CN104941539B - Preparation method of perovskite type composite oxide nanocrystal adhesive - Google Patents
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Abstract
The invention relates to a preparation method of perovskite type composite oxide nanocrystal adhesive, which is represented by the following general formula (a): ba1‑xMxTi1‑yNyO3+z(a) (ii) a In the general formula (a), x is more than or equal to 0 and less than 1, y is more than or equal to 0 and less than 1, and z is an oxygen excess part; m is at least one of alkaline earth metal elements, rare earth elements, VIIB group elements and VIII group elements; n is at least one of IVB group elements, VIIB group elements and VIII group elements; the preparation method of the nano-crystal glue represented by the general formula (a) is that various metal organic sources are dissolved in alcohol solvent to form transparent solution, and various perovskite type composite oxides are synthesized by adopting a self-aggregation technology under the condition of near room temperature and static state. The nano particles synthesized by the preparation method have excellent monodispersity, and can be dispersed into a polar solvent to form a high-stability nano colloidal solution without the help of a surface ligand.
Description
Technical Field
The invention relates to a preparation method of perovskite type composite oxide nanocrystal adhesive, belonging to the field of composite oxide manufacturing.
Background
With the trend of miniaturization and high integration, complex multi-component oxides represented by perovskites have great application potential in various aspects such as energy, electronics and biomedical imaging, and especially monodisperse ferroelectric phase perovskites type oxide nanocrystals having high polarizability at the nanoscale (below 20 nm) are receiving great attention. Monodisperse nanocrystals serve as the basic "building block", on the one hand allowing the production of multifunctional ordered structures by means of their self-assembly. On the other hand, it can be uniformly dispersed in other media such as various polymers, liquid crystal phases or carbon materials to form multifunctional stable colloidal solutions. Another advantage of monodisperse colloidal nanocrystals is printability. Since the building units are fully crystallized and form stable colloidal solutions, it can be directly applied to various low-temperature liquid phase processing techniques, such as spray coating, spin coating or ink-jet printing (including 3D printing), and is particularly advantageous for material processing on flexible substrates and the construction of flexible devices. The monodisperse composite oxide nanoparticles are not only beneficial to researching physical and chemical properties related to size, but also have good controllability, and can conveniently integrate nanocrystals into various electronic, optical, mechanical or biomedical devices. In addition, nanocrystals with different compositions and properties can self-assemble into superlattices (such as ferromagnetic and ferroelectric), exhibiting new functions and applications.
Barium titanate (BaTiO)3) And various doped or substituted derivative compounds thereof are the most valuable and widely researched perovskite materials, and are widely applied to memories, infrared detection, energy storage and conversion (such as solar cells, fuel cells, energy storage capacitors, nano-generators and the like) and biomedical imaging due to the excellent ferroelectric, piezoelectric, thermoelectric and high dielectric properties of the perovskite materials. From the synthesis angle, monodisperse BaTiO less than 20nm3The synthesis method of (2) is not many, and the mass synthesis production can be carried out less.
The synthesis of monodisperse nanocrystals based on solution processes allows for good control of the process from reaction of the precursor to the final product, and thus is widely used. The synthesis of monodisperse barium titanate nanocrystals is currently generally carried out under solvothermal/hydrothermal conditions or at high pH values (pH)>13) Under the condition and at the reaction temperature of 130-200 ℃. Meanwhile, in order to obtain highly dispersed nanoparticles, it is generally necessary to introduce an alkyl acid, a polymer or a surfactant having a surface ligand function to stabilize the nanoparticles against aggregation therebetween. For example, the Liyadona group at Beijing university adopts a 'liquid-solid-solution phase' method to synthesize BaTiO taking Octadecenoic Acid (OA) as a surface active ligand3The nano particles can be well dispersed in a non-polar solvent. BaTiO taking polyvinylpyrrolidone (PVP) as surface ligand is synthesized by the Wang Xiaohui and Lilongtu group of Qinghua university3And SrTiO3Nanoparticles can be stably present in the solvent. In addition, due to the high stability of the synthesized nanoparticles, cumbersome high speed centrifugation collection and consumption of large amounts of solvent are often required for collection and purification of the nanocrystals. At present, there are few methods for synthesizing nanocrystalline colloidal solutions that are stable and free of surface ligands. Recently, the group d.e. morse at the university of san babara, ca, usa and Brutchey at university of southern californiaThe panel reported a combination of acidic water vapor (HCl/H)2O) as catalyst to diffuse into the gas-liquid interface of bimetallic alkoxide solution to induce hydrolysis to prepare BaTiO below 10nm3The method of nanocrystals, and the method disclosed in Nature journal, can be further scaled up to a scale that can produce 250 grams at a time. But the complex kinetic control during synthesis and the diffusion and corrosiveness of acid gases may further limit their large scale production.
