A kind of NP0 ceramic dielectric material and preparation method

Abstract

The present invention relates to an NPO ceramic dielectric material and a preparation method. Specifically provided is an NPO ceramic dielectric material comprising the following raw materials: BLT phase powder, CNT phase powder, a modifying additive, and a sintering aid. The NPO ceramic dielectric material provided by the present invention exhibits both a high dielectric constant and low dielectric loss.

Description

Technical Field

[0001] The present invention relates to ceramic dielectric materials used in the fields of electronic devices, communication systems, capacitors, and the like, and in particular to an NPO ceramic dielectric material and a preparation method thereof. Background Art

[0002] With the continuous advancement of modern electronic technology, the demand for high-performance ceramic dielectric materials is increasing, especially for materials with high dielectric constants and low dielectric losses. NP0 ceramics, due to their excellent temperature characteristics and relatively stable electrical properties, have been widely used in high-frequency circuits, wireless communications, microwave devices, and capacitors. NP0 ceramics typically exhibit a near-zero temperature coefficient, meaning their dielectric constant varies very little with temperature, making them suitable for high-performance electronic applications requiring temperature stability.

[0003] However, existing NP0 type ceramic materials still face some challenges, especially in the balance between dielectric constant and dielectric loss. At present, there are few NP0 type ceramic materials on the market that have both high dielectric constant and low dielectric loss. For example, the domestic invention patent CN102690118A proposes an NP0 type ceramic material based on BRT as the main phase, ZnB as a sintering aid, and BiTi as the second phase. The dielectric loss of this material at room temperature is less than 0.05%, but its dielectric constant is low, ranging from 45-70, which is difficult to meet the demand for high dielectric constant materials. In addition, the domestic invention patent CN110483034A proposes a high dielectric constant NP0 type ceramic material, using Although the system has the advantage of a high dielectric constant, according to common knowledge in the art, the dielectric loss of the system is usually high.

[0004] In view of the defects of the existing technology, developing a new type of NP0 type ceramic dielectric material with high dielectric constant and low dielectric loss is an urgent problem to be solved by those skilled in the art, and it has broad application prospects. Summary of the Invention

[0005] The present invention aims to address the difficulty of achieving both a high dielectric constant and low dielectric loss in existing NPO ceramic dielectric materials. The present invention provides an NPO ceramic dielectric material and a method for preparing the same. The NPO ceramic dielectric material provided by the present invention has the advantages of both a high dielectric constant and low dielectric loss.

[0006] The present invention provides an NP0 ceramic dielectric material, which is made of the following raw materials: BLT phase powder, CNT phase powder, modification additives and sintering aids, wherein the chemical formula of the BLT phase powder is (Bi 0.9 La 0.1 )2Ti2O7; the chemical formula of the CNT phase powder is Ca 0.6Nd 0.8 / 3 TiO3.

[0007] In the present invention, the BLT phase powder is prepared by the following method: bismuth oxide (Bi2O3), titanium dioxide (TiO2) and lanthanum oxide (La2O3) are mixed according to (Bi 0.9 La 0.1 )2Ti2O7 are weighed in a stoichiometric ratio, and the ingredients are prepared into fine powder by wet planetary ball milling, and then the fine powder is sintered at 900-1100 ° C to form BLT phase powder.

[0008] In the present invention, the CNT phase powder is prepared by the following method: calcium carbonate (CaCO3), titanium dioxide (TiO2) and neodymium oxide (Nd2O3) are mixed according to Ca 0.6 Nd 0.8 / 3 TiO3 is weighed and mixed in a stoichiometric ratio, and is then milled into fine powder by wet planetary ball milling. The fine powder is then sintered at 1000-1200°C to form CNT phase powder.

[0009] In the present invention, the weight ratio of the BLT phase powder to the CNT phase powder is 3:7, 4:6, 5:5, 6:4 or 7:3; preferably 4:6, 5:5, 6:4 or 7:3; more preferably 5:5, 6:4 or 7:3; and most preferably 6:4.

[0010] In the present invention, the modifying additive is one or more of niobium pentoxide (Nb2O5) and zirconium oxide (ZrO2).

