阅读说明：本技术 一种低温烧结微波介质材料及其制备方法 (Low-temperature sintered microwave dielectric material and preparation method thereof ) 是由 刘志甫 杨燕 马名生 于 2021-09-06 设计创作，主要内容包括：本发明涉及一种低温烧结微波介质材料及其制备方法。所述低温烧结微波介质材料的化学组成为xM-(u)Al-(v)O-(w)+y(aCuO-bTiO-(2)-cNbO-(2.5))；其中,M为Mg、Zn、Ca、Ba中的至少一种,1≤u≤2、1≤v≤2、4≤w≤5；x、y为质量百分数,1 wt%≤y≤10 wt%,x+y=100 wt%；a、b、c为摩尔百分含量,其中0≤a≤100%,0≤b≤100%,0≤c≤100%,且a+b+c=100%。(The invention relates to a low-temperature sintered microwave dielectric material and a preparation method thereof. The chemical composition of the low-temperature sintered microwave dielectric material is xM u Al v O w +y(aCuO‑bTiO 2 ‑cNbO 2.5 ) (ii) a Wherein M is at least one of Mg, Zn, Ca and Ba, u is more than or equal to 1 and less than or equal to 2, v is more than or equal to 1 and less than or equal to 2, and w is more than or equal to 4 and less than or equal to 5; x and y are mass percent, y is more than or equal to 1 wt% and less than or equal to 10 wt%, and x + y =100 wt%; a. b and c are mole percentage, wherein a is more than or equal to 0 and less than or equal to 100 percent, b is more than or equal to 0 and less than or equal to 100 percent, c is more than or equal to 0 and less than or equal to 100 percent, and a + b + c =100 percent.)

1. The low-temperature sintering microwave dielectric material is characterized in that the chemical composition of the low-temperature sintering microwave dielectric material is xM_uAl_vO_w+y(aCuO-bTiO₂-cNbO_2.5) (ii) a Wherein M is at least one of Mg, Zn, Ca and Ba, u is more than or equal to 1 and less than or equal to 2, v is more than or equal to 1 and less than or equal to 2, and w is more than or equal to 4 and less than or equal to 5; x and y are mass percent, y is more than or equal to 1 wt% and less than or equal to 10 wt%, and x + y =100 wt%; a. b and c are mole percentage, wherein a is more than or equal to 0 and less than or equal to 100 percent, b is more than or equal to 0 and less than or equal to 100 percent, and c is more than or equal to 0 and less than or equal to 100 percent100%, and a + b + c = 100%.

2. The low-temperature sintering microwave dielectric material as claimed in claim 1, wherein 50. ltoreq. a.ltoreq.55%, 35. ltoreq. b.ltoreq.40%, 10. ltoreq. c.ltoreq.15%, and a + b + c = 100%.

3. The low-temperature sintered microwave dielectric material as claimed in claim 1, wherein the dielectric constant of the low-temperature sintered microwave dielectric material is 8-13, and the dielectric loss is (1-15) × 10^-4The quality factor Q ∙ f is 8000-45000 GHz.

4. The low-temperature sintering microwave dielectric material as claimed in claim 1, wherein the density of the low-temperature sintering microwave dielectric material is 4.41-4.58 g/cm³The thermal conductivity is 5 to 15W/m.K.

5. The low-temperature sintered microwave dielectric material as claimed in claim 1, wherein the bending strength of the low-temperature sintered microwave dielectric material is 150-300 MPa, and the thermal expansion coefficient at 25-350 ℃ is 7.2-7.7 ppm/° C.

6. The low-temperature sintering microwave dielectric material as claimed in claim 1, wherein the low-temperature sintering microwave dielectric material is co-fired with gold, silver and copper metal electrodes at a temperature below 950 ℃.

7. A method for preparing a low-temperature sintering microwave dielectric material as claimed in any one of claims 1-6, comprising:

(1) according to the chemical composition xM of low-temperature sintering microwave dielectric material_uAl_vO_w+y(aCuO-bTiO₂-cNbO_2.5) Weighing M_uAl_vO_wMixing aluminate powder and oxide powder in the sintering aid to obtain raw material powder;

(2) granulating and tabletting the raw material powder to obtain a biscuit;

(3) and sintering the biscuit at 950-1200 ℃ for 1-8 hours to obtain the low-temperature sintering microwave dielectric material.

