Alkali metal selenide composite based on direct preheating method, preparation method and application thereof

Abstract

The application relates to the field of synthesis of selenide, and aims at the technical problems of complicated operation steps and slow reaction process in the implementation of the existing method, and provides an alkali metal selenide compound based on a direct preheating method, a preparation method and application thereof, which comprises the following steps: in a glove box in an inert gas atmosphere, heating alkali metal elements until the alkali metal elements are in a liquid state; mixing selenium elements with the liquid alkali metal elements and reacting for 1-3 seconds to form a molten state, after the molten substance is solidified, standing and cooling, and grinding to obtain an alkali metal selenide compound; the molar mass ratio of the selenium elements to the alkali metal elements is 1:0.5-2. x Se y The precursor compound can simplify a precursor synthesis process, reduce a synthesis condition threshold, reduce synthesis time cost and money cost, and improve precursor product synthesis efficiency.

Description

Technical Field

[0001] This invention relates to the field of selenide synthesis, and more particularly to an alkali metal selenide complex based on a direct preheating method, its preparation method, and its application. Background Technology

[0002] In laboratory chemical synthesis processes involving alkali metals and chalcogens, a prominent problem arises from the high reactivity of alkali metals: excessively vigorous reactions lead to the loss of raw materials, consequently affecting the purity of the final product. To address this issue, a stepwise (precursor) synthesis method is generally employed in such experiments.

[0003] Currently, the most commonly used synthesis methods in laboratories The experimental method is the liquid ammonia method (taking KSe precursor as an example, freshly cut K blocks and Se particles are weighed in a 1:1 ratio (stoichiometric ratio / molar ratio) and placed in a glass reaction vessel. High-purity ammonia gas is introduced, and the reaction vessel is cooled to -70°C with dry ice and alcohol to liquefy the ammonia gas and dissolve the K. Magnetic stirring is used to make the reaction more complete. After about 30 minutes of reaction, the liquid ammonia is evaporated and discharged to obtain a relatively pure KSe precursor.) This method is complicated to implement, the reaction process is slow, and the waste ammonia gas needs to be recovered and treated after the reaction, involving various safety hazards. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide an alkali metal selenide complex based on a direct preheating method, its preparation method, and its application, enabling the small-batch, multiple-stage synthesis of A... x Se y Precursor complexes simplify the synthesis process of precursors, lower the threshold for synthesis conditions, reduce synthesis time and monetary costs (no need for liquid ammonia), and improve the synthesis efficiency of precursor products.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, this application discloses an alkali metal selenide complex, which is obtained by heating and liquefying an alkali metal element at 80-90°C in a glove box under an inert gas atmosphere, and then mixing and reacting it with an elemental selenium.

[0006] Secondly, this application discloses a method for preparing alkali metal selenide complexes based on a direct preheating method, comprising the following steps: S1. In a glove box with an inert gas atmosphere, the alkali metal element is heated until it becomes liquid. S2. Mix elemental selenium with liquid alkali metal and react for 1-3 seconds until molten. After the melt solidifies, allow it to stand and cool, then grind to obtain the alkali metal selenide complex as described in claim 1. The molar mass ratio of elemental selenium to alkali metal elemental selenium is 1:0.5~2.

[0007] Furthermore, the inert gas in S1 is any one of He, Ne, Ar, Kr, Xe, Rn, and Og.

[0008] Furthermore, the heating temperature in S1 is 80-90℃.

[0009] Furthermore, the alkali metal element in S1 is any one of K, Rb, and Cs.

[0010] Thirdly, this application discloses the use of the above-mentioned alkali metal selenide complex in the synthesis of alkali metal-containing compounds or selenium-containing compounds.