Disclosure of Invention
The invention aims to solve the technical problem of providing a preparation method of perovskite type composite oxide nano-crystal glue which has simple preparation steps and easy operation, and the perovskite type composite oxide nano-crystal glue prepared by the method has high purity and better crystallinity and dispersibility.
The technical scheme adopted by the invention for solving the first technical problem is as follows: a method for preparing a perovskite-type composite oxide nanocrystal gel, which is represented by the following general formula (a):
Ba1-xMxTi1-yNyO3+z(a)
in the general formula (a), x is more than or equal to 0 and less than 1, y is more than or equal to 0 and less than 1, and z is an oxygen excess part;
m is at least one of alkaline earth metal elements, rare earth elements, VIIB group elements and VIII group elements;
n is at least one of IVB group elements, VIIB group elements and VIII group elements;
the preparation method of the perovskite type composite oxide nanocrystal adhesive represented by the general formula (a) comprises the following steps:
(1) respectively providing an M source, a barium source, an N source and a titanium source;
the M source is an organic alkoxide or acetylacetone salt of M;
the barium source is barium organic alkoxide;
the N source is N organic alkoxide or acetylacetone salt;
the titanium source is organic alkoxide of titanium;
(2) under the protection of inert gas, dissolving an M source, a barium source, an N source and a titanium source in a water-containing alcohol solvent according to the atomic ratio in the general formula (a) to prepare a transparent mixture, and standing the transparent mixture in an environment at 15-70 ℃ to prepare the nanocrystal adhesive shown in the general formula (a). Standing for 15-70 ℃ to ensure that a gel-like solid is generated, wherein the generated gel-like solid is the nanocrystal adhesive shown in the general formula (a).
The perovskite type composite oxide comprises two main types, wherein the first type is BaTiO3Based on various doped or substituted oxides, e.g. Ba (La, Sr) Ti (Hf) O3) (ii) a The second main group is other barium-containing or titanium-containing composite oxides. The above-mentioned production method is a production method of the above-mentioned first large-class composite perovskite-type composite oxide. Wherein, when M is rare earth element, it refers to p-BaTiO3Is rare earth doped, e.g. Ba (La) TiO rare earth doped Ba3(ii) a When M is an alkaline earth metal element, it refers to p-BaTiO3Is partially substituted, e.g. Ba (Sr) TiO partially Sr substituted for Ba3(ii) a N is then to BaTiO3By partial substitution of Ti of, e.g. BaTi (Hf) O3. When x is 0 and y is 0 in the above formula (a), the formula (a) actually represents BaTiO3。
Preferably, in the general formula (a), M is La, Nd, Sm, Gd, Y, Sr, Mn, Fe, Co or Ni;
preferably, N is Hf, Zr, Mn, Fe, Co or Ni;
preferably, in the step (2), the inert gas is nitrogen;
preferably, in the step (2), the M source, the barium source, the N source and the titanium source are dissolved in an aqueous alcohol solvent at room temperature to prepare a transparent mixture;
preferably, in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol;
preferably, in the step (2), the volume percentage of water in the transparent mixture is 1-10%, such as 2%, 3%, 5%, 7%, 8%;
preferably, in the step (2), the molar concentration of the barium source or the titanium source in the transparent mixture is 0.05-0.12 mol/L, such as 0.06mol/L, 0.08mol/L, 0.09mol/L, 0.10mol/L, 0.11 mol/L;
preferably, in the step (2), the transparent mixture is first stood and aged, and then the aged transparent mixture is stood in an environment of 15 to 70 ℃, for example, 20 ℃, 23 ℃, 25 ℃, 30 ℃, 35 ℃, 38 ℃, 40 ℃, 45 ℃, 48 ℃, 50 ℃, 55 ℃, 60 ℃ and 65 ℃;
preferably, in the step (2), the aging temperature is room temperature, and the aging time is 4-12 hours, such as 5 hours, 8 hours, 10 hours, and 11 hours;
preferably, in the step (1), the M source is an organic alkoxide of an alkaline earth metal element, an acetylacetonate of a rare earth element, an acetylacetonate of a group VIIB element or an acetylacetonate of a group VIII element;
preferably, in the step (1), the N source is an organic alkoxide of a group IVB element, an acetylacetone salt of a group VIIB element, or an acetylacetone salt of a group VIII element;
preferably, in the step (1), the organic alkoxide is one of isopropoxide, n-butoxide and ethoxide of the corresponding metal.
