Spherical and flake doped silver powder, and preparation method therefor and use thereof

Abstract

The present invention provides a spherical and flake doped silver powder, and a preparation method therefor and a use thereof. In the spherical and flake doped silver powder, the particle size of spherical silver powder is 0.8-2.0 μm, and the spherical silver powder accounts for 70-95%; the flake diameter of flake silver powder is 2.5-6.5 μm, and the flake silver powder accounts for 5-30%. In the spherical and flake doped silver powder provided by the present invention, the proportion of the spherical silver powder and the flake silver powder is controllable, and the overlapping is compact, so that a conductive paste prepared from the spherical and flake doped silver powder has low resistance and excellent conductivity.

Description

Spherical and flaky doped silver powder, preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of noble metal powder materials, in particular to a spherical and flaky doped silver powder, a preparation method and application thereof. BACKGROUND

[0002] Flaky silver powder is an important functional material in conductive paste, and reasonable jointing of flaky silver powder and spherical silver powder is conducive to reducing resistance and reducing silver consumption. Therefore, flaky silver powder is usually mixed with spherical silver powder in a certain proportion and applied to the fields of low-temperature silver paste such as light-emitting diode (LED) packaging conductive adhesive, chip packaging conductive adhesive and heterojunction (HJT) photovoltaic silver paste. With the rapid development of the downstream industry chain, component integration and printed fine line have become the current mainstream trend, and the requirements of each paste enterprise for silver powder performance, raw material cost and production efficiency are becoming increasingly stringent.

[0003] Silver powder prepared by liquid phase reduction method is mostly spherical, and flaky silver powder is generally prepared by mechanical ball milling method. Under the current research conditions, single spherical silver powder or flaky silver powder cannot meet the customer's demand, and the technology for synthesizing flaky and spherical silver powder at one time is difficult. The customers at the paste end need to purchase spherical silver powder and flaky silver powder respectively and explore the mixing ratio, resulting in high investment cost and low production efficiency.

[0004] Therefore, there is an urgent need for a spherical and flaky doped silver powder, a preparation method and application thereof to meet the application requirements of customers. SUMMARY

[0005] The purpose of the present application is to solve the technical problem that the preparation method of silver powder is difficult to prepare spherical and flaky doped silver powder.

[0006] To solve the above technical problems, the present application first provides a spherical and flaky doped silver powder, wherein in the spherical and flaky doped silver powder: the particle size of the spherical silver powder is 0.8-2.0 mu m, and the proportion is 70-95%; the flake diameter of the flaky silver powder is 2.5-6.5 mu m, and the proportion is 5-30%.

[0007] Correspondingly, the present application also provides a preparation method of a spherical and flaky doped silver powder, comprising:

[0008] S1, mixing silver nitrate solution, activator, core inhibitor and reducing liquid to obtain a primary product;

[0009] S2, mixing the primary product with a coating agent and stirring to obtain a reaction mother liquor;

[0010] S3, sequentially performing precipitation, cleaning, drying and screening treatment on the reaction mother liquor to obtain a spherical and flaky doped silver powder.

[0011] Preferably, the step S1 specifically comprises:

[0012] S11, mixing the silver nitrate solution and the activating agent, and then stirring in a reaction kettle to obtain a first mixed solution;

[0013] S12, mixing the blocking agent and the reducing solution to obtain a second mixed solution, and then adding the second mixed solution into the first mixed solution for stirring treatment to obtain a primary product;

[0014] In the step S12, the adding time of the second mixed solution into the first mixed solution is 5-15 s, and the stirring speed of the stirring treatment is 200-400 r / min.

[0015] Preferably, in the step S11, the activating agent comprises one or more of methanol, ethanol, formic acid, acetic acid, n-propanol, n-butanol, ethylene glycol and glycerol; and the mass ratio of the activating agent to the silver nitrate in the silver nitrate solution is (0.05-0.3) : 1.

[0016] Preferably, in the step S12, the blocking agent comprises one or more of sodium phosphate, potassium phosphate, sodium sulfate, potassium sulfate, sodium carbonate, potassium carbonate, sodium chloride and potassium chloride; and the mass ratio of the blocking agent to the silver nitrate in the silver nitrate solution is (0.01-0.1) : 1.

