Barium complex as well as preparation method and application thereof

Abstract

The invention provides a barium complex as well as a preparation method and application thereof. The barium complex comprises barium ions, anion ligands and auxiliary ligands, the anion ligands comprise beta-diketone ligands, and the auxiliary ligands comprise neutral nitrogen heterocyclic ligands. The barium complex provided by the invention has lower initial volatilization temperature and residual rate, thereby being more favorable for realizing an efficient and stable chemical vapor deposition process.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film material preparation, and in particular relates to a barium complex and a preparation method and application thereof. Background Art

[0002] Barium occupies an important position in the fields of microelectronics and high-temperature superconducting thin film preparation technology. Specifically, barium titanate (BaTiO3), as the cornerstone material of the electronic ceramic component industry, is widely embedded in electronic components such as multilayer ceramic capacitors (MLCC), positive temperature coefficient thermistors (PTC), optoelectronic components and various types of random access memories due to its excellent dielectric constant, ferroelectric and piezoelectric properties, as well as excellent voltage resistance and insulation performance. It is known as the "pillar of the electronic ceramic industry". At the same time, research in the field of high-temperature superconducting thin films also focuses on yttrium barium copper oxide (YBa2Cu3O 7-x , YBCO) film, YBCO film has attracted much attention due to its wide application prospects in power transmission and energy storage, medical imaging, magnetic levitation transportation systems and quantum computing.

[0003] In recent years, the challenge faced by chemical vapor deposition (CVD) technology in the efficient synthesis of the above-mentioned thin film materials is mainly the lack of barium organic complexes with high volatility, stable vapor pressure and low cost as precursors for deposited thin films. This problem mainly stems from the unique chemical properties and coordination selection preferences of barium ions, which makes it difficult to find suitable barium organic complexes as efficient precursors. Although barium ions play a specific role in the perovskite structure due to their large size (about 149pm) and low charge, most of the barium organic complexes formed have a high coordination number (usually 8-13) and tend to form oligomers through oxygen bridges to meet their high coordination requirements. However, these high-coordination barium organic complexes are often difficult to volatilize. In order to further improve their volatility, it is necessary to effectively inhibit the polymerization of barium organic complexes. In addition, the low charge characteristics of barium ions limit the ability of individual anionic ligands to meet their coordination requirements. In summary, there are many challenges in designing and synthesizing barium organic complexes with high volatility.

[0004] Based on this, the currently commonly used volatile barium organic complexes are mainly Ba(TMHD)2·xH2O, which is simple to prepare and has a low synthesis cost. However, Ba(TMHD)2·xH2O is prone to form a low-poly structure during the thin film deposition process, which affects the performance and quality of the film. Therefore, some researchers have tried to introduce other types of ligands to protect Ba(TMHD)2 to improve the volatility of barium organic complexes. However, due to the large ionic radius of barium ions, it is difficult for general organic ligands to form a tight bond with them, resulting in the formation of barium organic complexes. The phenomenon of multi-stage weight loss during thermal decomposition, and the volatility has not been significantly improved. It can be seen that the development of organic ligands with strong coordination ability to achieve a tight bond with barium ions and effectively inhibit their polymerization is still a key direction in the current research field.

[0005] In addition, as the core material in the thin film deposition process, the cost of metal organic complexes has a decisive influence on the production cost of thin films. At present, the preparation of barium organic complexes generally relies on metal barium as the initial raw material. This preparation process needs to be carried out under strictly controlled anhydrous and oxygen-free conditions, and a large amount of organic solvents are usually used as dissolution aids, such as the technical solutions of Chinese patents CN102503962A and CN108707159A. This is mainly because barium salts are difficult to dissolve directly in organic solvents, but can only be dissolved in aqueous solutions or mixed solutions of water and alcohol. In fact, in the above-mentioned aqueous solvent system, some organic ligands cannot maintain structural stability; while another part of the organic ligands, such as open-chain ligands such as tetraethylenepentamine and pentaethylenehexamine, can accommodate a large number of water molecules bound in the form of hydrogen bonds, resulting in a high degree of solvation of the open-chain ligands, so that in the subsequent process of forming the complex, the energy required for the above-mentioned open-chain ligands to remove the water solvent is high, thereby hindering them from forming stable coordination with barium ions in aqueous solutions or mixed solutions of water and alcohol.

[0006] As mentioned above, the methods disclosed in the prior art for preparing barium organic complexes using open-chain ligands as raw materials mainly include two categories: one is to directly use the relatively expensive metal barium as a raw material, but this significantly increases the production cost; the other is to use barium salts as raw materials through a complex step-by-step reaction process, specifically: first, Ba(TMHD)2·xH2O is synthesized using barium salts as raw materials in a water-alcohol system, and then a barium organic complex containing an organic ligand is further synthesized in the presence of a large amount of organic solvents, which not only increases the complexity of the operation, but also goes against the concept of green chemistry.