A method for preparing a perovskite-type composite oxide nanocrystal gel, which is represented by the following general formula (b):
ATiO3(b)
in the general formula (b), A is one of VIIB group elements, VIII group elements or rare earth elements;
the preparation method of the perovskite type composite oxide nanocrystal adhesive represented by the general formula (b) comprises the following steps:
(1) respectively providing an A source and a Ti source;
wherein the source A is acetylacetone salt of A, and the source Ti is organic alkoxide of Ti;
(2) under the protection of inert gas, dissolving A source and Ti source in water-containing alcohol solvent according to each atomic ratio in the general formula (b) to prepare transparent mixture, and standing the transparent mixture in an environment of 15-70 ℃, such as 20 ℃, 23 ℃, 25 ℃, 30 ℃, 35 ℃, 38 ℃, 40 ℃, 45 ℃, 48 ℃, 50 ℃, 55 ℃, 60 ℃ and 65 ℃ to prepare the nanocrystal adhesive shown in the general formula (b).
The preparation method is to one of the second major perovskite type composite oxides, namely to BaTiO3With total substitution of Ba, e.g. MnTiO3、NdTiO3、SmTiO3、GdTiO3、YTiO3And the like.
Preferably, in the general formula (b), A is Mn, Fe, Co, Ni, Nd, Sm, Gd or Y;
preferably, in the step (2), the inert gas is nitrogen;
preferably, in the step (2), the A source and the Ti source are dissolved in an aqueous alcohol solvent at room temperature to prepare a transparent mixture;
preferably, in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol;
preferably, in the step (2), the volume percentage of water in the transparent mixture is 1-10%, such as 2%, 3%, 5%, 7%, 8%;
preferably, in the step (2), the molar concentration of the titanium source in the transparent mixture is 0.05-0.12 mol/L L, such as 0.06mol/L, 0.08mol/L, 0.09mol/L, 0.10mol/L, 0.11 mol/L;
preferably, in the step (2), the transparent mixture is firstly kept stand and aged, and then the aged transparent mixture is kept stand in an environment at 15-70 ℃;
preferably, in the step (2), the aging temperature is room temperature, and the aging time is 4-12 hours, such as 5 hours, 8 hours, 10 hours, and 11 hours;
preferably, in the step (1), the Ti source is one of an isopropoxide, an n-butoxide and an ethoxide of Ti.
A method for producing a perovskite-type composite oxide nanocrystal gel, characterized in that the perovskite-type composite oxide nanocrystal gel is represented by the following general formula (c):
BaBO3(c)
in the general formula (c), B is one of VIIB elements;
the preparation method of the perovskite type composite oxide nanocrystal adhesive represented by the general formula (c) comprises the following steps:
(1) respectively providing a Ba source and a B source;
wherein, Ba source is organic alkoxide of Ba, B source is acetylacetone salt of B;
(2) dissolving a Ba source and a B source in an aqueous alcohol solvent according to each atomic ratio in the general formula (c) under the protection of inert gas to prepare a transparent mixture, and standing the transparent mixture in an environment of 15-70 ℃ to prepare the nanocrystal adhesive shown in the general formula (c), wherein the nanocrystal adhesive is prepared by 20 ℃, 23 ℃, 25 ℃, 30 ℃, 35 ℃, 38 ℃, 40 ℃, 45 ℃, 48 ℃, 50 ℃, 55 ℃, 60 ℃ and 65 ℃.
The above preparation method is directed to another case of the above second major perovskite-type composite oxide, i.e., B to BaTiO3By total substitution of Ti, e.g. BaMnO3And the like.
Preferably, in the general formula (c), B is Mn;
preferably, in the step (2), the inert gas is nitrogen;
preferably, in step (2), the Ba source and the B source are dissolved in an aqueous alcoholic solvent at room temperature to prepare a transparent mixture;
preferably, in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol;
preferably, in the step (2), the volume percentage of water in the transparent mixture is 1-10%, such as 2%, 3%, 5%, 7%, 8%;
preferably, in the step (2), the molar concentration of the barium source in the transparent mixture is 0.05-0.12 mol/L, such as 0.06mol/L, 0.08mol/L, 0.09mol/L, 0.10mol/L, 0.11 mol/L;
preferably, in the step (2), the transparent mixture is firstly kept stand and aged, and then the aged transparent mixture is kept stand in an environment at 15-70 ℃;
preferably, in the step (2), the aging temperature is room temperature, and the aging time is 4-12 hours, such as 5 hours, 8 hours, 10 hours, and 11 hours;
preferably, in the step (1), the Ba source is one of isopropoxide, n-butoxide and ethoxide of Ba.
Preferably, step (3) is further included after step (2), and the nano-crystal colloid prepared in step (2) is dispersed into a polar solvent to prepare a perovskite composite oxide nano-crystal colloid solution.
Preferably, the nanocrystal gel is dispersed into a polar solvent by an ultrasonic cleaner because the nanocrystal gel has high dispersibility.
Preferably, the polar solvent is one or a mixture of at least two of ethanol, furfuryl alcohol and dimethylformamide.
Preferably, in the perovskite composite oxide nanocrystal colloidal solution, the concentration of the nanocrystal glue is 10-60 mg/mL.
