Microfluidic equipment with three-dimensional Tesla valve structure and method for preparing ultrafine barium titanate precursor powder by using microfluidic equipment

Abstract

The invention relates to the technical field of micro-reactions, in particular to three-dimensional Tesla valve structure microfluidic equipment and a method for preparing superfine barium titanate precursor powder thereof.The three-dimensional Tesla valve structure microfluidic equipment is internally provided with a micro-channel serving as a main path, one end of the micro-channel is provided with a plurality of liquid inlets, and the other end of the micro-channel is provided with a plurality of liquid outlets; one end of the micro-channel is provided with a liquid inlet, the other end of the micro-channel is provided with a liquid outlet, the micro-channel is communicated with a plurality of three-dimensional Tesla valve structures, the three-dimensional Tesla valve structures are used as branches, the three-dimensional Tesla valve structures are formed by rotating 180 degrees by taking the micro-channel as an axis, and the rotating directions can be different. And the micro-fluidic method has natural ultrahigh mass transfer efficiency, and the barium titanate precursor synthesized by the method disclosed by the invention has an ultra-small particle size compared with the barium titanate precursor synthesized by the traditional method, and is an ideal material for subsequent preparation of tetragonal-phase barium titanate.

Description

Technical Field

[0001] The present invention relates to the field of microreaction technology, and particularly relates to a three-dimensional Tesla valve structure microfluidic device and a method for preparing ultrafine barium titanate precursor powder using the same. Background Art

[0002] Barium titanate is known as the "pillar of the electronic ceramics industry" and is one of the most widely used materials in electronic ceramics. It is mainly used to manufacture multilayer ceramic capacitors, multilayer substrates, electro-optical display panels, etc. Multilayer ceramic capacitors are widely used in communication, computer and peripheral products, consumer electronics, automotive electronics, and other information electronics fields. With the continuous development of the electronic information industry, the demand for barium titanate will also continue to grow. At the same time, in order to meet the requirements of higher-performance electronic components, higher demands will also be placed on the preparation process and performance optimization of barium titanate. Tetragonal barium titanate has better ferroelectric properties and higher application value compared to cubic barium titanate. However, synthesizing tetragonal barium titanate with a small size of ~100 nm and a uniform particle size has always been a significant challenge in the industry. The barium titanate prepared by the hydrothermal method in the laboratory has a small and uniform particle size, but the yield is very small and it is not suitable for industrial production. The tetragonal barium titanate prepared by the traditional solid-phase method has a large particle size, poor uniformity and dispersibility, and is only suitable for mass production of medium and low-end multilayer ceramic capacitor products. For high-end fine tetragonal barium titanate powder, there is currently no mature mass production method. Generally speaking, barium titanate synthesized at a low temperature below 200 degrees is either cubic or contains only a small amount of tetragonal phase. In order to completely convert barium titanate into the tetragonal phase, high-temperature calcination is required, and the barium titanate before calcination is called barium titanate precursor powder. Since calcination will cause the precursor powder to fuse and the grain size to grow, the size of the precursor powder is crucial.

[0003] A microreactor is a reaction device with a characteristic scale in the range of 5 micrometers to 10 millimeters. It has precisely designed microchannels inside and is suitable for reaction operations in multiple fields such as chemistry, chemical engineering, biology, and medicine. Compared with traditional macroreactors, microreactors have attracted increasing attention from the academic and industrial communities due to their advantages such as an extremely high surface area-to-volume ratio, low reactant consumption, and fast reaction rate.

[0004] However, the fluid in the microchannel often presents a laminar flow state, which is not conducive to the mixing and reaction processes. Therefore, the microchannel structure needs to be specially designed to enhance the mixing and reaction effects. Currently, researchers have developed a variety of passive microreactors to optimize the mixing process. For example, in a spiral microchannel, liquid is introduced from the upper part, and under the acceleration of gravity, the liquids collide with each other below to achieve mixing; in a multi-branch microreaction system, the reactants enter from the upper and lower layers respectively and mix in the middle layer, effectively shortening the reaction time and improving the mixing efficiency; and in a coiled microchannel, the actual reaction path is extended by folding the microchannel, thereby strengthening the mixing. As a classic two-dimensional planar flow structure, the Tesla valve has the characteristics of unidirectional flow and enhanced mixing. CN219356194U uses an improved double-Tesla valve structure for mixing, but this improved structure will increase the flow resistance and is not suitable for large-scale industrial production. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a three-dimensional Tesla valve structure microfluidic device and a method for preparing ultrafine barium titanate precursor powder by using the same. The three-dimensional Tesla valve structure of the present invention can significantly improve the mixing performance of the microfluidic device, and the microfluidic method has a natural ultra-high mass transfer efficiency. The barium titanate precursor synthesized by the method of the present invention has an ultra-small particle size compared with the traditional method and is an ideal material for the subsequent preparation of tetragonal barium titanate.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A three-dimensional Tesla valve structure microfluidic device, wherein a microchannel is provided inside the three-dimensional Tesla valve structure microfluidic device, and the microchannel serves as the main path.