[0007] Therefore, there is an urgent need to develop a barium organic complex and a preparation method thereof to solve the above problems. Summary of the invention

[0008] In view of the technical problems of insufficient volatility, high preparation cost and complicated preparation method commonly existing in barium organic complexes in the prior art, the object of the present invention is to provide a barium complex and a preparation method and use thereof, so as to prepare a low-cost and highly volatile barium organic complex. The preparation method provided by the present invention not only achieves the goal of simplifying the process flow and improving production efficiency, but also greatly reduces the production cost of the barium organic complex, and the prepared barium complex has a lower initial volatilization temperature and residual rate.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a barium complex, which comprises a barium ion, an anionic ligand and an auxiliary ligand, wherein the anionic ligand comprises a β-diketone ligand, and the auxiliary ligand comprises a neutral nitrogen heterocyclic ligand.

[0011] The present invention selects a neutral nitrogen heterocyclic chelate ligand with abundant coordination sites as an auxiliary ligand, so that the neutral nitrogen heterocyclic chelate ligand can produce a strong coordination effect with the barium ion, thereby forming a stable barium complex. Even under high temperature conditions, the neutral nitrogen heterocyclic chelate ligand can still remain in an undissociated state, and finally effectively inhibits the agglomeration of barium ions, thereby significantly improving the volatility of the barium complex. In addition, the barium complex provided by the present invention can still maintain sufficient saturated vapor pressure at a relatively low temperature, which is more conducive to realizing an efficient and stable chemical vapor deposition process.

[0012] Preferably, the structure of the β-diketone ligand is as shown in Formula I:

[0013]

[0014] Among them, R A , R B Each is independently selected from at least one of methyl, alkoxy, trifluoromethyl or tert-butyl. For example, the alkoxy group may be, for example, methoxy, ethoxy, propoxy, etc.

[0015] More preferably, the anionic ligand is 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD).

[0016] Preferably, the neutral nitrogen heterocyclic ligand includes at least one of the 1,4,7-triazacyclononane ligand shown in formula II, the 1,4,7,10-tetraazacyclododecane ligand shown in formula III, the 1,4,7,10,13-pentazacyclopentadecane ligand shown in formula IV, or the 1,4,7,10,13,16-hexaazacyclooctadecane ligand shown in formula V:

[0017]

[0018] Wherein, R1, R2, R3, R4, R5 and R6 are each independently selected from at least one of a hydrogen atom, an alkyl group or an alkoxy group. For example, the alkyl group may be, for example, a methyl group, an ethyl group, a propyl group or a butyl group; and the alkoxy group may be, for example, a methoxy group, an ethoxy group, a propoxy group or the like.

[0019] Compared with the open-chain ligands disclosed in the prior art that can accommodate a large number of water molecules bound by hydrogen bonds, the 1,4,7,10-tetraazacyclododecane ligands with a macrocyclic structure exhibit a lower degree of solvation and excellent chelating ability. This feature enables the 1,4,7,10-tetraazacyclododecane ligands to stably coordinate with barium ions in aqueous solution, and the formed barium complex can also maintain structural stability in a complex environment containing water and oxygen.

[0020] Further preferably, the neutral nitrogen heterocyclic ligand is any one of cyclopentane or 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, or a combination of at least two thereof.

[0021] Further preferably, the chemical formula of the barium complex is Ba(L1)2(L2)(H2O) m , wherein L1 is a β-diketone ligand, L2 is a 1,4,7,10-tetraazacyclododecane ligand, and m is 0 or 1.

[0022] Preferably, the saturated vapor pressure of the barium complex at 350° C. is higher than 4000 Pa.

[0023] In a second aspect, the present invention provides a method for preparing the barium complex according to the first aspect, the method comprising the following steps:

[0024] The first solution containing anionic ligands is mixed with the second solution containing barium metal salt and auxiliary ligands, and the barium complex is obtained after reaction.

[0025] Preferably, the pH value of the first solution containing anionic ligands is 7-8, for example, it can be 7, 7.2, 7.5, 7.8, 8, etc.

[0026] Preferably, the first solution containing anionic ligands comprises anionic ligands and an organic solvent.

[0027] In the present invention, the organic solvent exemplarily includes ethanol.

[0028] Preferably, the amount of substance of the anionic ligand is twice the amount of substance of the barium metal salt.