The invention provides a self-aggregation technology, namely a green technology for synthesizing high-purity perovskite type composite oxide nano-crystals and stable colloidal solution thereof under the conditions of low temperature, static state and no surfactant. Compared with the prior art, the technology has the advantages that:
(1) the method adopts high-activity organic metal alkoxide or acetylacetone salt with moderate price as a reaction raw material, and does not add any surfactant, surface ligand or high molecular dispersant or any strong-alkaline inorganic mineralizer (such as KOH, NaOH and the like) except simple solvent alcohol (such as ethanol or isopropanol), thereby simplifying the reaction and reducing the introduction of reaction impurities. The preparation method can obtain high-purity BaTiO by 100 percent conversion3The perovskite type composite oxide product has no interference of surface ligand, surfactant or other inorganic cation impurities, and the only by-product is solvent, such as isopropanol, which can be reused as solvent together with reaction solvent, such as ethanol;
(2) under the condition of static state and near room temperature, the self-aggregation of the nano-crystals is induced by controlling the hydrolysis of the metal alkoxide, the product is integrally separated from the reaction system, the device and the steps for synthesizing are greatly simplified, the separation and the purification of the product are simplified, and the nano-particles are not required to be collected by a high-speed centrifugation method, so that the synthesis efficiency and the yield are improved, and the final yield is close to 100%. Meanwhile, the solvent can be recycled, the possibility is provided for green synthesis with low energy consumption and low emission, and the method can be applied to large-scale synthesis development;
(3) the synthesized nano particles have high crystallinity and excellent dispersibility, can be well dispersed in various solvents or media without the aid of a surfactant, a dispersing agent or high-energy grinding, and can be dispersed into a polar solvent to form a high-stable nano colloidal solution without the aid of any surface ligand. On the basis, various nanocrystals with core-shell structures can be synthesized.
In conclusion, the preparation method prepares the perovskite type composite oxide nanocrystal adhesive by adopting the self-aggregation of the nanoparticles, and particularly synthesizes various perovskite type composite oxides (including BaTiO) by adopting the self-aggregation technology under the conditions of near room temperature and static state3Various types of substitution or doping on a base) of the nanocrystal paste. By selecting a proper metal organic precursor and an alcohol solvent and inducing the self-aggregation capability of the nanoparticles under proper reaction conditions, the synthesis steps are simplified, the separation and the purification are simplified, the synthesis efficiency and the yield (nearly 100 percent) can be greatly improved, the use of the solvent is reduced, and the method can be applied to large-scale synthesis and development as a green synthesis method. The synthesized nano particles have excellent monodispersity, and can be well dispersed in various solvents or media to form various high-stability nano particle colloidal solutions without the help of surface ligands, dispersing agents or high-energy grinding. They can be directly applied to various low-temperature liquid phase processing techniques such as spray coating, spin coating or ink jet printing (including 3D printing), and are particularly advantageous for material processing on flexible substrates and the construction of flexible devices.
Drawings
FIG. 1 is a nanocrystalline colloidal solution prepared by dissolving nanocrystals of example 1 in ethanol and furfuryl alcohol, respectively;
FIG. 2 is a transmission electron micrograph of nanoparticles prepared in example 1;
FIG. 3 is a graph of the change in volume over time at different temperatures for the white gel produced in example 3;
FIG. 4 is a graph showing the effect of forming perovskite type composite oxide nanocrystal gels in examples 3, 5, 6 and 7;
fig. 5 is an XRD chart of the perovskite-type composite oxide nanocrystal paste prepared in examples 1, 3 and 4.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
Example 1: BaTiO 23Preparation of nanocrystalline gels
BaTiO3The preparation method of the perovskite type composite oxide as the most basic comprises the following steps:
(1) providing a barium source and a titanium source;
under the protection of dry nitrogen, 0.719g of metal barium was first dissolved in 32 ml of absolute ethanol to form a transparent solution, a barium source (barium ethoxide); the titanium source is titanium isopropoxide Ti (OiPr)4(ii) a Wherein, the titanium isopropoxide can be directly obtained by commercial products or by the reaction of titanium tetrachloride and isopropanol;
(2) under the protection of dry nitrogen, 1.5 ml of titanium isopropoxide Ti (OiPr) is slowly added into the barium source prepared in the step (1) in sequence under stirring4And 32 ml of a solvent, ethanol (the volume percentage of water in the solvent is about 5%). As the stirring proceeded, the solution gradually became a viscous clear solution. And removing the stirring rod, sealing the transparent solution in a closed container, and aging for 4-12 hours at room temperature. And (3) placing the aged transparent gel in an oven with the temperature of 45-55 ℃ to heat for 2-6 hours. Over time, the white block of gel solid formed a monolithic structure and separated from the solution; the final gel solid is BaTiO3A nanocrystalline glue;
(3) the block-shaped gel product obtained in step (2) can be easily dispersed into various polar solvents (alcohol solvents such as ethanol or furfuryl alcohol, or common solvents for polymers such as dimethyl formamide DMF, etc.) by an ultrasonic cleaner to obtain transparent and stable nanocrystalline colloid solution as shown in figure 1, wherein in figure 1, the solvent of a is ethanol, and the solvent of b is furfuryl alcohol. In the nano-crystalline colloidal solution, the concentration of the nano-crystalline colloidal is controllable within the range of 10-60 mg/ml. In addition, as shown in fig. 2, Transmission Electron Microscopy (TEM) analysis shows that the nano-particles of the nano-crystal glue prepared in the embodiment do not agglomerate, and have good dispersibility, and the particle size is between 7 nm and 12 nm.
