A B-site doped silver niobate high-entropy ceramic and its preparation method

Abstract

The present invention belongs to the technical field of high-entropy ceramic materials, and more specifically relates to a B-site doped silver niobate high-entropy ceramic and a preparation method thereof. The chemical general formula of the B-site doped silver niobate high-entropy ceramic is Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3. The preparation steps include: weighing raw materials Ag2O, Nb2O5, Ta2O5, V2O5 and MoO3 according to the above chemical general formula; performing first wet ball milling on the raw materials, followed by first drying and calcination to obtain high-entropy ceramic powder; performing second wet ball milling on the high-entropy ceramic powder, followed by second drying, grinding, pressing into shape and sintering to obtain the product. The Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 high-entropy ceramic prepared by the present invention has a dielectric constant of 314 at about 1 kHz and a loss lower than 0.05, with a relatively high dielectric constant and a relatively small dielectric loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-entropy ceramic materials, and more specifically relates to a B-site doped silver niobate high-entropy ceramic and a preparation method thereof. Background Art

[0002] High-entropy ceramic materials are multi-principal element solid solution ceramics formed by doping five or more elements in equal proportions. In recent years, with the in-depth research, single-phase solid solution ceramics formed by doping four principal elements in equal proportions can also be called high-entropy ceramics.

[0003] In the field of dielectric ceramics, the application of traditional lead-based ceramics has been greatly affected due to pollution problems. In order to cope with the air pollution situation, the development of lead-free ceramics has become a new direction. Silver niobate ceramics have become a research hotspot in dielectric energy storage ceramics because of their cleanliness and pollution-free properties. Previously, the modification of silver niobate mainly involved doping elements at the A-site or B-site, or double doping at both the A-site and B-site.

[0004] At present, there has been no research or report on the high-entropy design of silver niobate. How to design the B-site high-entropy of silver niobate, doping four or five suitable elements with equimolar ratio into the B-site lattice of silver niobate, causing the lattice distortion effect of silver niobate and increasing its degree of disorder, and further improving the dielectric properties of silver niobate has become a difficult problem that needs to be overcome by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a B-site doped silver niobate high-entropy ceramic and a preparation method thereof to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: Provide a B-site doped silver niobate high-entropy ceramic, and the chemical general formula of the B-site doped silver niobate high-entropy ceramic is Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3.

[0008] Another technical solution of the present invention: Provide a preparation method of a B-site doped silver niobate high-entropy ceramic, and the steps include:

[0009] Weigh the raw materials Ag2O, Nb2O5, Ta2O5, V2O5 and MoO3 according to the chemical general formula of the B-site doped silver niobate high-entropy ceramic;

[0010] Perform the first wet ball milling on the raw materials, and then obtain high-entropy ceramic powder through the first drying and calcination;

[0011] The high-entropy ceramic powder is subjected to a second wet ball milling, followed by a second drying, grinding, pressing and sintering to obtain the B-site doped silver niobate high-entropy ceramic.

[0012] Further, the rotation speed of the first wet ball milling is 300 rpm, the time is 12 - 24 h, and the ball milling medium is ethanol and zirconia balls. Among them, the mass ratio of the zirconia balls, raw materials and ethanol is 2:1:2.

[0013] Further, the temperature of the first drying is 80 - 100 °C, and the time is 12 - 24 h.

[0014] Further, the temperature of the calcination is 780 - 850 °C, the time is 2 - 3 h, and the calcination atmosphere is an oxygen atmosphere.

[0015] Further, the rotation speed of the second wet ball milling is 300 rpm, the time is 12 - 24 h, and the ball milling medium is ethanol and zirconia balls. Among them, the mass ratio of the zirconia balls, high-entropy ceramic powder and ethanol is 2:1:2.

[0016] Further, the temperature of the second drying is 80 - 100 °C, and the time is 12 - 24 h.

[0017] Further, the grinding time is 30 - 50 min.

[0018] Further, the pressure of the pressing is 150 - 240 MPa, and the pressure holding time is 5 - 15 min.

[0019] Further, the sintering temperature is 1050 - 1100 °C, the heat preservation time is 3 - 4 h, and the sintering atmosphere is an oxygen atmosphere.

[0020] The present invention discloses the following technical effects:

[0021] The steps of preparing the B-site doped silver niobate high-entropy ceramic by the present invention have a simple process, and have the characteristics of low production cost and high efficiency.