[0011] Compared with the prior art, the beneficial effects of the present invention are: Existing liquid ammonia methods require prolonged stirring of alkali metals and elemental selenium in liquid ammonia until complete dissolution, followed by volatilization of the liquid ammonia and collection of the solid powder. This process is complex, slow, and involves the recovery and treatment of waste ammonia, posing multiple safety risks such as gas leaks and poisoning. In contrast, this invention, based on the redox reaction of alkali metals and elemental selenium, innovatively adopts a core strategy of "small-volume, multiple-feed + self-exothermic reaction maintenance." In an inert gas atmosphere, the alkali metal is liquefied by heating, allowing it to mix with elemental selenium for an exothermic reaction. This achieves efficient and safe preparation of alkali metal selenide complexes. In other words, overall, this invention improves synthesis efficiency while effectively avoiding the safety hazards of existing technologies, achieving safer, more efficient, and more economical precursor preparation. Specifically: From a thermodynamic and kinetic perspective, the redox reaction between alkali metals and selenium exhibits strong spontaneity. Traditional liquid ammonia methods, to control the reaction rate and avoid side reactions, involve conducting the reaction at a low temperature of -70°C. While this allows for the initial controllability of the reaction by dissolving the alkali metal in liquid ammonia to form electron-containing ammonium compounds, the low temperature severely restricts the atomic diffusion rate, resulting in an extremely slow reaction process. This invention takes the opposite approach, heating the alkali metal above its melting point, transforming it into a liquid state. The atomic diffusion coefficient of liquid alkali metals is much higher than that of the solid state, enabling rapid contact with selenium and triggering the reaction, thus significantly accelerating the reaction process from a kinetic perspective.

[0012] The "small-volume, multiple-times" feeding strategy of this invention is not a simple adjustment of the operation method, but an innovative mechanism based on precise control of the reaction process. In the initial stage, after the alkali metal is heated and liquefied, the addition of elemental selenium in small amounts and multiple times ensures that the system always maintains a state of slight excess of alkali metal. Each time elemental selenium is added, it will quickly react with the surrounding liquid alkali metal. The heat released can not only maintain the system temperature, but also further increase the local reaction temperature, forming a virtuous cycle of "reaction exothermic - temperature rise - diffusion acceleration - more complete reaction".

[0013] An inert gas atmosphere plays multiple crucial roles in the reaction system of this invention. An inert gas atmosphere, such as argon or helium, can form a dense protective layer, which on the one hand isolates the system from air, preventing the oxidation of alkali metals and the volatilization of elemental selenium; on the other hand, it prevents the alkali metals from reacting with air after it has entered the system. The reaction carries the risk of exothermic explosion. Compared with the traditional liquid ammonia method, this invention completely eliminates dangerous reagents and equipment such as ammonia, dry ice-alcohol cryogenic bath, and eliminates the safety hazards of personnel poisoning caused by ammonia volatilization and explosion caused by ammonia mixing with air from the source. It also avoids the high investment and maintenance costs of cryogenic refrigeration equipment.

[0014] In terms of reaction efficiency, the traditional liquid ammonia method is limited by the low-temperature atomic diffusion rate, and the reaction time is usually more than 12 hours. However, the self-exothermic reaction system of this invention maintains the temperature at 200 to 500°C. The improved atomic diffusion efficiency shortens the reaction time to 30 to 60 minutes. As the operators become more skilled, the interval between "small amount and multiple" feedings can be further shortened, and the synthesis time can be reduced by up to 90% or more. The efficiency improvement in industrial production is extremely significant.

[0015] In terms of safety, this invention not only eliminates the risk of poisoning and explosion from liquid ammonia volatilization, but also allows for precise control of the reaction rate through the "small amount, multiple times" feeding method. This avoids problems such as violent reactions and sudden temperature rises caused by adding a large amount of selenium at once. The heat released by the reaction is slowly dissipated through inert gas, and the system temperature is always within a controllable range. Stable reaction can be achieved without the need for complex temperature control equipment.

[0016] In terms of economics, the traditional liquid ammonia method requires cryogenic refrigeration equipment, ammonia storage and transportation equipment, resulting in high initial investment and maintenance costs, as well as ammonia volatilization losses and low raw material utilization. This invention only requires simple heating devices such as small heating platforms, alumina crucibles or zirconium oxide crucibles, which significantly reduces equipment costs, raw material and energy costs, and gives it a strong competitive edge in the market. Attached Figure Description

[0017] Figure 1 The present invention relates to liquid rubidium (Rb) element.

[0018] Figure 2 This is the Rb2Se precursor complex of the present invention.

[0019] Figure 3 The diagram shows the Rb2Se precursor complex after grinding according to the present invention. From left to right, the diagrams show the Rb2Se precursor complex after grinding for 5 minutes, grinding for 10 minutes, grinding for 20 minutes, and bottling.

[0020] Figure 4 This is an image showing the X-ray diffraction pattern and structural refinement results of RbV2Se2O powder according to the present invention.