8. The method of claim 7, wherein the mixing is performed by ball milling; the solvent used for ball milling and mixing is absolute ethyl alcohol; the rotation speed of ball milling mixing is 200-250 r/min, and 12-24 hours; preferably, drying and sieving are performed after ball milling and mixing.

9. The method of claim 7, wherein M is_uAl_vO_wThe particle size of the aluminate powder is 0.1-1 μm; the particle diameter of the CuO powder is 0.1-1 mu m, and the particle diameter of the CuO powder is TiO₂The particle diameter of the powder is 0.1-1 μm, Nb₂O₅The particle size of the powder is 0.1-1 μm.

10. The process according to claim 7, wherein M is_uAl_vO_wWeighing and mixing Al oxide and M oxide according to the stoichiometric ratio of the chemical reaction, and calcining at 1100-1200 ℃ for 1-4 hours to obtain M_uAl_vO_wAluminate powder.

Technical Field

The invention relates to a composition of a low-temperature sintering microwave dielectric material and a preparation method thereof, in particular to a low-temperature sintering microwave dielectric material which is prepared by grain boundary activation sintering and has high quality factor and adjustable dielectric constant and a preparation method thereof, belonging to the field of functional ceramic materials.

Background

Low Temperature Cofired Ceramics (LTCC) refers to a ceramic material which can be Cofired with metal or alloy electrode materials such as Au, Ag, Cu and the like with excellent electric conductivity at a lower Temperature (less than 950 ℃) to obtain a functional component or a packaging substrate.

With the rapid development of electronic information technology, the demand for novel high-performance LTCC materials capable of meeting the differentiated application scenarios is more and more urgent. For example, 5G and future communication systems require LTCC dielectric materials with ultra-low dielectric loss to meet the requirements for operation at millimeter wave and higher frequencies; the high-density high-power electronic integrated module puts higher requirements on the mechanical and thermal properties of the LTCC medium material. However, the traditional LTCC material has the problems of large loss, low strength and low thermal conductivity, so that it is difficult to meet the application requirements. The source of such problems is mainly because the traditional LTCC materials mostly contain glass components, and although the introduction of the glass phase can reduce the sintering temperature, the problems of reducing the thermal conductivity, reducing the mechanical strength and increasing the dielectric loss also exist.

In recent years, researchers of domestic and foreign LTCC materials have conducted many beneficial studies to solve the above problems: starting from the composition and structural design of glass, novel low-loss LTCC glass is developed; the research of glass-phase-free LTCC dielectric materials based on intrinsic low-melting-point crystalline compound series, such as molybdate, tellurate, tungstate and the like; Li-Nb-Ti-O LTCC microwave dielectric material based on low melting point liquid phase sintering additive; and a Cold-firing (Cold-sintering) technology is adopted to obtain a novel low-loss LTCC dielectric material without a glass phase. Although most of the novel LTCC dielectric material systems in the research reports show excellent dielectric properties and sintering characteristics, the novel LTCC dielectric material systems still have the problems of complex components, unsatisfactory stability, special and sensitive sintering process and the like, and some systems also have the problems of chemical reaction with silver, raw material toxicity and the like.

Disclosure of Invention

Aiming at the problems, the invention provides a low-temperature sintering microwave dielectric material with high quality factor and adjustable dielectric constant prepared by grain boundary activation sintering and a preparation method thereof, which is a new way for obtaining high-performance LTCC dielectric material, and the preparation process is simple, the comprehensive performance and sintering characteristic of the material are easy to regulate and control, and the material has great practical value.

In one aspect, the present invention providesA low-temperature sintered microwave dielectric material is disclosed, and the chemical composition of the low-temperature sintered microwave dielectric material is xM_uAl_vO_w+y(aCuO-bTiO₂-cNbO_2.5) (ii) a Wherein M is at least one of Mg, Zn, Ca and Ba, u is more than or equal to 1 and less than or equal to 2, v is more than or equal to 1 and less than or equal to 2, and w is more than or equal to 4 and less than or equal to 5; x and y are mass percent, y is more than or equal to 1 wt% and less than or equal to 10 wt%, and x + y is equal to 100 wt%; a. b and c are mole percentage, wherein a is more than or equal to 0 and less than or equal to 100 percent, b is more than or equal to 0 and less than or equal to 100 percent, c is more than or equal to 0 and less than or equal to 100 percent, and a + b + c is equal to 100 percent. Preferably, 50 ≦ a ≦ 55%, 35 ≦ b ≦ 40%, 10 ≦ c ≦ 15%, and a + b + c 100%.

