Method for determining oxygen content in high-purity selenium for infrared optical glass

Abstract

The application provides a method for determining oxygen content in high-purity selenium for infrared optical glass. The method comprises the following steps: introducing 5N high-purity aluminum particles as a conversion agent, combining two-stage constant temperature heating, and first converting the selenium into aluminum selenide by a combination reaction at low temperature, and then detecting and analyzing by a higher power; and inserting a "oven" step in the middle of each sample detection to avoid the interference of the oxidation of the selenium adhered to the surface of the electrode of the pulse electrode furnace, and to solve the problem of the detection and analysis of the oxygen content in the high-purity selenium for infrared optical glass, thereby providing support for the quality control of the infrared optical glass and the high-purity selenium.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and specifically relates to a method for determining the oxygen content in high-purity selenium used in infrared optical glass. Background Technology

[0002] High-purity selenium has wide applications in infrared optical materials and optoelectronic semiconductor materials. However, the oxygen content in selenium directly affects the performance of optical materials prepared from it. In infrared optical materials, the infrared absorption impurities in chalcogenide glasses are mainly related to elements such as H and O, which seriously affect the application of chalcogenide glasses in the mid-infrared spectral range. In photovoltaic materials, in addition to high purity requirements, there are also requirements for oxygen content and material shape to adapt to its distillation coating process. For example, for the post-selenization process of CIGS, semi-circular granules with an oxygen content of less than 5 ppm are required. In photosensitive materials, the oxygen content in the raw material of selenium photosensitive film directly affects the photoelectric performance of the photosensitive film, such as increased surface residual potential and easy aging, thereby reducing the product qualification rate.

[0003] In the fabrication process of infrared optical glass, a raw material pretreatment step is included, which involves adding small amounts of metals such as magnesium, aluminum, and titanium as oxygen scavengers to remove oxygen from the raw materials. If selenium, which has a low oxygen content, can be used directly, it will be even more beneficial to achieve deep removal of oxygen impurities from the glass, further improving the optical performance of the material.

[0004] Common methods for oxygen elemental analysis include: high-temperature fusion method, chemical titration, and spectroscopic analysis. Chemical titration utilizes the chemical reaction properties of oxygen or an oxidizing agent to determine the oxygen concentration through titration. This method is widely used in water quality analysis and the detection of other liquid samples. Spectroscopic analysis includes techniques such as X-ray fluorescence spectroscopy (XRF), infrared spectroscopy (IR), and mass spectrometry (MS). These methods are typically used for the analysis of complex compounds and can provide qualitative and quantitative information on oxygen.

[0005] The high-temperature melting method involves heating a sample to react with carbon, producing carbon monoxide or carbon dioxide. The oxygen content is then inferred by detecting the amount of these gases. This method is highly accurate and suitable for the analysis of metals and alloys. Specifically, in a pulsed electrode furnace, the oxygen released from the heated sample reacts with carbon in a graphite crucible to form CO and a small amount of CO2. These are then propelled by high-purity helium gas into a high-carbon dioxide and carbon monoxide non-dispersive infrared (NDIR) cell to detect the oxygen content. The sample then passes through a heated rare-earth oxide copper tube, where the CO is oxidized to CO2. The carrier gas continues through another set of NDIR cells to detect the CO2, ultimately determining the oxygen content in the sample. The analytical power typically needs to be set above 3000W (crucible heating temperature approximately 1667℃). If the analytical power is too low, the reaction temperature between the oxygen in the sample and the graphite crucible will not be reached, resulting in insufficient CO and CO2 production and thus lower-than-expected results.

