Preparation method of high-purity aluminum fluoride powder sample for glow discharge mass spectrometry

Abstract

The invention discloses a preparation method of a high-purity aluminum fluoride powder sample for glow discharge mass spectrometry, which comprises the following steps: mixing aluminum fluoride powder with absolute ethyl alcohol, performing ultrasonic dispersion, and drying to remove moisture; uniformly spreading aluminum fluoride powder on a quartz substrate, placing the quartz substrate in a plasma reaction chamber, introducing argon, starting a radio frequency plasma source, and forming a fluorinated passivation layer on the surface of the aluminum fluoride powder; the passivated aluminum fluoride powder is placed in a pressing mold, graphite powder is added to the periphery of the mold for fixing, and an aluminum fluoride sheet is prepared; the aluminum fluoride sheet is transferred to a magnetron sputtering instrument for sputtering coating, a first layer is subjected to graphite target sputtering, and a second layer is switched to gold target sputtering; and standing the coated aluminum fluoride sheet sample under the protection of nitrogen to obtain the aluminum fluoride film. Through collaborative innovation of plasma passivation and gradient sputtering coating technologies, the technical problems of poor conductivity, fluorine volatilization corrosion, low trace impurity sensitivity and the like in GDMS detection of non-conductive high-purity aluminum fluoride powder are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of analytical detection, and particularly relates to a preparation method of a high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis. BACKGROUND

[0002] Traditional aluminum fluoride (purity 90%-95%) cannot meet the needs of high-end applications such as optical coating, fluoride optical fiber and new energy battery materials due to its high impurity content, and is mainly used in low-end fields such as electrolytic aluminum flux and organic catalyst. High-purity aluminum fluoride (purity ≥ 99.5%) has become a key material in the above-mentioned fields due to its excellent anti-reflection, oxidation resistance and stability, but the precise detection of trace impurities (such as Li, B and Fe) in high-purity aluminum fluoride powder faces technical bottlenecks such as non-conductivity, fluorine volatilization and insufficient sensitivity. In the production of lithium battery materials, impurity elements in high-purity aluminum fluoride powder can cause side reactions with electrolyte, reducing the charge-discharge efficiency and cycle stability of the battery. Therefore, accurate and rapid detection of trace elements in high-purity aluminum fluoride powder is of great significance for quality control and product performance optimization.

[0003] However, there are many technical difficulties in detecting trace elements in high-purity aluminum fluoride powder. First, high-purity aluminum fluoride powder is a non-conductive material, while the commonly used glow discharge mass spectrometer (GDMS) detection method usually requires the sample to have good conductivity, otherwise it will cause unstable discharge, affecting the accuracy and repeatability of the detection signal. Second, the fluorine element in high-purity aluminum fluoride is prone to volatilization during detection, which not only causes deviation in the detection results, but also causes corrosion to the detection instrument, reducing the service life and detection accuracy of the instrument. In addition, the traditional chemical digestion method may introduce new impurities or cause loss of some trace elements when processing high-purity aluminum fluoride powder, thereby affecting the accuracy and reliability of the detection results. Therefore, there is an urgent need for a sample pretreatment method that is easy to operate, has controllable pollution and high detection sensitivity, to solve the problems of poor conductivity of the sample, fluorine volatilization and corrosion of the instrument, and insufficient sensitivity of trace element detection in GDMS detection of high-purity aluminum fluoride powder.

[0004] The patent "Method for analyzing non-conductor materials by glow discharge mass spectrometry" (publication number: CN102175754A) uses an indium coating method to analyze non-conductor materials by direct current glow discharge mass spectrometry. This method has simple pretreatment, ideal signal-to-noise ratio (S / N), shortens the analysis time and improves the analysis efficiency. Although it has strong universality, the indium coating method is more suitable for conventional block-shaped non-conductors, and the indium coating method has poor compatibility with fluorides (indium-fluorine reaction), which can increase the risk of pollution. SUMMARY

[0005] The application aims to provide a preparation method of high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis, and solves the problems of non-conductive fluoride sample that cannot be directly detected, fluoride volatilization corrosion equipment and insufficient sensitivity of trace elements.

