CN109503162B

CN109503162B - Co-Sn-Ta-based microwave dielectric ceramic material and preparation method thereof

Info

Publication number: CN109503162B
Application number: CN201811530024.2A
Authority: CN
Inventors: 李恩竹; 杨鸿宇; 杨鸿程; 陈亚伟; 钟朝位; 张树人
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2018-12-14
Filing date: 2018-12-14
Publication date: 2021-05-04
Anticipated expiration: 2038-12-14
Also published as: CN109503162A

Abstract

The invention belongs to the field of electronic ceramics and manufacturing thereof, and particularly relates to a Co-Sn-Ta-based microwave dielectric ceramic material and a preparation method thereof. The crystal structure of the material provided by the invention is a Trirutile phase, the sintering temperature is 1250-^‑4‑6.02×10^‑4The temperature stability coefficient of the resonance frequency is-2.65 to-0.59 ppm/DEG C. Mixing the raw material Co₂O₃、SnO₂And Ta₂O₅According to the general formula Co_0.5Sn_0.5TaO₄Proportioning and preparing by a solid phase method. Co of the invention_0.5Sn_0.5TaO₄The microwave dielectric ceramic has moderate dielectric constant and near-zero temperature stability coefficient of resonant frequency, and the sintering temperature is relatively low; the preparation method is simple and easy for industrial production.

Description

Co-Sn-Ta-based microwave dielectric ceramic material and preparation method thereof

Technical Field

The invention belongs to the field of electronic ceramics and manufacturing thereof, and particularly relates to a Co-Sn-Ta-based microwave dielectric ceramic material and a preparation method thereof.

Background

Microwave communication is an important transmission form of modern electronic communication, and has wide application in the aspects of mobile communication, military radar, satellite, broadcasting and the like. There is an increasing demand for microwave devices such as resonators, filters, dielectric antennas, dielectric guided wave loops and the like. The microwave mixed integrated circuit formed by the resonator made of microwave dielectric ceramics and the microwave tube, the microstrip line and the like can enable the size of the device to reach millimeter level, so that the microwave ceramics becomes a basic and key material for realizing the microwave control function. The microwave dielectric ceramic should have moderate dielectric constant, high Q x f value and near-zero resonant frequency temperatureCoefficient of degree stability τ_fThe value is obtained. Wherein, the dielectric ceramic is close to zero tau for practical application_fThe value is critical.

Trirutile phase microwave dielectric ceramic CoTa₂O₆Has moderate dielectric constant: epsilon_r＝29、Q×f＝2300GHz、τ_f23 ppm/c. But the temperature required for sintering densification reaches 1500 ℃, which greatly limits the application.

Disclosure of Invention

Aiming at the problems or the defects, the invention provides a Co-Sn-Ta-based microwave dielectric ceramic material and a preparation method thereof, aiming at solving the problems of poor temperature stability and sintering temperature of the existing Trirutile-phase microwave dielectric ceramic.

The Co-Sn-Ta-based microwave dielectric ceramic material provided by the invention is Co_0.5Sn_0.5TaO₄The microwave dielectric ceramic material has a Trirutile phase crystal structure, the pre-sintering temperature is 850-1000 ℃, the sintering temperature is moderate (1250-^-4-6.02×10^-4The temperature stability coefficient of the resonance frequency is nearly zero (-2.65-0.59 ppm/. degree.C.). The raw material composition of the material is Co₂O₃、SnO₂And Ta₂O₅Chemical formula Co_0.5Sn_0.5TaO₄Prepared by a solid phase method.

The preparation method comprises the following steps:

step 1: cobalt oxide (Co)₂O₃) Tin oxide (SnO)₂) And tantalum oxide (Ta)₂O₅) According to the chemical formula Co_0.5Sn_0.5TaO₄And (4) batching.

Step 2: mixing the ingredients obtained in the step 1: zirconia balls: deionized water, which is prepared by mixing the components according to the mass ratio of 1:4-6:3-6, ball-milling for 6-8 hours in a planet way, drying at the temperature of 80-120 ℃, sieving by a sieve with 60-200 meshes, and presintering for 3-5 hours in the atmosphere at the temperature of 850-1000 ℃ to synthesize the main crystal phase Co_0.5Sn_0.5TaO₄；

And step 3: the powder obtained in the step 2 is prepared into powder: zirconia balls: carrying out planetary ball milling and mixing for 4-6 hours at the mass ratio of deionized water of 1:3-5:2-4, then drying at 80-100 ℃, adding a PVA solution with the mass percentage of 2-5% as a binder for granulation, carrying out compression molding, and finally sintering for 4-6 hours at 1250-1350 ℃ in an atmosphere to prepare Co_0.5Sn_0.5TaO₄Microwave dielectric ceramic material.

Invention pair CoTa₂O₆Introduction of SnO from raw materials₂Considering Sn⁴⁺Ions and Co²⁺And Ta⁵⁺Ions have similar ionic radii, so that in the crystal structure, Sn⁴⁺The ions can enter the lattice sites to form solid solutions. The formation temperature of the solid solution is low (the presintering temperature is 850 ℃ C.) and Sn is used for forming a crystal phase structure⁴⁺The introduction of ions, the temperature stability coefficient of the resonant frequency of the finally prepared material system is near zero (-2.65 to-0.59 ppm/DEG C), the material system has higher temperature stability, and the sintering temperature is 1250-₂O₆1500 ℃ for the ceramic.