[0021] Figure 5 Rb synthesized in this invention x Se y Scanning electron microscopy results and EDS composition diagram of RbV2Se2O single crystals grown by flux using the composite (composition ratio is shown in the clean square area in the figure). Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] Example 1 like Figure 1-3 As shown, this application first discloses an alkali metal selenide complex, which is obtained by heating and liquefying an alkali metal element at 80-90°C in a glove box under an inert gas atmosphere, and then mixing and reacting it with an elemental selenium.

[0024] This application also discloses a method for preparing alkali metal selenide complexes based on a direct preheating method, comprising the following steps: S1. In a glove box with an inert gas atmosphere, an alkali metal element is heated until it becomes liquid; wherein the inert gas is any one of He, Ne, Ar, Kr, Xe, Rn, and Og; the heating temperature is 80-90℃. It should be noted that the reaction can only occur when the alkali metal is heated to a liquid state or a solid-liquid coexistence state (mostly liquid).

[0025] In this embodiment, rubidium (Rb) is used as an example. Specifically, 50 mg of elemental Rb is taken in an inert gas glove box, placed into an alumina crucible, and heated on a heating platform (the temperature of the heating platform needs to be adjusted to 80-90°C to account for heat loss) until the elemental Rb is liquid. It should be noted that the alumina crucible is as follows: height 100 mm, diameter Φ30, thickness 2 mm, maximum capacity 50 ml, and material 99%... It weighs 80g.

[0026] S2. Mix elemental selenium with liquid alkali metal and react for 1-3 seconds until it melts. After the melt solidifies, let it stand and cool, then grind to obtain alkali metal selenide complex. The molar mass ratio of elemental selenium to alkali metal elemental selenium is 1:0.5~2.

[0027] Therefore, when 50 mg of elemental Rb is taken in S1, 22 mg of elemental selenium (Se) is mixed with the liquid alkali metal element to react and obtain the Rb2Se precursor complex; the Rb2Se precursor complex here is the alkali metal selenide complex, which includes, but is not limited to, various components of Rb. x Se y The products, but the overall chemical formula molar ratio of the products is close to 2:1 (considering the losses during the reaction process and the weighing error, this error is less than 5%). It is important to note that this reaction is an oxidation (exothermic) reaction, and the procedure of adding reactants in small amounts multiple times must be strictly followed. Adding too many reactants at once is strictly prohibited, as it may cause the reaction to become too violent and out of control.

[0028] Furthermore, regarding the amounts of alkali metal and selenium added in S1 and S2, it should be noted that the range of these amounts depends on the size of the reaction vessel. Using a large crucible allows for a more appropriate increase in the amount of reactants. For example, the crucible used in this embodiment has a height of 100mm, a diameter of Φ30, a thickness of 2mm, a maximum capacity of 50ml, and is made of 99% [material name missing]. The initial reaction can use 50-100 mg of alkali metal, weighing 80 g. Then, add the required stoichiometric ratio of selenium powder (this value should be adjusted according to experimental requirements to prepare Rb-related products. If the required stoichiometric ratio (molar ratio) is Rb:Se = 2:1, then 50-100 mg of Rb corresponds to 23.12 mg-46.23 mg of selenium. If the required stoichiometric ratio (molar ratio) is Rb:Se = 1:1, then 50-100 mg of Rb corresponds to 46.23 mg-92.46 mg of selenium). The same applies to K and Cs.

[0029] Note: 1. The reaction is roughly divided into two parts: the initial reaction and the later reaction. The initial reaction is more vigorous. The limit of alkali metals that can be added at one time (taking Rb2Se as an example) is about 100mg (±5mg), while that of selenium is 46.23mg. The total amount of products from one reaction is 146mg.

[0030] 2. In the initial reaction stage, after the reaction has been carried out 7-8 times, the total amount of product inside the crucible is approximately 1022mg-1168mg.

[0031] 3. At this point, the reaction enters the later stage. The reaction in the later stage is milder than that in the initial stage. The amount of alkali metal (Rb) used at one time can be doubled to 200 mg, and the corresponding amount of selenium is 92.46 mg. The total amount of reactants in this stage is 292.46 mg.

[0032] 4. In the later stage of the reaction, after 7-8 cycles, the total amount of product inside the crucible should be the sum of the initial and later reaction amounts = 3069mg - 3508mg. At this point, depending on the situation, the amount of alkali metal can be doubled to 400mg, corresponding to a selenium amount of 184.92mg. The total amount obtained from one reaction is 584.92mg. After 3-4 cycles, the amount of alkali metal can be doubled to 800mg, corresponding to a selenium amount of 369.84mg.