[0006] Because high-purity selenium is solid at room temperature and pressure and has a low oxygen content, it can only be detected using the inert gas protected melting method. However, existing inert gas protected melting methods combined with multi-channel infrared detection equipment are mainly designed for metals or alloys with high melting points. For low-melting-point, volatile samples, the current method often uses the addition of "fluxants" such as nickel and tin to inhibit the volatilization of low-melting-point, volatile components in the sample. For example, Chinese patent CN 108693133 A discloses a method for determining the oxygen content in high-manganese steel by adding an appropriate amount of bath material-tin sheet to inhibit manganese volatilization using inert melting-infrared absorption. However, applying this method to detect materials like selenium, which have extremely low melting and boiling points, does not achieve a significant effect in inhibiting selenium volatilization. Specifically, the following problems exist: Analysis power: Using metal reagents such as nickel, tin, and copper as "fluxes" cannot significantly suppress selenium volatilization. If the detection power is set above 1200W (crucible heating temperature is about 1199℃), the selenium sample to be tested will rapidly vaporize during the process of being put into the molten metal pool. The oxygen in it will not have the opportunity to fully contact with the graphite crucible to generate CO and CO2, resulting in a lower detection result. If the detection power is set below 3000W, the reaction temperature between the oxygen element in the selenium sample to be tested and the graphite crucible will not be reached, resulting in too little CO and CO2 generated, leading to a lower detection result.

[0007] Equipment maintenance: During the melting process, selenium volatilizes and splashes in large quantities, which can adhere to and corrode the upper electrode of the pulse electrode furnace, causing poor contact between the electrode and the crucible of the analytical instrument, making it impossible to use continuously and normally. Frequent maintenance and cleaning of the upper electrode are required. Interference in results: During the melting process, a large amount of selenium volatilizes and splashes, which adheres to the surface of the upper electrode of the pulse electrode furnace. During the crucible replacement operation interval in the continuous detection process, it comes into contact with air and oxidizes, thus interfering with the detection results. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a method for determining the oxygen content in high-purity selenium used in infrared optical glass.

[0009] The technical solution of this invention is implemented as follows: A method for determining the oxygen content in high-purity selenium for infrared optical glass, comprising the following steps: Step 1, Instrument Preparation: Turn on the external circulation cooling water and universal cover switch, check for leaks in the oxygen, nitrogen and hydrogen analyzer, and level and calibrate the matching electronic balance. After the leak check is passed, start the detection program. Step 2: Take the high-purity graphite crucible out of the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take the steel standard sample out of the super clean glove box and place a steel standard sample into the automatic sampling system with tweezers. Run the system's default "Oxygen content in iron" detection program. Then, the steel standard sample in the automatic sampling system is put into the furnace head for oxygen content analysis. Step 3: Repeat step 2 10 times and check the image and data of the measured steel standard sample. Verify the accuracy and repeatability of the instrument based on the oxygen content value marked on the steel standard sample. If there is a deviation between the detected value and the nominal value of the steel standard sample, the instrument should be calibrated first. Step 4: Weigh 10 portions each of 0.100g~1.000g of 5N high-purity aluminum granules and 0.010g~1.000g of standard graphite powder in the glove box, mix 10 portions of each mixture separately and put them into high-purity graphite crucibles for testing. Step 5: Remove the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box and place it on the lower electrode of the oxygen, nitrogen, and hydrogen analyzer. Run the "Oxygen Content in Selenium" detection program with a degassing power of 3000W, a degassing time of 60s, and a cooling time of 5s. The analysis method is two-stage isothermal heating: the first stage has a conversion power of 500W~1000W and a duration of 30s, and the second stage has an analysis power of 3500W~4300W and a duration of 150s. Adding standard graphite powder to the high-purity graphite crucible helps to improve the deoxygenation effect of the conversion agent in the "degassing" step, keeping the oxygen content blank value at a low level and with a high degree of consistency. It also enhances the contact effect between oxygen and carbon elements in the sample in subsequent detection steps, further improving the accuracy of the detection results. Step 6: Repeat step 5 4 times and check the measured data. If the repeatability is good, determine the measured value as a blank value and use this blank value to zero out the experimental method. Step 7: In a glove box, crush the high-purity selenium sample to be tested into small particles, and weigh 3 to 11 portions of high-purity selenium sample particles with a mass of 0.10~0.13g for later use; Step 8: Take out the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take out a high-purity selenium sample particle from the super clean glove box and place it in the automatic sample introduction system. Run the "Oxygen Content in Selenium" detection program with a degassing power of 3000w, a degassing time of 60s, and a cooling time of 5s. Put the high-purity selenium sample in the automatic sample introduction system into the furnace head for two-stage isothermal heating oxygen content analysis. The first stage selenium fixation power is 500W~1000W and the selenium fixation time is 30s. The second stage analysis power is 3500W~4300W and the analysis time is 150s. Step 9: After analyzing a high-purity selenium sample, place an empty crucible on the lower electrode of the oxygen, nitrogen, and hydrogen analyzer. Select the "furnace drying" method, with a degassing power of 4500W, a degassing time of 60s, and a cooling time of 5s. Then, select a furnace drying power of 4000W and a furnace drying time of 60s. To prevent substances remaining in the instrument after the analysis of the previous set of samples and the graphite crucible itself from affecting the analysis results of the next set, and to increase the accuracy of the analysis results, a "furnace drying" step is added after each sample is tested. The higher temperature causes the selenium and selenium oxides adhering to the electrode surface of the pulse electrode furnace to volatilize, avoiding interference from the detection results caused by the oxidation of selenium adhering to the electrode surface of the pulse electrode furnace, and further improving the accuracy and precision of the detection results. Step 10: Repeat steps 8 and 9 2 to 10 times each. The equipment will automatically calculate and output the oxygen content value in the measured high-purity selenium sample. Preferably, in step eight, the oxygen content analysis involves two stages of constant-temperature heating. The first stage involves heating at 500W-1000W for 30 seconds, with the crucible temperature at 852℃-1141℃, creating conditions for aluminum selenide formation. This converts selenium into aluminum selenide, which has a melting point of 217℃ and a boiling point of 685℃. Aluminum powder and selenium powder react under an inert atmosphere, heating to 500℃-800℃ to produce aluminum selenide (melting point approximately 960℃). The chemical equation is as follows:

