CN116213746A - Rod-shaped superfine silver powder and preparation method and application thereof - Google Patents

Rod-shaped superfine silver powder and preparation method and application thereof Download PDF

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Publication number
CN116213746A
CN116213746A CN202310095144.9A CN202310095144A CN116213746A CN 116213746 A CN116213746 A CN 116213746A CN 202310095144 A CN202310095144 A CN 202310095144A CN 116213746 A CN116213746 A CN 116213746A
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silver
silver powder
agent
rod
contact reaction
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周冰
胡恒广
闫冬成
张玉娇
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Tunghsu Technology Group Co Ltd
Hebei Guangxing Semiconductor Technology Co Ltd
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Tunghsu Technology Group Co Ltd
Hebei Guangxing Semiconductor Technology Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0553—Complex form nanoparticles, e.g. prism, pyramid, octahedron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Abstract

The invention relates to the technical field of metallic silver nano materials, and discloses a rod-shaped superfine silver powder, a preparation method and application thereof. The method comprises the following steps: (1) In the presence of ammonia water, carrying out a first contact reaction on a silver source and a reducing agent to obtain a mixed solution I; (2) And in the presence of a dispersing agent, sequentially carrying out a second contact reaction and a third contact reaction on the mixed solution I, the guiding agent and the capping agent. The average particle size of the superfine silver powder prepared by the method provided by the invention is obviously reduced, the superfine silver powder can be close to the monodispersity, and the impurity content in the superfine silver powder can be obviously reduced.

Description

Rod-shaped superfine silver powder and preparation method and application thereof
Technical Field
The invention relates to the technical field of metallic silver nano materials, in particular to a rod-shaped superfine silver powder and a preparation method and application thereof.
Background
The electrodes and circuits of the HJT heterojunction solar cells, touch screen displays, infrared releasing detectors and other emerging electronic and electric equipment are all manufactured by printing and sintering low-temperature conductive silver paste. As the demand for improving the performance potential of these electronic and electrical devices continues to increase, significantly finer electrodes and circuits are required, along with higher wiring densities and higher accuracy.
On the other hand, in the printed circuit forming process using low temperature silver paste, the heating sintering temperature is lower than 300 ℃ or even lower to a sintering temperature of 100 ℃ and excellent sintering properties are obtained at low temperature. The above performance requirements are not a small technical challenge for the production of ultra-fine silver powder for low temperature silver pastes.
Obviously, the high fineness and high precision and the lower sintering temperature requirements all require superfine silver powder with smaller granularity and better monodispersity.
The average grain diameter of the superfine silver powder produced by the silver powder manufacturer in China is less than or equal to 0.5 mu m, the grain diameter dispersibility is poor, the difference between the average grain diameter of the superfine silver powder required by the prior process and the quality of the monodispersion is large, and the superfine silver powder is not suitable for forming fine-pitch circuits. For these reasons, silver powder having finer particle size, which is more nearly monodisperse in dispersibility, less agglomeration of powder particles, and excellent low-temperature sinterability, has been demanded in the market than ever before.
At the same time, achieving a dense and strong joint sintered at low temperatures (< 200 ℃) remains a great challenge. The minimum sintering temperature is strongly dependent on particle shape, inter-particle spacing and surface energy. In this respect, the rod-like silver powder has an advantage over the spherical silver powder: the surface atoms of the rod-shaped silver powder are higher in proportion, and the rod-shaped silver powder can be assembled into denser 3D colloid.
Disclosure of Invention
The invention aims to solve the problems of larger average grain diameter, poor dispersibility and high impurity content of silver powder in the prior art.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a rod-shaped ultrafine silver powder, the method comprising:
(1) In the presence of ammonia water, carrying out a first contact reaction on a silver source and a reducing agent to obtain a mixed solution I;
(2) In the presence of a dispersing agent, sequentially carrying out a second contact reaction and a third contact reaction on the mixed solution I, the guiding agent and the capping agent;
wherein in the step (1), the reducing agent is used in a molar ratio of 0.01-0.2:1 with ethylene glycol; the concentration of the silver source is 0.01-0.5mol/L based on silver ion, and the concentration of the reducing agent is 0.02-0.4mol/L;
in the step (2), the capping agent is used in an amount of 0.5-5 by mole: 1 with ethylenediamine tetraacetic acid.