[0011] In the present invention, the weight ratio of niobium pentoxide (Nb2O5) to zirconium oxide (ZrO2) in the modifying additive is 1:3.

[0012] In the present invention, the sintering aid is one or more of boron oxide (B2O3) and aluminum oxide (Al2O3).

[0013] In the present invention, in the sintering aid, the weight ratio of boron oxide (B2O3) to aluminum oxide (Al2O3) is 2:1.

[0014] In the present invention, the raw material further includes an adhesive, and the adhesive is polyvinyl alcohol (PVA).

[0015] The present invention also provides a method for preparing an NP0 ceramic dielectric material, which comprises the following steps: (1) mixing BLT phase powder and CNT phase powder in a weight ratio of 1:(0.4-2.5), and adding a modifying additive and a sintering aid to obtain a mixed powder.

[0016] (2) The mixed powder is then passed through a wet planetary ball mill, and the milled slurry is then dried and passed through a 100-mesh sieve.

[0017] (3) Adding 0.5-2.5% by mass of polyvinyl alcohol to the mixed powder passing through a 100-mesh sieve to granulate the mixed powder, and then forming the mixed powder into a blank by cold isostatic pressing, and then sintering the blank at 950-1200° C. to prepare the NP0 ceramic dielectric material.

[0018] The BLT phase powder, the CNT phase powder, the modifying additive and the sintering aid are all as defined above.

[0019] In the present invention, BLT phase powder and CNT phase powder are weighed and prepared according to a weight ratio of 3:7, 4:6, 5:5, 6:4 or 7:3; preferably 4:6, 5:5, 6:4 or 7:3; more preferably 5:5, 6:4 or 7:3; and most preferably 6:4.

[0020] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0021] The reagents and raw materials used in the present invention are commercially available.

[0022] The positive progress effect of the present invention is that the present invention obtains a high dielectric constant and low dielectric loss NP0 ceramic dielectric material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron microscope image of NP0 ceramic dielectric material 1, showing the surface morphology of the material after sintering.

[0024] Figure 2 This is a scanning electron microscope image of NP0 ceramic dielectric material 2, showing the surface morphology of the material after sintering.

[0025] Figure 3 This is a scanning electron microscope image of NP0 ceramic dielectric material 3, showing the surface morphology of the material after sintering.

[0026] Figure 4 This is a scanning electron microscope image of NP0 ceramic dielectric material 4, showing the surface morphology of the material after sintering.

[0027] Figure 5 This is a scanning electron microscope image of NP0 ceramic dielectric material 5, showing the surface morphology of the material after sintering. DETAILED DESCRIPTION

[0028] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0029] Example 1: Preparation of BLT phase powder: Raw materials bismuth oxide (Bi2O3), titanium dioxide (TiO2) and lanthanum oxide (La2O3) were mixed in a stoichiometric ratio (Bi 0.9 La 0.1 )2Ti2O7 were weighed and mixed using a wet planetary ball mill with a nylon jar, zirconia balls, and anhydrous ethanol as the grinding medium. The milling process was carried out for four hours at a weight ratio of 1:1:0.8 between the material, zirconium balls, and ethanol. The milling was performed at a speed of 200 r / min. The milled slurry was dried in an electric forced-air oven at 80°C and then passed through a 100-mesh sieve. The sieved powder was then calcined at 950°C for four hours to produce a BLT phase powder.

[0030] Preparation of CNT phase powder: Raw materials calcium carbonate (CaCO3), titanium dioxide (TiO2) and neodymium oxide (Nd2O3) are mixed according to the stoichiometric ratio of Ca 0.6 Nd 0.8 / 3 TiO₃ was weighed and mixed using a wet planetary ball mill. The milling jar was made of nylon, the grinding media was zirconium oxide balls, and the ball medium was anhydrous ethanol. The weight ratio of material, zirconium oxide balls, and ethanol was 1:1:0.8. The ball speed was 200 r / min and the milling time was 4 hours. The milled slurry was dried in an electric forced air oven at 80°C. After drying, it was passed through a 100-mesh sieve. The sieved powder was calcined at 1100°C for 4 hours to obtain the final CNT phase powder.