[0006] The technical scheme adopted by the application is as follows: Step 1, mix aluminum fluoride powder with anhydrous ethanol and ultrasonically disperse, and then dry to remove water; Step 2, uniformly spread aluminum fluoride powder on a quartz substrate, place it in a plasma reaction cavity and introduce argon, start a radio frequency plasma source, and form a fluorinated passivation layer on the surface of the aluminum fluoride powder; Step 3, place the passivated aluminum fluoride powder in a pressing mold, add graphite powder around the mold to fix it, and make an aluminum fluoride sheet; Step 4, transfer the aluminum fluoride sheet to a magnetron sputtering instrument for sputtering and coating, use a graphite target for sputtering for the first layer, and switch to a gold target for sputtering for the second layer; Step 5, place the coated aluminum fluoride sheet sample under nitrogen protection and let it stand.

[0007] The application also has the following characteristics: In step 1, the aluminum fluoride powder is mixed with anhydrous ethanol at a mass ratio of 1:5 to 1:10, ultrasonically dispersed for 30 to 60 minutes, and the ultrasonically dispersed aluminum fluoride powder is dried at 100 to 150°C for 1 to 2 hours.

[0008] In step 2, the aluminum fluoride powder is uniformly spread on a quartz substrate with a thickness of ≤1mm.

[0009] In step 2, the argon introduced into the plasma reaction cavity has a purity of ≥99.999%, and the gas pressure is maintained at 10 to 15 Pa, then the radio frequency plasma source is started, the radio frequency power is 80 W, the radio frequency frequency is 13.56 MHz, and the discharge treatment is performed for 20 minutes.

[0010] In step 3, the purity of the graphite powder is ≥5N5, the tablet pressing time is ≤30s, and the tablet pressing pressure is 20 to 25t.

[0011] After adding graphite powder around the mold to fix it in step 3, an aluminum fluoride sheet with a graphite periphery is made, and then a ring-shaped isolation groove is etched outside the edge of the aluminum fluoride sheet using ultraviolet laser.

[0012] In step 4, after transferring the aluminum fluoride sheet to the magnetron sputtering instrument, the cavity of the magnetron sputtering instrument is evacuated to 5×10 -3 Pa.

[0013] The graphite target used in the first layer in step 4 has a purity of greater than or equal to 99.999%, a sputtering power of 150 W, an argon flow rate of 20 sccm, and a deposition time of 15-50 min; the second layer is switched to a gold target with a purity of greater than or equal to 99.99%, a sputtering power of 100 W, and a deposition time of 15-30 min, and then sputtering is repeated once again; and the sample table is rotated at a speed of 15-20 rpm during the magnetron sputtering process.

[0014] In step 5, the fluorinated aluminum flaky sample after coating is placed in a vacuum nitrogen-filled drying box for 1 hour to stabilize the coating structure and meet the conductivity requirements.

[0015] After step 5 is completed, the obtained sample is loaded into a sample holder of a glow discharge mass spectrometer, argon gas is introduced as a discharge gas, and pulse glow discharge mass spectrometer analysis is performed to collect the signal intensity of the elements to be detected, and the mass fraction of trace impurity elements is calculated by using the relative sensitivity factor.

[0016] The preparation method of the high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis provided by the present application, through the synergistic innovation of plasma passivation and gradient sputtering coating technology, solves the technical problems of poor conductivity, fluorine volatilization corrosion, and low sensitivity of trace impurities in the detection of non-conductive high-purity aluminum fluoride powder by GDMS. The argon plasma pretreatment forms a dense fluorinated layer on the surface of the powder, reducing the fluorine release by more than 80%, effectively protecting the instrument and improving the data stability; through magnetron sputtering, a nanoscale carbon layer (enhancing signal penetration) and a gold layer (providing conductivity) are deposited in sequence, direct detection can be realized without chemical digestion, the sensitivity is improved by 5-10 times compared with the traditional method, and acid dissolution pollution and element loss are avoided. The present application supports the precise detection of trace impurities in high-purity aluminum fluoride powder (purity greater than or equal to 99.5%) and ultra-high-purity aluminum fluoride powder (purity greater than or equal to 99.99%) in the fields of semiconductors, lithium battery materials, etc., and has the advantages of high efficiency, environmental protection, and industrialization promotion value, and promotes the upgrading of high-value-added high-purity aluminum fluoride powder quality control technology. DETAILED DESCRIPTION

[0017] The present application will be described in detail below in conjunction with specific embodiments.