Preferably, in the step (1), the reducing agent is used in a molar ratio of 0.02-0.05:1 with ethylene glycol.
Preferably, in the step (1), the concentration of the silver source in terms of silver ions is 0.05 to 0.2mol/L, and the concentration of the reducing agent is 0.05 to 0.2mol/L.
Preferably, in step (1), the conditions of the first contact reaction include at least: the temperature is 30-70deg.C, and the time is 30-60min.
Preferably, in step (2), the directing agent is an aqueous sodium sulphide and/or sodium hydrosulphide solution.
Preferably, in step (2), the silver source is used in a molar ratio of 1, calculated as silver ion, to the guiding agent is used in dry basis: 0.001-0.01.
Preferably, in the step (2), the capping agent is used in a molar ratio of 2.3 to 3.6:1 with ethylenediamine tetraacetic acid.
Preferably, in step (2), the polyvinylpyrrolidone has a number average molecular weight of no more than 15000.
Preferably, in step (2), the conditions of the second contact reaction include at least: the temperature is 50-80deg.C, and the time is 30-60min.
Preferably, in step (2), the conditions of the third contact reaction include at least: the temperature is 60-100deg.C, the pressure is 0.3-0.6MPa, and the time is 50-100min.
In a second aspect, the present invention provides a rod-shaped ultrafine silver powder prepared by the method of the first aspect.
The third aspect of the invention provides the application of the rod-shaped superfine silver powder in the second aspect in preparing conductive silver paste.
The average particle size of the superfine silver powder prepared by the method provided by the invention is obviously reduced, the particle size distribution is narrow, the superfine silver powder can be close to the monodispersity, and the impurity content in the superfine silver powder can be obviously reduced; in particular, the average particle diameter of the superfine silver powder is reduced to below 0.3 mu m.
Drawings
FIG. 1 is a scanning electron microscope characterization view of the rod-shaped ultrafine silver powder prepared in example 1 of the present invention;
FIG. 2 is an X-ray diffraction pattern of the ultra-fine silver powder in the form of rod prepared in example 1 of the present invention.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In the present invention, unless otherwise stated, the room temperature or the normal temperature represents 25.+ -. 2 ℃.
In the present invention, unless otherwise stated, the pressures are gauge pressures.
As described above, the first aspect of the present invention provides a method for preparing a rod-shaped ultrafine silver powder, the method comprising:
(1) In the presence of ammonia water, carrying out a first contact reaction on a silver source and a reducing agent to obtain a mixed solution I;
(2) In the presence of a dispersing agent, sequentially carrying out a second contact reaction and a third contact reaction on the mixed solution I, the guiding agent and the capping agent;
wherein in the step (1), the reducing agent is used in a molar ratio of 0.01-0.2:1 with ethylene glycol; the concentration of the silver source is 0.01-0.5mol/L based on silver ion, and the concentration of the reducing agent is 0.02-0.4mol/L;
in the step (2), the capping agent is used in an amount of 0.5-5 by mole: 1 with ethylenediamine tetraacetic acid.
In the invention, the reducing agent is used in a molar ratio of 0.01-0.2:1 with ethylene glycol, i.e., the reducing agent is a mixture. The concentration of the reducing agent represents the ratio of the total molar amount of hydrazine hydrate and ethylene glycol to the total volume of the reducing agent.
Preferably, in the step (1), the reducing agent is used in a molar ratio of 0.02-0.05:1 with ethylene glycol. In the invention, the hydrazine hydrate has high reducibility, which is beneficial to rapidly obtaining seed bodies for silver particle growth; while ethylene glycol has a low reducibility relative to hydrazine hydrate and a slow reaction rate, the slow reaction is beneficial to controlling the shape of silver particles, and can promote the generation of silver particles with high yield and monodisperse size. However, the inventors found that the molar ratio of hydrazine hydrate to ethylene glycol was 0.02-0.05:1, by compounding and matching with other technical characteristics of the technical scheme provided by the invention, the shape of silver particles can be better controlled, and the superfine silver powder with better dispersibility can be obtained.
