Low dielectric rare earth oxide microwave dielectric ceramic with ultralow dielectric loss and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of electronic information functional materials, and discloses ultralow-dielectric-loss low-dielectric rare earth oxide microwave dielectric ceramic and a preparation method thereof, and the chemical expression is Y < 2-x > Sm < x > O < 3 >, wherein x is more than or equal to 0.35 and less than or equal to 0.45 Y2O3 and Sm2O3 are used as raw materials, the rare earth oxide microwave dielectric ceramic is obtained through a one-step sintering method, the dielectric constant epsilon r is 11.5-12.5, the dielectric loss tan delta is 8.1 E-5-7.4 E-5, and the temperature coefficient of resonance frequency tau f is-46 ppm / DEG C to-44 ppm / DEG C. By adjusting the content of Sm2O3 in the Y2O3 ceramic, the prepared Y2O3-based microwave dielectric ceramic maintains the cubic single-phase structure of the Y2O3 ceramic, SEM analysis shows that the prepared ceramic is highly compact, EDS analysis shows that elements are uniformly distributed, the purposes of low dielectric constant and ultralow dielectric loss are achieved in performance, and the reason of ultralow dielectric loss is higher conductivity activation energy Ea.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of electronic information functional materials, and relates to a low-dielectric rare earth oxide microwave dielectric ceramic material having ultra-low dielectric loss obtained by adjusting the Sm content in Y2O3 and a preparation method thereof. Background Art

[0002] Microwave dielectric ceramics refer to ceramics used as dielectric materials in microwave (300MHz ~ 300GHz) frequency band circuits and perform one or more functions. They are key basic materials in modern communication technology and are widely used in microwave components such as dielectric resonators, filters, dielectric substrates, dielectric waveguide circuits, microwave capacitors, duplexers, antennas, etc. There are three main factors to evaluate the performance of microwave dielectric ceramics: dielectric constant (ε r ), quality factor (Q×f, Q is the inverse of dielectric loss 1 / tanδ) and resonant frequency temperature coefficient (τ f ). Low dielectric constant (ε r <20) is conducive to shortening the time delay of high-frequency signal transmission, and the high quality factor (Q×f>100,000GHz) can ensure good frequency selection characteristics and signal fidelity, and the near-zero τ f It can make the device have operating frequency stability.

[0003] Rare earths are important strategic resources and generally have special physical and chemical properties, so their development and application have received widespread attention. For example, rare earth ions can be used as luminescent centers in phosphors; rare earth oxides can be used as modifiers for glass or ceramics; and cubic rare earth oxides can be directly sintered into transparent ceramics. However, there is relatively little research on the microwave dielectric properties of rare earth oxide ceramics. The microwave dielectric properties of xTiO2-(1-x)CeO2 ceramics reported in the 2002 article "The microwave dielectric properties of xTiO2-(1-x)CeO2 ceramics" in Materials Letters are: ε r =24, Q×f=57,000GHz, τ f =-104ppm / ℃. The 2023 article "Effects of Ionic Polarizability and Crystal Structure on the Relative τ fEffects of ionic polarizability and crystal structure on microwavedielectric properties of RE2O3(RE=La,Eu)ceramics with oppositeτ f The microwave dielectric properties of La2O3 and Eu2O3 reported by the authors are: ε r =18.6, Q×f=71,400GHz, τ f =-35.1ppm / ℃ and ε r =17.9, Q×f=35,000GHz, τ f = +19.6ppm / °C. The 2024 article "Cracking behavior of Sm2O3 ceramics and enhanced microwave dielectric properties with MgO addition: Insights from chemical bond characteristics and microstructure" published in Ceramics International reported the following properties of Sm2O3 ceramics: ε r =21.95, Q×f=47,000GHz, τ f = +30.15ppm / ℃. Ceramics International 2024 article "Constructing the cation rattling effect to realize Nd 2-x Sm x Constructing the cationicrattling effect to realize the adjustability of the temperature coefficientin Nd 2-x Sm x The properties of Nd2O3 ceramics reported by the International Standard for Conductive Materials (ISBN) are: r =19.48, Q×f=48,447GHz, τ f= -43ppm / °C. Except for CeO2, the Q×f values of the La2O3, Nd2O3, Sm2O3, and Eu2O3 ceramics reported above are below 72,000GHz, and all of them will decompose, so they are not of practical value.