[0018] The present application provides a preparation method of a high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis, which is specifically implemented according to the following steps: Step 1: Mix high-purity aluminum fluoride powder with anhydrous ethanol at a mass ratio of 1:5-1:10, ultrasonically disperse for 30-60 min, and then place in a drying box at 100-150°C for 1-2 hours to remove the surface adsorbed water, and obtain loose distributed high-purity aluminum fluoride powder.

[0019] Step 2, evenly spread high-purity aluminum fluoride powder on a quartz substrate with a thickness of ≤1 mm, and place it in a plasma reaction chamber. Introduce argon gas with a purity of ≥99.999% and maintain a pressure of 10-15 Pa. Start the radio frequency plasma source discharge with a power of 80 W and a frequency of 13.56 MHz. Treat the powder for 20 minutes to form a dense fluorinated passivation layer on the surface.

[0020] Step 3, place the passivated high-purity aluminum fluoride powder in a pressing mold, fill the surrounding with high-purity graphite powder (≥5N5), and apply pressure to press the powder. The high-purity aluminum fluoride powder and graphite powder will tightly bond to form a solid circular sheet with graphite on the outside and aluminum fluoride in the center. The pressing time is ≤30 s, the pressing pressure is 20-25 t, and the surface floating powder is blown off with an ear bulb after demolding. A PTFE rod is gently tapped on the back without powder falling off to obtain the desired sheet-shaped sample. The sample diameter of the graphite-fixed aluminum fluoride circular sheet obtained by pressing is 30 mm, and the thickness is 4-6 mm. Subsequently, cover the sample surface center with a diameter of 6 mm in the aluminum fluoride sheet region outside the sputtering area, and use an ultraviolet laser to etch a ring-shaped isolation groove in the covered area. The groove width is 1 mm. Due to the presence of the groove, the plasma can only sputter on the aluminum fluoride sheet, and cannot contact the graphite sheet outside, ensuring physical isolation effect.

[0021] Step 4, transfer the etched sheet-shaped sample to a magnetron sputtering instrument, and vacuum the cavity to 5×10 -3 Pa. The first layer uses a high-purity graphite target for sputtering, and the second layer switches to a gold target for sputtering, and repeats sputtering twice. Specifically: the first layer (carbon layer): use a high-purity graphite target with a purity of ≥99.999%, sputtering power 150 W, argon flow rate 20 sccm, and deposition time 15-50 min; the second layer (gold layer): switch to a gold target with a purity of ≥99.99%, sputtering power 100 W, and deposition time 15-30 min. Then repeat sputtering once again, i.e., switch to a gold target after sputtering with a high-purity graphite target. The sample table rotates at a speed of 15-20 rpm during magnetron sputtering to ensure uniformity of the coating.

[0022] Step 5, place the coated high-purity aluminum fluoride sheet sample in a vacuum nitrogen-filled drying box for 1 hour to stabilize the coating structure and ensure that the sample meets the sample conductivity requirements.

[0023] Step 6, the sample is loaded into the sample holder of the glow discharge mass spectrometer, high-purity argon gas is introduced as the discharge gas, and pulse glow discharge mass spectrometry analysis is carried out, the signal intensity of the element to be detected is collected, and the mass fraction of the trace impurity element is calculated by using the relative sensitivity factor. Specifically, the sample to be detected is stably fixed in the sample holder, stably glow discharge in the Thermo Fisher glow discharge ion source, the discharge current is set to 10-30 mA, the discharge gas flow is 400-500 mL / min, the discharge voltage is 0.5-1.0 kV, the pulse mode active mode is opened, the pulse time is 40-60 mu s, the signal intensity of the sample to be detected is greater than or equal to 1*10E 8 , the resolution of the sample to be detected is greater than or equal to 4000, and the test data can be obtained after 30 minutes of testing.

