Temperature-stable high-dielectric microwave dielectric ceramic and preparation method thereof

Abstract

The invention provides a temperature-stable high-dielectric microwave dielectric ceramic and a preparation method thereof, and belongs to the technical field of electronic ceramics. The composition expression of the temperature-stable high-dielectric microwave dielectric ceramic provided by the invention is Ba < 3.75 > Sm < 7.5 > Nd < 2 > Ti < 18-x > Ga < x > O < 54 >, wherein x is 0.2-0.8. The temperature-stable high-dielectric microwave dielectric ceramic provided by the invention is good in temperature stability, and has a relatively high dielectric constant and a high Qf value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic ceramics, in particular to a temperature-stable high-dielectric microwave dielectric ceramic and a preparation method thereof. BACKGROUND

[0002] With the continuous progress of mobile communication technology, miniaturization, high frequency and high performance have become the development trend of contemporary passive devices, and the corresponding microwave dielectric ceramic should have high dielectric constant, low dielectric loss and good temperature stability.

[0003] Firstly, high dielectric constant (ε r > 70) can make electromagnetic wave energy more concentrated, promoting the miniaturization of equipment. Secondly, high Qf value can meet the low loss requirement of the device and improve the frequency selection characteristics of the device. In addition, the near-zero resonance frequency temperature coefficient (τ f ) can ensure that the center resonance frequency of the device does not change greatly with the change of environmental temperature. In the application of wireless communication field, temperature-stable microwave dielectric ceramic can reduce the center frequency drift caused by temperature change and thermal expansion of device shell. For example, in the deployment of communication base station, the application scene is complex and changeable in different regions, such as the winter temperature in some high latitude areas can be reduced to minus 40-50℃, and the summer temperature in some African regions can reach plus 40-50℃, which puts higher requirements on the stability of microwave passive devices. SUMMARY

[0004] Therefore, the present application aims to provide a temperature-stable high-dielectric microwave dielectric ceramic and a preparation method thereof. The temperature-stable high-dielectric microwave dielectric ceramic provided by the present application has good temperature stability, high dielectric constant and high Qf value.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a temperature-stable high-dielectric microwave dielectric ceramic, whose composition expression is Ba 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 , wherein x is 0.2-0.8, preferably 0.2, 0.4, 0.6 or 0.8.

[0006] The present application also provides a preparation method of the temperature-stable high-dielectric microwave dielectric ceramic described in the above technical scheme, comprising the following steps:

[0007] 1) BaCO3, Sm2O3, Nd2O3, TiO2 and Ga2O3 are mixed according to the chemical equation Ba 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54Weigh the required raw materials, mix the weighed materials, ball mill, dry, pulverize, and sieve them, then pre-sinter to initially synthesize tungsten bronze structure Ba. 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 Dielectric ceramic powder;

[0008] 2) The powder obtained in step 1) is added to polyvinyl alcohol and then ball-milled, dried, pulverized and sieved, and then pressed into cylindrical ceramic green bodies using an electric tablet press.

[0009] 3) Sinter the ceramic green body obtained in step 2) at 1340-1380℃ for 4-8 hours to obtain temperature-stable high dielectric microwave ceramic.

[0010] Preferably, the ball milling in step 1) further includes adding zirconia balls and deionized water or ethanol for ball milling; the ball milling speed is 400 rpm and the ball milling time is 5-8 h.

[0011] Preferably, the drying temperature in step 1) is 100°C; the sieving is done through a 40-mesh sieve.

[0012] Preferably, the pre-sintering temperature in step 1) is 1050-1150℃, and the pre-sintering time is 5-8h.

[0013] Preferably, the amount of polyvinyl alcohol added in step 2) is 0.5%-2% of the powder mass.

[0014] Preferably, the ball milling time in step 2) is 10-12 hours.

[0015] Preferably, the sieving in step 2) is sieving through an 80-mesh sieve.

[0016] Preferably, the ceramic green body in step 2) has a diameter of 10 mm and a thickness of 5 mm.

[0017] Beneficial technical effects:

[0018] This invention provides a temperature-stable high-dielectric microwave dielectric ceramic and its preparation method. The compositional formula of the temperature-stable high-dielectric microwave dielectric ceramic provided by this invention is Ba. 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 In the formula, x is 0.2-0.8. The temperature-stable high-dielectric microwave dielectric ceramic provided by the present invention has good temperature stability, that is, a microwave dielectric ceramic system with a near-zero temperature coefficient of resonant frequency, and at the same time has a high dielectric constant and a high Qf value. Attached Figure Description

[0019] Figure 1 Ba 3.75 Sm 7.5 Nd2Ti 17.6 Ga 0.4O XRD diffraction pattern of the microwave dielectric ceramic 54. DETAILED DESCRIPTION

[0020] For a better understanding of the present application, the following examples are set forth further illustrating the present application, but the present application is not limited to the following examples.