[0029] Preferably, the mass volume ratio of the anionic ligand to the organic solvent is 1 g:10 mL.

[0030] Preferably, the second solution containing the barium metal salt and the auxiliary ligand is an aqueous solution containing the barium metal salt and the auxiliary ligand.

[0031] In the present invention, the barium salt illustratively includes barium chloride or barium nitrate.

[0032] Preferably, the molar ratio of the barium metal salt to the auxiliary ligand is 1:(1.1-1.2), for example, it can be 1:1.1, 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, 1:1.2, etc.

[0033] Preferably, the mass volume ratio of the auxiliary ligand to water is 1 g:50 mL.

[0034] Preferably, the mixing process comprises dropping a first solution containing anionic ligands into a second solution containing barium metal salt and auxiliary ligands.

[0035] Preferably, the mixing is performed under an inert atmosphere.

[0036] Preferably, the reaction temperature is 60°C-80°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, etc.

[0037] Preferably, the reaction time is 12 h-18 h, for example, it can be 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, etc.

[0038] Preferably, the reaction is carried out under an inert atmosphere.

[0039] Preferably, the reaction further includes a purification process.

[0040] In the present invention, the purification process includes cooling the solution after the reaction to room temperature and filtering it, vacuum drying the obtained white solid to obtain a crude product; adding the crude product to an organic solvent to dissolve and stir it, and standing it at a low temperature of -15°C to -5°C (for example, -15°C, -12°C, -10°C, -8°C, -5°C, etc.) to obtain colorless crystals, vacuum drying the obtained colorless crystals, and crushing them to obtain the Ba(L1)2(L2)(H2O) m powder.

[0041] In the present invention, the organic solvent includes any one of n-pentane, n-hexane or toluene. The mass volume ratio of the crude product to the organic solvent is 1 g:20 mL.

[0042] In the present invention, the temperature of the vacuum drying is 50° C., and the equipment for achieving the vacuum drying exemplarily includes a vacuum oven.

[0043] In the present invention, the device for achieving the low temperature exemplarily includes a refrigerator.

[0044] As a preferred technical solution of the present invention, the present invention provides a method for preparing the barium complex (Ba(TMHD)2(L2)(H2O) according to the first aspect m ), the method comprising the following steps:

[0045] (1) First, add the barium salt and the neutral nitrogen heterocyclic chelating ligand into a glass three-necked flask with an air inlet, dissolve them with water, stir, and perform the chelating reaction for 6 hours until the solution changes from a clear liquid to a slightly turbid liquid;

[0046] (2) dissolving 2,2,6,6-tetramethyl-3,5-heptanedione in ethanol, adding dropwise a 50 wt% sodium hydroxide solution to neutralize the system to a pH value of 7-8, stirring and mixing until the solution is clear;

[0047] (3) nitrogen is introduced into a glass three-necked flask, and then the ethanol solution containing 2,2,6,6-tetramethyl-3,5-heptanedione in step (2) is added to the solution containing barium salt and neutral nitrogen heterocyclic chelating ligand in step (1) through a dropping funnel, heated and stirred at 60° C.-80° C. for 12-18 hours, cooled to room temperature and filtered;

[0048] (4) The filtered white solid was vacuum dried to obtain Ba(TMHD)2(L2)(H2O) m crude powder;

[0049] (5) The obtained Ba(TMHD)2(L2)(H2O) m The crude powder is added to an organic solvent to dissolve and stir, and then allowed to stand at low temperature to obtain colorless crystals. The obtained colorless crystals are vacuum dried and crushed to obtain high-purity Ba(TMHD)2(L2)(H2O) m powder.

[0050] The invention firstly adopts a cost-effective barium salt to complex with a macrocyclic neutral nitrogen heterocyclic chelating ligand in an aqueous solution, and then adds a deprotonated 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) ethanol solution under nitrogen protection to prepare a crude product Ba(TMHD)2(L2)(H2O) m , and then purified Ba(TMHD)2(L2)(H2O) by recrystallization m The crude product was then used to obtain high-purity Ba(TMHD)2(L2)(H2O) with a complex ligand. m .

[0051] The preparation method adopted by the present invention has significant advantages: the preparation method does not require a strict anhydrous and oxygen-free environment, avoids the use of high-cost, easily deteriorating metal barium raw materials, and the entire synthesis process can be completed in only one step of reaction. This not only greatly reduces the production difficulty of highly volatile barium organic complexes, but also significantly reduces their preparation costs.

[0052] The high-purity barium complex prepared by the present invention is preferably Ba(TMHD)2(L2)(H2O) m The yield of powder was greater than 75%.