Preferably, in the step (1), the concentration of the silver source in terms of silver ions is 0.05 to 0.2mol/L, and the concentration of the reducing agent is 0.05 to 0.2mol/L. In the invention, with the increase of the concentration of silver ions, a higher amount of superfine silver powder can be obtained. If the concentration of silver ions is too high, the precipitated silver particles tend to agglomerate into very coarse particles, the particle size is not different from that of conventional silver powder, and the monodispersity is poor. And when the silver ion concentration is too low, the average particle diameter of the ultrafine silver powder is too small, and the oil absorption increases, resulting in an increase in the viscosity of the silver paste. However, the inventors found that the concentration of the silver source calculated by silver ions is controlled to be in the range of 0.05-0.2mol/L, and the concentration of the reducing agent is controlled to be in the range of 0.05-0.2mol/L, so that the yield of the superfine silver powder can be higher and the monodispersity is better by matching with the other technical characteristics of the technical scheme provided by the invention.
According to a particularly preferred embodiment of the invention, in step (1), the silver source is silver nitrate.
Preferably, in step (1), the molar ratio of the aqueous ammonia on a dry basis to the silver source on a silver ion basis is 1-5:1.
Preferably, in step (1), the conditions of the first contact reaction include at least: the temperature is 30-70deg.C, and the time is 30-60min.
Preferably, in step (1), the directing agent is an aqueous sodium sulphide solution and/or an aqueous sodium bisulphide solution.
According to a particularly preferred embodiment of the invention, in step (1), the silver source is used in a molar ratio of 1, calculated as silver ion, to the guiding agent, calculated on a dry basis: 0.001-0.01. In the present invention, sodium sulfide (Na 2 S) and/or sodium hydrogen sulfide (NaHS) can increase the yield of rod-shaped silver particles. When the concentration of the sulfide added is too high, ag is generated 2 S，Ag 2 The S nanoparticles catalyze the reduction of Ag ions by significantly lowering the reduction potential. On the other hand, the presence of sulfide anions can accelerate the polyol synthesis of the silver nanocubes, such that the reduction rate of silver ions is significantly increased. However, the inventors found that the molar ratio of the silver source on a silver ion basis to the amount of the directing agent on a dry basis was 1:0.001-0.01, and the yield of the superfine silver powder can be higher and the monodispersity is better by matching with the other technical characteristics of the technical scheme provided by the invention.
Preferably, in the step (2), the capping agent is used in a molar ratio of 2.3 to 3.6:1 with ethylenediamine tetraacetic acid. In the present invention, capping agents are factors that affect the growth kinetics of liquid phase synthesis. The higher concentration of PVP resulted in isotropic coverage of the seed surface and formation of rod-like nano silver particles. However, the inventors found that the molar ratio of polyvinylpyrrolidone to ethylenediamine tetraacetic acid in the capping agent was controlled to be 2.3-3.6: in the range of 1, the balance between adsorption and desorption can be established on the surface of the silver growth particles by matching with the other technical characteristics of the technical scheme provided by the invention, so that the superfine silver powder with the average particle size meeting the requirement is obtained.
Preferably, in step (2), the polyvinylpyrrolidone has a number average molecular weight of no more than 15000.
Preferably, in step (2), the conditions of the second contact reaction include at least: the temperature is 50-80deg.C, and the time is 30-60min.
According to a particularly preferred embodiment of the invention, in step (2), the dispersant is triethanolamine.
Preferably, in step (2), the molar ratio of the dispersant to the capping agent is 1:3-5.
Preferably, in step (2), the conditions of the third contact reaction include at least: the temperature is 60-100deg.C, the pressure is 0.3-0.6MPa, and the time is 50-100min.
As described above, the second aspect of the present invention provides the rod-shaped ultrafine silver powder prepared by the method of the first aspect.
As described above, the third aspect of the present invention provides the use of the rod-shaped ultrafine silver powder according to the second aspect for preparing a conductive silver paste.
The invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the experimental apparatus and the raw materials involved are commercially available.
The starting materials referred to in the examples below are analytical and analytical reagents.