[0022] The Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 high-entropy ceramic prepared by the present invention does not need to add any binder and sintering aid.

[0023] The Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 high-entropy ceramic prepared by the present invention has a dielectric constant of 314 at about 1 kHz, a loss lower than 0.05, a relatively high dielectric constant and a relatively small dielectric loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0025] Figure 1 XRD pattern of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 prepared in Example 1;

[0026] Figure 2 Dielectric constant of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 prepared in Example 1 under the frequency condition of 1 kHz to 1 MHz;

[0027] Figure 3 Dielectric loss of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 prepared in Example 1 under the frequency condition of 1 kHz to 1 MHz. DETAILED DESCRIPTION OF THE INVENTION

[0028] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation to the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0031] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the specification of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0032] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0033] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products; the "room temperature" and "normal temperature" involved herein are 20-30°C unless otherwise specified.

[0034] Example 1

[0035] A preparation method of B-site doped silver niobate high-entropy ceramics, the steps are as follows:

[0036] S1. Weigh Ag2O, Nb2O5, Ta2O5, V2O5, MoO3 powders as raw materials according to the chemical general formula Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 and set aside;

[0037] S2. Put the raw materials into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: raw materials: absolute ethanol = 2:1:2, the ball milling speed is 300 rpm. Then put the ball milled slurry into an oven and dry it at 80°C for 12 h. After that, put it into a tube furnace and calcine it at 800°C. The calcination environment is an oxygen atmosphere, and the holding time is 2 h to obtain high-entropy ceramic powder;

[0038] S3. Put the high-entropy ceramic powder into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: high-entropy ceramic powder: absolute ethanol = 2:1:2, the ball milling speed is 300 rpm. Then put the ball milled slurry into an oven and dry it at 80°C for 12 h. After drying, grind it in a grinding jar for 30 min, and then press it into a ceramic green body with a diameter of 10 mm under a uniaxial pressure of 150 MPa, and the pressure holding time is 10 min;

[0039] S4. Place the ceramic green body in a boat-shaped crucible (lay a layer of ceramic powder with the same composition at the bottom of the ceramic green body to prevent adhesion), heat it at a heating rate of 6°C / min to 1050°C, keep it warm for 3 h in an oxygen atmosphere, and cool it to room temperature with the furnace, then the B-site doped silver niobate high-entropy ceramic (Ag(Nb 0.25 Ta 0.25 V 0.25 Mo0.25 )O3).

[0040] Example 2

[0041] Preparation method of B-site doped silver niobate high-entropy ceramics, the steps are as follows:

[0042] S1. Weigh Ag2O, Nb2O5, Ta2O5, V2O5, MoO3 powders as raw materials according to the chemical general formula Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 and set aside;

[0043] S2. Put the raw materials into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: raw materials: absolute ethanol = 2:1:2. The ball milling speed is 300 rpm. Then put the ball-milled slurry into an oven and dry it at 80 °C for 12 h. Then put it into a tube furnace and calcine it at 800 °C. The calcination environment is an oxygen atmosphere, and the holding time is 2.5 h to obtain high-entropy ceramic powder;

[0044] S3. Put the high-entropy ceramic powder into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: high-entropy ceramic powder: absolute ethanol = 2:1:2. The ball milling speed is 300 rpm. Then put the ball-milled slurry into an oven and dry it at 90 °C for 12 h. After drying, grind it in a grinding jar for 30 min, and then press it into a ceramic green body with a diameter of 10 mm under a uniaxial pressure of 150 MPa. The pressure holding time is 8 min;

[0045] S4. Place the ceramic green body in a boat-shaped crucible (lay a layer of ceramic powder with the same composition at the bottom of the ceramic green body to prevent adhesion), heat it to 1060 °C at a heating rate of 6 °C / min, keep it warm for 3.5 h in an oxygen atmosphere, and cool it to room temperature with the furnace, then the B-site doped silver niobate high-entropy ceramic (Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3) is obtained.

