A method for preparing barium-samarium-titanium microwave dielectric ceramic by reaction sintering

Abstract

The application discloses a method for preparing barium-samarium-titanium microwave dielectric ceramic by reaction sintering and belongs to the microwave dielectric ceramic field. The method comprises the following steps: BaCO3, Sm2O3 and TiO2 are proportioned according to a chemical formula, and then are subjected to wet ball milling, drying, granulation, screening and pressing into a cylindrical blank, and finally are sintered. The chemical formula of the barium-samarium-titanium microwave dielectric ceramic prepared by the method is Ba4Sm 28 / 3 Ti 18 O 54 , the relative dielectric constant is 68.56-80.26, the quality factor is 8342-9519 GHz, and the resonance frequency temperature coefficient is -10.9--7.9 ppm / ℃. The reaction sintering method provided by the application omits the powder pre-sintering, secondary ball milling and drying in the solid-phase sintering method, greatly simplifies the preparation process of the barium-samarium-titanium ceramic, saves the production time and cost, and provides a reaction sintering method for the high-dielectric barium-samarium-titanium microwave dielectric ceramic, which has simple process and good temperature stability, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of microwave dielectric ceramics, specifically relating to a method for preparing barium samarium titanium-based microwave dielectric ceramics by reaction sintering. Background Technology

[0002] With the rapid development of 5G / 6G mobile communication technologies, the market demand for high-performance microwave components (microwave dielectric antennas, dielectric filters, dielectric resonators, etc.) is growing rapidly. As a core material for manufacturing microwave components, microwave dielectric ceramics have always been an important research direction in the field of electronic ceramics. Microwave components made from microwave dielectric ceramic materials have advantages such as high quality factor and good temperature stability, and have been widely used in 5G communication systems.

[0003] Barium samarium titanium ceramics with tungsten bronze structure possess advantages such as high dielectric constant, low dielectric loss, good temperature stability, and non-toxicity and environmental friendliness, and have been widely used in the miniaturization of microwave devices. Currently, the main methods for preparing barium samarium titanium ceramics include the traditional solid-state method, the sol-gel method, and spark plasma sintering. The sol-gel method for preparing barium samarium titanium ceramics is complex, has limited raw material powder yield, and is unsuitable for large-scale production. Spark plasma sintering requires expensive spark plasma sintering furnaces. The traditional solid-state method for preparing barium samarium titanium ceramics is complex, energy-intensive, and requires steps such as batching, ball milling, drying, pre-firing, secondary ball milling, secondary drying, granulation, pressing, and sintering. This invention uses a reaction sintering method to prepare barium samarium titanium ceramics, overcoming the disadvantages of existing technologies such as complex processes, low yield, and high energy consumption. The dielectric ceramics prepared under simple process conditions exhibit excellent comprehensive microwave dielectric properties. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, the present invention aims to provide a method for preparing barium samarium titanium-based microwave dielectric ceramics using reaction sintering. The method provided by the present invention uses BaCO3, Sm2O3, and TiO2 as the main raw materials, and has the advantages of simple process, low energy consumption, and high yield. The prepared dielectric ceramics have good comprehensive microwave dielectric properties.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] A method for preparing barium samarium titanium-based microwave dielectric ceramics by reaction sintering, specifically including the following steps:

[0007] (1) Mix the raw materials BaCO3, Sm2O3, and TiO2 according to the chemical formula Ba4Sm 28 / 3 Ti 18 O 54 Mix evenly in a dry environment;

[0008] (2) Put the mixed raw materials into a ball mill and add deionized water for ball milling for 1-4 hours; then dry at 100-130℃ for 12 hours and sieve.

[0009] (3) Use an 8% polyvinyl alcohol solution as a binder, granulate, and sieve;

[0010] (4) A powder tablet press is used to press the preform to obtain the preform. The forming pressure of the powder tablet press is 100 MPa.

[0011] (5) The blank is sintered at 1300~1450℃ for 4h to obtain barium samarium titanium microwave dielectric ceramic.

[0012] Preferably, the purity of the raw materials BaCO3, Sm2O3 and TiO2 in step (1) is greater than 99%.

[0013] Preferably, the ball mill in step (2) is a star ball mill.

[0014] Preferably, the amount of binder added in step (3) is 6% to 8% of the mass of the mixture to be granulated.