[0053] In a third aspect, the present invention provides a use of the barium complex according to the first aspect, wherein the barium complex is used for preparing electronic thin film materials or superconducting thin film materials.

[0054] In the present invention, the electronic thin film material or high temperature superconducting thin film material can be prepared by chemical vapor deposition method.

[0055] In the application field of chemical vapor deposition, the traditional barium organic complex Ba(TMHD)2·xH2O is easy to form a low-poly structure during the deposition process, which not only leads to an increase in the volatilization temperature, but also significantly increases the residual rate, thereby seriously affecting its actual application effect. In contrast, the barium complex provided by the present invention is preferably Ba(TMHD)2(L2)(H2O) m It shows significant advantages: it has a lower initial volatilization temperature and residual rate, and can still maintain sufficient saturated vapor pressure at a relatively low temperature, which is more conducive to achieving an efficient and stable deposition process.

[0056] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] The present invention provides a barium complex, which selects a neutral nitrogen heterocyclic chelate ligand with abundant coordination sites as an auxiliary ligand, so that the neutral nitrogen heterocyclic chelate ligand can produce a strong coordination effect with the barium ion, thereby forming a stable barium complex. Even under high temperature conditions, the neutral nitrogen heterocyclic chelate ligand can still remain in an undissociated state, and finally effectively inhibits the agglomeration of barium ions, thereby significantly improving the volatility of the barium complex. In addition, the barium complex provided by the present invention can still maintain sufficient saturated vapor pressure at a relatively low temperature, which is more conducive to realizing an efficient and stable chemical vapor deposition process.

[0059] The present invention uses a relatively cheap barium salt instead of metallic barium as the initial raw material, and preferentially coordinates with a macrocyclic neutral nitrogen heterocyclic chelating ligand with a low degree of solvation and strong coordination ability in an aqueous solution, and then directly adds a deprotonated anionic ligand solution to the reaction system to obtain the barium complex after the reaction. The barium complex prepared by the method provided by the present invention has a simpler and more efficient preparation process than barium organic complexes containing other types of auxiliary ligands, and the production cost is more economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is the infrared spectrum of Ba(TMHD)2(CYC)(H2O) prepared by the present invention.

[0061] Figure 2 It is the infrared spectrum of Ba(TMHD)2(TMCYC) prepared by the present invention.

[0062] Figure 3 3. Thermogravimetric analysis curves of Ba(TMHD)2(CYC)(H2O) prepared in Example 1, Ba(TMHD)2(TMCYC) prepared in Example 3, and Ba(TMHD)2·xH2O prepared in Comparative Example 1.

[0063] Figure 4 The curves showing the variation of saturated vapor pressure at different temperatures of Ba(TMHD)2(CYC)(H2O) prepared in Example 1, Ba(TMHD)2(TMCYC) prepared in Example 3 and Ba(TMHD)2·xH2O prepared in Comparative Example 1. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below by combining the accompanying drawings and specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0065] Example 1

[0066] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(CYC)(H2O), the barium complex includes a barium metal complex and a cyclazone auxiliary ligand (abbreviated as CYC), and the structural formula of the cyclazone auxiliary ligand is shown in Formula A:

[0067]

[0068] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0069] (1) In a 250 mL three-necked flask with an air inlet, 1.22 g of barium chloride dihydrate and 0.99 g of cyclopentane were added in sequence, and then 50 mL of ultrapure water was added. The mixture was stirred for 6 h until the solution changed from a clear liquid to a slightly turbid liquid.

[0070] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0071] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -5° C. refrigerator. After five days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.62 g of Ba(TMHD)2(CYC)(H2O) in the form of a white powder, with a yield of 75.6%.

[0072] like Figure 1 As shown, the barium complex Ba(TMHD)2(CYC)(H2O) prepared in this example is characterized by infrared absorption spectrum, wherein the vibration peaks corresponding to different groups are as follows: ν(-NH): 3320cm -1 ; ν(CH3, CH2):2950cm -1 、2850cm -1 ;δ(-NH2):1602cm -1 ; ν(CO):1586cm -1 、1571cm -1 ; ν(CC):1550cm -1 ;ν(CO)+ν(CC)+ν(CH):1504cm -1 ; ν(CC)+ν(CH):1420cm -1 ; ν[C-(CH3)3]+δ(CC):1297cm -1 、1240cm -1 、1221cm -1 ; ν[C-(CH3)3]+δ(CH):1188cm -1 ; ν[C-(CH3)3]+ν(CO):1023cm -1 、975cm -1 、930cm -1;ν[C-(CH3)3]+ν(CCO)+ν(Ba-O):811cm -1 、787cm -1 、754cm -1 、730cm -1 ; ν(Ba-O):596cm -1 、469cm -1 In addition, the purity of the barium complex is determined by organic element analysis (theoretical values ​​are in brackets), and the results are as follows: C: 51.97 (51.91), H: 8.49 (8.71) and N: 8.28 (8.07), indicating that it has a high purity.