[0010] Therefore, in the two-stage isothermal heating oxygen content analysis method, the first stage is to heat with a power of 500W~1000W for 30s (the crucible heating temperature is about 852℃~1141℃) to create the conditions for the formation of aluminum selenide, convert selenium into aluminum selenide, and thus increase the melting and boiling points of the sample to be tested.

[0011] The beneficial effects of this invention are as follows: This invention solves the problem of oxygen content in high-purity selenium used in infrared optical glass, providing support for quality control of infrared optical glass and high-purity selenium. It introduces 5N high-purity aluminum particles as a conversion agent, directly adding them to a high-purity graphite crucible and heating them together at 3000W for 60 seconds to deoxidize. Combined with a two-stage isothermal heating oxygen content analysis method, first heating at a lower power for 30 seconds promotes the combination reaction between selenium (with its extremely low melting and boiling points) and excess aluminum, generating aluminum selenide with higher melting and boiling points. Then, the sample is heated at a higher power for 150 seconds for detection. This invention addresses the dilemma in selenium oxygen content analysis where low analysis temperatures result in low detection values, while high analysis temperatures prevent equipment from operating properly. Furthermore, it adds a "furnace drying" step after each sample is tested to prevent interference from selenium and aluminum oxide adhering to the electrode surface of the pulse electrode furnace, further improving the accuracy and precision of the results. The invention also incorporates standard graphite powder into a high-purity graphite crucible to enhance the contact between oxygen and carbon in the sample, while simultaneously improving the deoxidation effect of the conversion agent, further enhancing the accuracy of the test results. Attached Figure Description

[0012] Figure 1 From left to right, the oxygen, nitrogen, and hydrogen release curves and detection values ​​in the American LECO502-903 steel standard sample are shown. Figure 2 From left to right are the release curves and detection values ​​of oxygen, nitrogen, and hydrogen elements in the high-purity selenium sample GCX20250218F-3 of this invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example