[0015] Preferably, the sieving in steps (2) and (3) is done through a 60-mesh sieve.

[0016] Preferably, in step (4), the diameter of the blank is 8 mm and the thickness of the blank is 2~6 mm.

[0017] Preferably, the sintering in step (5) is performed in an air atmosphere.

[0018] The aforementioned barium samarium titanium-based microwave dielectric ceramics possess excellent comprehensive microwave dielectric properties, with a relative permittivity reaching up to 80.26, a quality factor reaching up to 9519 GHz, and a resonant frequency temperature coefficient as low as -7.9 ppm / ℃. The microwave dielectric ceramics of this invention are prepared using a reaction sintering method, sintered at specific temperatures and times. The resulting microwave dielectric ceramics exhibit a rod-shaped grain morphology, high density, and low vacancy defects.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. This invention provides a reaction sintering method that is simple, energy-efficient, and yields high output, which is beneficial for industrialization. The barium samarium titanium-based microwave dielectric ceramics prepared by this method have excellent comprehensive microwave dielectric properties, with a relative permittivity of 68.56~80.26, a quality factor of 8342~9519 GHz, and a resonant frequency temperature coefficient close to zero (-10.9~-7.9ppm / ℃).

[0021] 2. This preparation method eliminates the need for powder pre-calcination, secondary ball milling, and drying in the solid-state method, greatly simplifying the preparation process of barium samarium titanium ceramics, saving production time and costs, and making it suitable for large-scale production.

[0022] 3. The ceramics prepared by this invention have a comparable relative permittivity and a significantly improved quality factor compared to ceramics prepared by traditional solid-state methods, and have broad application prospects. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the preparation of barium samarium titanium-based microwave dielectric ceramics using the reaction sintering method of the present invention;

[0024] Figure 2 X-ray diffraction patterns of the barium samarium titanium-based microwave dielectric ceramics prepared in Examples 1-4 of this invention;

[0025] Figure 3 The images are scanning electron microscope images of the barium samarium titanium-based microwave dielectric ceramics prepared in Examples 1-4 of this invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] The barium samarium titanium-based microwave dielectric ceramic of this embodiment is prepared by the following steps:

[0029] (1) BaCO3, Sm2O3, and TiO2 with a purity greater than 99% are arranged according to the composition Ba4Sm 28 / 3 Ti 18 O 54 Mix evenly;

[0030] (2) The mixed raw materials are put into a ball mill and deionized water is added for ball milling. The ball milling time is 2 hours. Then the ball-milled raw materials are dried at 120°C.

[0031] (3) Use a polyvinyl alcohol solution with a mass fraction of 8% as a binder. The amount of binder added is 6% of the mass of the mixture to be granulated. Granulate and pass through a 60-mesh sieve to obtain powder with uniform particles.

[0032] (4) A powder tablet press is used to press the blank to obtain the blank. The forming pressure of the powder tablet press is 100MPa; the diameter of the blank is 8mm and the thickness of the blank is 2~6mm.

[0033] (5) The green body was sintered at 1300℃ and held for 4 hours to obtain barium samarium titanium microwave dielectric ceramic material;

[0034] (6) Test the microwave dielectric properties of the prepared barium samarium titanium microwave dielectric ceramic.

[0035] Example 2

[0036] The preparation method of barium samarium titanium microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (5) is 1350℃.

[0037] Example 3

[0038] The preparation method of barium samarium titanium microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (5) is 1400℃.

[0039] Example 4

[0040] The preparation method of barium samarium titanium microwave dielectric ceramic in this embodiment is basically the same as that in Example 1, except that the sintering temperature in step (5) is 1450℃.

[0041] Comparative Example 1

[0042] (1) BaCO3, Sm2O3, and TiO2 with a purity greater than 99% are arranged according to the composition Ba4Sm 28 / 3 Ti 18 O 54 Mix evenly;

[0043] (2) The mixed raw materials are put into a ball mill and deionized water is added for ball milling. The ball milling time is 2 hours. Then the ball-milled raw materials are dried at 120°C and passed through a 60-mesh sieve to obtain powder with uniform particles.

[0044] (3) Heat the uniformly sized powder to 1150°C at 5°C / min for 3 hours for pre-firing and holding.