Reducing agent I: the molar ratio of the dosage is 0.025:1 with ethylene glycol;
reducing agent II: the dosage mole ratio is 0.032:1 with ethylene glycol;
reducing agent III: the dosage mole ratio is 0.05:1 with ethylene glycol;
reducing agent IV: the molar ratio of the dosage is 0.1:1 with ethylene glycol;
reducing agent V: the molar ratio of the dosage is 0.025:1 hydroquinone in combination with ethylene glycol;
guiding agent I: an aqueous sodium sulfide solution;
guiding agent II: aqueous sodium hydrosulfide solution;
capping agent I: the dosage mole ratio is 3:1 with ethylenediamine tetraacetic acid;
capping agent II: the dosage mole ratio is 3.6:1 with ethylenediamine tetraacetic acid;
capping agent III: the dosage mole ratio is 4:1 with ethylenediamine tetraacetic acid;
polyvinylpyrrolidone: PVP360, available from Sigma-aldrich;
dispersing agent: triethanolamine, analytically pure reagent.
Example 1
The present embodiment provides a method for preparing a rod-shaped ultrafine silver powder, the method comprising:
(1) At 40 ℃, carrying out contact reaction on 100mL of silver nitrate solution with the concentration of 0.15mol/L, 200mL of reducing agent I with the concentration of 0.2mol/L and 70mL of ammonia water with the concentration of 0.5mol/L for 50min to obtain a mixed solution I;
(2) And (3) reacting the mixed solution I, 3mL of the guiding agent I with the concentration of 0.02mol/L and 4mol of the capping agent I with 1mol of the dispersing agent under normal pressure at 60 ℃ for 40min, then reacting for 70min in a high-pressure reaction kettle with the temperature of 80 ℃ and the pressure of 0.5MPa, diluting the final reaction product with acetone, centrifugally collecting, washing with water, and suspending in water with 100 times of the volume of the silver powder to obtain the rod-shaped superfine silver powder S1.
Example 2
The present embodiment provides a method for preparing a rod-shaped ultrafine silver powder, the method comprising:
(1) At 60 ℃, carrying out contact reaction on 100mL of silver nitrate solution with the concentration of 0.075mol/L, 200mL of reducing agent II with the concentration of 0.12mol/L and 70mL of ammonia water with the concentration of 0.5mol/L for 40min to obtain a mixed solution I;
(2) And (2) reacting the mixed solution I, 3mL of the guiding agent I with the concentration of 0.02mol/L and 4mol of the capping agent I with 1mol of the dispersing agent under normal pressure at 80 ℃ for 30min, then reacting for 50min in a high-pressure reaction kettle with the temperature of 100 ℃ and the pressure of 0.5MPa, diluting the final reaction product with acetone, centrifugally collecting, washing with water, and suspending in water with the volume 100 times that of the silver powder to obtain the rod-shaped superfine silver powder S2.
Example 3
The present embodiment provides a method for preparing a rod-shaped ultrafine silver powder, the method comprising:
(1) At 70 ℃, carrying out contact reaction on 100mL of silver nitrate solution with the concentration of 0.15mol/L, 200mL of reducing agent III with the concentration of 0.2mol/L and 70mL of ammonia water with the concentration of 0.5mol/L for 30min to obtain a mixed solution I;
(2) And (3) reacting the mixed solution I, 3mL of the guiding agent II with the concentration of 0.02mol/L and 4mol of the capping agent II with 1mol of the dispersing agent under normal pressure at 50 ℃ for 60min, then reacting for 80min in a high-pressure reaction kettle with the temperature of 60 ℃ and the pressure of 0.4MPa, diluting the reaction product with acetone, centrifugally collecting, washing with water, and suspending in water with 100 times of the volume of the silver powder to obtain the rod-shaped superfine silver powder S3.
Example 4
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1, except that in step (1), the reducing agent I was replaced with an equal volume amount of the reducing agent IV.
The other steps were the same as in example 1, to obtain a rod-like ultrafine silver powder S4.
Example 5
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1, except that in step (2), capping agent I was replaced with an equimolar amount of capping agent III.