[0004] In contrast, cubic Y2O3 ceramics were once used as structural and functional components due to their stable chemical properties and have a wide range of practical applications. In terms of the microwave dielectric properties of Y2O3 ceramics, the only report on the microwave dielectric properties of Y2O3 ceramics is the 2016 article "Effects of sintering parameters and Nd doping on the microwave dielectric properties of Y2O3 ceramics" published in Ceramics International. The microwave dielectric properties of Y2O3 ceramics reported in the article are: ε r =10.76, Q×f=82,188GHz, τ f =-54.4ppm / ℃; 2at.% Nd2O3 doped Y2O3 ceramic performance improved to: ε r =10.4,Q×f=94,149GHz,τ f =-46.2ppm / ℃. Nd doping maintains the low ε of Y2O3 ceramics r , but the Q×f value is still lower than 100,000GHz.

[0005] In summary, structurally stable Y2O3 ceramics are valuable for research, and appropriate rare earth ion substitution can help improve Q×f values. By selecting appropriate rare earth ions, dielectric loss can be further reduced, raising Q×f values to over 100,000 GHz. Summary of the Invention

[0006] This invention addresses the high dielectric loss of pure-phase Y2O3 ceramics and their potential for high-frequency applications. By replacing lanthanide rare earth ions, this ceramic achieves ultra-low dielectric loss. Compared to other rare earth oxide-based microwave dielectric ceramics, the Y2O3-based ceramics provided by this invention exhibit significantly lower dielectric loss.

[0007] The present invention is achieved through the following technical solutions:

[0008] According to one aspect of the present invention, a low dielectric loss rare earth oxide microwave dielectric ceramic material is provided, the system chemical expression is Y 2-x Sm x O3; where 0.35≤x≤0.45.

[0009] Furthermore, it is obtained by a one-step sintering method using Y2O3 and Sm2O3 as raw materials.

[0010] Furthermore, the structure of the prepared ceramics is stable and can exist stably in the air.

[0011] Furthermore, the dielectric constant ε r is 11.5~12.5, the dielectric loss tanδ is 8.1E-5~7.4E-5, and the resonant frequency temperature coefficient τ f It is -46~-44ppm / ℃.

[0012] Preferably, x=0.40.

[0013] According to another aspect of the present invention, a method for preparing a low-dielectric rare earth oxide microwave dielectric ceramic material with ultra-low dielectric loss is provided, the method being carried out according to the following steps:

[0014] Step 1: Ingredients; pre-burn Y2O3 and Sm2O3 raw material powder to remove moisture; according to the chemical formula Y 2-x Sm x O3, 0.35≤x≤0.45 Y2O3 and Sm2O3 raw materials are weighed and mixed to form a mixture;

[0015] Step 2: ball milling: using ZrO2 balls as the milling medium and anhydrous ethanol as the dispersion medium, the raw materials, anhydrous ethanol, and milling balls are placed in a nylon jar and milled on a planetary ball mill to obtain a uniformly mixed slurry;

[0016] Step 3: Drying and sieving: Drying the slurry obtained in step 2 and sieving to obtain dry powder;

[0017] Step 4: Granulation and tableting: Add 5 wt.% polyvinyl alcohol solution to the dry powder obtained in step 3 for granulation. The granulated powder is initially pressed into a green billet using a manual tablet press, and then further pressed in a cold isostatic press.

[0018] Step 5: Debinding the green blank pressed in step 4 at 500°C to 600°C for 1.5 to 2.5 hours;

[0019] Step 6: Sinter the green blank after debinding in step 5 at 1400℃~1750℃ for 2~6 hours to make Y 2-x Sm x O3, 0.35≤x≤0.45 microwave dielectric ceramics.

[0020] Furthermore, in step 1, the pre-firing temperature of the Y2O3 and Sm2O3 raw materials is 900°C, and the pre-firing time is 2 hours.

[0021] Furthermore, in step 2, the mass ratio of the mixture: anhydrous ethanol: grinding balls is 1: (1.5-2.5): (4-6), the ball milling time is 4-8 hours, and the speed of the planetary ball mill is 200-300 rpm.

[0022] Furthermore, in step 3, the drying temperature is 60-80° C., and the sieving is through a 100-mesh nylon sieve.

[0023] Furthermore, in step 4, the pressure of manually pressing the green billet is 3 MPa, the pressure of the cold isostatic press is 200 MPa, and the holding time is 3 minutes.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention adopts the traditional solid-state sintering method to produce a low dielectric loss rare earth oxide microwave dielectric ceramic material Y 2-x Sm x O3, 0.35≤x≤0.45, by adjusting the amount of Sm, while maintaining low ε r At the same time, the goal of ultra-low dielectric loss was achieved, with Q×f values above 100,000 GHz.

[0026] 2. The microwave dielectric ceramic material of the present invention does not contain volatile toxic metals such as Pb and Cd, and can be widely used in microwave devices such as dielectric resonators, filters, oscillators, etc. in satellite communications. It is green, environmentally friendly and pollution-free, and meets the strict standards of the latest RHOS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive) and the Recycling and Treatment Management Regulations (WEEE) issued by the European Community.