Drawings

FIG. 1 is an XRD pattern for examples 1-5;

FIGS. 2a-e are SEM images of the surface topography of examples 1-5 in sequence.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Step 1, mixing Co₂O₃、SnO₂And Ta₂O₅According to the chemical formula Co_0.5Sn_0.5TaO₄And (4) batching.

Step 2, mixing the powder obtained in the step 1 according to the following ratio: zirconia balls: adding deionized water into a nylon tank according to the mass ratio of 1:4:3, carrying out planetary ball milling and mixing for 6 hours, taking out, drying at 100 ℃, sieving by using a 200-mesh sieve, and presintering at 900 ℃ for 4 hours in the atmosphere to synthesize the main crystal phase Co_0.5Sn_0.5TaO₄。

Step 3, pre-burning the powder obtained in the step 2 according to the following powder: zirconia balls: adding deionized water into a nylon tank according to the mass ratio of 1:5:1, carrying out planetary ball milling and mixing for 4 hours, taking out, drying at 100 ℃, adding a PVA solution with the mass percentage of 4% as a binder for granulation after drying, then carrying out compression molding, and finally sintering for 6 hours in an atmosphere at 1250-1350 ℃ to prepare the microwave dielectric ceramic material.

FIG. 1 is the XRD patterns of examples 1-5 with the Si peak as an internal standard for calibration experiments and instrument error. Diffraction peaks of the samples with Trirutile phase CoTa at different sintering temperatures₂O₆Cards (JCPDS #32-0314) matched, indicating that a Trirutile phase solid solution Co was formed at this time_0.5Sn_0.5TaO₄. The actual diffraction peak position has a shift phenomenon. According to bragg's law, the shift in peak position to the right is due to the change in unit cell volume. Compare CoTa₂O₆In other words, Co_0.5Sn_0.5TaO₄Phase Sn⁴⁺The ionic radius of the ion is equal to that of Co under the same coordination number²⁺And Ta⁵⁺The diffraction peaks shift due to the cell volume changes due to ion differences.

FIGS. 2a-e are SEM images of the surface topography of examples 1-5 in sequence. It can be seen from the graphs a-e that as the sintering temperature increases, the sample porosity decreases, the densification increases, and the grain size increases. However, when the sintering temperature is further increased, it is apparent from the graph d that the grain boundaries are blurred and pores appear, indicating that the sample is over-sintered when the optimal sintering temperature is exceeded.

The compositions and microwave dielectric properties of the examples are as follows

As can be seen from the above table, the samples of examples 1-5 did not shrink significantly after sintering. The dielectric constant of the sample shows a tendency of increasing and then decreasing with the increase of the sintering temperature, and the increase of the dielectric constant can be known by combining with the SEM pictureAt high, the dielectric constant is reduced by the increase in densification, followed by over-firing of the sample. The quality factor Qxf value of the sample shows the change consistent with the dielectric constant, which shows that the compactness and the sintering state of the sample have great influence on the quality factor Qxf value of the system. In examples 1 to 5, it can be found that_fThe value is near zero, and the method has application prospect.

In conclusion, the Co-Sn-Ta-based dielectric ceramic material provided by the invention has moderate sintering temperature, moderate dielectric constant, lower dielectric loss, near-zero temperature stability coefficient of resonant frequency and good performance parameters; and the preparation method is simple and easy for industrial production.

Claims

1. A Co-Sn-Ta-based microwave dielectric ceramic material is characterized in that:

is Co_0.5Sn_0.5TaO₄The microwave dielectric ceramic material has a crystal structure of Trirutile phase, the presintering temperature is 850-1000 ℃, and the presintering is carried out to synthesize a main crystal phase Co_0.5Sn_0.5TaO₄Sintering temperature 1250-^oC, dielectric constant of 15-20, loss of 4.81X 10^-4-6.02×10^-4The temperature stability coefficient of the resonance frequency is-2.65 to-0.59 ppm/DEG C;

the raw material composition of the material is Co₂O₃、SnO₂And Ta₂O₅Chemical formula Co_0.5Sn_0.5TaO₄Prepared by a solid phase method.

2. The preparation method of the Co-Sn-Ta-based microwave dielectric ceramic material as claimed in claim 1, comprising the following steps:

step 1: cobalt oxide Co₂O₃Tin oxide SnO₂And tantalum oxide Ta₂O₅According to the chemical formula Co_0.5Sn_0.5TaO₄Preparing materials;

step 2: mixing the ingredients obtained in the step 1: zirconia balls: deionized water, the weight ratio of which is 1:4-6:3-6, ball milling for 6-8 hours in a planet way, then drying at 80-120 ℃, sieving by a 60-200 mesh sieve, and finally sieving by a sievePresintering at 850-1000 deg.c for 3-5 hr to synthesize main crystal phase Co_0.5Sn_0.5TaO₄；

And step 3: and (3) mixing the powder obtained in the step (2) according to the following powder: zirconia balls: carrying out planetary ball milling and mixing for 4-6 hours at the mass ratio of deionized water of 1:3-5:2-4, then drying at 80-100 ℃, adding a PVA solution with the mass percentage of 2-5% as a binder for granulation, carrying out compression molding, and finally sintering for 4-6 hours at 1250-1350 ℃ in an atmosphere to prepare Co_0.5Sn_0.5TaO₄Microwave dielectric ceramic material.