[0033] Specifically, the alkali metal selenide complex in this patent application should be a mixture, not a pure single compound. The reaction equations involved in the above reaction stages are all: XA+YSe=a(A x1 Se y1 )+b(A x2 Se y2 )+c(A x3 Se y3 )+…+n(A xn Se yn ); Where A represents the alkali metal (K, Rb, Cs); X and Y are the molar mass ratios of the alkali metal and selenium, respectively; x1 to xn are the molar percentages of the alkali metal in the compound, y1 to yn are the molar percentages of selenium in the compound, and a, b, c...n represent the percentages of the compound in the total product. a*x1+b*x2+c* x3 +…+n*xn=X; a*y1+b*y2+c*y3+…+n*yn=Y, and the reaction conditions are: heating (Cs corresponds to 50℃; Rb corresponds to 90℃; K corresponds to 130℃). It should be noted that, according to the law of conservation of mass, the amount of input material should equal the sum of the components of the output. Considering the simplest case, when the molar mass ratio of alkali metal to selenium is 1:1 (let A = Rb, then X = Y = 1), and assuming there is one and only one product, the formula should be described as Rb + Se = aRb. x1 Se y1 (At this point, there is only one product, a*x1=1, a*y1=1). If we assume there are exactly two products, then the formula should be described as Rb+Se=aRb x1 Se y1 +bRb x2 Se y2(At this point there are exactly 2 products, a*x1+b*x2=1, a*y1+b*y2=1,) and the formulas for more products follow the same logic.

[0034] 5. Taking this embodiment as an example, when using this type of crucible, the maximum amount of elemental Rb used at one time during the later stages of the reaction was 1300 mg, corresponding to 600.98 mg of selenium. At this point, the reaction could still proceed gently. After the reaction was completed, the crucible was allowed to stand for 3-5 minutes until it reached room temperature before the product was poured into an agate mortar for grinding.

[0035] It should be noted that the alkali metal selenide complex is completely hydrolyzed (oxidized) within 3 seconds of being removed from the inert gas environment, making it impossible to support complete XRD and scanning electron microscopy (SEM+EDS) tests. Therefore, this application uses auxiliary means to use the alkali metal selenide complex as an alkali metal source and selenium source for the synthesis of other substances to verify whether the product is an alkali metal selenide complex. Furthermore, when using the alkali metal selenide complex of this application as a raw material to synthesize other substances, it must be carried out in an inert gas environment to ensure that the reaction can proceed smoothly.

[0036] For example, the synthesized product has the molecular formula RbV₂Se₂O, and the reaction equation is 1 / 2Rb₂Se + 1 / 5V₂O₅ + 3 / 2Se + 8 / 5V = RbV₂Se₂O. After structural refinement and single-crystal X-ray diffraction characterization, the product's structure was confirmed as the target phase structure (RbV₂Se₂O tetragonal high-symmetry phase), and the experiment is reproducible. This eliminates experimental randomness. Furthermore, using the synthesized product of this application as a raw material, it is possible to synthesize tetragonal phases including, but not limited to, chromium (Cr)-based compounds RbCr₂Se₂O and other quasi-trigonal-hexagonal orthorhombic phases based on vanadium (V), thus overcoming the limitation of using alkali metal selenide complexes obtained in this application as raw materials for the target product and broadening its application pathways.

[0037] Specifically, such as Figure 4 As shown, the refined X-ray diffraction pattern of the RbV₂Se₂O polycrystalline sample is presented (the black circles represent experimental observations, the red lines represent theoretical fitting values, the blue lines represent the difference between the two, and the pink bar icons indicate the locations of the diffraction peaks theoretically calculated for RbV₂Se₂O). Figure 4 As can be seen from the data, all the crystal diffraction peaks obtained from the X-ray diffraction experiments of the RbV2Se2O polycrystalline sample of this application can be accurately fitted, and R... wp With χ 2The fitted values ​​are within a reasonable range, indicating high sample purity. This further demonstrates that the high-purity RbV₂Se₂O sample in this embodiment was synthesized using the Rb₂Se precursor complex of this application. The specific reaction equation is 1 / 2Rb₂Se + 1 / 5V₂O₅ + 3 / 2Se + 8 / 5V = RbV₂Se₂O. In this chemical reaction equation, the Rb source is taken from the Rb₂Se complex synthesized in this application, rather than directly synthesizing elemental Rb. This indirectly indicates that the alkali metal selenide (taking Rb₂Se as an example) of this application is an alkali metal selenide containing both Rb and Se. According to the above chemical reaction equation, when balancing the chemical formula, 1 / 2 mol of the Rb₂Se complex is required as a raw material to obtain a relatively pure RbV₂Se₂O polycrystalline sample. This again demonstrates that the sample of this application is an alkali metal selenide.