[0027] 3. The raw materials for preparing the microwave dielectric ceramic materials of the present invention are in sufficient supply in China and are relatively inexpensive, making it possible to produce high-performance microwave ceramics at low costs, and therefore have important industrial application value; moreover, the sintering temperature of the microwave dielectric ceramic materials of the present invention is 1400-1750°C, the sintering temperature range is relatively wide, and the materials have good process adaptability.

[0028] 4. The raw materials used in the formula of the present invention are all simple oxides, and the ceramics can be sintered in a one-step process, which is simple, efficient and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD spectrum of the microwave dielectric ceramic material prepared in Example 2 of the present invention.

[0030] Figure 2 1. The SEM image and EDS element content analysis of the microwave dielectric ceramic material prepared in Example 2 of the present invention.

[0031] Figure 3Graph showing the performance changes of microwave dielectric ceramic materials prepared in Examples 1-3 of the present invention.

[0032] Figure 4 These are the complex impedance spectra and conductivity activation energies of the microwave dielectric ceramic materials prepared in Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] Example 1

[0035] Step 1: Ingredients; Pre-sinter Y2O3 and Sm2O3 raw powder at 900℃ for 2 hours to remove moisture; According to the chemical formula Y 2- x Sm x O3, x=0.35 Weigh Y2O3 and Sm2O3 raw materials and mix them to form a mixture;

[0036] Step 2: ball milling; using ZrO2 balls as the ball milling medium and anhydrous ethanol as the dispersion medium, the mixture was ball milled in a nylon jar at a mass ratio of 1:2:5 of anhydrous ethanol to grinding balls at a planetary ball mill speed of 250 rpm for 6 hours to obtain a uniformly mixed slurry;

[0037] Step 3: drying and sieving: drying the slurry obtained in step 2 at 80°C and passing it through a 100-mesh nylon sieve to obtain a dry powder;

[0038] Step 4: Granulation and tableting: 5 wt.% polyvinyl alcohol solution was added to the dry powder obtained in step 3 for granulation. The granulated powder was initially pressed into a green tablet using a manual tablet press at 3 MPa, and then further pressed in a cold isostatic press at 200 MPa for 3 minutes.

[0039] Step 5: Debind the green blank pressed in step 4 at 600°C for 2 hours;

[0040] Step 6: Sinter the green blank after debinding in step 5 at 1700℃ for 4 hours to make Y 1.65 Sm 0.35 O3 microwave dielectric ceramics.

[0041] Example 2

[0042] Y2O3-based microwave dielectric ceramics were prepared using the method of Example 1, except that x=0.40.

[0043] Example 3

[0044] Y2O3-based microwave dielectric ceramics were prepared using the method of Example 1, except that x=0.45.

[0045] The Y2O3-based microwave dielectric ceramics prepared in Examples 1-3 were tested for phase structure using XRD; microstructure and element content were tested using SEM combined with EDS; and dielectric resonant cavity combined with vector network analyzer was used to test the dielectric constant ε. r , quality factor Q×f and resonant frequency temperature coefficient τ f ; The complex impedance spectrum was tested using an impedance analyzer, and the conductivity activation energy E was calculated based on the spectrum data. a .

[0046] Figure 1 This is the XRD pattern of the microwave dielectric ceramic material prepared in Example 2. Figure 1 There is only the diffraction peak of cubic Y2O3, and no trace of the second phase, which proves that Y 1.6 Sm 0.4 O3 ceramics are single-phase components.

[0047] Figure 2 The SEM image and EDS element content results of the microwave dielectric ceramic material prepared in Example 2. Figure 2 Show Y 1.6 Sm 0.4 O3 ceramics have good density, no obvious pores, and most of the grains are large (~10μm); EDS analysis shows that the element content of large and small grains is close to the component design value, indicating that Y 1.6 Sm 0.4 Elements are evenly distributed in O3 ceramics.

[0048] Figure 3 The performance change diagram of the microwave dielectric ceramic material prepared in Examples 1-3. Figure 3 It can be seen that with the increase of Sm content in Y2O3, the dielectric constant ε r The dielectric loss tanδ shows an upward trend, increasing from 11.7 at x = 0.35 to 12.1 at x = 0.45. The dielectric loss tanδ first decreases and then increases. Correspondingly, the quality factor Q×f value increases from 142,040 GHz at x = 0.35 to 165,000 GHz at x = 0.4, and then decreases to 150,500 GHz at x = 0.45. The resonant frequency temperature coefficient τ f Fluctuates within the range of -46 to -44ppm / ℃.