[0073] Example 2

[0074] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(CYC)(H2O), the barium complex includes a barium metal complex and a cyclazone auxiliary ligand (abbreviated as CYC), and the structural formula of the cyclazone auxiliary ligand is shown in Formula A:

[0075]

[0076] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0077] (1) In a 250 mL three-necked flask with an air inlet, 1.31 g of barium nitrate and 1.03 g of cyclopentane were added in sequence, followed by 55 mL of ultrapure water. The mixture was stirred for 6 h until the solution changed from a clear liquid to a slightly turbid liquid.

[0078] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0079] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -10° C. refrigerator. After seven days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.68 g of Ba(TMHD)2(CYC)(H2O) in the form of a white powder, with a yield of 77.4%.

[0080] Example 3

[0081] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(TMCYC), the barium complex includes a barium metal complex and a 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane auxiliary ligand (TMCYC for short), the structural formula of the 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane auxiliary ligand is shown in Formula B:

[0082]

[0083] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0084] (1) In a 250 mL three-necked flask with an air inlet, 1.22 g of barium chloride dihydrate and 1.31 g of 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane were added in sequence, and then 50 mL of ultrapure water was added. The mixture was stirred for 6 h until the solution changed from a clear liquid to a slightly turbid liquid.

[0085] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0086] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred and reacted at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -5° C. refrigerator. After five days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.77 g of Ba(TMHD)2(TMCYC) in the form of a white powder, with a yield of 75.9%.

[0087] like Figure 2 As shown, the barium complex Ba(TMHD)2(TMCYC) prepared in this example is characterized by infrared absorption spectrum, wherein the vibration peaks corresponding to different groups are as follows: ν(CH3, CH2): 2946cm -1 、2897cm -1 、2850cm -1 、2827cm -1 ;δ(CN):1625cm -1 ; ν(CO):1585cm -1 、1571cm-1 ; ν(CC):1550cm -1 ;ν(CO)+ν(CC)+ν(CH):1503cm -1 ; ν(CC)+ν(CH):1429cm -1 ; ν[C-(CH3)3]+δ(CC):1304m -1 、1276cm -1 、1225cm -1 ; ν[C-(CH3)3]+δ(CH):1178cm -1 ; ν[C-(CH3)3]+ν(CO):1030cm -1 、970cm -1 、931cm -1 ;ν[C-(CH3)3]+ν(CCO)+ν(Ba-O):896cm -1 、862cm -1 、788cm -1 、776cm -1 、748cm -1 、730cm -1 ; ν(Ba-O):591cm -1 、466cm -1 In addition, the purity of the barium complex was determined by organic element analysis (theoretical values ​​are in brackets), and the results were as follows: C: 55.89 (55.77), H: 8.72 (9.09) and N: 7.43 (7.65), indicating that it has a high purity.

[0088] Example 4

[0089] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(N3), the barium complex includes a barium metal complex and a 1,4,7-triazacyclononane auxiliary ligand (referred to as N3), and the structural formula of the 1,4,7-triazacyclononane auxiliary ligand is shown in Formula C:

[0090]

[0091] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0092] (1) In a 250 mL three-necked flask with an air inlet, 1.22 g of barium chloride dihydrate and 0.72 g of 1,4,7-triazacyclononane were added in sequence, and then 50 mL of ultrapure water was added. The mixture was stirred for 6 h until the solution changed from a clear liquid to a slightly turbid liquid.

[0093] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0094] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -5° C. refrigerator. After five days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.40 g of Ba(TMHD)2(N3) in the form of a white powder, with a yield of 76.2%.

[0095] The chemical structure of the barium complex Ba(TMHD)2(N3) prepared in this example is characterized by infrared absorption spectrum, where the vibration peaks corresponding to different groups are as follows: ν(-NH): 3260cm -1 ; ν(CH3, CH2):2953cm -1 、2863cm -1 ;δ(-NH2):1596cm -1 ; ν(CO):1588cm -1 、1577cm -1 ; ν(CC):1556cm -1 ;ν(CO)+ν(CC)+ν(CH):1521cm -1 ; ν(CC)+ν(CH):1426cm -1 ; ν[C-(CH3)3]+δ(CC):1301cm -1 、1245cm -1 、1226cm -1 ; ν[C-(CH3)3]+δ(CH):1198cm -1 ; ν[C-(CH3)3]+ν(CO):1029cm -1 、978cm -1 、936cm -1 ;ν[C-(CH3)3]+ν(CCO)+ν(Ba-O):816cm -1 、789cm -1 、750cm -1 、736cm -1 ; ν(Ba-O):598cm-1 、471cm -1 In addition, the purity of the barium complex is determined by organic element analysis (theoretical values ​​are in brackets), and the results are as follows: C: 53.02 (53.12), H: 8.55 (8.44) and N: 6.52 (6.44), indicating that it has a high purity.