Preferably, the dielectric constant of the low-temperature sintered microwave dielectric material is 8-13, and the dielectric loss is (1-15) × 10^-4。

Preferably, the density of the low-temperature sintering microwave dielectric material is 4.41-4.58 g/cm³The thermal conductivity is 5 to 15W/m.K.

Preferably, the bending strength of the low-temperature sintered microwave dielectric material is 150-300 MPa, and the thermal expansion coefficient at 25-350 ℃ is 7.2-7.7 ppm/DEG C.

Preferably, the low-temperature sintered microwave dielectric material is matched and co-fired with the metal gold, silver and copper electrodes at the temperature of below 950 ℃.

In another aspect, the present invention provides a method for preparing the low temperature sintering microwave dielectric material, including:

(1) according to the chemical composition xM of low-temperature sintering microwave dielectric material_uAl_vO_w+y(aCuO-bTiO₂-cNbO_2.5) Weighing M_uAl_vO_wMixing aluminate powder and oxide powder in the sintering aid to obtain raw material powder;

(2) granulating and tabletting the raw material powder to obtain a biscuit;

(3) and sintering the biscuit at 950-1200 ℃ for 1-8 hours to obtain the low-temperature sintering microwave dielectric material.

Preferably, the mixing mode is ball milling mixing; the solvent used for ball milling and mixing is absolute ethyl alcohol; the rotation speed of ball milling mixing is 200-250 r/min, and 12-24 hours; preferably, drying and sieving are performed after ball milling and mixing.

Preferably, M is_uAl_vO_wThe particle size of the aluminate powder is 0.1-1 μm; the particle diameter of the CuO powder is 0.1-1 mu m, and the particle diameter of the CuO powder is TiO₂The particle diameter of the powder is 0.1-1 μm, Nb₂O₅The particle size of the powder is 0.1-1 μm.

Preferably, according to M_uAl_vO_wWeighing and mixing Al oxide and M oxide according to the stoichiometric ratio of the chemical reaction, and calcining at 1100-1200 ℃ for 1-4 hours to obtain M_uAl_vO_wAluminate powder.

Has the advantages that:

1. compared with the traditional LTCC dielectric material containing a glass phase, the invention adopts non-low melting point oxide as a sintering aid and does not contain the glass phase, and the prepared LTCC dielectric material does not contain any glass, thereby avoiding the influence of the intrinsic low loss of the glass phase on the dielectric property of the LTCC dielectric material; in addition, compared with the glass preparation process, the preparation method has the advantages of simple preparation process and low cost;

2. the dielectric property and sintering temperature of the low-temperature sintering microwave dielectric material prepared by the invention can be adjusted by the composition and content of the oxide with high sintering temperature and the oxide activator. Therefore, the invention ensures that the microwave dielectric material has low sintering temperature, has the advantages of adjustable dielectric constant, low dielectric loss, low thermal expansion coefficient and high mechanical strength, and can realize low-temperature co-sintering with the silver electrode below 950 ℃.

Drawings

FIG. 1 is an XRD pattern of the sample of example 1;

FIG. 2 is an SEM photograph of a natural section of a sample of example 1;

FIG. 3 is an XRD pattern of the sample of example 2;

FIG. 4 is a SEM photograph of a natural section of a sample in example 2;

FIG. 5 is an XRD pattern of the sample of example 3;

FIG. 6 is a back-scattered SEM photograph of a polished section of the sample of example 3;

FIG. 7 is an XRD pattern of the sample of example 4;