[0007] One end of the microchannel is provided with a plurality of liquid inlets, and the other end is provided with a liquid outlet. A plurality of three-dimensional Tesla valve structures are communicated with the microchannel, and the three-dimensional Tesla valve structures serve as branch paths.

[0008] The rotation directions of adjacent three-dimensional Tesla valve structures are different, so that the velocity directions of the fluids flowing out of the branch paths are different everywhere, increasing the probability of mutual mixing between the fluids and improving the mixing performance of the three-dimensional Tesla valve microfluidic device.

[0009] In the traditional planar Tesla valve structure, there is only one velocity direction for the fluid flowing out of the branch path. However, in the three-dimensional Tesla valve structure of the present invention, since the three-dimensional Tesla valve structure of the branch path is obtained by rotating 180 degrees around the main path, the velocity directions of the fluids flowing out of the branch paths are different everywhere. During the impact between the branch path fluid and the main path fluid, momentum exchange occurs in all directions, making the flow field chaotic, greatly increasing the probability of mutual mixing between the fluids, thereby significantly improving the mixing performance of the microfluidic device and solving the problem that the existing improved double-Tesla valve structure for mixing increases the flow resistance and is not suitable for large-scale industrial production.

[0010] In a preferred embodiment of the present invention, the three-dimensional Tesla valve structure is rotatably connected to the microchannel, and the three-dimensional Tesla valve structure is formed by rotating 180 degrees around the microchannel as the axis.

[0011] In a preferred embodiment of the present invention, the cross-section of the microchannel is circular, square, elliptical or triangular.

[0012] In a preferred embodiment of the present invention, the characteristic scale of the cross-section of the microchannel is 0.005 nm to 10 nm.

[0013] In a preferred embodiment of the present invention, the height of the cross-sectional branch of the three-dimensional Tesla valve is 0.1 times to 10 times the diameter of the microchannel.

[0014] In a preferred embodiment of the present invention, the number of the liquid inlets is ≥2, and a Y-shaped, T-shaped or U-shaped is formed between adjacent liquid inlets.

[0015] In a preferred embodiment of the present invention, the structural type of the microchannel is linear, wavy, arc-shaped, spiral-shaped, S-shaped or annular.

[0016] Another object of the present invention is to provide a method for preparing ultrafine barium titanate precursor powder, which is prepared by the three-dimensional Tesla valve structure microfluidic equipment described in any one of the above, and includes the following steps: A barium source, a titanium source, an alkali solution, an organic acid and a surfactant are introduced through the liquid inlets of the three-dimensional Tesla valve structure microfluidic equipment, and are fully mixed in the three-dimensional Tesla valve structure microfluidic equipment, and the mixed solution flows out from the liquid outlet, and after standing and post-treatment, ultrafine barium titanate precursor powder is obtained.

[0017] In a preferred embodiment of the present invention, the barium source is barium acetate, barium bromate, barium chloride, barium hydroxide or barium nitrate, the titanium source is titanium tetrachloride, tetrabutyl titanate, metatitanic acid, titanium trichloride, tetraethyl titanate or isopropyl titanate, the alkali solution is sodium hydroxide, potassium hydroxide or ammonia water, the organic acid is oleic acid, and the surfactant is oleylamine.

[0018] In a preferred embodiment of the present invention, the molar ratio of the barium source to the titanium source is 0.8 to 1.2:1, the mass percentage of the alkali solution in the mixed solution is 5% to 8%, the mass percentage of the organic acid in the mixed solution is 5% to 10%, and the mass percentage of the surfactant in the mixed solution is 2.5% to 5%.