The other steps were the same as in example 1, to obtain a rod-like ultrafine silver powder S5.
Example 6
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1 except that in step (1), the concentration of the silver nitrate solution used was 0.3mol/L.
The other steps were the same as in example 1, to obtain a rod-like ultrafine silver powder S6.
Example 7
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1 except that in step (1), the concentration of the reducing agent I used was 0.3mol/L.
The other steps were the same as in example 1, to obtain a rod-like ultrafine silver powder S7.
Comparative example 1
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1, except that in step (1), reducing agent I was replaced with an equimolar amount of hydrazine hydrate.
The remaining steps were the same as in example 1, to obtain a rod-like ultrafine silver powder DS1.
Comparative example 2
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1, except that in step (2), the capping agent I was replaced with an equimolar amount of polyvinylpyrrolidone.
The remaining steps were the same as in example 1, to obtain a rod-like ultrafine silver powder DS2.
Comparative example 3
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1 except that in step (1), the concentration of the silver nitrate solution used was 0.6mol/L.
The remaining steps were the same as in example 1, to obtain a rod-like ultrafine silver powder DS3.
Comparative example 4
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1 except that in step (1), the concentration of the reducing agent I used was 0.5mol/L.
The remaining steps were the same as in example 1, to obtain a rod-like ultrafine silver powder DS4.
Comparative example 5
A rod-shaped ultrafine silver powder was prepared in the same manner as in example 1, except that in step (1), the reducing agent I was replaced with an equal volume amount of the reducing agent V.
The remaining steps were the same as in example 1, to obtain a rod-like ultrafine silver powder DS5.
Test example 1
The rod-shaped ultrafine silver powder prepared in the examples and the comparative examples was subjected to performance test, and the specific test results are shown in table 1.
The testing method of the average particle size and the particle size distribution comprises the following steps: according to the method described in the standard GB/T19077.1-2008/ISO 13320-1, testing the particle size and the particle size distribution of the superfine silver powder by using a Mastersizer 3000 laser particle sizer;
the method for testing the impurity content comprises the following steps: the impurity content of the superfine silver powder was tested by using a WFX-120B atomic absorption spectrophotometer according to the method described in standard GB/T11067-2006.
TABLE 1
Figure BDA0004085475260000101
Figure BDA0004085475260000111
As can be seen from the results of the table, the average particle size of the superfine silver powder prepared by the method provided by the invention is obviously reduced, the particle size distribution is narrow, the superfine silver powder can be close to the monodispersity, and the impurity content in the superfine silver powder can be obviously reduced; in particular, the average particle diameter of the superfine silver powder is reduced to below 0.3 mu m.
Test example 2
The rod-shaped ultrafine silver powder prepared in examples and comparative examples was prepared into silver wire electrodes, and the obtained silver wire electrodes were subjected to conductivity test, and specific test results are shown in table 2.
The preparation method of the silver wire electrode comprises the following steps: the rod-shaped ultrafine silver powder and the oxide binder (Bi 2 O 3 ) And an organic carrier (prepared from a mass ratio of 1:1 and ethyl 2- (2-n-butoxyethoxy) acetate according to a mass ratio of 72:8:20, mixing, and adopting ultrasonic dispersion and three-roller mixing method to make the above-mentioned materials undergo the process of ultrafine grinding treatmentAnd uniformly dispersing silver powder to prepare the conductive silver paste. The conductive silver paste is printed on the alumina substrate by a screen printer, the silver paste printed electrode is linear, the line width is about 60 mu m, the line spacing is about 80 mu m, and the thickness of the silver paste film wet film is about 40 mu m. Drying the silver paste film at 150 ℃ under an infrared lamp, and circularly sintering the silver paste film in a BTU furnace at 250 ℃ for 30 minutes in 60 minutes, wherein the thickness of the sintered film is about 15 mu m, so as to prepare a silver wire electrode;
the conductivity test method comprises the following steps: according to the method described by the national standard JJG376-2007, the conductivity of the silver wire electrode is tested by adopting a Loresta-GXMCP-T700 conductivity tester direct current four-probe method.