FIG. 8 is a back-scattered SEM photograph of a polished section of the sample of example 4.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, by using a compound M in a binary oxide_uAl_vO_wThe non-glass phase substance with specific composition and content is introduced as a sintering aid, and the M with high intrinsic sintering temperature_uAl_vO_wThe actual sintering temperature of the base material is reduced to below 1200 ℃ while maintaining good overall properties of the material. In an alternative embodiment, when M is Zn, x and y are mass percentages, 1 wt% or more and y less than or equal to 10 wt%, and x + y is 100 wt%; u, v, w are constants that satisfy the stoichiometric ratios of the corresponding components; preferably 0.50. ltoreq. a.ltoreq.0.875, 0. ltoreq. b.ltoreq.50, 0.125. ltoreq. c.ltoreq.0.15, and a + b + c 100%. The microwave dielectric material with lower sintering temperature (T < 1000 ℃) can be obtained by the composition

In one embodiment of the present invention, the components of the low-temperature sintering microwave dielectric material (or named aluminate microwave dielectric material) are composed of an aluminate dielectric material with a high sintering temperature (a main crystal phase of the low-temperature sintering microwave dielectric material) and a small amount of oxide activator (non-low melting point oxide sintering aid) containing Cu, Nb and Ti. Wherein the content of the activating agent can be 1-10 wt%. The dielectric property and sintering temperature of the low-temperature sintering microwave dielectric material can be adjusted by the composition and content of the aluminate and oxide activator with high sintering temperature.

Compared with the existing traditional microwave dielectric material, the low-temperature sintering microwave dielectric material does not contain amorphous glass, microcrystalline glass or low-melting-point compounds; the low-temperature sintering microwave dielectric material realizes low-temperature sintering by a grain boundary activation sintering mechanism of a small amount (less than or equal to 10 wt%) of a specific oxide activator.

In the invention, the low-temperature sintering microwave dielectric material can be sintered in the temperature range of 950-.

In the invention, the process for preparing the aluminate microwave dielectric material is simple, and the composition does not contain any amorphous glass, microcrystalline glass or low-melting-point compound. In addition, the aluminate microwave dielectric material prepared by the invention has the advantages of adjustable dielectric property, higher mechanical property and thermal conductivity while realizing low sintering temperature, and is expected to be applied to LTCC materials and realize low-temperature co-sintering with silver electrodes below 950 ℃. The preparation method of the aluminate microwave dielectric material is exemplarily described as follows.

Weighing the oxide initial raw materials of Al and M according to the stoichiometric ratio of the chemical reaction. The initial raw materials are ball-milled, mixed evenly and dried, then placed in a high-temperature furnace and calcined at 1100-1200 ℃ to obtain the matrix material aluminate M_uAl_vO_wAnd (3) powder.

According to the chemical composition xM of low-temperature sintering microwave dielectric material_uAl_vO_w+y(aCuO-bTiO₂-cNbO_2.5) Weighing the corresponding aluminate and the oxide powder in the activator. Putting all the weighed raw material powder, grinding balls and absolute ethyl alcohol into a ball milling tank according to a certain mass percentage, carrying out ball milling and mixing for 12-24 hours at the rotating speed of 200-250 rpm, drying and sieving to obtain mixed powder.

And granulating the mixed powder to obtain granulated powder. .

And carrying out tabletting and other forming processes on the granulated powder to obtain a biscuit of the low-temperature sintering microwave dielectric material.

And (3) putting the biscuit into a high-temperature furnace, heating the biscuit to a corresponding sintering temperature from room temperature, preserving the heat for a certain time, and cooling the biscuit along with the furnace to obtain the low-temperature sintering microwave dielectric material. The sintering temperature can be 950-1200 ℃. The sintering heat preservation time can be 1-8 hours, preferably 2-4 hours.

In the invention, a network analyzer is adopted to test the obtained low-temperature sintering microwave dielectric material, wherein the dielectric constant of the low-temperature sintering microwave dielectric material is 8-13, and the dielectric loss is (1-15) multiplied by 10^-4. The density of the low-temperature sintering microwave dielectric material tested by the Archimedes method is 4.41-4.58 g/cm³. By usingAnd testing the thermal diffusion coefficient and the specific heat of the obtained low-temperature sintering microwave dielectric material by using a laser thermal conductivity meter and a high-temperature specific heat meter to further calculate that the thermal conductivity is 5-15W/m.K. The bending strength of the low-temperature sintering microwave dielectric material tested by a three-point bending method is 150-300 MPa. The thermal expansion coefficient of the low-temperature sintering microwave dielectric material obtained by adopting a thermal expansion instrument method or instrument to test is 7.2-7.7 at the temperature of 25-350 ℃.

