Multistage-granularity nitride powder preparation device

Abstract

The utility model discloses a multistage-granularity nitride powder preparation device which comprises a reaction kettle, a baffle, a raw material basket, a temperature adjusting device and the like. A plurality of reaction areas are distributed in the inner cavity of the reaction kettle along the axial direction. The baffle is arranged between the adjacent reaction areas, at least one through hole is formed in the baffle, and / or a gap is reserved between the edge of the baffle and the inner wall of the reaction kettle, and the through hole and / or the gap are / is used for communicating the adjacent reaction areas with each other. Each raw material basket is arranged in the corresponding reaction area and used for containing raw materials of nitride powder. And the temperature adjusting device is used for adjusting and controlling the temperature of the plurality of reaction areas. Compared with the prior art, the multi-stage particle size nitride powder can be prepared in the same reaction kettle at a time, the quality is high, the dispersity is good, the nitride powder with similar particle sizes is distributed in the same reaction area, the nitride powder can be directly used without being screened, the cost is low, and the multi-stage particle size nitride powder preparation device is suitable for large-scale production.

Description

Technical Field

[0001] The utility model relates to a nitride powder preparation device, in particular to a multi - level particle size nitride powder preparation device, belonging to the field of semiconductor technology. Background Art

[0002] Nitride materials have a relatively wide bandgap, and their light - transmitting range can extend from the ultraviolet region to the near - infrared region. At the same time, they also have good chemical stability, high thermal conductivity, and low compressibility. They are widely used in optoelectronic devices, high - frequency, high - power electronic devices, and high - thermal - conductivity ceramics, etc., and have significant applications in fields such as semiconductor lighting, new - generation mobile communication, and national defense and military industry. It is a key area of high - technology competition among countries in the world.

[0003] High - quality powder raw materials are a prerequisite for obtaining high - performance nitride single crystals and ceramics. The indicators reflecting the characteristics of powder raw materials mainly include purity, dispersibility, particle size, etc. Among them, particle size is one of the most concerned indicators in all application fields. For example, the particle size and purity of aluminum nitride powder raw materials directly affect the crystallization quality and electrical properties of growing AlN single crystals by physical vapor transport method (PVT). The preparation of high - performance ceramics also requires powder raw materials with fine particle size, high purity, and good sintering performance. Therefore, it is very important to realize the controllable preparation of the particle size of nitride powder raw materials.

[0004] Traditional methods for preparing nitride powders include direct nitridation method, chemical vapor transport method, self - propagating high - temperature synthesis method, etc. However, these methods all have some defects. For example, the reaction temperature is relatively high and the reaction is violent, resulting in difficult control of the reaction process, incomplete reaction, and easy caking of products, etc. As a result, it is more difficult to control the particle size of the products. The ammonothermal method is a nitride preparation method with broad application prospects, which has the advantages of high quality, large size, environmental protection, low cost, and high yield. However, currently, when using the ammonothermal method to prepare nitride crystal materials, generally, only one specification of nitride crystal material can be prepared in one batch in a high - pressure autoclave, which is difficult to meet the actual application requirements. Summary of the Invention

[0005] The main purpose of the utility model is to provide a multi - level particle size nitride powder preparation device to overcome the deficiencies in the prior art.

[0006] To achieve the foregoing invention purpose, the technical solutions adopted by the utility model include:

[0007] One aspect of the utility model provides a multi - level particle size nitride powder preparation device, including:

[0008] An autoclave, in the inner cavity of which there are a plurality of reaction zones, and the plurality of reaction zones are distributed in sequence along the axial direction of the autoclave;

[0009] Baffle, the baffle is arranged between two adjacent reaction zones, at least one through hole is provided on the baffle, and / or a gap is formed between at least one side edge of the baffle and the inner wall of the reaction kettle, and the through hole and / or the gap are used to communicate two adjacent reaction zones with each other;

[0010] Raw material basket, each raw material basket is arranged in a corresponding reaction zone, and the raw material basket is used to contain the raw materials of the nitride powder;

[0011] Temperature regulating device, the temperature regulating device is used to regulate the temperatures of multiple reaction zones and make the temperatures of at least two of the reaction zones different, so that the fluid filled in the inner cavity of the reaction kettle forms convection between at least two reaction zones.