[0019] In a preferred embodiment of the present invention, the inlet flow rate of the microchannel is ≤100 mL / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. The microfluidic device with a three-dimensional Tesla valve structure of the present invention is internally provided with a microchannel. One end of the microchannel is provided with a plurality of liquid inlets, and the other end is provided with a liquid outlet. A plurality of three-dimensional Tesla valve structures are arranged inside the microchannel. The three-dimensional Tesla valve structure is formed by rotating 180 degrees around the microchannel, and its rotation direction can be different. In the traditional planar Tesla valve structure, the fluid flowing out of the branch has only one velocity direction. However, in the three-dimensional Tesla valve structure of the present invention, since the branch three-dimensional Tesla valve structure is obtained by rotating 180 degrees around the main channel, the velocity directions of the fluid flowing out of the branch are different everywhere. During the impact between the branch fluid and the main channel fluid, momentum exchange occurs in all directions, making the flow field chaotic, greatly increasing the probability of mutual mixing between fluids, and thus significantly improving the mixing performance of the microfluidic equipment, solving the problem that the existing improved double Tesla valve structure increases the flow resistance and is not suitable for large-scale industrial production.

[0021] 2. The microfluidic method has a natural ultra-high mass transfer efficiency. In the traditional method for synthesizing barium titanate, heating is usually required. However, barium titanate can be synthesized at room temperature by using the microfluidic technology, and the microfluidic method has a high degree of automation and can automatically complete the continuous reaction after feeding. The barium titanate precursor powder synthesized by using the three-dimensional Tesla valve structure of the present invention has an ultra-small particle size compared with the traditional method and is an ideal material for the subsequent preparation of tetragonal barium titanate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the front view of the microfluidic equipment with a three-dimensional Tesla valve structure of the present invention, 1 - microchannel, 2 - liquid inlet, 3 - liquid outlet, 4 - three-dimensional Tesla valve.

[0023] Figure 2 It is the front elevation view of the microfluidic equipment with a three-dimensional Tesla valve structure of the present invention, 1 - microchannel, 2 - liquid inlet, 3 - liquid outlet, 4 - three-dimensional Tesla valve.

[0024] Figure 3 It is the side view of the microfluidic equipment with a three-dimensional Tesla valve structure of the present invention, 1 - microchannel, 2 - liquid inlet, 3 - liquid outlet, 4 - three-dimensional Tesla valve.

[0025] Figure 4 It is the mixing simulation diagram of the traditional Tesla valve structure.

[0026] Figure 5 It is the mixing simulation diagram of the improved double Tesla valve structure in the prior art.

[0027] Figure 6 It is the mixing simulation diagram of the three-dimensional Tesla valve structure of the present invention.

[0028] Figure 7SEM image of the ultrafine barium titanate precursor powder synthesized by the three-dimensional Tesla valve structure microfluidic equipment of the present invention.

[0029] Figure 8 Comparison diagram of the barium titanate precursor powder synthesized by the present invention and the standard barium titanate PDF card. Detailed implementation manners

[0030] The following combines the embodiments of the present invention, and uses preferred embodiments and accompanying drawings for detailed description. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] It should be noted that all the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0032] Example 1 A three-dimensional Tesla valve structure microfluidic equipment, the front view of which is as Figure 1 shown, the front elevation view is as Figure 2 shown, the side view is as Figure 3 shown. A microchannel 1 is provided inside the three-dimensional Tesla valve structure microfluidic equipment. Two Y-shaped liquid inlets 2 are provided at one end of the microchannel 1, and a liquid outlet 3 is provided at the other end. The cross-section of the microchannel 1 is a circle with a diameter of 3 mm. Six three-dimensional Tesla valve 4 structures are provided on the overall S-shaped microchannel 1. The height of the cross-sectional branch of the three-dimensional Tesla valve 4 structure is 5 times the diameter of the microchannel, and the rotation directions formed by adjacent three-dimensional Tesla valve 4 structures are different, constituting a three-dimensional Tesla valve structure microfluidic device.

[0033] Figure 4 Is the hybrid simulation diagram of the traditional Tesla valve structure, Figure 5 Is the hybrid simulation diagram of the improved double Tesla valve structure in CN21935619U, Figure 6 Is the hybrid simulation diagram of the three-dimensional Tesla valve structure of the present invention, composed of Figure 4 , Figure 5 and Figure 6As shown, two streams of liquid flow from left to right. One liquid is white in the figure, corresponding to 1 on the color scale, and the other liquid is black, corresponding to 0 on the color scale. If they are mixed after passing through the structure, the liquid mixture will be gray, corresponding to 0.5 on the color scale. The traditional Tesla valve structure has almost no mixing effect, and the two streams of liquid still show distinct black and white. The improved double Tesla valve structure has a mixing effect, but the mixing is not uniform, and the color shows lighter or darker gray. The three-dimensional Tesla valve structure proposed in the present invention has an excellent mixing effect. The two streams of liquid at the inlet are almost completely mixed after passing through a structure, and the color shows uniform gray, indicating that the three-dimensional Tesla valve structure of the present invention is obtained by rotating the branch by 180 degrees around the main path. The velocity directions of the fluid flowing out of the branch are different everywhere. During the impact between the branch fluid and the main path fluid, momentum exchange occurs in all directions, making the flow field chaotic, greatly increasing the probability of mutual mixing between fluids, and thus significantly improving the mixing performance of the microfluidic device.