[0046] Example 3

[0047] Preparation method of B-site doped silver niobate high-entropy ceramics, the steps are as follows:

[0048] S1. Weigh Ag2O, Nb2O5, Ta2O5, V2O5, MoO3 powders as raw materials according to the chemical general formula Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3 and set aside;

[0049] S2. Put the raw materials into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: raw materials: absolute ethanol = 2:1:2. The ball milling speed is 300 rpm. Then put the ball-milled slurry into an oven and dry it at 80 °C for 12 h. After that, put it into a tube furnace and calcine it at 830 °C. The calcination environment is an oxygen atmosphere, and the holding time is 3 h to obtain high-entropy ceramic powder;

[0050] S3. Put the high-entropy ceramic powder into a ball mill for wet ball milling and mixing. Ball mill for 12 h according to the mass ratio of zirconia balls: high-entropy ceramic powder: absolute ethanol = 2:1:2. The ball milling speed is 300 rpm. Then put the ball-milled slurry into an oven and dry it at 100 °C for 24 h. After drying, grind it in a grinding jar for 30 min, and then press it into a ceramic green body with a diameter of 10 mm under a uniaxial pressure of 150 MPa. The pressure holding time is 13 min;

[0051] S4. Place the ceramic green body in a boat-shaped crucible (lay a layer of ceramic powder with the same composition at the bottom of the ceramic green body to prevent adhesion), heat it to 1070 °C at a heating rate of 6 °C / min, hold it for 4 h in an oxygen atmosphere, and then cool it to room temperature with the furnace to obtain the B-site doped silver niobate high-entropy ceramic (Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 ))O3).

[0052] Effect example

[0053] Figure 1 The XRD pattern of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 ))O3 prepared in Example 1 is shown in the figure. It can be seen from the figure that Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 ))O3 has a silver niobate phase structure and no other phase structures.

[0054] Figure 2 The dielectric constant of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 ))O3 prepared in Example 1 under the frequency condition of 1 kHz to 1 MHz; Figure 3 The dielectric loss of Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 ))O3 prepared in Example 1 under the frequency condition of 1 kHz to 1 MHz. FromFigures 2 - 3 It can be seen that the dielectric constant of this ceramic is stable. Under the test from 1 kHz to 1 MHz, the dielectric constant decreases from 314 to 200, and the dielectric constant is stable. The dielectric loss is in the range of 0.028 to 0.049.

[0055] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0056] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A B-site doped silver niobate high entropy ceramic, characterized in that: The chemical formula of the B-site doped silver niobate high entropy ceramic is Ag(Nb 0.25 Ta 0.25 V 0.25 Mo 0.25 )O3.

2. A method for preparing B-doped silver niobate high entropy ceramics, characterized in that the steps include: Weigh the raw materials Ag2O, Nb2O5, Ta2O5, V2O5 and MoO3 according to the chemical general formula of the B-site doped silver niobate high entropy ceramic according to claim 1; The raw material is subjected to a first wet ball milling, followed by a first drying and calcining to obtain a high entropy ceramic powder; The high entropy ceramic powder is subjected to a second wet ball milling, followed by a second drying, grinding, pressing and sintering to obtain the B-site doped silver niobate high entropy ceramic.

3. The preparation method according to claim 2, characterized in that: The rotation speed of the first wet ball milling is 300 rpm, the time is 12-24 hours, and the ball milling media are ethanol and zirconia balls, wherein the mass ratio of the zirconia balls, the raw materials and the ethanol is 2:1:

2.

4. The preparation method according to claim 2, characterized in that: The first drying is carried out at a temperature of 80-100° C. and for a time of 12-24 hours.

5. The preparation method according to claim 2, characterized in that: The calcination temperature is 780-850° C. and the calcination time is 2-3 hours.

6. The preparation method according to claim 2, characterized in that: The rotation speed of the second wet ball milling is 300 rpm, the time is 12-24 hours, and the ball milling media are ethanol and zirconia balls, wherein the mass ratio of the zirconia balls, high entropy ceramic powder and ethanol is 2:1:

2.

7. The preparation method according to claim 2, characterized in that: The second drying process is carried out at a temperature of 80-100° C. and for a time of 12-24 hours.

8. The preparation method according to claim 2, characterized in that: The grinding time is 30-50 min.

9. The preparation method according to claim 2, characterized in that: The compression molding pressure is 150-240 MPa, and the holding time is 5-15 min.

10. The preparation method according to claim 2, characterized in that: The sintering temperature is 1050-1100° C., and the heat preservation time is 3-4 hours.

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