Although the nanoparticles are not stable by the surfactant, the nanoparticles show high dispersibility and stability in the solvent, for example, the nanoparticles can form a high-stable transparent solution in furfuryl alcohol, and no precipitation occurs after the nanoparticles are stored for 2 years at room temperature. The furfuryl alcohol capable of being polycondensed is a good solvent and a high-molecular precursor, can be mutually dissolved with a conventional polar solvent, can well disperse oxide nanocrystals, has strong affinity and permeability, and can be polycondensed into resin with high dielectric constant and high mechanical strength under the condition of heating. The highly dispersed nanoparticles can be uniformly dispersed in other media, such as various polymers, liquid crystal phases or carbon materials to form multifunctional stable colloidal solutions, and are particularly beneficial to printable device processing, such as printing to form films with high dielectric constants for applications in LED lighting drivers, energy storage capacitors and nano-generators.
Example 2: BaTiO 23Preparation of nanocrystalline gels
BaTiO of this example3The preparation method comprises the following steps:
(1) providing a barium source and a titanium source, wherein the barium source is barium isopropoxide, and the titanium source is titanium isopropoxide; wherein, the barium isopropoxide can be directly prepared from commercial products or obtained by reacting titanium tetrachloride with isopropanol; in addition, the barium source of this embodiment may also be barium ethoxide, for example, obtained by reacting metal barium with ethanol;
(2) firstly, 1.758 g of barium isopropoxide was dissolved in 80 ml of anhydrous ethanol under a nitrogen atmosphere at room temperature to obtain a transparent solution, and 2 ml of titanium isopropoxide was slowly added dropwise while stirring to obtain a transparent solution. After 2 minutes, another 20 ml of solvent, hydrous ethanol (10% by volume of water in solvent), was slowly added to form a clear solution, at which point the volume percent of water in the solution was 2%. With stirring, the solution gradually became viscous and transparentAnd (4) gelling. And removing the stirring rod, sealing the solution in a closed container, and aging for 4-12 hours at room temperature. And (3) heating the aged transparent gel in an oven at the temperature of 45-55 ℃ for 2-6 hours. Over time, the white block of gel solid formed a monolithic structure and separated from the solution; the final gel solid is BaTiO3A nanocrystalline glue;
(3) dispersing the nanocrystal adhesive prepared in the step (2) into a polar solvent such as an alcohol solvent such as ethanol and furfuryl alcohol or a solvent for a polymer such as dimethylformamide DMF by using an ultrasonic cleaner to obtain a transparent and stable nanocrystal colloidal solution, which is specifically referred to in example 1.
BaTiO of this example3The preparation process of the nanocrystal adhesive is as follows:
according to the reaction process, the preparation method synthesizes the high-purity perovskite type composite oxide nanocrystal adhesive under the conditions of low temperature, static state and no surfactant; the self-aggregation technology of the nano particles is adopted, so that the nano particles are separated from a reaction system in an integral mode, the steps of synthesis, separation and purification are greatly simplified, and the synthesis efficiency is improved.
Example 3: ba0.65Sr0.35TiO3Preparation of nanocrystalline gels
Ba of the present embodiment0.65Sr0.35TiO3(BST, barium strontium titanate nanocrystalline) is a perovskite type composite oxide based on the synthesis of various doped or substituted barium titanates, in particular BaTiO3Wherein Ba is partially substituted by Sr.
Ba of the present embodiment0.65Sr0.35TiO3The preparation method of the nanocrystal adhesive comprises the following steps:
(1) providing a barium source, a Sr source and a titanium source, wherein the barium source is barium isopropoxide, the Sr source is strontium isopropoxide or is obtained by reacting metal strontium with isopropanol, and the titanium source is titanium isopropoxide;
(2) first, 1.150 g of barium isopropoxide and 0.487 g of strontium isopropoxide were dissolved in 80 ml of anhydrous ethanol under a nitrogen atmosphere at room temperature to prepare a transparent solution, and 2 ml of titanium isopropoxide was slowly added dropwise while stirring to prepare a transparent solution. After 2 minutes, another 20 ml of ethanol (10% by volume of water in the solvent) was slowly added to form a clear solution. In a clear solution, barium isopropoxide or Ti (OiPr)4The molar concentration of (A) is 0.05-0.12 mol/L), and the total water content is 2-10 vol%.