[0034] Example 2 A microfluidic device with a three-dimensional Tesla valve structure, in which a microchannel 1 is provided inside the microfluidic device with a three-dimensional Tesla valve structure. One end of the microchannel 1 is provided with two Y-shaped liquid inlets 2, and the other end is provided with an outlet 3. The cross-section of the microchannel 1 is a rectangle with a length and width of 0.005 mm. Six three-dimensional Tesla valve 4 structures are provided on the overall S-shaped microchannel 1. The height of the cross-section branch of the three-dimensional Tesla valve 4 structure is 5 times the diameter of the microchannel, and the rotation directions formed by adjacent three-dimensional Tesla valve 4 structures are different, constituting a microfluidic device with a three-dimensional Tesla valve structure.

[0035] Example 3 A microfluidic device with a three-dimensional Tesla valve structure, in which a microchannel 1 is provided inside the microfluidic device with a three-dimensional Tesla valve structure. One end of the microchannel 1 is provided with two Y-shaped liquid inlets 2, and the other end is provided with an outlet 3. The cross-section of the microchannel 1 is a circle with a diameter of 3 mm. Six three-dimensional Tesla valve 4 structures are provided on the overall S-shaped microchannel 1. The height of the cross-section branch of the three-dimensional Tesla valve 4 structure is 0.1 times the diameter of the microchannel, and the rotation directions formed by adjacent three-dimensional Tesla valve 4 structures are different, constituting a microfluidic device with a three-dimensional Tesla valve structure.

[0036] Example 4 A three-dimensional Tesla valve structure microfluidic device. Inside the three-dimensional Tesla valve structure microfluidic device, there is a microchannel 1. One end of the microchannel 1 is provided with 4 liquid inlets 2, and a U shape is formed between adjacent liquid inlets 2. The other end is provided with a liquid outlet 3. The cross-section of the microchannel 1 is a circle with a diameter of 3 mm. There are 6 three-dimensional Tesla valve 4 structures on the overall S-shaped microchannel 1. The height of the cross-section branch of the three-dimensional Tesla valve 4 structure is 5 times the diameter of the microchannel, and the rotation directions formed by adjacent three-dimensional Tesla valve 4 structures are different, constituting a three-dimensional Tesla valve structure microfluidic device.

[0037] Example 5 A three-dimensional Tesla valve structure microfluidic device. Inside the three-dimensional Tesla valve structure microfluidic device, there is a microchannel 1. One end of the microchannel 1 is provided with two Y-shaped liquid inlets 2, and the other end is provided with a liquid outlet 3. The cross-section of the microchannel 1 is a circle with a diameter of 3 mm. There are 6 three-dimensional Tesla valve 4 structures on the overall wavy microchannel 1. The height of the cross-section branch of the three-dimensional Tesla valve 4 structure is 5 times the diameter of the microchannel, and the rotation directions formed by adjacent three-dimensional Tesla valve 4 structures are different, constituting a three-dimensional Tesla valve structure microfluidic device.

[0038] Figure 7 Barium titanate precursor powder synthesized by the three-dimensional Tesla valve structure microfluidic device of Example 1. 1 mM barium acetate, 1 mM metatitanic acid, 30 mM ammonia water, 5 wt% oleic acid, and 2.5 wt% oleylamine were introduced through the liquid inlets of the three-dimensional Tesla valve structure microfluidic device, and these chemical reagents were fully mixed in the three-dimensional Tesla valve structure microfluidic device. After the mixed solution flowing out from the liquid outlet was left standing for 10 hours, it was centrifuged, washed, dried, and ground to obtain ultrafine barium titanate precursor powder, the particle size of which is less than 10 nm and has good uniformity. Figure 8 The XRD result of the synthesized barium titanate precursor powder was compared with the standard card of barium titanate, which confirmed that the synthesized powder is indeed barium titanate.