[0024] The preparation method of the high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis has the advantages that: by combining plasma passivation and gradient sputtering coating technology, vacuum drying adsorption of moisture and ultrasonic dispersion are adopted to reduce agglomeration; argon plasma pretreatment forms a dense fluorinated layer, which reduces the fluorine volatilization amount by more than 80%, and significantly reduces the corrosion of the instrument; the carbon-gold double-layer coating design takes into account the conductivity and signal penetration, and the detection limit of trace elements (such as Li, B, Fe) is as low as 0.02 ppm, and the whole process does not need complex sample processing, and the universality is strong; the process parameters are compatible with existing GDMS equipment, and are suitable for high-throughput, high-precision impurity analysis in the fields of semiconductors and new energy materials, and have the values of high efficiency, environmental protection and industrialization promotion.

[0025] Example 1 The preparation method of the high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis is provided, and the steps are as follows: Step 1, mix the dried high-purity aluminum fluoride powder with anhydrous ethanol according to a mass ratio of 1:5, ultrasonically disperse for 30 minutes, and then dry at 100 DEG C for 1 hour to obtain loose distributed high-purity aluminum fluoride powder.

[0026] Step 2, evenly spread the high-purity aluminum fluoride powder on the quartz substrate with a thickness of 1 mm. Argon gas is introduced into the plasma reaction cavity, and the gas pressure is maintained at 10 Pa. Start the radio frequency plasma source, the radio frequency power is 80 W, the radio frequency frequency is 13.56 MHz, and the discharge treatment is 20 minutes.

[0027] Step 3, use a PTEF spoon to take the passivated high-purity graphite powder into a pressing mold and press for 30 seconds, the tablet pressing pressure is 20 t, and then take it out, blow off the surface floating powder with an ear cleaning ball, and gently tap the back with a PTFE rod without powder falling off, to obtain an overall tablet sample with a diameter of 30 mm and a thickness of 4 mm. Then, cover the aluminum fluoride tablet sample region with a diameter of 6 mm at the center of the sample surface, and use a ultraviolet laser to etch a ring-shaped isolation groove outside the covered area, the groove width is 1 mm, to ensure the physical isolation effect.

[0028] Step 4, transfer the sample to be tested to the magnetron sputtering instrument, and vacuumize the cavity. The first layer is sputtered with a high-purity graphite target with a purity of 99.999%, a sputtering power of 150W, an argon flow rate of 20sccm, and a deposition time of 15min; the second layer is switched to a gold target with a purity of 99.99%, a sputtering power of 100W, and a deposition time of 15min. Repeat sputtering twice. During the magnetron sputtering process, the sample table rotates at a constant speed of 15rpm to ensure the uniformity of the coating.

[0029] Step 5, after coating, the sample is placed in a vacuum nitrogen-filled drying box for 1 hour to ensure that the sample meets the sample conductivity requirements.

[0030] Step 6, the sample to be tested is stably fixed in the sample holder and placed in the ThermoFisher glow discharge ion source for stable glow discharge. Set the discharge current to 10mA, the discharge gas flow to 400mL / min, the discharge voltage to 0.5kV, the pulse mode to active, the pulse time to 40μs, and the signal intensity of the sample to be tested to be ≥4.2×10 8 , the sample resolution is 4200, and the test data is obtained after 30min of testing.

[0031] Example 2 Comparative experiment: Compared with the traditional tantalum strip-graphite tablet pressing method, the detection limit is reduced from 0.2ppm to 0.05ppm, and the fluorine volatilization amount is reduced by 84.4%.

[0032] Table 1 Comparative Example 1 and Example 1

[0033] Example 3 The present application provides a preparation method for high-purity aluminum fluoride powder samples for glow discharge mass spectrometry analysis, and the steps are as follows: Step 1, mix high-purity aluminum fluoride powder with anhydrous ethanol at a mass ratio of 1:8, ultrasonically disperse for 45min, and then dry at 120℃ for 1.5 hours to obtain loose-distributed high-purity aluminum fluoride powder.

[0034] Step 2, evenly spread the high-purity aluminum fluoride powder on the quartz substrate with a thickness of 0.8mm. Introduce argon into the plasma reaction cavity, and maintain the gas pressure at 13Pa. Start the radio frequency plasma source with a radio frequency power of 80W, a radio frequency frequency of 13.56MHz, and a discharge treatment time of 20min.