[0014] In this embodiment, a method for determining the oxygen content in high-purity selenium for infrared optical glass is described, and the equipment and auxiliary materials used in the oxygen content determination process are as follows: (1) Oxygen, nitrogen and hydrogen analyzer: manufactured by LECO, USA, with high-purity argon gas (≥99.999%) as the power gas and a pressure of 40psi±10%; and high-purity helium gas (≥99.999%) as the carrier gas and a pressure of 22psi±5%. (2) Electronic balance: with an accuracy of 0.0001g, weighing the sample mass, recording the weight, and equipped with two small weighing pans; (3) Constant temperature and humidity testing environment: The ambient temperature is controlled at 20℃±5℃, and the ambient humidity is controlled at 25%±5%; (4) Super cleanroom glove box: It protects the materials and auxiliary reagents used in the analysis under a high-purity argon atmosphere, preventing environmental factors from changing the composition and structure of the materials and auxiliary reagents, which in turn affects the analysis results; (5) Conversion agent: 5N high-purity aluminum granules; (6) Steel standard sample: low oxygen content standard material, LECO502-903 from the United States, with an oxygen content of 65ppm±6ppm, 1.0g / particle; (7) Agate mortar: used for grinding and testing samples; (8) Graphite crucible: LECO Standard 776-247, USA; (9) Standard graphite powder: LECO Graphite Powder 501-073 (USA); (10) Auxiliary tools: including graphite crucible clamps, tweezers, and spatula; In this embodiment, a method for determining the oxygen content in high-purity selenium for infrared optical glass includes the following steps: Step 1, Instrument Preparation: Turn on the external circulation cooling water and universal cover switch, check for leaks in the oxygen, nitrogen and hydrogen analyzer, and level and calibrate the matching electronic balance. After the leak check is passed, start the detection program. Step 2: Take the high-purity graphite crucible out of the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take the steel standard sample out of the super clean glove box and place a steel standard sample into the automatic sampling system with tweezers. Run the system's default "oxygen content in iron" detection program. Then, the steel standard sample in the automatic sampling system is put into the furnace head for oxygen content analysis. Step 3: Repeat Step 2 10 times and check that the oxygen content in the measured steel standard sample is 65.0±1.07ppm, which is consistent with its nominal value of 65ppm±6ppm. The accuracy and repeatability of the instrument are normal. The oxygen, nitrogen, and hydrogen release curves and detection values ​​in the American LECO502-903 steel standard sample are shown in [reference needed]. Figure 1 ; Step 4: Weigh 10 portions each of 0.300g of 5N high-purity aluminum granules and 0.050g of standard graphite powder in the glove box, mix 10 portions of each mixture separately and put them into high-purity graphite crucibles for testing. Step 5: Take out the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box, place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer, and run the "Oxygen content in selenium" detection program. The degassing power is 3000w, the degassing time is 60s, and the cooling time is 5s. The analysis method is two-stage constant temperature heating. The first stage selenium fixation power is 900w, the selenium fixation time is 30s, and the second stage analysis power is 4000w, the analysis time is 150s. Step six: Repeat step five four times and measure the deviation as ±1.12 ppm. Use this measurement value to zero out the experimental method. Step 7: In the glove box, crush the high-purity selenium sample to be tested, batch number GCX20250218F-3, into small particles, and weigh out three portions of high-purity selenium sample particles with masses of 0.1217g, 0.1210g, and 0.1372g respectively for later use. Step 8: Take out the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take out a high-purity selenium sample particle from the super clean glove box and place it in the automatic sample introduction system. Run the "Oxygen Content in Selenium" detection program with a degassing power of 3000w, a degassing time of 60s, and a cooling time of 5s. Put the high-purity selenium sample in the automatic sample introduction system into the furnace head for two-stage isothermal heating oxygen content analysis. The first stage conversion power is 900W and the duration is 30s. The second stage analysis power is 4000W and the duration is 150s. Step 9: After the analysis of a high-purity selenium sample is completed, take an empty crucible and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Change to the "furnace drying" method, with a degassing power of 4500w, a degassing time of 60s, and a cooling time of 5s. Then, set the furnace drying power to 4000w and the furnace drying time to 60s. Step 10: Repeat steps 8 and 9 twice each. The equipment automatically calculates and outputs that the average oxygen content in the tested batch number GCX20250218F-3 high-purity selenium sample is 220ppm ± 40.1ppm. See the oxygen, nitrogen, and hydrogen release curves and detection values ​​in the GCX20250218F-3 high-purity selenium sample. Figure 2 .