[0017] Preferably, in the step S12, the reducing solution comprises one or more of ascorbic acid, hydrogen peroxide, glucose and hydrazine hydrate; and the mass ratio of the reducing solution to the silver nitrate in the silver nitrate solution is (0.5-1.0) : 1.

[0018] Preferably, in the step S2, the coating agent comprises one or more of stearic acid, lauric acid and oleic acid.

[0019] Preferably, the step S3 specifically comprises:

[0020] S31, performing solid-liquid separation on the reaction mother liquor to obtain a filter residue;

[0021] S32, washing the filter residue with deionized water until the conductivity is less than or equal to 20 μs / cm to obtain a wet powder;

[0022] S33, drying the wet powder and passing it through a 200-mesh screen to obtain the spherical and flaky doped silver powder.

[0023] Correspondingly, the application further provides a use of the spherical and flaky doped silver powder in the preparation of conductive paste.

[0024] The beneficial effects of the present application are: different from the prior art, the present application provides a kind of spherical and flaky doped silver powder and its preparation method and application, the spherical and flaky doped silver powder described above: the particle size of spherical silver powder is 0.8-2.0 μm, and the proportion is 70-95%; The flake diameter of flaky silver powder is 2.5-6.5 μm, and the proportion is 5-30%; The proportion between spherical silver powder and flaky silver powder in the spherical and flaky doped silver powder provided by the present application is controllable, and the lap joint is dense, so that the conductive paste prepared by the spherical and flaky doped silver powder described above has low resistance and excellent conductivity. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a preparation method flow chart of the spherical and flaky doped silver powder provided by the present application;

[0026] Figure 2 is an electron microscope graph of the spherical and flaky doped silver powder provided by Example 1 of the present application;

[0027] Figure 3 is an electron microscope graph of the spherical and flaky doped silver powder provided by Example 2 of the present application;

[0028] Figure 4 is an electron microscope graph of the spherical and flaky doped silver powder provided by Example 3 of the present application;

[0029] Figure 5 is an electron microscope graph of the spherical and flaky doped silver powder provided by Comparative Example 1. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application, obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] In view of the technical problem that the existing silver powder preparation method is difficult to prepare spherical and flaky doped silver powder, the present application provides a kind of spherical and flaky doped silver powder and its preparation method and application, the spherical and flaky doped silver powder prepared by the method has the characteristics of good dispersibility, controllable proportion of spherical and flaky, and the whole process is prepared at one time, the operation method is fast, simple and convenient, green and harmless, suitable for large-scale production.

[0032] In order to achieve the above technical purpose, the present application adopts the following technical scheme:

[0033] In the first aspect, the present application first provides a kind of spherical and flaky doped silver powder, wherein the spherical and flaky doped silver powder: the particle size of spherical silver powder is 0.8-2.0 μm, and the proportion is 70-95%; The flake diameter of flaky silver powder is 2.5-6.5 μm, and the proportion is 5-30%.

[0034] In a second aspect, the present application further provides a preparation method of the spherical and flaky doped silver powder.

[0035] Referring to FIG. 1, FIG. 1 is a flow chart of the preparation method of the spherical and flaky doped silver powder according to the embodiment of the present application; the preparation method specifically includes the following steps:

[0036] S1, mixing silver nitrate solution, activator, nucleation inhibitor and reducing liquid to obtain a primary product.

[0037] Specifically, the step S1 further includes:

[0038] S11, mixing the silver nitrate solution and the activator, and then stirring in a reaction kettle to obtain a first mixed liquid;

[0039] S12, mixing the nucleation inhibitor and the reducing liquid to obtain a second mixed liquid, and then adding the second mixed liquid into the first mixed liquid for stirring treatment to obtain the primary product;

[0040] In the step S12, the adding time of the second mixed liquid into the first mixed liquid is 5-15 s, and the stirring speed of the stirring treatment is 200-400 r / min.

[0041] Specifically, the silver nitrate solution and the reducing liquid undergoes an oxidation-reduction reaction, so that the silver ions in the silver nitrate solution are reduced into silver powder.