[0031] 30 grams of BLT phase powder and CNT powder were mixed in a weight ratio of 3:7. Modifying additives included 0.5 grams of niobium pentoxide (Nb2O5) and 1.5 grams of zirconium oxide (ZrO2), as well as 1.2 grams of boron oxide (B2O3) and 0.6 grams of aluminum oxide (Al2O3) as sintering aids to produce a mixed powder. The mixed powder was then ball-milled a second time using a wet planetary ball mill with deionized water as the milling medium. The weight ratio of the materials, zirconium balls, and deionized water was 1:1:0.8, at a speed of 200 r / min for 12 hours. The milled slurry was dried in an 80°C electric forced-air oven and passed through a 100-mesh sieve.

[0032] Polyvinyl alcohol (PVA) with a mass fraction of 2% was added to the mixed powder passing through a 100-mesh sieve for granulation; then, cold isostatic pressing was performed at a pressure of 180 MPa to form a disc-shaped green body with a diameter of about 20 mm and a thickness of about 1 mm.

[0033] The disc-shaped green body was sintered at 1100℃ for 3 hours. The heating rate was 2℃ / min, and the temperature was kept at 550℃ for 3 hours to perform binder removal. Finally, the NP0 ceramic dielectric material 1 was obtained. The scanning electron microscope photo of the NP0 ceramic dielectric material 1 after sintering is shown in FIG. Figure 1 shown.

[0034] Example 2: The preparation method of Example 2 is basically the same as that of Example 1, the main difference being that 30 grams of BLT phase powder and CNT phase powder are mixed in a weight ratio of 4 to 6; finally, NP0 ceramic dielectric material 2 is obtained. The scanning electron microscope photo of NP0 ceramic dielectric material 2 after sintering is shown in FIG. Figure 2 shown.

[0035] Example 3: The preparation method of Example 3 is basically the same as that of Example 1, the main difference being that 30 grams of BLT phase powder and CNT phase powder are mixed in a weight ratio of 1:1; finally, NP0 ceramic dielectric material 3 is obtained. The scanning electron microscope photo of NP0 ceramic dielectric material 3 after sintering is shown in FIG. Figure 3 shown.

[0036] Example 4: The preparation method of Example 4 is basically the same as that of Example 1, the main difference being that 30 grams of BLT phase powder and CNT phase powder are mixed in a weight ratio of 6 to 4; finally, NP0 ceramic dielectric material 4 is obtained. The scanning electron microscope photograph of NP0 ceramic dielectric material 4 after sintering is shown in FIG. Figure 4 shown.

[0037] Example 5: The preparation method of Example 5 is basically the same as that of Example 1, the main difference being that 30 grams of BLT phase powder and CNT phase powder are mixed in a weight ratio of 7 to 3; finally, NP0 ceramic dielectric material 5 is obtained. The scanning electron microscope photo of the sintered NP0 ceramic dielectric material is shown in FIG. Figure 5 shown.

[0038] Effect Example 1: The ceramic materials obtained in the five previous examples were metallized for dielectric performance testing. A silver-containing slurry was applied to the upper and lower surfaces of a ceramic disc sample, followed by drying and high-temperature sintering to form conductive silver electrodes, thereby fabricating a disc capacitor. These samples were then tested using the capacitance method for room-temperature dielectric constant, room-temperature dielectric loss, and dielectric constant-temperature change rate.

[0039] (1) Dielectric constant at room temperature (ε r ) Test: Test instrument: Agilent E4980A precision LCR AC impedance meter.

[0040] Test conditions: frequency 1kHz, test environment temperature 25°C, humidity 50%.

[0041] The calculation formula is ε r = (C×d) / (S×ε0), where C is the measured capacitance of the ceramic capacitor; d is the thickness of the ceramic dielectric along the electric field direction; S is the area of ​​the ceramic capacitor plate; ε0 is the vacuum dielectric constant, which is 8.85×10 -12 F / m.