[0012] Among them, the raw materials of the nitride powder may include metal sources and the like, and are not limited thereto. The fluid is used as a solvent, and it is generally liquid ammonia.

[0013] In one embodiment, multiple reaction zones are sequentially distributed in the vertical direction.

[0014] In one embodiment, the volumes of at least two reaction zones are different. By adjusting the volumes of each reaction zone, the temperature difference between each reaction zone can be controlled, so that the particle size of the nitride powder can be controlled more precisely. Of course, the diameters, lengths, etc. of each reaction zone can be determined according to the specifications of the reaction kettle. The reaction kettle is a high-pressure reaction kettle.

[0015] In one embodiment, the porosity of the baffle is greater than 0 and less than or equal to 50%, and the porosity is the ratio of the sum of the radial cross-sectional areas of all through holes on the baffle and / or the area of the gap between the baffle edge and the inner wall of the reaction kettle in the radial direction to the radial cross-sectional area of the inner cavity of the reaction kettle.

[0016] That is, in some cases, two adjacent reaction zones are communicated with each other through the through holes on the baffle arranged between them. Further, a plurality of the through holes are provided on the baffle. In other cases, there are no through holes on the baffle, and two adjacent reaction zones communicate with each other through the gap between the edge of the baffle arranged between them and the inner wall of the reaction kettle. In other cases, two adjacent reaction zones communicate with each other through the through holes on the baffle arranged between them and the gap between the edge of the baffle and the inner wall of the reaction kettle.

[0017] By placing the baffle between every two adjacent reaction zones and setting the baffle porosity ≤ 50%, the required temperature gradient and solubility gradient can be formed in the corresponding reaction zone, so as to better promote the growth and particle size control of the nitride powder in the reaction zone.

[0018] Further, according to the requirements for preparing the nitride powder particle size in each reaction zone, the porosity of each baffle can be the same or different.

[0019] Further, by synergistically correlating the porosity of each baffle with the temperature of each reaction zone, the temperature and temperature gradient of each reaction zone can be determined, thereby affecting the solubility or supersaturation of the nitride in the fluid - homogeneous nucleation - growth coarsening, and ultimately determining the particle size of the nitride powder in each reaction zone.

[0020] By adopting the above settings, as the reaction time increases, for the reaction zone with a lower solubility of the nitride (defined as the low - solubility reaction zone), the solubility of the nitride in the fluid flowing from the reaction zone with a higher solubility of the nitride (defined as the high - solubility reaction zone) becomes supersaturated with respect to the low - solubility reaction zone, and then the nitride precipitates and grows in the low - solubility reaction zone, thereby growing the nitride grains; conversely, for the high - solubility reaction zone, the solubility of the nitride in the fluid flowing from the low - solubility reaction zone is unsaturated with respect to the high - solubility reaction zone, and then the nitride in the high - solubility reaction zone needs to be continuously dissolved, thereby making the nitride grains smaller. In this way, by controlling the temperature of each reaction zone, the temperature gradient between different reaction zones, and the reaction time, the regulation of the particle size of the nitride powder can be achieved.

[0021] Further, the through - holes can be through - holes with regular or irregular shapes, such as circular through - holes, conical through - holes, etc., which penetrate the baffle along the thickness direction of the baffle, and the thickness direction of the baffle is parallel to the axial direction of the reaction kettle.

[0022] In one embodiment, the device further includes a raw material rack, and a plurality of the raw material baskets are arranged on the raw material rack and are sequentially distributed along the axial direction of the reaction kettle.

[0023] In one embodiment, the raw material basket includes a crucible.

[0024] In one embodiment, the raw material rack extends along the axial direction of the reaction kettle, and a plurality of the crucibles are connected in series and fixed in the inner cavity of the reaction kettle through the raw material rack.

[0025] In one embodiment, the temperature adjustment device includes a plurality of heating mechanisms, and each heating mechanism is arranged corresponding to one reaction zone or a group of reaction zones, and a group of reaction zones includes two or more adjacent reaction zones.

