative analysis process, the spectroscopic crystal used for the F element is a TAPL spectroscopic crystal, and the area of the TAPL spectroscopic crystal is 2 to 3 times that of the TAP spectroscopic crystal.

[0014] Preferably, the quantitative analysis conditions include accelerating voltage, beam current, and beam spot;

[0015] Among them, the acceleration voltage is 10 to 30 kV, the beam current is 100 nA to 500 nA, and the beam spot is 1 to 30 μm.

[0016] Preferably, the acceleration voltage is 15 kV, the beam current is 300 nA, and the beam spot size is 20 μm.

[0017] Preferably, the standard sample is fluoride.

[0018] The electron probe quantitative analysis method for trace fluorine in iron-containing samples of the present invention has the following beneficial effects compared with the prior art:

[0019] 1. The quantitative analysis method of trace fluorine in iron-containing samples of the present invention uses a TAPL spectroscopic crystal during quantitative analysis. The interplanar spacing of the TAPL spectroscopic crystal and the TAP spectroscopic crystal are the same, and the peak shapes in the figure are basically the same. However, the area of the TAPL spectroscopic crystal is 2 to 3 times that of the TAP spectroscopic crystal. The TAPL spectroscopic crystal has a larger diffraction area and obtains higher counts. However, the interference of Fe in the LDE1L spectroscopic crystal is difficult to handle. Therefore, the present invention uses a TAPL spectroscopic crystal to replace the LDE1L spectroscopic crystal and the TAP spectroscopic crystal.

[0020] 2. The quantitative analysis method of trace fluorine in iron-containing samples of the present invention has the following quantitative analysis conditions: an accelerating voltage of 15 kV, a beam current of 300 nA, and a beam spot of 20 μm; using a TAPL spectroscopic crystal, the detection limit of the F content is 76 ppm (3σ), and using a TAP spectroscopic crystal, the detection limit of the F content is 195 ppm (3σ); when the present invention uses a TAPL spectroscopic crystal to test trace fluorine in iron-containing samples, not only is the detection limit lower, but the detected value is also closer to the reference value, and the accuracy is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0022] Figure 1 This is a diagram showing the scanning results of the TAPL spectroscopic crystal fine spectrum tested by the method in Example 1;

[0023] Figure 2 This is a graph showing the fine spectrum scanning results of the TAP spectroscopic crystal tested using the method in Comparative Example 1;

[0024] Figure 3 This is a graph showing the results of a fine spectrum scan of the LDE1L spectroscopic crystal tested using the method in Comparative Example 2;

[0025] Figure 4 For Figure 1 The middle curve is a schematic diagram of the background acquisition position and background fitting method in various different ways;

[0026] Figure 5 This is the relationship between the accelerating voltage, test current and detection limit of F element under TAPL spectroscopic crystal conditions;

[0027] Figure 6 The F signal intensity of the BHVO-2G sample changes with time under the conditions of 15kV, 300nA, and different beam spot diameters;

[0028] Figure 7 The absorption current of the BHVO-2G sample changes with time under the conditions of 15kV, 300nA, and different beam spot diameters;

[0029] Figure 8 This is a figure showing the fitting results of performing a multi-point background test on the iron-containing sample BHVO-2G using a TAPL spectroscopic crystal according to the method in Example 1, and performing a multi-point background fitting on the background curve;

[0030] Figure 9 This is a graph showing the results of testing the iron-containing sample BHVO-2G using a TAPL spectroscopic crystal according to the method in Example 1 and calculating the F content;

[0031] Figure 10 The multi-point background test of the iron-containing sample BHVO-2G was performed using the TAP spectroscopic crystal according to the method in Comparative Example 1, and the fitting result of the multi-point background fitting of the background curve was performed;

[0032] Figure 11 This is a graph showing the results of testing the iron-containing sample BHVO-2G using a TAP spectroscopic crystal according to the method in Comparative Example 1 and calculating the F content;