[0049] Figure 4Complex impedance spectra and calculated conductivity activation energy E of the microwave dielectric ceramic materials prepared in Examples 1-3 a As can be seen from the figure, E a The change trend of is opposite to that of tanδ, that is, it is consistent with the change trend of Q×f value, indicating that E a The value greatly affects tanδ, because higher E a This means better insulation performance and helps reduce conductivity losses.

[0050] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A low dielectric loss rare earth oxide microwave dielectric ceramic material, characterized in that: The chemical expression of the system is Y 2-x Sm x O3; where 0.35≤x≤0.45; dielectric constant ε r is 11.5~12.5, the dielectric loss tanδ is 8.1E-5~7.4E-5, and the resonant frequency temperature coefficient τ f -46 to -44 ppm / °C; and is prepared by the following steps: Step 1: Ingredients; pre-burn Y2O3 and Sm2O3 raw material powder to remove moisture; according to the chemical formula Y 2-x Sm x O3, 0.35≤x≤0.45 Weigh Y2O3 and Sm2O3 raw materials for batching; Step 2: ball milling: using ZrO2 balls as the milling medium and anhydrous ethanol as the dispersion medium, the raw materials, anhydrous ethanol, and milling balls are placed in a nylon jar and milled on a planetary ball mill to obtain a uniformly mixed slurry; Step 3: Drying and sieving: Drying the slurry obtained in step 2 and sieving to obtain dry powder; Step 4: Granulation and tableting: Add 5 wt.% polyvinyl alcohol solution to the dry powder obtained in step 3 for granulation. The granulated powder is initially pressed into a green billet using a manual tablet press, and then further pressed in a cold isostatic press. Step 5: Debinding the green blank pressed in step 4 at 500°C to 600°C for 1.5 to 2.5 hours; Step 6: Sinter the green blank after debinding in step 5 at 1400℃~1750℃ for 2~6 hours to make Y 2-x Sm x O3, 0.35≤x≤0.45 microwave dielectric ceramics.

2. The ultra-low dielectric loss low-dielectric rare earth oxide microwave dielectric ceramic material according to claim 1, characterized in that ,x＝0.40。 3. The method for preparing a low-dielectric rare earth oxide microwave dielectric ceramic material with ultra-low dielectric loss according to any one of claims 1 to 2, characterized in that: The method proceeds as follows: Step 1: Ingredients; pre-burn Y2O3 and Sm2O3 raw material powder to remove moisture; according to the chemical formula Y 2-x Sm x O3, 0.35≤x≤0.45 Y2O3 and Sm2O3 raw materials are weighed and mixed to form a mixture; Step 2: ball milling: using ZrO2 balls as the milling medium and anhydrous ethanol as the dispersion medium, the raw materials, anhydrous ethanol, and milling balls are placed in a nylon jar and milled on a planetary ball mill to obtain a uniformly mixed slurry; Step 3: Drying and sieving: Drying the slurry obtained in step 2 and sieving to obtain dry powder; Step 4: Granulation and tableting: Add 5 wt.% polyvinyl alcohol solution to the dry powder obtained in step 3 for granulation. The granulated powder is initially pressed into a green billet using a manual tablet press, and then further pressed in a cold isostatic press. Step 5: Debinding the green blank pressed in step 4 at 500°C to 600°C for 1.5 to 2.5 hours; Step 6: Sinter the green blank after debinding in step 5 at 1400℃~1750℃ for 2~6 hours to make Y 2-x Sm x O3, 0.35≤x≤0.45 microwave dielectric ceramics.

4. The method for preparing a low dielectric loss rare earth oxide microwave dielectric ceramic material according to claim 3, characterized in that In step 1, the pre-firing temperature of Y2O3 and Sm2O3 raw materials is 900℃, and the pre-firing time is 2 hours.

5. The method for preparing a low dielectric loss rare earth oxide microwave dielectric ceramic material according to claim 3, characterized in that In step 2, the mass ratio of the mixed powder: anhydrous ethanol: grinding balls is 1: (1.5-2.5): (4-6), the ball milling time is 4-8 hours, and the speed of the planetary ball mill is 200-300 rpm.

6. The method for preparing a low dielectric loss rare earth oxide microwave dielectric ceramic material according to claim 3, characterized in that In step 3, the drying temperature is 60-80°C, and the sieving is through a 100-mesh nylon screen.

7. The method for preparing a low dielectric loss rare earth oxide microwave dielectric ceramic material according to claim 3, characterized in that In step 4, the pressure of manual pressing of the green billet is 3 MPa, the pressure of the cold isostatic press is 200 MPa, and the holding time is 3 minutes.

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