[0026] In one embodiment, the heating mechanism includes a heating resistance wire, the heating resistance wire is arranged around the outer wall of the reaction kettle, and the working state of each heating resistance wire can be independently regulated.

[0027] Exemplarily, a heating mechanism can be provided for each reaction zone to independently regulate the temperature of the reaction zone. The heating mechanism can employ an electric heating device, a steam heating device, an infrared heating device, etc., and is not limited thereto.

[0028] Exemplarily, by using the temperature regulating device, the temperature of the upper part of the inner cavity of the reaction kettle can be generally lower than that of the lower part, so as to form a convection in the up-down direction to achieve the transportation and reaction of raw materials.

[0029] In the present utility model, the reaction kettle is a high-pressure reaction kettle, and an inert inner lining can be added inside it to prevent the constituent elements of the high-pressure reaction kettle from dissolving in the solvent and participating in the synthesis reaction of polycrystals, so as to obtain polycrystalline raw materials with higher purity. The material of the inert inner lining can be elements such as Au, Ag, Pt, Mo, W, Ti or their alloy materials, and is not limited thereto.

[0030] Correspondingly, another aspect of the present utility model also provides a method for preparing a multi-level granular nitride powder. This method is implemented based on the multi-level granular nitride powder preparation device and includes:

[0031] Add the raw materials of the nitride powder into each raw material basket, and fill the inner cavity of the reaction kettle with a fluid, and the fluid includes liquid ammonia;

[0032] Respectively adjust the temperature of each reaction zone to the corresponding growth temperature through the temperature regulating device, so as to grow nitride powders with different particle sizes in different reaction zones.

[0033] In the present utility model, the raw materials of the nitride powder include metals and / or nitride powders and doping elements that can be selectively added or not added. Among them, the metals include group III metals, such as one or more combinations of In, Ga, and Al. The nitride powder is mainly a polycrystalline material, including III-V group compound powders, such as binary nitride powders such as GaN, InN, and AlN, ternary nitride powders such as InGaN and AlGaN, or quaternary nitride powders such as AlInGaN, so as to achieve adjustable bandgap. The doping elements include rare earth metal elements or transition metal elements, etc., so as to achieve functional doping of the magnetic, luminescent, electrical properties, etc. of the nitride powder.

[0034] In the present utility model, the raw material compositions provided in different reaction zones are generally the same, and the raw material addition amounts in each reaction zone depend on temperature difference, flow rate, etc. The main purpose is to consider the conversion rate of raw materials.

[0035] In some cases, along the direction from top to bottom, the temperature change trend of multiple reaction zones is an increasing trend.

[0036] Exemplarily, along the direction from top to bottom, the temperatures of the plurality of reaction zones gradually increase.

[0037] Preferably, along the direction from top to bottom, the temperatures of the plurality of reaction zones increase stepwise to better promote the convection of the fluid in the reaction kettle, and thus the transport and reaction of the raw materials.

[0038] Furthermore, due to the different temperatures of each reaction zone, the solubility of the nitride in each reaction zone is different. Therefore, the supersaturation of each reaction zone can be controlled by the temperature gradient, and thus homogeneous nucleation can be achieved. Through growth and coarsening, nitride powders with controllable particle sizes can be prepared.

[0039] In addition, according to the requirements for preparing the nitride powder particle size, the temperature gradients between adjacent reaction zones can be set to be the same or different.

[0040] In the present utility model, the temperature difference between two reaction zones can be 10 - 100 °C. Generally speaking, the temperature difference of the reaction zones depends on the size of the required synthesized particle size. The greater the temperature difference between each reaction zone, the greater the difference in the particle sizes of the nitride powders grown in each reaction zone.

[0041] In the present utility model, a mineralizer can also be added to at least one of the raw material baskets to increase the solubility of the nitride in the solvent, and thus improve the reaction rate. Further, the mineralizer includes an alkaline mineralizer or an acidic mineralizer. For example, the alkaline mineralizer includes alkali metal amide compounds (such as NaNH2, KNH2, LiNH2, etc. or mixtures of different ratios thereof) or alkali metals (such as Li, Na, K, Cs, etc. or mixtures of different ratios thereof), and the acidic mineralizer includes ammonium halides (such as NH4F, NH4Cl, NH4Br, etc. or mixtures of different ratios thereof). Further, the weight of the mineralizer in one raw material basket is 1% - 30% of the weight of the raw material of the nitride powder.