[0045] (4) Put the pre-calcined powder into a ball mill and add deionized water for ball milling for 2 hours; then dry the ball-milled raw material at 120°C.

[0046] (5) Use a polyvinyl alcohol solution with a mass fraction of 8% as a binder. The amount of binder added is 6% of the mass of the mixture to be granulated. Granulate and pass through a 60-mesh sieve to obtain powder with uniform particles.

[0047] (6) A powder tablet press is used to press the blank to obtain the blank. The forming pressure of the powder tablet press is 100MPa; the diameter of the blank is 8mm and the thickness of the blank is 2~6mm.

[0048] (7) The green body was sintered at 1300℃ and held for 4 hours to obtain barium samarium titanium microwave dielectric ceramic material;

[0049] (8) Test the microwave dielectric properties of the prepared barium samarium titanium microwave dielectric ceramic.

[0050] Comparative Example 2

[0051] The preparation method of microwave dielectric ceramics in this comparative example is basically the same as that in comparative example 1, except that the sintering temperature in step (7) is 1350℃.

[0052] Comparative Example 3

[0053] The preparation method of microwave dielectric ceramics in this comparative example is basically the same as that in comparative example 1, except that the sintering temperature in step (7) is 1400℃.

[0054] Comparative Example 4

[0055] The preparation method of microwave dielectric ceramics in this comparative example is basically the same as that in comparative example 1, except that the sintering temperature in step (7) is 1450℃.

[0056] The microwave dielectric properties of the barium samarium titanium microwave dielectric ceramics prepared in the above examples and comparative examples were tested using an Agilent 5071C network analyzer. The test results are detailed in Table 1. As shown in Table 1, the reaction sintering method not only greatly simplifies the preparation process of barium samarium titanium ceramics, but also significantly improves the microwave dielectric properties, especially the quality factor (Q×f = 9519 GHz), of the ceramics prepared at the optimal sintering temperature (Example 3, 1400 ℃), compared to the traditional solid-state method (Comparative Example 3, 1400 ℃, Q×f = 8230 GHz).

[0057] The proportion of trivalent Ti in ceramic samples sintered at 1400 °C by reaction sintering and conventional solid-state sintering was compared using X-ray photoelectron spectroscopy (XPS). Details of the results are shown in Table 2. Under high-temperature sintering conditions, Ti in ceramic compounds is easily reduced from tetravalent to trivalent, thus deteriorating the quality factor. Table 2 shows that the proportion of trivalent titanium in the reaction sintering method (11.87%) is lower than that in the conventional solid-state method (27.63%), indicating that the reaction sintering method can effectively suppress Ti reduction in barium samarium titanium ceramics.

[0058] Table 1: Microwave Dielectric Properties of Barium Samarium Titanium Ceramics

[0059]

[0060] Table 2: Binding energy of Ti 2p and Ti in barium samarium titanium ceramics 3+ Relative content comparison

[0061]

[0062] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing barium samarium titanium-based microwave dielectric ceramics by reaction sintering, characterized in that, Includes the following steps: The raw materials BaCO3, Sm2O3, and TiO2 were prepared according to the chemical formula Ba4Sm 28 / 3 Ti 18 O 54 The mixture is prepared by mixing, ball milling, drying, granulation, sieving, pressing, and then sintering at 1400~1450℃ for 4h to obtain barium samarium titanium microwave dielectric ceramic.

2. The method for preparing microwave dielectric ceramics according to claim 1, characterized in that, The purity of the raw materials BaCO3, Sm2O3, and TiO2 is greater than 99%.

3. The method for preparing microwave dielectric ceramics according to claim 1, characterized in that, The ball milling process uses a star ball mill.

4. The method for preparing microwave dielectric ceramics according to claim 1, characterized in that, The granulation process uses an 8% polyvinyl alcohol solution as a binder; the amount of binder added is 6% to 8% of the mass of the mixture to be granulated.

5. The method for preparing microwave dielectric ceramics according to claim 1, characterized in that, The sieving process involves passing the material through a 60-mesh sieve.

6. The method for preparing microwave dielectric ceramics according to claim 1, characterized in that, The diameter of the blank obtained by pressing is 8 mm, and the thickness of the blank is 2~6 mm.

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