[0096] Example 5

[0097] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(N5), the barium complex includes a barium metal complex and a 1,4,7,10,13-pentaazacyclopentadecane auxiliary ligand (referred to as N5), and the structural formula of the 1,4,7,10,13-pentaazacyclopentadecane auxiliary ligand is shown in Formula D:

[0098]

[0099] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0100] (1) In a 250 mL three-necked flask with an air inlet, 1.22 g of barium chloride dihydrate and 1.18 g of 1,4,7,10,13-pentaazacyclopentadecane were added in sequence, and then 50 mL of ultrapure water was added. The mixture was stirred for 6 h until the solution changed from a clear liquid to a slightly turbid liquid.

[0101] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0102] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -5° C. refrigerator. After five days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.75 g of Ba(TMHD)2(N5) in the form of a white powder, with a yield of 76.8%.

[0103] The chemical structure of the barium complex Ba(TMHD)2(N5) prepared in this example was characterized by infrared absorption spectrum, where the vibration peaks corresponding to different groups are as follows: ν(-NH): 3270 cm -1 ; ν(CH3, CH2):2965cm-1 、2861cm -1 ;δ(-NH2):1608cm -1 ; ν(CO):1590cm -1 、1578cm -1 ; ν(CC):1563cm -1 ;ν(CO)+ν(CC)+ν(CH):1521cm -1 ; ν(CC)+ν(CH):1441cm -1 ; ν[C-(CH3)3]+δ(CC):1301cm -1 、1255cm -1 、1227cm -1 ; ν[C-(CH3)3]+δ(CH):1192cm -1 ; ν[C-(CH3)3]+ν(CO):1028cm -1 、979cm -1 、936cm -1 ;ν[C-(CH3)3]+ν(CCO)+ν(Ba-O):818cm -1 、790cm -1 、762cm -1 、735cm -1 ; ν(Ba-O):601cm -1 、475cm -1 In addition, the purity of the barium complex was determined by organic element analysis (theoretical values ​​are in brackets), and the results were as follows: C: 53.62 (53.44), H: 8.71 (8.83) and N: 9.62 (9.74), indicating that it has a high purity.

[0104] Example 6

[0105] This embodiment provides a barium complex, the chemical formula of the barium complex is Ba(TMHD)2(N6), the barium complex includes a barium metal complex and a 1,4,7,10,13,16-hexaazacyclooctadecane auxiliary ligand (referred to as N6), and the structural formula of the 1,4,7,10,13,16-hexaazacyclooctadecane auxiliary ligand is shown in Formula E:

[0106]

[0107] This embodiment also provides a method for preparing the above-mentioned barium complex, which comprises the following steps:

[0108] (1) In a 250 mL three-necked flask with an air inlet, add 1.22 g of barium chloride dihydrate and 1.42 g of 1,4,7,10,13,16-hexaazacyclooctadecane in sequence, and then add 50 mL of ultrapure water. Stir for 6 h until the solution changes from a clear liquid to a slightly turbid liquid;

[0109] (2) 1.84 g of 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD) was dissolved in 20 mL of ethanol, and a 50 wt% sodium hydroxide solution was added dropwise to neutralize the system to a pH value of 7.5, and stirred until the solution was clear;

[0110] (3) Nitrogen was introduced into the three-necked flask in step (1), and the mixed solution containing TMHD and sodium hydroxide in step (2) was slowly added dropwise to the three-necked flask through a dropping funnel under a nitrogen atmosphere, and the mixture was stirred at 75° C. for 16 h. The mixed solution was then filtered, and the filtered white solid was placed in a vacuum drying oven at 55° C. for 12 h, and the dried white powder was dissolved in 50 mL of n-pentane and placed in a -5° C. refrigerator. After five days, a large amount of colorless crystals were precipitated, filtered, placed in a vacuum drying oven at 50° C. for 12 h, and crushed to obtain 2.89 g of Ba(TMHD)2(N6) in the form of a white powder, with a yield of 76.1%.