[0021] Example 1

[0022] 1) BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 were weighed according to the stoichiometric formula Ba 3.75 Sm 7.5 Nd2Ti 17.6 Ga 0.4 O 54 The powder was prepared by weighing BaCO3 2.3919 g, Sm2O3 3.9428 g, Nd2O3 1.009 g, TiO2 4.2595 g, Ga2O3 0.1142 g, about 10 g of the powder was put into a polyester tank, 200 ml of deionized water and 150 g of zirconium balls were added, and then a planetary ball mill was used for ball milling at a speed of 400 rpm for 6 hours in one-way operation. The slurry after ball milling was transferred to a drying box and dried at 100°C, crushed and sieved through a 40 mesh sieve. The sieved powder was put into a sintering furnace and pre-sintered at 1100°C for 5 hours;

[0023] 2) 1.1 wt% of polyvinyl alcohol was added to the powder after pre-sintering in step 1, mixed and put into a ball mill tank, zirconium oxide balls and deionized water were added, and ball milling was carried out for 12 hours. After drying, crushing and sieving through an 80 mesh sieve, a cylindrical green body was prepared by using an electric tablet press at a pressure of 2 MPa;

[0024] 3) The green body was sintered at 1360°C for 6 hours to obtain Ba 3.75 Sm 7.5 Nd2Ti 17.6 Ga 0.4O 54 microwave dielectric ceramic.

[0025] The obtained Ba 3.75 Sm 7.5 Nd2Ti 17.6 Ga 0.4O 54 microwave dielectric ceramic was characterized by XRD, and Figure 1It can be seen that the phase composition of the ceramic is typical tungsten bronze structure by X-ray powder diffraction analysis, which matches with the standard card PDF33-0166. No other diffraction peaks are found, which indicates that the introduction of Ga2O3 does not change the phase composition

[0026] Example 2

[0027] The same as example 1, except that BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 are proportioned according to the stoichiometric formula Ba 3.75 Sm 7.5 Nd2Ti 17.8 Ga 0.2 O 54 .

[0028] Example 3

[0029] The same as example 1, except that BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 are proportioned according to the stoichiometric formula Ba 3.75 Sm 7.5 Nd2Ti 17.4 Ga 0.6 O 54 .

[0030] Example 4

[0031] The same as example 1, except that BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 are proportioned according to the stoichiometric formula Ba 3.75 Sm 7.5 Nd2Ti 17.2 Ga 0.8 O 54 .

[0032] Comparative example 1

[0033] The same as example 1, except that BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 are proportioned according to the stoichiometric formula Ba 3.75 Sm 7.5 Nd2Ti 18 O 54 , and the sintering temperature is 1360℃.

[0034] The microwave dielectric ceramics of examples 1-4 and comparative example 1 are tested for the microwave dielectric properties of the products by network analyzer, and the test results are shown in table 1.

[0035] Table 1 Microwave dielectric properties of examples 1-4 and comparative example 1

[0036]

[0037] As shown in Table 1, compared with the microwave dielectric ceramic of Comparative Example 1, the microwave dielectric ceramics of Examples 1-4 have more excellent microwave dielectric properties, and have higher dielectric constant, high Qf value and near-zero resonance frequency temperature coefficient, and have better temperature stability. Among them, the microwave dielectric ceramic of Example 1 has relatively optimal microwave dielectric comprehensive performance.

[0038] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A temperature-stable high-dielectric microwave dielectric ceramic, characterized by, The composition expression is Ba 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 where x is 0.2-0.

8.

2. The temperature-stable high-dielectric microwave dielectric ceramic of claim 1, wherein, X is 0.2, 0.4, 0.6 or 0.

8.

3. The method of producing a stable, high-dielectric constant microwave dielectric ceramic according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: 1) BaCO3, Sm2O3, Nd2O3, TiO2, Ga2O3 are weighed according to the chemical equation Ba 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 The required raw materials are weighed, the weighed materials are mixed, ball-milled, dried, crushed, sieved, and then pre-sintered to preliminarily synthesize the tungsten bronze structure Ba 3.75 Sm 7.5 Nd2Ti 18-x Ga x O 54 dielectric ceramic powder; 2) The powder obtained in step 1) is added into polyvinyl alcohol, and then ball-milling, drying, crushing and sieving are carried out, and a cylindrical ceramic green body is prepared by using an electric tablet press; 3) The ceramic green body obtained in step 2) is sintered at 1340-1380 DEG C for 4-8 h to obtain a temperature-stable high-dielectric microwave dielectric ceramic.

4. The preparation method according to claim 3, characterized in that, The ball-milling in step 1) further comprises adding zirconium oxide balls and deionized water or ethanol for ball-milling; the rotation speed of the ball-milling is 400 r / min, and the ball-milling time is 5-8 h.

5. The preparation method according to claim 3, characterized in that, The drying temperature in step 1) is 100 DEG C; and the sieving is 40-mesh sieving.

6. The preparation method according to claim 3, characterized in that, The pre-sintering temperature in step 1) is 1050-1150 DEG C, and the pre-sintering time is 5-8 h.

7. The preparation method according to claim 3, characterized in that, The adding amount of the polyvinyl alcohol in step 2) is 0.5%-2% of the mass of the powder.

8. The preparation method according to claim 3, characterized in that, The ball-milling time in step 2) is 10-12 h.

9. The preparation method according to claim 3, characterized in that, The sieving in step 2) is 80-mesh sieving.

10. The method of claim 3, wherein, The diameter of the ceramic green body in step 2) is 10 mm, and the thickness is 5 mm.

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