[0015] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for determining the oxygen content in high-purity selenium for infrared optical glass, characterized in that... Includes the following steps: Step 1, Instrument Preparation: Turn on the external circulation cooling water and universal cover switch, check for leaks in the oxygen, nitrogen and hydrogen analyzer, and level and calibrate the matching electronic balance. After the leak check is passed, start the detection program. Step 2: Take the high-purity graphite crucible out of the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take the steel standard sample out of the super clean glove box and place a steel standard sample into the automatic sampling system with tweezers. Run the system's default "Oxygen content in iron" detection program. Then, the steel standard sample in the automatic sampling system is put into the furnace head for oxygen content analysis. Step 3: Repeat step 2 10 times and check the image and data of the measured steel standard sample. Verify the accuracy and repeatability of the instrument based on the oxygen content value marked on the steel standard sample. If there is a deviation between the detected value and the nominal value of the steel standard sample, the instrument should be calibrated first. Step 4: Weigh 10 portions each of 0.100g~1.000g of 5N high-purity aluminum granules and 0.010g~1.000g of standard graphite powder in the glove box, mix 10 portions of each mixture separately and put them into high-purity graphite crucibles for testing. Step 5: Take out the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box, place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer, and run the "Oxygen content in selenium" detection program. The degassing power is 3000w, the degassing time is 60s, and the cooling time is 5s. The analysis method is two-stage constant temperature heating. The first stage conversion power is 500W~1000W, the duration is 30s, and the second stage analysis power is 3500W~4300W, the duration is 150s. Step 6: Repeat step 5 4 times and check the measured data. If the repeatability is good, determine the measured value as a blank value and use this blank value to zero out the experimental method. Step 7: In a glove box, crush the high-purity selenium sample to be tested into small particles, and weigh 3 to 11 portions of high-purity selenium sample particles with a mass of 0.10~0.13g for later use; Step 8: Take out the high-purity graphite crucible containing the conversion agent and standard graphite powder from the glove box and place it on the lower electrode of the oxygen, nitrogen and hydrogen analyzer. Take out a high-purity selenium sample particle from the super clean glove box and place it in the automatic sample introduction system. Run the "Oxygen content in selenium" detection program with a degassing power of 3000w, a degassing time of 60s, and a cooling time of 5s. Put the high-purity selenium sample in the automatic sample introduction system into the furnace head for two-stage isothermal heating oxygen content analysis. The first stage selenium fixation power is 500W~1000W and the selenium fixation time is 30s. The second stage analysis power is 3500W~4300W and the analysis time is 150s. Step 9: After analyzing a high-purity selenium sample, place an empty crucible on the lower electrode of the oxygen, nitrogen and hydrogen analyzer, and switch to the "furnace drying" method. The degassing power is 4500w, the degassing time is 60s, and the cooling time is 5s. The furnace drying power is 4000w, and the furnace drying time is 60s. Step 10: Repeat steps 8 and 9 2 to 10 times each. The equipment will automatically calculate and output the oxygen content value in the measured high-purity selenium sample.

2. The method for determining the oxygen content in high-purity selenium for infrared optical glass as described in claim 1, characterized in that... In step eight, the oxygen content analysis involves two stages of constant-temperature heating. The first stage involves heating at 500W-1000W for 30 seconds, with the crucible temperature ranging from 852℃ to 1141℃, creating conditions for aluminum selenide formation. Selenium has a melting point of 217℃ and a boiling point of 685℃. Under an inert atmosphere, aluminum powder and selenium powder undergo a combination reaction at 500℃-800℃ to produce aluminum selenide. The chemical equation is as follows: .

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