[0111] The chemical structure of the barium complex Ba(TMHD)2(N6) prepared in this example is characterized by infrared absorption spectrum, where the vibration peaks corresponding to different groups are as follows: ν(-NH): 3255 cm -1 ; ν(CH3, CH2):2955cm -1 、2868cm -1 ;δ(-NH2):1618cm -1 ; ν(CO):1592cm -1 、1580cm -1 ; ν(CC):1566cm -1 ;ν(CO)+ν(CC)+ν(CH):1527cm -1 ; ν(CC)+ν(CH):1449cm -1 ; ν[C-(CH3)3]+δ(CC):1306cm -1 、1260cm -1 、1231cm -1 ; ν[C-(CH3)3]+δ(CH):1201cm -1 ; ν[C-(CH3)3]+ν(CO):1032cm -1 、981cm -1 、942cm -1;ν[C-(CH3)3]+ν(CCO)+ν(Ba-O):820cm -1 、791cm -1 、763cm -1 、742cm -1 ; ν(Ba-O):593cm -1 、478cm -1 In addition, the purity of the barium complex is determined by organic element analysis (theoretical values ​​are in brackets), and the results are as follows: C: 53.12 (52.97), H: 8.79 (8.89) and N: 11.02 (11.23), indicating that it has a high purity.

[0112] Comparative Example 1

[0113] This comparative example provides a commercially available Ba(TMHD)2·xH2O. After elemental analysis, it is determined to be Ba(TMHD)2·2H2O, and the results are as follows (theoretical values ​​are in brackets): C: 48.82 (48.97), H: 7.75 (7.84).

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 1 is that cyclopentane is replaced with tetraethylenepentamine of the same content, and the rest is the same as Example 1. The obtained complex does not contain N element after elemental analysis, and the elemental analysis results are basically consistent with Ba(TMHD)2·2H2O, and the results are as follows (theoretical values ​​in brackets): C: 48.72 (48.97), H: 7.92 (7.84) and N: 0 (0). It shows that tetraethylenepentamine cannot synthesize barium organic complexes with tetraethylenepentamine as auxiliary ligands in an aqueous solution system. The results of various tests of this comparative example 2 and comparative example 1 are the same.

[0116] Test conditions

[0117] The barium organic complexes obtained in Examples 1 to 6 and Comparative Examples 1 to 2 were subjected to performance tests, and the test method was as follows:

[0118] (1) Infrared spectrum test: Fourier transform infrared spectrometer is used for testing.

[0119] (2) Thermogravimetric analysis: The test was performed using a synchronous thermal analyzer STA 449F3 in an argon atmosphere with a heating rate of 10°C / min and a gas flow rate of 50 mL / min.

[0120] (3) Saturated vapor pressure:

[0121] At temperature T (unit K) and in a slow inert gas flow, a thermogravimeter is used to measure the mass loss of the sample in a certain period of time to obtain its evaporation rate. Then, based on the reference material and the Langmuir equation (see the following equation) which is widely accepted in the free evaporation theory, a standard curve is first established to determine logP T For the slope (s) and intercept b of the evaporation rate function line, a standard curve was established using the standard substance benzoic acid, and then the saturated vapor pressure of the barium complex was determined using the same experimental conditions.

[0122]

[0123] P T : Vapor pressure at a certain temperature;

[0124] s:logP T The slope of the log(dm / dt / a)T function line;

[0125] (dm / dt / a): evaporation rate, where a is the crucible bottom area;

[0126] b is the intercept of the line.

[0127] The test results are shown in Table 1:

[0128] Table 1

[0129] Yield (%) Initial volatilization temperature (℃) Example 1 75.6 255 Example 2 77.4 255 Example 3 75.9 245 Example 4 76.2 275 Example 5 76.8 295 Example 6 76.1 305 Comparative Example 1 / 320 Comparative Example 2 / 320

[0130] As can be seen from the data in Table 1, the present invention selects a neutral nitrogen heterocyclic chelate ligand with abundant coordination sites as an auxiliary ligand, so that the neutral nitrogen heterocyclic chelate ligand can produce a strong coordination effect with the barium ion, thereby forming a stable barium complex. Even under high temperature conditions, the neutral nitrogen heterocyclic chelate ligand can still remain in an undissociated state, and finally effectively inhibits the agglomeration of barium ions, thereby significantly improving the volatility of the barium complex. In addition, the barium complex provided by the present invention can still maintain sufficient saturated vapor pressure at a relatively low temperature, which is more conducive to achieving an efficient and stable chemical vapor deposition process.