[0033] Figure 12 This is a fitting result diagram of a multi-point background test on the iron-containing sample BHVO-2G using the LDE1L spectroscopic crystal according to the method in Comparative Example 1, and a multi-point background fitting of the background curve;

[0034] Figure 13 The results of testing the iron-containing sample BHVO-2G using the LDE1L spectroscopic crystal according to the method in Comparative Example 1 and calculating the F content are shown. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are the directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0037] The order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be understood as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0038] The present invention provides a method for quantitative analysis of trace fluorine in an iron-containing sample by electron probe, comprising the following steps:

[0039] S1. preparing the iron-containing sample into a sample suitable for electron probe analysis;

[0040] S2, spraying a carbon conductive film on the sample to be tested;

[0041] S3, placing the sample to be tested with the carbon conductive film sprayed on the sample stage of the electron probe microanalyzer, and using the X-ray spectrum to search and determine the peak position and background position of the F element to be tested in the sample to be tested;

[0042] S4, measuring the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested;

[0043] S5. Comparing and analyzing the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested, and obtaining the fluorine content in the sample to be tested by matrix correction;

[0044] In the quantitative analysis process, the spectroscopic crystal used for the F element is a TAPL spectroscopic crystal, and the area of the TAPL spectroscopic crystal is 2 to 3 times that of the TAP spectroscopic crystal.

[0045] Specifically, the theoretical basis for the electron probe quantitative analysis of the present invention is the positive correlation between element content and characteristic X-ray intensity under certain conditions. Electron probe analysis analyzes the intensity of elemental characteristic X-rays in a specific microregion on the surface of a solid sample. If a standard sample with a known F content is introduced, the F content of the test sample can be calculated based on the ratio of the F characteristic X-ray intensities between the test sample and the standard sample, after correcting for matrix effects.

[0046] The quantitative analysis of the present invention uses TAPL spectroscopic crystals. TAP is a common spectroscopic crystal of ammonium hydrogen phthalate with an area of 3 cm 2 TAPL is a large-area ammonium hydrogen phthalate spectroscopic crystal. Specifically, the area of TAPL spectroscopic crystal is 2 to 3 times that of TAP spectroscopic crystal. The area of TAPL spectroscopic crystal is 6 to 9 cm 2 The TAPL and TAP spectroscopic crystals have the same interplanar spacing, and the peak shapes in the figure are essentially the same. However, the TAPL spectroscopic crystal has a larger diffraction area, resulting in higher counts. However, the Fe interference of the LDE1L spectroscopic crystal is difficult to handle; therefore, the present invention uses the TAPL spectroscopic crystal instead of the LDE1L and TAP spectroscopic crystals.

[0047] In some embodiments, the quantitative analysis conditions include acceleration voltage, beam current, and beam spot;

[0048] Among them, the acceleration voltage is 10 to 30 kV, the beam current is 100 nA to 500 nA, and the beam spot is 1 to 30 μm.

[0049] In some embodiments, the accelerating voltage is 15 kV, the beam current is 300 nA, and the beam spot size is 20 μm.

[0050] In some embodiments, the standard sample is a fluoride, including but not limited to barium fluoride.

[0051] In some embodiments, the counting intensity of the standard sample and the counting intensity of the sample to be tested are compared and analyzed, and the comparative analysis results are corrected to obtain the F element content. The ZAF method is used to correct the comparative analysis results.

[0052] In some embodiments, the carbon conductive film is deposited to a thickness of about 20 nm.

[0053] The following further illustrates the electron probe quantitative analysis method for trace fluorine in an iron-containing sample of the present application with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0054] The iron-containing samples in the following examples include three basaltic glass samples: BHVO-2G, BCR-2G, and BIR-1G. The weight percentages (wt%) of their components are shown in Table 1 (excluding unavoidable impurities). These samples contain trace amounts of the element F, with all three containing approximately 10 wt% FeO. Barium fluoride was used as the standard sample for quantitative F analysis.