As the stirring proceeded, the solution gradually became a viscous transparent gel. And removing the stirring rod, sealing the transparent gel in a closed container, and aging for 4-12 hours at room temperature. And (3) heating the aged transparent gel in an oven at the temperature of 45-55 ℃ for 2-6 hours. It was found that, as shown in fig. 2, a white gelatinous solid began to appear from the solution after 1 hour; the massive white gel shrinks continuously with the time to form an integral massive white solid gel product, and simultaneously, the volume of the colorless liquid phase increases continuously. After 5 hours of reaction, the volume of the white gel did not change any more. The speed of formation of the block gel is related to the reaction temperature, and under the condition of low temperature (15 ℃), white block gel is obtained in 15-30 days. The massive solid phase product is collected and rinsed by ethanol, and the final yield can reach 99%.
(3) Referring to example 1, a transparent and stable nanocrystalline colloidal solution was also prepared.
Example 4: ba0.65Sr0.35Ti0.5Hf0.5O3Preparation of nanocrystalline gels
Ba of the present embodiment0.65Sr0.35Ti0.5Hf0.5O3(BSTH) is a perovskite type composite oxide based on the synthesis of various doped or substituted barium titanates, in particular BaTiO3Ba in the alloy is partially substituted by Sr, while Ti is partially substituted by Hf.
Ba of the present embodiment0.65Sr0.35Ti0.5Hf0.5O3Nanocrystal adhesiveThe preparation method comprises the following steps:
(1) providing a barium source, a Sr source, a titanium source and a Hf source, wherein the barium source is barium isopropoxide, the Sr source is strontium isopropoxide or is obtained by reacting metal strontium and isopropanol, the titanium source is titanium isopropoxide, and the Hf source is n-butyl alcohol hafnium (IV);
(2) under the conditions of nitrogen atmosphere and room temperature, 1.150 g of barium isopropoxide and 0.487 g of strontium isopropoxide are dissolved in 80 ml of anhydrous ethanol to form a transparent solution, and 1.542 g of hafnium n-butoxide and 1 ml of titanium isopropoxide are slowly added dropwise with stirring to form a transparent solution. After 2 minutes, another 20 ml of aqueous ethanol (10% by volume water in solvent) was slowly added to form a clear solution (in clear solution, barium isopropoxide or Ti (OiPr)4The concentration of (a): 0.05-0.12 m/L, and the total water content is 2-10 vol%). As the stirring proceeded, the solution gradually became a viscous transparent gel. The stirring bar was removed and the solution was sealed in a closed container and aged at room temperature for 4-12 hours. Placing the aged transparent gel in an oven with the temperature of 45-55 ℃ to heat for 2-6 hours for self-aggregation crystallization of the sample to prepare Ba0.65Sr0.35Ti0.5Hf0.5O3A nanocrystalline glue;
(3) referring to example 1, a transparent and stable nanocrystalline colloidal solution was also prepared.
Example 5: rare earth lanthanum doped barium titanate (Ba)0.97La0.03TiO3) Preparation of nanocrystalline gels
This example Ba0.97La0.03TiO3The preparation method comprises the following steps:
(1) providing a barium source, a titanium source and a lanthanum source, wherein the barium source is barium isopropoxide, the titanium source is titanium isopropoxide, and the lanthanum source is lanthanum acetylacetonate (La (acac)3) (ii) a Wherein, the barium isopropoxide can be obtained by reacting metal barium with isopropanol or directly used as a commercial product; in addition, the barium source of this embodiment may also be barium ethoxide, for example, obtained by reacting metal barium with ethanol;
(2) first, 1.705 g of barium isopropoxide was dissolved in 80 ml of water under a nitrogen atmosphere at room temperatureA clear solution in aqueous ethanol was slowly added dropwise, while stirring, 2 ml of titanium isopropoxide and 0.094 g of lanthanum acetylacetonate (La (acac)3) A clear solution was formed. After 2 minutes, another 20 ml of aqueous ethanol (10% by volume of water in solvent) was slowly added to form a clear solution. As the stirring proceeded, the solution gradually became a viscous transparent gel. And removing the stirring rod, sealing the solution in a closed container, and aging for 4-12 hours at room temperature. And (3) heating the aged transparent gel in an oven at the temperature of 45-55 ℃ for 2-6 hours. Over time, the white or pale yellow block of gel solids forms a monolithic structure and separates from the solution; the final gel solid was lanthanum-doped barium titanate (Ba)0.97La0.03TiO3) A nanocrystalline glue;
(3) dispersing the nanocrystal adhesive prepared in the step (2) into a polar solvent such as an alcohol solvent such as ethanol and furfuryl alcohol or a solvent for a polymer such as dimethylformamide DMF by using an ultrasonic cleaner to obtain a transparent and stable nanocrystal colloidal solution, which is specifically referred to in example 1.