[0038] Table 1. Results of polycrystalline X-ray structure refinement and single-crystal X-ray diffraction deconstruction at different temperatures

[0039] Table 1 shows the Rietveld refinement results of the polycrystalline X-ray diffraction patterns of RbV₂Se₂O at room temperature. Among them, the weighted profile R factor (R...) wp =9.286%) and goodness-of-fit chi-square (χ²) 2 =1.26) are all within a reasonable range, indicating that the refinement results are accurate and the data are reliable; where a, c, V represent the crystal cell parameters and unit cell volume, ρ is the material density; x, y, z are the positions of each atom in space.

[0040] It should be noted that, Figure 4 In Table 1, R wp R-factor, representing the weighted profile fitting residual, is the most commonly used and intuitive evaluation metric in refinement, taking into account the intensity weights of diffraction peaks (the fitting contribution of high-angle / low-intensity peaks). It is calculated as the relative deviation of each data point, weighted by the square root of the experimental intensity, based on the difference between the experimental and theoretical intensities, thus preventing the fitting error of low-intensity peaks from being masked by high-intensity peaks. Generally, R... wp <10% is considered excellent fit, 10%~15% is good, and 15%~20% is acceptable (the threshold varies slightly for different systems; for example, the threshold can be appropriately relaxed for complex crystals / low crystallinity samples).

[0041] χ 2 Chi-squared / goodness-of-fit chi-squared represents the normalized weighted fit residuals, which is the ratio of R² to the goodness-of-fit. wp More statistically significant indicators directly reflect the theoretical model's ability to interpret experimental data. (Based on R...) wpIt is calculated in conjunction with the statistical error of the experimental data (such as counting statistical error), and is essentially the ratio of the "actual fit residual" to the "expected statistical error". Under ideal fitting conditions, χ² 2 ≈1 (the theoretical residual is consistent with the statistical error); χ 2 The greater the deviation from 1, the more the fitting residual exceeds the statistical error, which may be due to an unreasonable structural model or systematic errors in the experimental data. The weighted profile R-factor (R) in the crystal structure refinement results... wp ) and goodness-of-fit chi-square (χ²) 2 These cannot be discussed separately; any single value reaching the standard does not necessarily indicate the accuracy of the crystal structure refinement result. Only if the obtained R... wp <10% of the simultaneous obtained (χ) 2 Only when the value approaches and is greater than 1 can the refinement result be reliable. Figure 4 The high goodness-of-fit parameters in Table 1 indicate the accuracy and high purity of the synthesized RbV2Se2O crystals. Since the Rb source used in the synthesis process is derived from the Rb2Se complex of this application, the accuracy of the Rb2Se precursor complex in this application is demonstrated.

[0042] It is important to note that: χ 2 The computational essence of χ 2 =(R wp / R exp )2(R wp =Weighted profile R factor, R exp =Experimental statistical R-factor), its core is the ratio of the fitting residual to the experimental statistical error, χ² 2 ≈1 represents the ideal state where the fitting residuals perfectly match the statistical fluctuations of the experiment.

[0043] A reliable refinement result must satisfy χ². 2 In the above interval +R wp Within a reasonable range (normal <15%, complex systems <20%) + perfect match between experimental and theoretical peak shapes / positions are essential.

[0044] Example: If R wp =8% (Excellent) but χ 2 =6, which may still be due to overfitting or inaccurate correction of experimental statistical errors, and the result is unreliable; Crystal structure refinement in progress, χ 2 =1~2 is the optimal confidence interval (in this application). χ 2 =1.26), 2~5 is the acceptable range for complex systems, >5 requires model revision / experimental data optimization; and it must be consistent with R. wp The combination of visual matching of graphs and graphs makes it impossible to determine the reliability of results with a single indicator.

[0045] like Figure 5 As shown in the figure, the SEM results indicate that the crystal exhibits obvious natural right angles, consistent with the refined RbV2Se2O structure. RbV2Se2O belongs to the tetragonal crystal system, with α=β=γ=90°. Furthermore, the EDS test results show that the ratio of rubidium (Rb):V:Se:O is approximately 1:1.812:1.919:0.664, close to 1:2:2:1, which is consistent with the refined crystal structure results. This indicates that the crystal synthesized using the product of this application as a raw material is indeed an RbV2Se2O crystal, indirectly reflecting that the product of this application is indeed an alkali metal selenide complex.