[0042] In the present utility model, the temperature range of each reaction zone is also related to the mineralizer used. For example, if an acidic mineralizer is used, the temperature can be 400 - 550 °C; if an alkaline mineralizer is used, the temperature can be 500 - 650 °C; if a neutral mineralizer is used, the temperature can be 400 - 600 °C.

[0043] In the present utility model, the preparation method may further include: observing the growth of nitride powder in different reaction zones and correspondingly adjusting the temperatures of the respective reaction zones. For example, during the heating-up stage, rapid formation of nitride powder from the raw materials should be avoided to prevent the formation of a shell around the raw materials, which would prevent subsequent continuous reaction of the raw materials and cause incomplete conversion of the raw materials into the product. Therefore, during the heating-up stage, the temperature of the reaction zone located in the upper part of the reaction kettle should be relatively high, while the temperature of the reaction zone in the lower part should be relatively low, so as to avoid crust formation on the convective raw materials. After reaching the target temperature, the temperature of the reaction zone in the upper part of the reaction kettle should be kept relatively low, while the temperature of the reaction zone in the lower part should be relatively high until the raw materials are completely reacted.

[0044] In the present utility model, the preparation method may specifically include: after sealing the reaction kettle, setting the temperatures of multiple reaction zones to 400 - 800 °C and the pressures to 200 - 700 MPa to grow nitride powder in the multiple reaction zones.

[0045] Compared with the prior art, the multi-level granularity nitride powder preparation device provided by the present utility model has a simple structure and is easy to operate. It can prepare multi-level granularity nitride powder in multiple reaction zones at one time by the ammonothermal method, and the nitride powder grown in each reaction zone has uniform particle size, high quality and good dispersibility, thus eliminating the operation of screening the multi-level granularity nitride powder. Furthermore, by using the multi-level granularity nitride powder preparation device, the present utility model can realize the preparation of multi-level granularity nitride powder at one time only by regulating the volume of each reaction zone, the amount of raw materials used, the composition of raw materials, the reaction time and temperature, etc. The process is simple, highly controllable, the particle size of the nitride powder grown in each reaction zone is uniformly controllable, the cost is low, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The following describes exemplary embodiments of the present utility model with reference to the drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present utility model, rather than to exhaust all feasible ways of the present utility model, nor to limit the protection scope of the present utility model.

[0047] Figure 1 is a schematic structural diagram of a multi-level granularity nitride powder preparation device in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following will explain the technical solutions of the present utility model in more detail with reference to several embodiments. However, these specific descriptions are only used to teach those skilled in the art how to implement the present invention, rather than to exhaust all feasible ways of the present invention, nor to limit the scope of the present invention.

[0049] Embodiment 1

[0050] Please refer toFigure 1 As shown, a multi - level granularity nitride powder preparation device provided in this embodiment includes a high - pressure reactor 1, three baffles, a plurality of raw material baskets 3, and a temperature adjustment device.

[0051] Further, in the inner cavity of the reactor, there are four reaction zones, namely the first reaction zone 11, the second reaction zone 12, the third reaction zone 13, and the fourth reaction zone 14, which are distributed from top to bottom. These four reaction zones are arranged in sequence along the axial direction of the reactor. The lengths of the first reaction zone 11, the second reaction zone 12, the third reaction zone 13, and the fourth reaction zone 14 can be 130 ± 5 mm, 120 ± 5 mm, 110 ± 5 mm, and 90 ± 5 mm respectively, and the diameters can all be about 30 mm.

[0052] Further, the three baffles are respectively the first baffle 21, the second baffle 22, and the third baffle 23, which are distributed from top to bottom. Each baffle is arranged between two adjacent reaction zones. The peripheral part of each baffle is hermetically joined to the inner wall of the reactor, and a plurality of through - holes are formed on each baffle. Each through - hole penetrates the baffle along the thickness direction of the baffle, and is used to connect two adjacent reaction zones to each other. The porosity rates of the first baffle, the second baffle, and the third baffle are 5%, 6%, 7%, and 8% in sequence, and the definition of the porosity rate of each baffle is as described above.