Example 6: MnTiO 23Preparation of nanocrystalline gels
Unlike examples 1 to 5, MnTiO of this example3Is another type of perovskite type composite oxide, i.e. other barium-or titanium-containing composite oxides, in particular BaTiO3Wherein Ba is completely substituted by Mn.
MnTiO of the present embodiment3The preparation process is as follows:
(1) providing a Mn source and a titanium source, wherein the Mn source is manganese acetylacetonate (Mn (acac)2) The titanium source is titanium isopropoxide (Ti (OiPr)4)；
(2) 1.742 g of manganese acetylacetonate was dissolved in 80 ml of absolute ethanol, and 2 ml of titanium isopropoxide was slowly added dropwise with stirring to form a transparent solution. After 2 minutes, another 20 ml of aqueous ethanol (10% by volume of water in solvent) was slowly added to form a clear solution. Sealing the transparent solution in a reaction kettle, and heating in an oven at 55 ℃ for 12-24 hours;
(3) referring to example 1, a transparent and stable nanocrystalline colloidal solution was also prepared.
Example 7: NdTiO 23Preparation of nanocrystalline gels
Unlike examples 1 to 5, NdTiO according to this example3Is another type of perovskite type composite oxide, i.e. other barium-or titanium-containing composite oxides, in particular BaTiO3Wherein Ba is completely substituted by Nd. NdTiO of this embodiment3The preparation process is as follows:
(1) providing an Nd source and a titanium source, wherein the Nd source is neodymium acetylacetonate, and the titanium source is titanium isopropoxide;
(2) the preparation process can refer to example 6, except that: the manganese acetylacetonate is replaced by neodymium acetylacetonate, and the mass of the neodymium acetylacetonate correspondingly changes according to the relative molecular mass of the neodymium acetylacetonate;
(3) referring to example 1, a transparent and stable nanocrystalline colloidal solution was also prepared.
The solvent in the above examples 1 to 7, i.e., ethanol in the hydrous ethanol, may be replaced by methanol or isopropanol, or a mixture of at least two of methanol, ethanol and isopropanol, as long as the precursors of various metals can be dissolved.
From the above examples 1 to 7, it can be seen that nanoparticles that are easy to separate and purify can be synthesized by self-aggregation under static and moderate temperature conditions by using different metal organic salts, such as organic alkoxide and acetylacetone salt, as raw materials for the reaction. Perovskite-type composite oxide nanoparticles synthesized by the self-aggregation technique in the above examples are shown in fig. 4, and Ba prepared in example 3 is sequentially provided from left to right0.7Sr0.3TiO3Nanocrystal paste, Ba prepared in example 50.97La0.03TiO3Nanocrystal paste, MnTiO prepared in example 63Nanocrystalline paste and NdTiO prepared in example 73A nanocrystal glue. Further, it was confirmed by X-ray diffraction analysis (XRD) that the products obtained in examples 1 to 1 were highly crystalline and highly pure perovskite-type composite oxides, and as shown in FIG. 5, the X-ray diffraction patterns in FIG. 5 were aligned in order from top to bottomThe products of example 4, example 1 and example 3 should be addressed.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (20)
1. A self-assembly synthesis method of perovskite type composite oxide nanocrystal adhesive is characterized in that the perovskite type composite oxide nanocrystal adhesive is represented by the following general formula (a):
Ba1-xMxTi1-yNyO3+z(a)
in the general formula (a), x is more than or equal to 0 and less than 1, y is more than or equal to 0 and less than 1, and z is an oxygen excess part;
m is La, Nd, Sm, Gd, Y, Sr, Mn, Fe, Co or Ni;
n is Hf, Zr, Mn, Fe, Co or Ni;
the self-aggregation synthesis method of the perovskite type composite oxide nanocrystal gel represented by the general formula (a) comprises the following steps:
(1) respectively providing an M source, a barium source, an N source and a titanium source;
the M source is an organic alkoxide or acetylacetone salt of M;
the barium source is barium organic alkoxide;
the N source is N organic alkoxide or acetylacetone salt;
the titanium source is organic alkoxide of titanium;
(2) under the protection of inert gas, dissolving an M source, a barium source, an N source and a titanium source in an alcohol solvent containing water at room temperature according to the atomic ratio in the general formula (a) to prepare a transparent mixture with the water volume percentage of 1-10%, standing and aging the transparent mixture, and standing the aged transparent mixture in an environment at 15-70 ℃ to prepare the nanocrystal adhesive shown in the general formula (a);
the aging temperature is room temperature, and the aging time is 4-12 h;
and (3) dispersing the nano-crystal colloid prepared in the step (2) into a polar solvent to prepare a perovskite composite oxide nano-crystal colloid solution after the step (2).
2. The self-assembly synthesis method according to claim 1, wherein in step (2), the inert gas is nitrogen.
3. The self-aggregation synthesis method according to claim 1, wherein in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol.