[0055] Table 1 below shows the mass content (wt%) of each component in the iron-containing sample

[0056] Table 1 - Mass content of each component in iron-containing samples (wt%)

[0057]

[0058]

[0059] Among them, the F reference content in BHVO-2G is 300ppm, the F reference content in BCR-2G is 317ppm, and the F reference content in BIR-1G is <15ppm.

[0060] In the following examples and comparative examples, the area of the TAPL spectroscopic crystal is twice that of the TAP spectroscopic crystal, and the area of the TAP spectroscopic crystal is 3 cm 2 The area of the TAPL spectroscopic crystal is 6 cm 2 .

[0061] Example 1

[0062] The present invention provides a method for quantitative analysis of trace fluorine in an iron-containing sample by electron probe, comprising the following steps:

[0063] S1. Grind the iron-containing sample BHVO-2G into a light sheet-like sample suitable for electron probe analysis;

[0064] S2, spraying a carbon conductive film about 20 nm thick on the sample to be tested;

[0065] S3, placing the sample to be tested with the carbon conductive film sprayed on the sample stage of the electron probe microanalyzer, and using the X-ray spectrum to search and determine the peak position and background position of the F element to be tested in the sample to be tested;

[0066] S4, measuring the counting intensity of the standard sample F and the counting intensity of F in the sample to be tested;

[0067] S5. Comparing and analyzing the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested, and obtaining the fluorine content in the sample to be tested by matrix correction;

[0068] In the quantitative analysis process, the spectroscopic crystal used was a TAPL spectroscopic crystal. The quantitative analysis conditions included the accelerating voltage, beam current, and beam spot. The accelerating voltage was 15 kV, the beam current was 300 nA, and the beam spot was 20 μm.

[0069] The standard sample is barium fluoride.

[0070] The same method as in Example 1 was used to replace the iron-containing sample BHVO-2G with BCR-2G and BIR-1G, respectively.

[0071] Comparative Example 1

[0072] This comparative example provides an electron probe quantitative analysis method for trace fluorine in an iron-containing sample, comprising the following steps:

[0073] S1. Grind the iron-containing sample BHVO-2G into a light sheet-like sample suitable for electron probe analysis;

[0074] S2, spraying a carbon conductive film about 20 nm thick on the sample to be tested;

[0075] S3, placing the sample to be tested with the carbon conductive film sprayed on the sample stage of the electron probe microanalyzer, and using the X-ray spectrum to search and determine the peak position and background position of the F element to be tested in the sample to be tested;

[0076] S4, measuring the counting intensity of the standard sample F and the counting intensity of F in the sample to be tested;

[0077] S5. Comparing and analyzing the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested, and obtaining the fluorine content in the sample to be tested by matrix correction;

[0078] In the quantitative analysis process, the spectroscopic crystal used was a TAP spectroscopic crystal. The quantitative analysis conditions included the accelerating voltage, beam current, and beam spot. The accelerating voltage was 15 kV, the beam current was 300 nA, and the beam spot was 20 μm.

[0079] The standard sample is barium fluoride.

[0080] According to the same method as the above comparative example 1, the iron-containing sample BHVO-2G was replaced by BCR-2G and BIR-1G respectively.

[0081] Comparative Example 2

[0082] This comparative example provides an electron probe quantitative analysis method for trace fluorine in an iron-containing sample, comprising the following steps:

[0083] S1. Grind the iron-containing sample BHVO-2G into a light sheet-like sample suitable for electron probe analysis;

[0084] S2, spraying a carbon conductive film about 20 nm thick on the sample to be tested;

[0085] S3, placing the sample to be tested with the carbon conductive film sprayed on the sample stage of the electron probe microanalyzer, and using the X-ray spectrum to search and determine the peak position and background position of the F element to be tested in the sample to be tested;

[0086] S4, measuring the counting intensity of the standard sample F and the counting intensity of F in the sample to be tested;

[0087] S5. Comparing and analyzing the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested, and obtaining the fluorine content in the sample to be tested by matrix correction;

[0088] In the quantitative analysis process, the spectroscopic crystal used was the LDE1L spectroscopic crystal. The quantitative analysis conditions included the accelerating voltage, beam current, and beam spot. The accelerating voltage was 15 kV, the beam current was 300 nA, and the beam spot was 20 μm.