[0046] In addition, regarding the experimental description of preparing RbV2Se2O polycrystalline (single crystal) using the Rb2Se composite prepared in this application: Regarding polycrystalline materials, based on the chemical formula of the target product, the required molar mass of each element was calculated, and the corresponding actual mass to be weighed was determined. The reaction equation is 1 / 2Rb₂Se + 1 / 5V₂O₅ + 3 / 2Se + 8 / 5V = RbV₂Se₂O, which requires 1 / 2 mole of Rb₂Se, 1 / 5 mole of vanadium pentoxide (V₂O₅), 3 / 2 mole of elemental selenium (Se), and 8 / 5 mole of elemental vanadium (V) to participate in the reaction. According to the law of conservation of mass, the absence of any element during this reaction will lead to an imbalance in the overall elemental ratio, increasing the difficulty of obtaining the target product. In this experiment, using 1 / 2 mole of the synthesized Rb₂Se complex, near-pure phase RbV₂Se₂O polycrystalline materials can be accurately synthesized. During the experiment, the elements were weighed strictly according to the reaction equation, and no additional Rb source was introduced, indicating that the product synthesized in this application is an Rb-containing selenide complex.

[0047] Regarding single crystals, Rb-Se co-solvent was used for single crystal growth, with a molar ratio of Rb:V:Se:O of 6:2:7:1. The raw materials required for the reaction were the Rb2Se complex 3Rb2Se+1 / 5V2O5+4Se+8 / 5V synthesized in this application, which requires 3 moles of Rb2Se, 1 / 5 moles of vanadium pentoxide V2O5, 4 moles of elemental selenium (Se), and 8 / 5 moles of elemental vanadium (V) to participate in the reaction. During the experiment, each element was weighed strictly according to the reaction equation, and no additional Rb source was introduced. The synthesized RbV2Se2O single crystals indicate that the product synthesized in this application is an RbSe complex.

[0048] It should be noted that when preparing large quantities of precursor complexes (alkali metal selenide complexes), preparation can be carried out by repeating S1 and S2 in the same crucible, and the amounts of Rb and Se can be selectively doubled to shorten the total time required for large-scale preparation of precursors. (This reaction is exothermic, and no additional heating platform is required to heat the crucible during continuous reaction).

[0049] Example 2 In this embodiment, the alkali metal element is K. The method for synthesizing K2Se using K and Se is the same as in Example 1. The only difference is that the heating stage temperature needs to be adjusted to 120-130℃ to prepare K2Se. Example 3

[0050] In this embodiment, the alkali metal element is Cs. The method for synthesizing Cs2Se using Cs and Se is the same as in Example 1. The only difference is that the temperature of the heating stage needs to be adjusted to 50-60°C to prepare Cs2Se.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An alkali metal selenide complex, characterized in that, The alkali metal selenide complex is obtained by heating and liquefying an alkali metal element at 80-90°C in a glove box under an inert gas atmosphere, and then mixing and reacting it with an elemental selenium.

2. A method for preparing alkali metal selenide complexes based on direct preheating, characterized in that, Includes the following steps: S1. In a glove box with an inert gas atmosphere, the alkali metal element is heated until it becomes liquid. S2. Mix elemental selenium with liquid alkali metal and react for 1-3 seconds until molten. After the melt solidifies, allow it to stand and cool, then grind to obtain the alkali metal selenide complex as described in claim 1. The molar mass ratio of the elemental selenium to the elemental alkali metal is 1:0.5~2.

3. The method for preparing an alkali metal selenide complex based on direct preheating according to claim 2, characterized in that, The inert gas mentioned in S1 is any one of He, Ne, Ar, Kr, Xe, Rn, and Og.

4. The method for preparing an alkali metal selenide complex based on direct preheating according to claim 2, characterized in that, The heating temperature described in S1 is 80-90℃.

5. The method for preparing an alkali metal selenide complex based on direct preheating according to claim 2, characterized in that, The alkali metal element mentioned in S1 is any one of K, Rb, and Cs.

6. Use of the alkali metal selenide complex according to claim 1 in the synthesis of alkali metal-containing compounds or selenium-containing compounds.

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