The invention provides a microwave dielectric material which can be sintered at a low temperature below 1050 ℃ and is obtained by grain boundary activated sintering of a small amount of specific oxide activator without adding glass, and overcomes the defect that the sintering temperature of the LTCC dielectric material is reduced by introducing a large amount of low-melting-point glass phase into the existing LTCC material. The technical scheme of the invention can successfully prepare the low-temperature sintering microwave dielectric material with adjustable dielectric constant, low dielectric loss, low thermal expansion coefficient and high flexural strength. XRD analysis shows that the main crystal phase of the prepared low-temperature sintering microwave dielectric material is aluminate with high sintering temperature, and in addition, a small part of compound crystal phase formed by an oxide activator is also present; SEM analysis shows that the material system has higher sintering density at 950 ℃, and is a material suitable for the practical application of LTCC. The low-temperature sintering microwave dielectric material obtained by the invention has low cost and practical value of mass production. In the invention, the low-temperature sintered microwave dielectric material has a higher Qf value and is more advantageous to be applied to a packaging substrate under a high-frequency condition than alumina.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

Selecting M ═ Zn and u ═ U ═1. v is 2, w is 4, x is 90 wt%, y is 10 wt%, a is 4 (44.4%), b is 1 (11.2%), c is 4 (44.4%). The composition of the LTCC dielectric material can be expressed as 90 wt% ZnAl₂O₄+10wt％(4CuO-TiO₂-4NbO_2.5). Firstly, Al is added₂O₃The powder and ZnO powder are taken as raw materials, the raw materials are mixed according to the molar ratio of 1:1 by ball milling, and the dried mixture is sintered for 4 hours at the temperature of 1150 ℃ to obtain the base material ZnAl₂O₄And (3) powder. Then ZnAl is added₂O₄Powder, CuO powder, TiO₂Powder and Nb₂O₅The powder is taken as a raw material, the raw materials are proportioned according to the proportion and put into a nylon ball milling tank, absolute ethyl alcohol and milling balls are added, and the raw materials are uniformly mixed by ball milling for 12 hours. And drying the mixed raw materials, then carrying out forming treatment to obtain a cylindrical green compact, and sintering at 950 ℃ for 4 hours to obtain a sintered compact ceramic sample. X-ray diffraction (XRD) analysis shows that the phase composition of the ceramic is mainly ZnAl₂O₄The XRD pattern is shown in figure 1. The microwave dielectric property test (as shown in Table 1) showed that the obtained ceramic sample had a dielectric constant of 12.17(@10GHz) and a dielectric loss of 8.5X 10^-4(@10GHz), quality factor Q.f ~ 10920GHz, the thermal conductivity is 5.55W/m.K, show the excellent comprehensive properties. The microstructure of the sample was observed by a Scanning Electron Microscope (SEM), and fig. 2 is an SEM photograph. It can be seen from the photographs that such low temperature sintered ceramic materials are more densely sintered.

Example 2

The selection of M ═ Zn, u ═ 1, v ═ 2, w ═ 4, x ═ 95 wt%, y ═ 5 wt%, a ═ 4 (44.4%), b ═ 1 (11.2%), c ═ 4 (44.4%). The composition of the LTCC dielectric material can be expressed as 95 wt% ZnAl₂O₄+5wt％(4CuO-TiO₂-4NbO_2.5). Firstly, Al is added₂O₃The powder and ZnO powder are taken as raw materials, the raw materials are mixed according to the molar ratio of 1:1 by ball milling, and the dried mixture is sintered for 4 hours at the temperature of 1150 ℃ to obtain the base material ZnAl₂O₄And (3) powder. Then ZnAl is added₂O₄Powder, CuO powder, TiO₂Powder and Nb2O₅The powder is taken as raw material, mixed according to the proportion and put into a nylon ball milling tank, added withAdding absolute ethyl alcohol and grinding balls, and ball-milling for 12 hours to uniformly mix the raw materials. And drying the mixed raw materials, then carrying out forming treatment to obtain a cylindrical green body, and sintering at 1050 ℃ for 4 hours to obtain a sintered compact ceramic sample. X-ray diffraction (XRD) analysis showed that the phase composition of the ceramic was predominantly ZnA_l2O₄The XRD pattern is shown in figure 3. The microwave dielectric property test shows that the obtained ceramic sample has the dielectric constant of 11.51(@10GHz) and the dielectric loss of 5.9 multiplied by 10^-4(@10GHz), quality factor Q.f ~ 16530GHz, the thermal conductivity is 6.48W/m.K, show the excellent comprehensive properties, as shown in Table 1. The microstructure of the sample was observed by a Scanning Electron Microscope (SEM), and fig. 4 is an SEM photograph. It can be seen from the photographs that such low temperature sintered ceramic materials are more densely sintered.