4. The self-aggregation synthesis method according to claim 1, wherein in the step (2), the molar concentration of the barium source or the titanium source in the transparent mixture is 0.05 to 0.12 mol/L.
5. The self-assembly synthesis method according to claim 1, wherein in the step (1), the M source is an organic alkoxide of an alkaline earth metal element, an acetylacetonate of a rare earth element, an acetylacetonate of a group VIIB element, or an acetylacetonate of a group VIII element.
6. The self-aggregating synthesis process of claim 1, wherein in step (1), the N source is an organic alkoxide of a group IVB element, an acetylacetonate of a group VIIB element or an acetylacetonate of a group VIII element.
7. The self-aggregation synthesis method according to claim 1, wherein in the step (1), the organic alkoxide is one of isopropoxide, n-butoxide and ethoxide of the corresponding metal.
8. A self-assembly synthesis method of perovskite type composite oxide nanocrystal adhesive is characterized in that the perovskite type composite oxide nanocrystal adhesive is represented by the following general formula (b):
ATiO3(b)
in the general formula (b), A is Mn, Fe, Co, Ni, Nd, Sm, Gd or Y;
the self-aggregation synthesis method of the perovskite type composite oxide nanocrystal gel represented by the general formula (b) comprises the following steps:
(1) respectively providing an A source and a Ti source;
wherein the source A is acetylacetone salt of A, and the source Ti is organic alkoxide of Ti;
(2) under the protection of inert gas, dissolving a source A and a source Ti in an aqueous alcohol solvent at room temperature according to each atomic ratio in the general formula (b) to prepare a transparent mixture with the water volume percentage of 1-10%, standing and aging the transparent mixture, and standing the aged transparent mixture in an environment at 15-70 ℃ to prepare the nanocrystal adhesive shown in the general formula (b);
the aging temperature is room temperature, and the aging time is 4-12 h;
and (3) dispersing the nano-crystal colloid prepared in the step (2) into a polar solvent to prepare a perovskite composite oxide nano-crystal colloid solution after the step (2).
9. The self-assembly synthesis method according to claim 8, wherein in step (2), the inert gas is nitrogen.
10. The self-aggregation synthesis method according to claim 8, wherein in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol.
11. The self-aggregation synthesis method according to claim 8, wherein in the step (2), the molar concentration of the titanium source in the transparent mixture is 0.05-0.12 mol/L.
12. The self-aggregation synthesis method according to claim 8, wherein in the step (1), the Ti source is one of isopropoxide, n-butoxide and ethoxide of Ti.
13. A self-assembly synthesis method of perovskite type composite oxide nanocrystal adhesive is characterized in that the perovskite type composite oxide nanocrystal adhesive is represented by the following general formula (c):
BaBO3(c)
in the general formula (c), B is Mn;
the self-aggregation synthesis method of the perovskite type composite oxide nanocrystal gel represented by the general formula (c) comprises the following steps:
(1) respectively providing a Ba source and a B source;
wherein, Ba source is organic alkoxide of Ba, B source is acetylacetone salt of B;
(2) under the protection of inert gas, dissolving a Ba source and a B source in an aqueous alcohol solvent at room temperature according to each atomic ratio in the general formula (c) to prepare a transparent mixture with the water volume percentage of 1-10%, standing and aging the transparent mixture, and standing the aged transparent mixture in an environment at 15-70 ℃ to prepare the nanocrystal adhesive shown in the general formula (c);
the aging temperature is room temperature, and the aging time is 4-12 h;
and (3) dispersing the nano-crystal colloid prepared in the step (2) into a polar solvent to prepare a perovskite composite oxide nano-crystal colloid solution after the step (2).
14. The self-aggregating synthesis process according to claim 13, wherein in the step (2), the inert gas is nitrogen.
15. The self-aggregation synthesis method according to claim 13, wherein in the step (2), the alcohol solvent is one or a mixture of at least two of methanol, ethanol and isopropanol.
16. The self-aggregation synthesis method according to claim 13, wherein in the step (2), the molar concentration of the barium source in the transparent mixture is 0.05 to 0.12 mol/L.
17. The self-aggregation synthesis method according to claim 13, wherein in the step (1), the Ba source is one of isopropoxide, n-butoxide and ethoxide of Ba.
18. The self-aggregating synthesis process of any one of claims 1 to 17, wherein: and dispersing the nanocrystal adhesive into a polar solvent through an ultrasonic cleaner.
19. The self-aggregating synthesis process of claim 18, wherein: the polar solvent is one or a mixture of at least two of ethanol, furfuryl alcohol and dimethylformamide.
20. The self-aggregating synthesis process of claim 18, wherein: in the perovskite composite oxide nanocrystal colloidal solution, the concentration of the nanocrystal glue is 10-60 mg/mL.
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