[0042] Specifically, the activator refers to a solution capable of increasing the chemical reaction rate or improving the reaction performance. The activator is usually some substances capable of interacting with the reactants, thereby changing the reaction path or reducing the reaction activation energy; in the embodiment, the release of silver ions and the dispersion of silver particles are controlled by introducing the activator.

[0043] In the step S11, the activator includes one or more of methanol, ethanol, formic acid, acetic acid, n-propanol, n-butanol, ethylene glycol and glycerol; and the mass ratio of the activator to silver nitrate in the silver nitrate solution is (0.05-0.3):1.

[0044] Specifically, when the mass ratio of the activator to silver nitrate in the silver nitrate solution is less than 0.05:1, the release speed of silver ions is too low, which increases the reaction time; when the mass ratio of the activator to silver nitrate in the silver nitrate solution is greater than 0.3:1, the release speed of silver ions is too fast, which reduces the dispersion of silver particles.

[0045] Specifically, the nucleation inhibitor refers to a substance capable of inhibiting or preventing the formation of crystal nucleus in the process of crystal growth, the formation of crystal nucleus is a key step of crystal growth, the nucleation inhibitor works by combining with the active sites on the surface of the crystal, thereby inhibiting the formation and growth of the crystal nucleus; in the embodiment, the invention controls the anisotropy of the growth of silver crystal nucleus in the reaction system by introducing the nucleation inhibitor, so that part of the silver powder tends to grow in a flaky shape, thereby achieving controllable proportion of spherical and flaky silver powder. The overlap between flaky and spherical silver powder is dense, so that the prepared conductive paste has low resistance and excellent conductivity.

[0046] In the S12 step, the nucleation inhibitor includes one or more of sodium phosphate, potassium phosphate, sodium sulfate, potassium sulfate, sodium carbonate, potassium carbonate, sodium chloride and potassium chloride; the mass ratio of the nucleation inhibitor to silver nitrate in the silver nitrate solution is (0.01-0.1):1.

[0047] Specifically, when the mass ratio of the nucleation inhibitor to silver nitrate in the silver nitrate solution is less than 0.01:1, the amount of flaky silver powder generated after the reaction will be too small, thereby it is difficult to meet the needs of the client; when the mass ratio of the nucleation inhibitor to silver nitrate in the silver nitrate solution is greater than 0.1:1, the amount of powdery silver powder generated after the reaction will be too small, thereby it is difficult to meet the needs of the client.

[0048] In the S12 step, the reducing agent includes one or more of ascorbic acid, hydrogen peroxide, glucose and hydrazine hydrate; the mass ratio of the reducing agent to silver nitrate in the silver nitrate solution is (0.5-1.0):1.

[0049] Specifically, when the mass ratio of the reducing agent to silver nitrate in the silver nitrate solution is less than 0.5:1, the degree of oxidation of silver ions in the silver nitrate solution will be reduced, thereby the amount of oxidation product generated will be correspondingly reduced; when the mass ratio of the reducing agent to silver nitrate in the silver nitrate solution is greater than 1.0:1, too much reducing agent does not participate in the reaction completely, causing waste of reagents and increasing experimental costs.

[0050] S2, the primary product is mixed with a coating agent and then subjected to stirring treatment to obtain a reaction mother liquor.

[0051] Specifically, the S2 step further includes:

[0052] After the second mixed solution and the first mixed solution are completely oxidized and reduced, the primary product generated after the reaction is mixed with a coating agent and then subjected to stirring treatment to obtain a reaction mother liquor; wherein the coating agent includes one or more of stearic acid, lauric acid and oleic acid.

[0053] Specifically, the coating agent is used to coat the primary product, which can form a protective film on the surface of the silver powder, reducing the contact between the silver powder and the air, thereby reducing the degree of oxidation of the silver powder.

[0054] S3, the reaction mother liquor is sequentially subjected to precipitation, cleaning, drying and screening treatment, to obtain spherical and flaky doped silver powder.