[0039] In summary, the microfluidic device with a three-dimensional Tesla valve structure of the present invention is internally provided with a microchannel. One end of the microchannel is provided with a plurality of liquid inlets, and the other end is provided with a liquid outlet. A plurality of three-dimensional Tesla valve structures are provided inside the microchannel. The three-dimensional Tesla valve structure is formed by rotating 180 degrees around the microchannel, and its rotation direction can be different. In the traditional planar Tesla valve structure, the fluid flowing out of the branch has only one velocity direction. However, in the three-dimensional Tesla valve structure of the present invention, since the branch is obtained by rotating 180 degrees around the main channel, the velocity directions of the fluid flowing out of the branch are different everywhere. During the impact between the branch fluid and the main channel fluid, momentum exchange occurs in all directions, making the flow field chaotic, greatly increasing the probability of mutual mixing between fluids, thereby significantly improving the mixing performance of the microfluidic equipment, preparing tetragonal barium titanate with ultra-small particle size, and solving the problem that the existing improved double Tesla valve structure increases the flow resistance and is not suitable for large-scale industrial production.

[0040] It should be noted that when the present invention involves a numerical range, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the adopted step methods are the same as those in the embodiments, in order to prevent repetition, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the scope of the appended protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0041] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A three-dimensional Tesla valve structure microfluidic device, characterized in that: The three-dimensional Tesla valve structure microfluidic device has a microchannel (1) inside, and the microchannel (1) serves as a main path; One end of the microchannel (1) is provided with a plurality of liquid inlets (2), and the other end is provided with a liquid outlet (3), and the microchannel (1) is connected to a plurality of three-dimensional Tesla valve (4) structures, and the three-dimensional Tesla valve (4) structures serve as branches; The rotation directions of adjacent three-dimensional Tesla valve (4) structures are different, so that the directions of the fluid velocities flowing out of the branch are different.

2. The three-dimensional Tesla valve structure microfluidic device according to claim 1, characterized in that: The three-dimensional Tesla valve (4) structure is rotatably connected to the microchannel (1).

3. The three-dimensional Tesla valve structure microfluidic device according to claim 1, characterized in that: The cross section of the microchannel (1) is circular, square, elliptical or triangular, and the characteristic scale of the cross section of the microchannel is 0.005 nm to 10 nm.

4. The three-dimensional Tesla valve structure microfluidic device according to claim 1, characterized in that: The cross-sectional branch height of the three-dimensional Tesla valve (4) is 0.1 to 10 times the diameter of the microchannel.

5. The three-dimensional Tesla valve structure microfluidic device according to claim 1, characterized in that: The number of the liquid inlets (2) is ≥2, and adjacent liquid inlets (2) form a Y shape, a T shape or a U shape.

6. The three-dimensional Tesla valve structure microfluidic device according to claim 1, characterized in that: The microchannel (1) has a structure type of straight line, wave shape, arc shape, spiral line shape, S shape or ring shape.

7. A method for preparing ultrafine barium titanate precursor powder, characterized in that: The three-dimensional Tesla valve structure microfluidic device according to any one of claims 1 to 6 is prepared, comprising the following steps: A barium source, a titanium source, an alkaline solution, an organic acid and a surfactant are introduced into the liquid inlet (2) of the three-dimensional Tesla valve structure microfluidic device, and are fully mixed in the three-dimensional Tesla valve structure microfluidic device. The mixed solution is discharged from the liquid outlet (3), and after standing, it is post-processed to obtain an ultrafine barium titanate precursor powder.

8. The method for preparing ultrafine barium titanate precursor powder according to claim 7, characterized in that: The barium source is barium acetate, barium bromate, barium chloride, barium hydroxide or barium nitrate, the titanium source is titanium tetrachloride, tetrabutyl titanate, metatitanic acid, titanium trichloride, tetraethyl titanate or isopropyl titanate, the alkaline solution is sodium hydroxide, potassium hydroxide or ammonia water, the organic acid is oleic acid, and the surfactant is oleylamine.

9. The method for preparing ultrafine barium titanate precursor powder according to claim 7, characterized in that: The molar ratio of the barium source to the titanium source is 0.8-1.2:1, the mass percentage of the alkaline solution in the mixed solution is 5%-8%, the mass percentage of the organic acid in the mixed solution is 5%-10%, and the mass percentage of the surfactant in the mixed solution is 2.5%-5%.

10. The method for preparing ultrafine barium titanate precursor powder according to claim 7, characterized in that: The inlet flow rate of the microchannel is ≤100 mL / min.

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