[0053] Further, one or more raw material baskets 3 are arranged in each reaction zone, and the raw material baskets are used to hold the raw materials of the nitride powder. The raw material baskets can be crucibles. Exemplarily, one crucible can be arranged in each reaction zone, and four crucibles are connected in series and fixed in the inner cavity of the reactor by using a raw material rack (not shown in the figure) extending along the axial direction of the reactor.

[0054] Further, the temperature adjustment device is used to control the temperatures of the four reaction zones. The temperature adjustment device can include a plurality of resistance heating mechanisms 4. Each resistance heating mechanism is mainly composed of a heating resistance wire, is arranged around a corresponding reaction zone, and the working state of each resistance heating mechanism can be adjusted independently, so that the temperature of the corresponding reaction zone can be adjusted independently.

[0055] Based on the multi - level granularity nitride powder preparation device of this embodiment, the preparation of multi - level granularity nitride powder can be carried out. Exemplarily, a method for preparing multi - level granularity nitride powder includes:

[0056] S1. Place gallium metal and a mineralizer NaNH2 into each crucible. The mass of the mineralizer is 5% of the mass of the gallium metal, and place each crucible into the first reaction zone, the second reaction zone, the third reaction zone, and the fourth reaction zone in the high - pressure reactor respectively.

[0057] S2. Fill liquid ammonia into the high-pressure reactor, and set the pressure in the reactor to be about 300 MPa, the temperature T1 in the first reaction zone to be about 500 °C, the temperature T2 in the second reaction zone to be about 520 °C, the temperature T3 in the third reaction zone to be about 540 °C, and the temperature T4 in the fourth reaction zone to be about 560 °C.

[0058] S3. After reacting for 200 h, end the reaction. Obtain GaN polycrystalline powder with a particle size of about 20 - 23 μm from the first reaction zone, GaN polycrystalline powder with a particle size of about 15 - 18 μm from the second reaction zone, GaN polycrystalline powder with a particle size of about 10 - 14 μm from the third reaction zone, and GaN polycrystalline powder with a particle size of about 5 - 8 μm from the fourth reaction zone.

[0059] In this embodiment, by setting reaction zones with different temperatures in the reactor and making the fluid as the solvent form convection in the reactor, nitride powders with different particle sizes can be grown in different reaction zones. Finally, the preparation of nitride powders with multi-level particle sizes can be realized at one time in a single reactor, and the nitride powders with different particle sizes are distributed in different reaction zones, which can be directly collected without screening according to particle size. The process has high controllability, low cost, and the products are convenient for subsequent use.

[0060] Example 2

[0061] A device for preparing nitride powders with multi-level particle sizes provided in this embodiment is basically the same as that in Example 1, except that: a through hole is provided in the central region of each of the first baffle, the second baffle, and the third baffle for communicating two adjacent reaction zones with each other, and the porosity of the first baffle, the second baffle, and the third baffle is 2%, 4%, 6%, and 8% in sequence.

[0062] Example 3

[0063] A device for preparing nitride powders with multi-level particle sizes provided in this embodiment is basically the same as that in Example 1, except that: the first baffle, the second baffle, and the third baffle are all fixed on the inner wall of the reactor through connecting brackets, no through hole is provided on each baffle, and an annular gap is left between the outer peripheral edge of each baffle and the inner wall of the reactor for communicating two adjacent reaction zones with each other, and the porosity of the first baffle, the second baffle, and the third baffle is 5%, 8%, 12%, and 14% in sequence.

[0064] Example 4

[0065] The multi-level granularity nitride powder preparation device provided in this embodiment is basically the same as that in Embodiment 1, except that: the first baffle, the second baffle and the third baffle are all fixed on the inner wall of the reaction kettle through connecting brackets, and each baffle is provided with a plurality of through holes, and there is an annular gap between the outer peripheral edge of each baffle and the inner wall of the reaction kettle. The adjacent two reaction zones can be interconnected by using the through holes and the annular gap, and the porosity of the first baffle, the second baffle and the third baffle is 12%, 15%, 18% and 22% in sequence.