[0089] The standard sample is barium fluoride.

[0090] According to the same method as the above comparative example 2, the iron-containing sample BHVO-2G was replaced by BCR-2G and BIR-1G respectively.

[0091] According to the methods in Example 1 and Comparative Examples 1-2, the BHVO-2G, BCR-2G, and BIR-1G samples were scanned using TAPL spectroscopic crystals, TAP spectroscopic crystals, and LDE1L spectroscopic crystals, respectively. The results are as follows: Figures 1 to 3 shown. Figure 1 For Example 1, Figure 2 For comparative example 1, Figure 3 For comparative example 2; Figures 1 to 3 In the BHVO, BHVO means BHVO-2G, BCR means BCR-2G, and BIR means BIR-1G.

[0092] At an accelerating voltage of 15 kV, a fine spectrum scan of BHVO-2G, BCR-2G, and BIR-1G samples was performed using an electron beam excitation signal with a current of 300 nA and a beam spot diameter of 20 μm. Figures 1 to 3 ), the spectroscopic crystals used for analysis are TAPL, TAP and LDE1L, the step length between the two spectrometer positions is set to 30μm, and the dwell time of each position is set to 10s to obtain a fine spectrum to accurately identify interference. The theoretical F Kα peak position of the TAPL and TAP spectroscopic crystals is 199.15mm, and the theoretical F Kα peak position of the LDE1L spectroscopic crystal is 85.50mm, so the scanning band of the TAPL and TAP spectroscopic crystals is set to: L value 194mm-205mm, and the scanning band of the LDE1L is set to: L value 75-95mm. The interplanar spacing of the TAPL spectroscopic crystal and the TAP spectroscopic crystal is the same, and the peak shape in the figure ( Figure 1 and 2) are basically the same, but the TAPL spectroscopic crystal has a larger diffraction area and the obtained counts are higher. In the spectra of the TAPL spectroscopic crystal and the TAP spectroscopic crystal, the F Kα characteristic peak position is around L = 199 mm, there is a high-order peak of P element P Kα (n = 3) on the right side of F Kα, and a small peak of F element F SKA on the left side of F Kα + The F Kα counts obtained by the TAPL spectroscopic crystal are about 7200, and the F Kα counts obtained by the TAP spectroscopic crystal are about 2100. The diffraction efficiency of the TAPL spectroscopic crystal with a larger diffraction area is about 3.4 times that of the TAP spectroscopic crystal. According to the sample reference composition information, the F content of the BHVO-2G and BCR-2G samples is 300ppm and 317ppm respectively, and the F content of the BIR-1G sample is <15ppm, which is consistent with the spectrum. Figure 1 and 2 The F Kα peaks of BHVO-2G and BCR-2G are obvious, while the F Kα peak of BIR-1G is almost unrecognizable. Similarly, the P content of BHVO-2G and BCR-2G samples is 0.29wt% and 0.37wt% respectively, while the P content of BIR-1G sample is 0.02wt%. Figure 1 and 2 The P Kα (n=3) of the BHVO-2G and BCR-2G samples is clearly visible, while the P Kα (n=3) of the BIR-1G sample is not visible. The peak heights of F Kα (n=1) and P Kα (n=3) are similar, but the P content is much higher than the F content. This is because F Kα is a first-order line and P Kα is a third-order spectral line. Although the total amount of P element X-rays generated by the sample is large, they are attenuated after multiple diffraction inside the spectroscopic crystal. In addition, it can be observed that the background curves of the TAPL spectroscopic crystal and the TAP spectroscopic crystal have a certain curvature and are not straight. The influence of the background curvature needs to be considered when measuring the background. For the LDE1L spectroscopic crystal ( Figure 3 ), no distinct peak was identified at the theoretical characteristic F Kα peak position, L = 85.5 mm. The left side of L = 85.5 mm is the Fe Lα peak, and F Kα overlaps with F Kα at the right tail of Fe Lα. A Mg Kβ peak was present near L = 92 mm. Given the difficulty in addressing Fe interference from the LDE1L spectrometer crystal, TAPL counts were higher than TAP counts. Subsequent experiments were conducted using the TAPL spectrometer crystal. These results demonstrate that the spectral peaks of the TAPL and TAP spectrometer crystals are similar, but the TAPL spectrometer crystal achieves higher counts, while the F characteristic peak of the LDE1L spectrometer crystal is less distinct.