[0055] Specifically, the S3 step specifically comprises:

[0056] S31, the reaction mother liquor is subjected to solid-liquid separation after standing for 10 min, to obtain filter residue;

[0057] S32, the filter residue is washed with deionized water until the conductivity is less than or equal to 20 μs / cm, to obtain wet powder; wherein, the residual impurity ions are removed by repeatedly washing with deionized water, so that the conductivity meets the requirement of less than or equal to 20 μs / cm, thereby ensuring the quality and performance of the product.

[0058] S33, the wet powder is subjected to drying and 200-mesh screening, to obtain the spherical and flaky doped silver powder.

[0059] Correspondingly, the application further provides a use of the above spherical and flaky doped silver powder in preparation of conductive paste.

[0060] The technical solutions of the application will be further described in combination with specific embodiments.

[0061] Embodiment 1:

[0062] The embodiment 1 of the application provides a preparation method of spherical and flaky doped silver powder, comprising the following steps:

[0063] S1, raw material preparation: 200 g of analytical pure silver nitrate is dissolved in 2 L of deionized water to obtain a silver nitrate solution, and 20 g of ethanol is added and uniformly mixed for standby use; 6 g of potassium sulfate is dissolved in 100 mL of deionized water to obtain a nucleation inhibitor; 95 g of ascorbic acid is dissolved in 1.5 L of deionized water to obtain a reducing agent solution for standby use; and 5 g of oleic acid is dissolved in 20 mL of anhydrous ethanol to obtain a coating agent for standby use.

[0064] S2, the mixed solution of the silver nitrate solution and the activator is transferred to a reaction kettle, and stirring is started; under the condition of 300 r / min stirring, the mixed solution of the nucleation inhibitor and the reducing liquid is poured into the reaction kettle, the feeding time is controlled to be 10 s, and after the feeding is completed, the coating agent is poured into the kettle, and the stirring is continued for 10 min until the reaction is completed, to obtain a reaction mother liquor;

[0065] S3, the reaction mother liquor is placed in a solid-liquid separator after standing for 10 min, and is subjected to suction filtration; deionized water is added for washing until the conductivity is below 20 μs / cm; and the wet powder is placed in a blast drying oven and is dried at 70 ℃ for 10 h. The dried silver powder is subjected to 200-mesh screening, to obtain the spherical and flaky doped silver powder.

[0066] Specifically, the spherical and flaky doped silver powder obtained in the embodiment 1 has a D50 of 2.1 μm, and the electron microscope photograph is shown in Fig. 2, wherein the proportion of the spherical silver powder is about 85%, and the proportion of the flaky silver powder is about 15%. The silver powder obtained in the embodiment 1 is used to prepare a low-temperature conductive silver paste together with an organic resin, a binder and the like, a standard line is printed by using a screen printing machine, and the resistance value is 0.13 Ω after 1 h of baking at 150 ℃ and testing by using an ohmmeter.

[0067] Embodiment 2

[0068] The embodiment 2 of the present application provides a preparation method of a spherical and flaky doped silver powder, comprising the following steps:

[0069] S1, raw material preparation: 200 g of analytical pure silver nitrate is dissolved in 2 L of deionized water to obtain a silver nitrate solution, and 20 g of ethylene glycol is added and uniformly mixed for standby use; 8 g of potassium chloride is dissolved in 100 mL of deionized water to obtain a nucleation inhibitor; 95 g of ascorbic acid is dissolved in 1.5 L of deionized water to obtain a reducing agent solution for standby use; 5 g of lauric acid is dissolved in 20 mL of anhydrous ethanol to obtain a coating agent for standby use.

[0070] S2, the mixture of the silver nitrate solution and the activator is transferred to a reaction kettle, and stirring is started. Under the condition of 300 r / min stirring, the mixture of the nucleation inhibitor and the reducing liquid is poured into the reaction kettle, the feeding time is controlled to be 10 s, and after the feeding is completed, the coating agent is poured into the kettle, and the stirring is continued for 10 min until the reaction is completed, and the reaction mother liquor is obtained;

[0071] S3, the reaction mother liquor is placed for 10 min and then discharged into a solid-liquid separator, and suction filtration is performed. The wet powder is washed with deionized water until the conductivity is below 20 μs / cm, and then the wet powder is placed in a blast drying oven and dried at 70 ℃ for 10 h. The silver powder after drying is screened by a 200 mesh sieve to obtain the spherical and flaky doped silver powder.