[0066] Using the multi-level granularity nitride powder preparation devices of Embodiments 2-4 and referring to the method of Embodiment 1, nitride powders with different particle sizes can also be obtained in the first reaction zone, the second reaction zone, the third reaction zone and the fourth reaction zone respectively, and the particle size distribution of the nitride powders obtained in each reaction zone is relatively narrow and the morphology is uniform.

[0067] Based on the multi-level granularity nitride powder preparation device of the present invention, the preparation of nitride powder can be realized by the ammonothermal method. Compared with the direct nitridation method, chemical vapor transport method, self-propagating high-temperature synthesis method, etc., not only the reaction temperature is lower and the reaction controllability is high, but also the preparation of multi-level granularity nitride powder can be realized at one time in the same reaction kettle. Its quality is high, the dispersibility is good, and the nitride powders with the same or similar particle sizes are distributed in the same reaction zone. Therefore, it can be directly used without subsequent screening operation, with low cost and suitable for large-scale production.

[0068] Although the present invention has been described with reference to the illustrative embodiments, those skilled in the art will understand that various other changes, omissions and / or additions can be made and elements of the embodiments can be replaced with substantially equivalent ones without departing from the spirit and scope of the present invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope of the present invention. Therefore, it is not intended to limit the present invention to the specific embodiments disclosed for carrying out the present invention, but it is intended that the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A device for preparing multi-level particle size nitride powder, characterized in that: include: A reactor, wherein a plurality of reaction zones are arranged in the inner cavity of the reactor, and the plurality of reaction zones are sequentially distributed along the axial direction of the reactor; a baffle, the baffle being arranged between two adjacent reaction zones, the baffle being provided with at least one through hole, and / or a gap being formed between at least one side edge of the baffle and the inner wall of the reactor, the through hole and / or the gap being used to connect the two adjacent reaction zones to each other; Raw material baskets, each raw material basket is disposed in a corresponding one of the reaction zones, and the raw material basket is used to contain the raw material of the nitride powder; A temperature regulating device is used to regulate the temperature of the plurality of reaction zones and make the temperatures of at least two of the reaction zones different, so that the fluid filled in the inner cavity of the reactor forms convection between at least two of the reaction zones.

2. The device for preparing multi-grade nitride powder according to claim 1, characterized in that: The plurality of reaction zones are distributed in sequence along the vertical direction.

3. The device for preparing multi-grade nitride powder according to claim 1, characterized in that: At least two of the reaction zones have different volumes.

4. The device for preparing multi-grade nitride powder according to claim 1, characterized in that: The porosity of the baffle is greater than 0 and less than or equal to 50%, and the porosity is the ratio of the sum of the radial cross-sectional areas of all through holes on the baffle and / or the radial areas of the gaps between the edge of the baffle and the inner wall of the reactor to the radial cross-sectional area of ​​the inner cavity of the reactor.

5. The device for preparing multi-level particle size nitride powder according to claim 1, characterized in that: The baffle plate is provided with a plurality of the through holes; and / or an annular gap is formed between the outer periphery of the baffle plate and the inner wall of the reactor.

6. The device for preparing multi-level particle size nitride powder according to claim 1, characterized in that: The device also includes a raw material rack, and a plurality of raw material baskets are arranged on the raw material rack and are distributed in sequence along the axial direction of the reactor.

7. The device for preparing multi-grade nitride powder according to claim 6, characterized in that: The raw material basket includes a crucible.

8. The device for preparing multi-level particle size nitride powder according to claim 7, characterized in that: The raw material rack extends axially along the reaction kettle, and a plurality of crucibles are connected in series and fixed in the inner cavity of the reaction kettle via the raw material rack.

9. The device for preparing multi-grade nitride powder according to claim 1, characterized in that: The temperature regulating device comprises a plurality of heating mechanisms, each of which is arranged corresponding to one of the reaction zones or a group of reaction zones, and a group of reaction zones comprises two or more of the reaction zones arranged adjacent to each other.

10. The device for preparing multi-grade nitride powder according to claim 9, characterized in that: The heating mechanism comprises heating resistance wires, which are arranged around the outer wall of the reactor, and the working state of each heating resistance wire can be adjusted individually.

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