[0035] Step 3, use PTEF spoon to take the passivated high-purity graphite powder into the pressing mold and press for 25 s, the tabletting pressure is 22 t, and then take out, blow off the surface floating powder with an ear bulb, and gently tap the back with a PTFE rod without powder falling off, to obtain an integral tablet sample with a diameter of 30 mm and a thickness of 5 mm. Then, an aluminum fluoride tablet sample with a diameter of 6 mm is covered on the surface center of the sample, and a ring-shaped isolation groove is etched outside the covered area using an ultraviolet laser, the groove width is 1 mm, to ensure the physical isolation effect.

[0036] Step 4, transfer the tablet sample to be tested into a magnetron sputtering instrument, and vacuumize the cavity. The first layer is sputtered by a high-purity graphite target with a purity of 99.999%, a sputtering power of 150 W, an argon gas flow of 20 sccm, and a deposition time of 33 min; the second layer is switched to a gold target with a purity of 99.99%, a sputtering power of 100 W, and a deposition time of 23 min. Repeat the sputtering twice. During the magnetron sputtering process, the sample table rotates at a constant speed of 18 rpm to ensure the uniformity of the coating.

[0037] Step 5, place the sample after coating in a vacuum nitrogen-filled drying box for 1 hour to ensure that the sample meets the sample conductivity requirements.

[0038] Step 6, stably fix the sample to be tested into the sample holder and place it into the ThermoFisher glow discharge ion source to stably carry out glow discharge. Set the discharge current to 20 mA, the discharge gas flow to 420 mL / min, the discharge voltage to 0.65 kV, open the Pulse mode active mode, the pulse time is 48 μs, and the signal intensity of the sample to be tested is ≥4.2×10 8 , the resolution of the sample to be tested is 4186, and the test data is obtained after 30 min of testing.

[0039] Example 4 Comparative experiment: compared with the traditional tantalum strip-graphite tabletting method, the detection limit is reduced from 0.50 ppm to 0.10 ppm, and the fluorine volatilization amount is reduced by 85% by using the comparative experiment with the same GDMS parameter setting.

[0040] Table 2 Comparative Example 2 and Example 3

[0041] Example 5 The present application provides a preparation method of high-purity aluminum fluoride powder sample for glow discharge mass spectrometry analysis, and the steps are as follows: Step 1, mix high-purity aluminum fluoride powder and anhydrous ethanol according to a mass ratio of 1:10, ultrasonically disperse for 60 min, and then dry at 150℃ for 2 hours to obtain loose distributed high-purity aluminum fluoride powder.

[0042] Step 2, uniformly spread high-purity aluminum fluoride powder on a quartz substrate with a thickness of 0.6 mm. Introduce argon into the plasma reaction chamber, and maintain the gas pressure at 15 Pa. Start the radio frequency plasma source, with a radio frequency power of 80 W, a radio frequency frequency of 13.56 MHz, and a discharge treatment time of 20 minutes.

[0043] Step 3, use a PTEF spoon to take the passivated high-purity graphite powder into the pressing mold and press for 20 s with a tablet pressing pressure of 25 t. Remove the tablet and blow off the surface floating powder with an ear bulb. Gently tap the back with a PTFE rod without causing the powder to fall off. Obtain an overall tablet-shaped sample with a diameter of 30 mm and a thickness of 6 mm. Then cover the sample with an aluminum fluoride tablet sample with a diameter of 6 mm in the center of the surface. Use a UV laser to etch a ring-shaped isolation groove outside the covered area, with a groove width of 1 mm to ensure physical isolation.

[0044] Step 4, transfer the tablet-shaped sample to be tested to the magnetron sputtering instrument and vacuumize the cavity. Use a high-purity graphite target with a purity of 99.999% for sputtering, with a sputtering power of 150 W, an argon gas flow rate of 20 sccm, and a deposition time of 50 min. Switch to a gold target with a purity of 99.99% for the second layer, with a sputtering power of 100 W and a deposition time of 30 min. Repeat the sputtering twice. Rotate the sample table at a constant speed of 20 rpm during the magnetron sputtering process to ensure uniformity of the coating.

[0045] Step 5, place the coated sample in a vacuum nitrogen-filled drying box and let it stand for 1 hour to ensure that the sample meets the conductivity requirements.