[0093] Figure 4 For Figure 1The results in the figure use different background correction methods and background collection position diagram. According to the results obtained by fine spectrum scanning, multiple positions on both sides of F Kα can be selected to collect background counts. Based on the collected background counts, different background fitting correction methods can be performed ( Figure 4 ), including the traditional two-point linear interpolation method and the multi-point background fitting method. In addition, considering that the reference content of the BIR-1G sample is very low, the peak count of this sample can be used as the blank background for blank background correction. Figure 4 , which can roughly determine the differences and similarities between different background fitting methods. The conventional two-point linear interpolation method measures background counts at two locations on either side of F Kα, then calculates the background value at that location using linear interpolation. This method presents no significant issues for high-content samples, but for low-content samples, it can lead to significant deviations in the content due to poor background fitting. Figure 4 The conventional two-point linear interpolation method in

[15] fails to fit the background well, resulting in an overestimation of the background value and a low final content. Multi-point function fitting involves selecting multiple background positions on either side of F Kα to control the fitting background. Nonlinear function fitting can further fit the background curvature. The multi-point exponential function, multi-point power function, and polynomial function shown in the figure all provide similar fitting results, effectively fitting the background. Furthermore, the F content of the BIR sample can be considered "0," serving as a blank background with a composition similar to that of the BIR sample.

[0094] Example 2

[0095] This embodiment provides an electron probe quantitative analysis method for trace fluorine in an iron-containing sample. The method is the same as that in Example 1, except that the acceleration voltage is 10 kV. All other aspects are the same as those in Example 1.

[0096] Example 3

[0097] This embodiment provides an electron probe quantitative analysis method for trace fluorine in an iron-containing sample. The method is the same as that in Example 1, except that the acceleration voltage is 20 kV. All other aspects are the same as those in Example 1.

[0098] To improve the peak-to-background ratio and reduce the detection limit of trace elements, it is necessary to set a suitable acceleration voltage and test current. In order to explore the relationship between the detection limit of the F element electron probe and the acceleration voltage and test current, Examples 1 to 3 measured the F Kα X-ray signal intensity in glass at an acceleration voltage of 10 kV, 15 kV, and 20 kV, respectively, with a current of 10 nA, 20 nA, 50 nA, 100 nA, 200 nA, 300 nA, and 500 nA. The acquisition time was set to 100 s, and the detection limit ( Figure 5 ), the test sample is BHVO-2G.

[0099] The results show that the detection limit achieved at an accelerating voltage of 15 kV is lower than that achieved at 10 kV, but the detection limit achieved at 20 kV is actually higher compared to 15 kV. This indicates that increasing the accelerating voltage can lower the detection limit, but it also increases the excitation depth of X-rays, resulting in greater absorption damage to F Kα X-rays generated deep within the sample. Therefore, a higher voltage is ideal for lowering the detection limit, with 15 kV being a suitable voltage. The relationship between the detection limit and current indicates that increasing the current can lower the detection limit. To minimize the detection limit for F, high current analysis is necessary. However, as the current increases, interference factors caused by atomic excitation increase and become more significant, reducing the accuracy of the test results. Furthermore, the effect of reducing the detection limit decreases when the current exceeds 300 nA. The F content in the BHVO-2G and BCR-2G glasses analyzed in this study is approximately 300 ppm. Using a current of 300 nA, a detection limit of approximately 70 ppm (3σ) was achieved, which is generally sufficient for testing.