[0072] Specifically, the spherical and flaky doped silver powder obtained in the embodiment 2 has a D50 of 2.2 μm, and the electron microscope photograph is shown in Fig. 3, wherein the proportion of the spherical silver powder is about 95%, and the proportion of the flaky silver powder is about 5%. The silver powder obtained in the embodiment 2 is used to prepare a low-temperature conductive silver paste together with an organic resin, a binder and the like, a standard line is printed by using a screen printing machine, and the resistance value is 0.22 Ω after 1 h of baking at 150 ℃ and testing by using an ohmmeter.

[0073] Embodiment 3

[0074] The embodiment 3 provides a preparation method of a spherical and flaky doped silver powder, comprising the following steps:

[0075] S1, raw material preparation: 200 g of analytical pure silver nitrate was dissolved in 2 L of deionized water to obtain a silver nitrate solution, and then 10 g of ethanol was added and mixed uniformly for standby; 5 g of sodium sulfate was dissolved in 100 mL of deionized water to obtain a nucleation inhibitor; 95 g of ascorbic acid was dissolved in 1.5 L of deionized water to obtain a reducing agent solution for standby; 5 g of oleic acid was dissolved in 20 mL of anhydrous ethanol to obtain a coating agent for standby.

[0076] S2, the mixture of the silver nitrate solution and the activator was transferred to the reaction kettle, and stirring was started. Under the condition of 200 r / min stirring, the mixture of the nucleation inhibitor and the reducing liquid was poured into the reaction kettle, and the feeding time was controlled for 10 s. After the feeding was completed, the coating agent was poured into the kettle, and the stirring was continued for 10 min until the reaction was completed, and the reaction mother liquor was obtained;

[0077] S3, the reaction mother liquor was placed for 10 min and then discharged into a solid-liquid separator, and filtration was performed. After washing with deionized water until the conductivity was below 20 μs / cm, the wet powder was placed in a blast drying oven and dried at 70°C for 10 h. The silver powder after drying was screened through a 200 mesh sieve, and the spherical and flaky doped silver powder was obtained.

[0078] Specifically, the spherical and flaky doped silver powder obtained in Example 3 has a D50 of 2.0 μm, and the electron microscope photograph is shown in FIG. 4. The proportion of spherical silver powder is about 90%, and the proportion of flaky silver powder is about 10%. The silver powder obtained in Example 3 is used to prepare a low-temperature conductive silver paste together with organic resin, binder and the like. A standard line is printed using a screen printing machine, and after baking at 150°C for 1 h, the resistance value is 0.17Ω as tested by a resistance meter.

[0079] Comparative Example 1

[0080] Comparative Example 1 provides a preparation method of micro-nano silver powder, which is different from the present application in that no activator and nucleation inhibitor are added, and the other contents are the same as those in Example 1 of the present application.

[0081] Specifically, the silver powder prepared in Comparative Example 1 has a basic spherical morphology and poor dispersibility, and the electron microscope photograph is shown in FIG. 5. The resistance value of the low-temperature conductive silver paste prepared by the silver powder is 0.37Ω after baking by a printing machine, and the conductivity is poor.

[0082] Specifically, by comparing the spherical and flaky doped silver powder prepared in Example 1 of the present application with the silver powder prepared in Comparative Example 1, it can be found that the resistance value of the low-temperature conductive silver paste prepared by the spherical and flaky doped silver powder prepared in Example 1 of the present application is much lower than that of the low-temperature conductive silver paste prepared by the silver powder prepared in Comparative Example 1.

[0083] The spherical and flaky doped silver powder prepared by the fast reaction, simple operation, green and harmless process of the present application has good dispersibility, and the proportion of flaky silver powder is controllable at 5-30%. The spherical and flaky doped silver powder can be applied in the field of low-temperature conductive silver paste and is suitable for mass production.

[0084] In the process of generating spherical and flaky doped silver powder by the silver nitrate solution and the reducing liquid redox, the release of silver ions and the dispersion of silver particles are controlled by introducing the activator, and the anisotropy of the growth of silver crystal nucleus in the reaction system is controlled by introducing the nucleation inhibitor, so that part of the silver powder tends to grow in a flaky shape, so that the proportion of the spherical silver powder and the flaky silver powder is controllable, and the flaky silver powder and the spherical silver powder are densely overlapped, so that the prepared conductive paste has low resistance and excellent conductivity.