[0046] Step 6, stably fix the sample to be tested in the sample holder and place it in the ThermoFisher glow discharge ion source for stable glow discharge. Set the discharge current to 30 mA, the discharge gas flow rate to 500 mL / min, the discharge voltage to 1 kV, and the pulse mode to active mode with a pulse time of 60 μs. The signal intensity of the sample to be tested is ≥ 6 × 10 8 , the resolution of the sample to be tested is 4090, and the test data is obtained after 30 min of testing.

[0047] Example 6 Comparative Experiment: Compared with the traditional tantalum strip-graphite tablet pressing method, the detection limit is reduced from 0.15 ppm to 0.02 ppm, and the fluorine evaporation amount is reduced by 85.7% in Example 5.

[0048] Table 3 Comparative Example 3 and Example 5

Claims

1. A method for the preparation of high purity aluminum fluoride powder samples for glow discharge mass spectrometric analysis, characterized in that, The method comprises the following steps: Step 1, mixing aluminum fluoride powder with anhydrous ethanol and ultrasonic dispersion, and then drying to remove water; Step 2, uniformly spreading aluminum fluoride powder on a quartz substrate, placing in a plasma reaction chamber and introducing argon, starting a radio frequency plasma source to form a fluorinated passivation layer on the surface of the aluminum fluoride powder; Step 3, placing the passivated aluminum fluoride powder in a pressing mold, adding graphite powder around the mold to fix it, and making aluminum fluoride sheet; Step 4, transferring the aluminum fluoride sheet to a magnetron sputtering instrument for sputtering coating, using a graphite target for the first layer and switching to a gold target for the second layer; Step 5, placing the coated aluminum fluoride sheet sample in a nitrogen atmosphere for standing.

2. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, characterized by, In step 1, the aluminum fluoride powder is mixed with anhydrous ethanol at a mass ratio of 1:5 to 1:10, ultrasonic dispersion is performed for 30 to 60 minutes, and the ultrasonic dispersed aluminum fluoride powder is dried at 100 to 150°C for 1 to 2 hours.

3. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, characterized by, In step 2, the aluminum fluoride powder is uniformly spread on the quartz substrate with a thickness of ≤1mm.

4. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, characterized by, In step 2, the purity of argon introduced into the plasma reaction chamber is ≥99.999%, the gas pressure is maintained at 10 to 15 Pa, then the radio frequency plasma source is started, the radio frequency power is 80 W, the radio frequency frequency is 13.56 MHz, and the discharge treatment is performed for 20 minutes.

5. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, characterized by, In step 3, the purity of the graphite powder is ≥5N5, the tablet pressing time is ≤30s, and the tablet pressing pressure is 20 to 25t.

6. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, wherein, In step 3, after adding graphite powder around the mold to fix it, an aluminum fluoride sheet with a graphite periphery is made, and then a ring-shaped isolation groove is etched outside the edge of the aluminum fluoride sheet using ultraviolet laser.

7. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, wherein After the aluminum fluoride flake is transferred to the magnetron sputterer in step 4, the magnetron sputterer chamber is evacuated to 5 x 10 -3 Pa.

8. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, wherein, In step 4, the purity of the graphite target used for the first layer is ≥99.999%, the sputtering power is 150 W, the argon flow rate is 20sccm, the deposition time is 15 to 50 minutes; the second layer is switched to a gold target with a purity of ≥99.99%, the sputtering power is 100 W, the deposition time is 15 to 30 minutes, and then the sputtering is repeated once again, and the sample table rotates at a uniform speed of 15 to 20 rpm during the magnetron sputtering process.

9. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, wherein, In step 5, the coated aluminum fluoride sheet sample is placed in a vacuum nitrogen drying box for 1 hour to stabilize the coating structure and meet the conductivity requirements.

10. The method for preparing a high purity aluminum fluoride powder sample for glow discharge mass spectrometric analysis according to claim 1, wherein, After step 5 is completed, the obtained sample is loaded into a glow discharge mass spectrometer sample holder, argon is introduced as the discharge gas, pulse glow discharge mass spectrometer analysis is performed, the signal intensity of the elements to be measured is collected, and the mass fraction of trace impurity elements is calculated by applying the relative sensitivity factor.

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