[0100] Example 4

[0101] According to the method in Example 1, at an accelerating voltage of 15 kV, the emission current was set to 300 nA, and beam spot diameters of 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, and 30 μm were used on BHVO-2G and BCR-2G samples, respectively. The "ChartRecord" function was used to record the changes in FKα signal intensity and absorption current over time from 0 to 600 s. For ease of observation, the changes in F signal at different beam spot diameters have been plotted as trend lines.

[0102] Figure 6 Figure 3 shows the variation of F signal intensity of BHVO-2G sample with time (0-600s) under the conditions of 15kV, 300nA and different beam spot diameters. It shows that the F signal intensity can only remain stable under the beam spot diameters of 20μm and 30μm.

[0103] Figure 7 The figure shows the variation of the absorption current of the BHVO-2G sample with time (0 to 600s) under the conditions of 15kV, 300nA and different beam spot diameters. It shows that the absorption current can only remain stable under the beam spot diameters of 20μm and 30μm.

[0104] For the BHVO-2G sample, the signal F changes according to the beam spot diameter of 1, 2, 5, 10, 20, and 30 μm ( Figure 6 ) It can be seen that when using beam spot diameters of 1, 2, 5, and 10 μm, the F signal will increase or decrease, that is, the internal elements have migrated or the structure has been destroyed. When using beam spot diameters of 20 and 30 μm, the F signal changes more slowly. Combined with the relationship between the change of absorption current and time ( Figure 7). The absorption current varied significantly when using beam spot sizes of 1, 2, 5, and 10 μm, and the absorption current attenuated more severely with increasing current density. The absorption current was relatively stable when using beam spot diameters of 20 and 30 μm. Therefore, a 20 μm beam spot diameter can be used for testing at a current of 300 nA. A beam spot size that is too large will reduce spatial resolution. Samples with different compositions may experience varying X-ray signal stability under the action of an electron beam, necessitating different test currents and beam spots.

[0105] The above experimental studies have shown that when using an accelerating voltage of 15 kV, a current of 300 nA and a current density of a beam spot diameter of 20 μm, the F Kα signal is relatively stable, and this condition is used for counting acquisition.

[0106] Furthermore, the iron-containing sample BHVO-2G was tested using a TAPL spectroscopic crystal according to the method in Example 1, and the test curve was fitted and the F content was calculated. The results are as follows: Figures 8-9 The specific steps include:

[0107] 1: Use the electron probe TAPL spectrometer to scan the BHVO-2G crystal fine spectrum to determine the peak position of the F element and n background positions on both sides of the peak without interference (n ≥ 2, this time select 4 background positions on both sides, Figure 4 );

[0108] 2: Use electron probe TAPL spectroscopic crystal to measure the total intensity of characteristic X-rays of F element in BHVO-2G PEAK-unk and the X-ray intensity I at 8 background positions BG(n) ;

[0109] 3: X-ray intensity I at 8 background positions BG(n) Perform fitting (including power fitting, polynomial fitting, exponential fitting) to obtain the function y=f(x)( Figure 8 ), let x = the peak position of F, and find the y value as the background value I BG , and then calculate the net intensity I of the characteristic X-ray of F element in the unknown sample NET-unk =I PEAK-unk -I BG ;

[0110] 4: Use electron probe TAPL spectroscopic crystal to test the net count of characteristic X-rays of F element in the original standard sample (barium fluoride standard sample is selected in this experiment) NET-std ;

[0111] 5: According to I NET-unk and I NET-std Calculate the content of the element to be tested in the sample C by comparing it with the content of the element F in the original standard sample. unk=C std *(I NET-unk / I NET-std )*(M unk / M std ), where C std is the element content of the standard sample, M unk and M std are the background effect correction parameters of the test sample and the standard sample, respectively.