[0131] like Figure 3As shown, the present invention tests the thermogravimetric analysis curves of Ba(TMHD)2(CYC)(H2O), Ba(TMHD)2(TMCYC) and Ba(TMHD)2·xH2O, and the test conditions are in an argon atmosphere, a heating rate of 10°C / min, and a gas flow rate of 50mL / min. Comparing the thermogravimetric analysis curves corresponding to Ba(TMHD)2(CYC)(H2O and Ba(TMHD)2·xH2O, it can be seen that: Ba(TMHD)2(CYC)(H2O) not only has a much lower initial volatilization temperature than Ba(TMHD)2·xH2O, but also has a higher volatilization rate than Ba(TMHD)2·xH2O, that is, up to 80%. Comparing the thermogravimetric analysis curves of Ba(TMHD)2(TMCYC) and Ba(TMHD)2·xH2O, we can see that the initial volatilization temperature of Ba(TMHD)2(TMCYC) is not only much lower than that of Ba(TMHD)2·xH2O, but also the volatilization rate is higher than that of Ba(TMHD)2·xH2O, that is, as high as 84%. Figure 4 As shown in Figure 3, by comparing the change curves of the saturated vapor pressure of Ba(TMHD)2(CYC)(H2O), Ba(TMHD)2(TMCYC) and Ba(TMHD)2·xH2O at different temperatures, it can be seen that at 350°C, Ba(TMHD)2(TMCYC) and Ba(TMHD)2(CYC)(H2O) can still produce a relatively high saturated vapor pressure, which is more than twice that of Ba(TMHD)2·xH2O at the same temperature.

[0132] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A barium complex, characterized in that The barium complex comprises barium ions, anionic ligands and auxiliary ligands, wherein the anionic ligands comprise beta-diketone ligands, and the auxiliary ligands comprise neutral nitrogen heterocyclic ligands.

2. The barium complex according to claim 1, characterized in that The structure of the β-diketone ligand is shown in Formula I: Among them, R A , R B Each is independently selected from at least one of a methyl group, an alkoxy group, a trifluoromethyl group and a tert-butyl group.

3. The barium complex according to claim 2, characterized in that The anionic ligand is 2,2,6,6-tetramethyl-3,5-heptanedione.

4. The barium complex according to claim 1, characterized in that The neutral nitrogen heterocyclic ligand includes at least one of the 1,4,7-triazacyclononane ligand shown in formula II, the 1,4,7,10-tetraazacyclododecane ligand shown in formula III, the 1,4,7,10,13-pentazacyclopentadecane ligand shown in formula IV, or the 1,4,7,10,13,16-hexaazacyclooctadecane ligand shown in formula V: Wherein, R1, R2, R3, R4, R5 and R6 are each independently selected from at least one of a hydrogen atom, an alkyl group or an alkoxy group.

5. The barium complex according to claim 4, characterized in that The neutral nitrogen heterocyclic ligand is any one of cyclopentane or 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, or a combination of at least two thereof.

6. The barium complex according to claim 4, characterized in that The chemical formula of the barium complex is Ba(L1)2(L2)(H2O) m , wherein L1 is a β-diketone ligand, L2 is a 1,4,7,10-tetraazacyclododecane ligand, and m is 0 or 1.

7. The barium complex according to any one of claims 1 to 6, characterized in that The saturated vapor pressure of the barium complex at 350° C. is higher than 4000 Pa.

8. A method for preparing the barium complex according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: The first solution containing anionic ligands is mixed with the second solution containing barium metal salt and auxiliary ligands, and the barium complex is obtained after reaction.

9. The method according to claim 8, characterized in that The pH value of the first solution containing anionic ligands is 7-8; Preferably, the first solution containing anionic ligands comprises anionic ligands and an organic solvent; Preferably, the amount of substance of the anionic ligand is twice the amount of substance of the barium metal salt; Preferably, the mass volume ratio of the anionic ligand to the organic solvent is 1 g:10 mL; Preferably, the second solution containing barium metal salt and auxiliary ligand is an aqueous solution containing barium metal salt and auxiliary ligand; Preferably, the molar ratio of the barium metal salt to the auxiliary ligand is 1:(1.1-1.2); Preferably, the mass volume ratio of the auxiliary ligand to water is 1 g:50 mL; Preferably, the mixing process comprises dropping a first solution containing anionic ligands into a second solution containing barium metal salt and auxiliary ligands; Preferably, the mixing is carried out under an inert atmosphere; Preferably, the reaction temperature is 60°C-80°C; Preferably, the reaction time is 12h-18h; Preferably, the reaction is carried out under an inert atmosphere; Preferably, the reaction further includes a purification process.

10. Use of the barium complex according to any one of claims 1 to 7, characterized in that: The barium complex is used for preparing electronic thin film materials or superconducting thin film materials.

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