[0085] In summary, unlike the prior art, the present application provides a kind of spherical and flaky doped silver powder and its preparation method and application, the spherical and flaky doped silver powder described above: the particle size of spherical silver powder is 0.8-2.0 μm, and the proportion is 70-95%; the flaky silver powder has a flaky diameter of 2.5-6.5 μm, and the proportion is 5-30%; the spherical and flaky doped silver powder provided by the present application has a controllable proportion between the spherical silver powder and the flaky silver powder, and is densely overlapped, so that the conductive paste prepared by the spherical and flaky doped silver powder has low resistance and excellent conductivity.

[0086] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own emphasis. If not fully described in individual embodiments, please refer to the description in other embodiments.

[0087] The above examples only express the embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the inventive concept, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A spherical and flake-shaped doped silver powder, characterized in that, Of the spherical and flake-shaped doped silver powders: the particle size of the spherical silver powder is 0.8–2.0 μm, accounting for 70–95%; the flake-shaped silver powder has a diameter of 2.5–6.5 μm, accounting for 5–30%.

2. A method for preparing spherical and sheet-like doped silver powder as described in claim 1, characterized in that, include: S1, the initial product is obtained by mixing silver nitrate solution, activator, nucleation inhibitor and reducing solution; S2, the initial product is mixed with the coating agent and then stirred to obtain the reaction mother liquor; S3, the reaction mother liquor is subjected to precipitation, washing, drying and sieving in sequence to obtain spherical and flake-shaped doped silver powder.

3. The method for preparing spherical and sheet-like doped silver powder according to claim 2, characterized in that, The S1 step specifically includes: S11, The silver nitrate solution and the activator are mixed and placed in a reaction vessel and stirred to obtain the first mixture; S12, after mixing the nucleation inhibitor and the reducing solution to obtain a second mixture, the second mixture is then added to the first mixture and stirred to obtain the initial product; In step S12, the feeding time of the second mixture to the first mixture is 5 to 15 seconds, and the stirring speed of the stirring process is 200 to 400 r / min.

4. The method for preparing spherical and sheet-like doped silver powder according to claim 3, characterized in that, In step S11, the activator includes one or more of methanol, ethanol, formic acid, acetic acid, n-propanol, n-butanol, ethylene glycol, and glycerol.

5. The method for preparing spherical and sheet-like doped silver powder according to claim 3, characterized in that, In step S11, the mass ratio of the activator to the silver nitrate in the silver nitrate solution is (0.05-0.3):

1.

6. The method for preparing spherical and sheet-like doped silver powder according to claim 3, characterized in that, In step S12, the nucleation inhibitor includes one or more of sodium phosphate, potassium phosphate, sodium sulfate, potassium sulfate, sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride; the mass ratio of the nucleation inhibitor to silver nitrate in the silver nitrate solution is (0.01-0.1):

1.

7. The method for preparing spherical and sheet-like doped silver powder according to claim 3, characterized in that, In step S12, the reducing solution includes one or more of ascorbic acid, hydrogen peroxide, glucose, and hydrazine hydrate; the mass ratio of the reducing solution to silver nitrate in the silver nitrate solution is (0.5-1.0):

1.

8. The method for preparing spherical and sheet-like doped silver powder according to claim 2, characterized in that, In step S2, the coating agent includes one or more of stearic acid, lauric acid, and oleic acid.

9. The method for preparing spherical and sheet-like doped silver powder according to claim 2, characterized in that, The S3 step specifically includes: S31, after the mother liquor is allowed to stand, solid-liquid separation is performed to obtain filter residue; S32, the filter residue is washed with deionized water until the conductivity is less than or equal to 20 μs / cm to obtain wet powder; S33, the wet powder is dried and passed through a 200-mesh sieve to obtain the spherical and flake-shaped doped silver powder.

10. The application of the spherical and flake-shaped doped silver powder as described in claim 1 in the preparation of conductive paste.

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