TABLE 2
Figure BDA0004085475260000112
Figure BDA0004085475260000121
As can be seen from the results of the table, the conductive silver paste formed by the superfine silver powder prepared by the method provided by the invention has high conductivity.
The rod-shaped ultrafine silver powder prepared in example 1 of the present invention was analyzed by placing it under a scanning electron microscope (model number Sirion200, available from FEI company) equipped with an energy dispersive X-ray analyzer, observing the microstructure of the ultrafine silver powder, and placing it on an X-ray diffractometer (model number X' ProMPD, available from Philip company) with CuK alpha radiation, and the analysis results are shown in FIGS. 1 and 2, respectively.
Fig. 1 is a scanning electron microscope characterization view of the rod-shaped ultrafine silver powder prepared in example 1 of the present invention, and fig. 2 is an X-ray diffraction characterization view of the rod-shaped ultrafine silver powder prepared in example 1 of the present invention.
As can be seen from FIG. 1, the superfine silver powder prepared by the method mainly exists in the form of particles, the silver particles are in an obvious rod-shaped structure, the silver powder does not have obvious agglomeration phenomenon, most of the silver particles exist in the form of monodispersion, and the particle diameter distribution of the silver particles is uniform.
As can be seen from fig. 2, there are 4 diffraction peaks at 35 ° to 80 ° of 2θ, which correspond to the diffraction peaks of 4 crystal planes of (111), (200), (220), (311) and the like of face-centered cubic phase metallic silver, respectively, without other impurity peaks, in contrast to the metallic silver standard spectrum; that is, it is shown that single-phase silver particles of cubic structure can be prepared by the method provided by the invention.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (10)

1. A method for preparing a rod-shaped ultrafine silver powder, comprising:
(1) In the presence of ammonia water, carrying out a first contact reaction on a silver source and a reducing agent to obtain a mixed solution I;
(2) In the presence of a dispersing agent, sequentially carrying out a second contact reaction and a third contact reaction on the mixed solution I, the guiding agent and the capping agent;
wherein in the step (1), the reducing agent is used in a molar ratio of 0.01-0.2:1 with ethylene glycol; the concentration of the silver source is 0.01-0.5mol/L based on silver ion, and the concentration of the reducing agent is 0.02-0.4mol/L;
in the step (2), the capping agent is used in an amount of 0.5-5 by mole: 1 with ethylenediamine tetraacetic acid.
2. The method according to claim 1, wherein in step (1), the reducing agent is used in a molar ratio of 0.02 to 0.05:1 with ethylene glycol.
3. The method according to claim 1 or 2, wherein in step (1), the silver source concentration in terms of silver ions is 0.05 to 0.2mol/L and the reducing agent concentration is 0.05 to 0.2mol/L.
4. A method according to any one of claims 1-3, wherein in step (1), the conditions of the first contact reaction comprise at least: the temperature is 30-70deg.C, and the time is 30-60min.
5. The method according to any one of claims 1 to 4, wherein in step (2), the directing agent is an aqueous sodium sulphide solution and/or an aqueous sodium bisulphide solution; and/or
In step (2), the silver source on a silver ion basis and the directing agent on a dry basis are used in a molar ratio of 1:0.001-0.01.
6. The method according to any one of claims 1 to 5, wherein in step (2), the capping agent is used in a molar ratio of 2.3 to 3.6:1 with ethylenediamine tetraacetic acid.
7. The method according to any one of claims 1 to 6, wherein in step (2), the number average molecular weight of the polyvinylpyrrolidone is not more than 15000.
8. The method according to any one of claims 1 to 7, wherein in step (2), the conditions of the second contact reaction include at least: the temperature is 50-80 ℃ and the time is 30-60min; and/or
In step (2), the conditions of the third contact reaction include at least: the temperature is 60-100deg.C, the pressure is 0.3-0.6MPa, and the time is 50-100min.
9. A rod-shaped ultrafine silver powder produced by the method of any one of claims 1 to 8.
10. The use of the rod-shaped ultrafine silver powder of claim 9 for preparing conductive silver paste.
CN202310095144.9A 2023-02-10 2023-02-10 Rod-shaped superfine silver powder and preparation method and application thereof Pending CN116213746A (en)

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