[0112] The iron-containing sample BHVO-2G was tested using the TAP spectroscopic crystal according to the method in Comparative Example 1, and the test curve was fitted. The F content was calculated using the same method as above. The results are as follows: Figures 10-11 shown.

[0113] The iron-containing sample BHVO-2G was tested using the LDE1L spectroscopic crystal according to the method in Comparative Example 2, and the test curve was fitted. The F content was calculated using the same method as above. The results are as follows: Figures 12-13 shown.

[0114] from Figures 8-9 As can be seen from the figure, the 30-point BHVO-2G F content data measured using the TAPL spectroscopic crystal for the iron-containing sample BHVO-2G are all within the reference range except for the two-point linear fitting analysis result which deviates from the reference value. Figure 9 When the exponential fitting method was used for the background, the average F content was 296±18 ppm (n=30), and the test results were relatively concentrated, which was close to the reference content of 300 ppm.

[0115] from Figures 10-11 As can be seen in the figure, the iron-containing sample BHVO-2G was tested using the TAP spectroscopic crystal. The 50-point BHVO-2G F content data measured in this experiment, when the background was fitted using the exponential method, obtained an average F content of 234±55ppm (n=50). This not only has a large deviation, but is also far from the reference content of 300ppm.

[0116] from Figures 12-13 As can be seen in the figure, the iron-containing sample BHVO-2G was tested using the LDE1L spectroscopic crystal. The 50-point BHVO-2G F content data measured in this experiment, when the background was fitted using the exponential method, obtained an average F content of 749±155ppm (n=50). Not only is the deviation large, but it is also far from the reference content of 300ppm.

[0117] From the above, we can see that the F content detected by using the TAPL spectroscopic crystal is closer to the reference value than that by using the TAP spectroscopic crystal and the LDE1L spectroscopic crystal, which means that the F content detected by using the TAPL spectroscopic crystal is more accurate.

[0118] When the TAPL spectroscopic crystal of the present invention is used to test the actual sample to be tested, the detection limit of the F content can reach 76 ppm, while the detection limit of the F content using the TAP spectroscopic crystal is only 195 ppm. This shows that when the TAPL spectroscopic crystal is used to test the trace fluorine element in the iron-containing sample in the present invention, not only the detection limit is lower, but the detected value is closer to the actual value and the accuracy is higher.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for quantitative analysis of trace fluorine in iron-containing samples by electron probe, characterized in that: The following steps are involved: The iron-containing sample is prepared into a sample suitable for electron probe analysis; Spray-coating a carbon conductive film on the sample to be tested; The sample to be tested, which is coated with a carbon conductive film, is placed on the sample stage of an electron probe microanalyzer, and the peak position and background position of the F element to be tested are searched and determined in the sample using an X-ray spectrum. Measuring the counting intensity of F in the standard sample and the counting intensity of F in the sample to be tested; Compare and analyze the F counting intensity in the standard sample and the F counting intensity in the sample to be tested, and obtain the fluorine content in the sample to be tested through matrix correction; In the quantitative analysis process, the spectroscopic crystal used for the F element is a TAPL spectroscopic crystal, and the area of the TAPL spectroscopic crystal is 2 to 3 times that of the TAP spectroscopic crystal.

2. The method for quantitative analysis of trace fluorine in iron-containing samples according to claim 1, wherein: Quantitative analysis conditions include accelerating voltage, beam current, and beam spot; Among them, the acceleration voltage is 10 to 30 kV, the beam current is 100 nA to 500 nA, and the beam spot is 1 to 30 μm.

3. The electron probe quantitative analysis method for trace fluorine in iron-containing samples according to claim 2, characterized in that: The accelerating voltage is 15 kV, the beam current is 300 nA, and the beam spot size is 20 μm.

4. The method for quantitative analysis of trace fluorine in iron-containing samples by electron probe according to claim 2, wherein: The standard sample includes fluoride.

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