Example 3

The selection of M ═ Zn, u ═ 1, v ═ 2, w ═ 4, x ═ 95 wt%, y ═ 5 wt%, a ═ 1 (50%), b ═ 0, and c ═ 1 (50%). The composition of the LTCC dielectric material can be expressed as 95 wt% ZnAl₂O₄+5wt％(CuO-NbO_2.5). Firstly, Al is added₂O₃The powder and ZnO powder are taken as raw materials, the raw materials are mixed according to the molar ratio of 1:1 by ball milling, and the dried mixture is sintered for 4 hours at the temperature of 1150 ℃ to obtain the base material ZnAl₂O₄And (3) powder. Then ZnAl is added₂O₄Powder, CuO powder and Nb₂O₅The powder is taken as a raw material, the raw materials are proportioned according to the proportion and put into a nylon ball milling tank, absolute ethyl alcohol and milling balls are added, and the raw materials are uniformly mixed by ball milling for 12 hours. And drying the mixed raw materials, then carrying out forming treatment to obtain a cylindrical green body, and sintering at 975 ℃ for 4 hours to obtain a sintered compact ceramic sample. X-ray diffraction (XRD) analysis shows that the phase composition of the ceramic is mainly ZnAl₂O₄The XRD pattern is shown in figure 5. The microwave dielectric property test shows that the obtained ceramic sample has the dielectric constant of 11.36(@10GHz) and the dielectric loss of 1.42 multiplied by 10^-3(@10GHz), quality factor Q.f ~ 8245GHz, thermal expansion coefficient 7.56(25 ~ 350 ℃), bending strength 200MPa, showed excellent comprehensive properties, see Table 2. The microstructure of the sample was observed by a Scanning Electron Microscope (SEM), and fig. 6 is an SEM photograph. From the photo canIt is seen that this low temperature sintered ceramic material is more densely sintered.

Example 4

The selection of M ═ Zn, u ═ 1, v ═ 2, w ═ 4, x ═ 95 wt%, y ═ 5 wt%, a ═ 4 (50%), b ═ 3 (37.5%), c ═ 1 (12.5%). The composition of the LTCC dielectric material can be expressed as 95 wt% ZnAl₂O₄+5wt％(4CuO-3TiO₂-NbO_2.5). Firstly, Al is added₂O₃The powder and ZnO powder are taken as raw materials, the raw materials are mixed according to the molar ratio of 1:1 by ball milling, and the dried mixture is sintered for 4 hours at the temperature of 1150 ℃ to obtain the base material ZnAl₂O₄And (3) powder. Then ZnAl is added₂O₄Powder, CuO powder, TiO₂Powder and Nb₂O₅The powder is taken as a raw material, the raw materials are proportioned according to the proportion and put into a nylon ball milling tank, absolute ethyl alcohol and milling balls are added, and the raw materials are uniformly mixed by ball milling for 12 hours. And drying the mixed raw materials, then carrying out forming treatment to obtain a cylindrical green body, and sintering at 1150 ℃ for 4 hours to obtain a sintered compact ceramic sample. X-ray diffraction (XRD) analysis shows that the phase composition of the ceramic is mainly ZnAl₂O₄The XRD spectrum is shown in 7. The microwave dielectric property test shows that the obtained ceramic sample has a dielectric constant of 9.00 (@10GHz) and a dielectric loss of 2.64 x 10^-4(@10GHz), quality factor Q.f ~ 41673GHz, thermal expansion coefficient 7.34(25 ~ 350 ℃), bending strength is 230MPa, show excellent comprehensive properties, as shown in Table 2. The microstructure of the sample was observed by a Scanning Electron Microscope (SEM), and fig. 8 is an SEM photograph. It can be seen from the photographs that such low temperature sintered ceramic materials are more densely sintered.