[0042] (2) Room temperature dielectric loss (tanδ) test: The dielectric loss of the material is tested at a frequency of 1 kHz using an Agilent E4980A precision LCR AC impedance meter, which is the same as the dielectric constant.

[0043] (3) Temperature-dependent capacitance change (TCC) test: The test sample is placed in a temperature-controlled environment, and the dielectric constant value is measured every 10°C over a temperature range of -50°C to 150°C using an Agilent E4980A precision LCR AC impedance meter. The experiment is conducted in a temperature-controlled furnace (temperature adjustment accuracy ±1°C).

[0044] Calculate the temperature change rate (TCC) of the dielectric constant within the temperature range. The calculation formula is TCC = (10 6 ×(ε (T) -ε (25°C) )) / ((T-25)×ε (25°C) ). Where T is the test temperature, ε (T) is the dielectric constant at the test temperature, ε (25°C) is the dielectric constant at 25°C.

[0045]

[0046] The data in Table 1 show that the room-temperature dielectric constants of the various samples range from 45 to 155. The room-temperature dielectric constant increases with increasing BLT content, reaching a maximum of 155 at a BLT / CNT ratio of 6:4 (Example 4), demonstrating high room-temperature dielectric properties. However, when the ratio increases to 7:3, the room-temperature dielectric constant decreases slightly, but still remains at a high level.

[0047] The room-temperature dielectric loss of each sample ranged from 0.194 to 0.040, generally falling in the lower dielectric loss range. As the BLT content increased, the dielectric loss gradually decreased, reaching a minimum of 0.040 in Example 4 (6:4 ratio), indicating that this ratio of material has the lowest energy loss in practical applications.

[0048] The capacitance-temperature variation rate of the sample in Example 1 is a positive 13.2 ppm / °C, indicating that the capacitance value increases with increasing temperature. In the other examples, the capacitance-temperature variation rates are all negative, and the absolute values ​​gradually decrease with increasing BLT content. The best example is Example 4, with a capacitance-temperature variation rate of -2.1 ppm / °C, indicating that the sample obtained with this ratio has the best stability and is suitable for use in environments with large temperature fluctuations.

[0049] Further analysis of the surface morphology differences revealed Figure 1-Figure 5 As shown in the scanning electron microscope images of the samples of Examples 1-5, it can be seen that the surface of the sample of Example 4 is the most dense and flat sintered.

[0050] In summary, the ceramic dielectric material obtained in Example 4 has excellent NP0 performance and has the characteristics of high dielectric constant and low dielectric loss.

Claims

1. An NP0 ceramic dielectric material, characterized in that It is made of the following raw materials: BLT phase powder, CNT phase powder, modification additives and sintering aids, wherein: NP0 ceramic dielectric materials are prepared by the following steps: (1) BLT phase powder and CNT phase powder are mixed in a weight ratio of 6:4, and a modification additive and a sintering aid are added to obtain a mixed powder; (2) The mixed powder is then passed through a wet planetary ball mill, and the milled slurry is then dried and passed through a 100-mesh sieve; (3) Adding 0.5-2.5% by mass of polyvinyl alcohol to the mixed powder passing through a 100-mesh sieve to granulate the mixed powder, and then forming the mixed powder into a blank by cold isostatic pressing, and then sintering the blank at 950-1200°C to prepare the NP0 ceramic dielectric material. The chemical formula of the BLT phase powder is ; The chemical formula of the CNT phase powder is .

2. The NPO ceramic dielectric material according to claim 1, wherein The BLT phase powder is prepared by the following method: bismuth oxide, titanium dioxide and lanthanum oxide are mixed according to The ingredients are weighed in a stoichiometric ratio, and are ground into fine powder by wet planetary ball milling. The fine powder is then sintered at 900-1100°C to form a BLT phase powder.

3. The NPO ceramic dielectric material according to claim 1, wherein The CNT phase powder is prepared by the following method: calcium carbonate, titanium dioxide and neodymium oxide are mixed according to The ingredients are weighed and mixed in a stoichiometric ratio, and then the fine powder is sintered at 1000-1200°C to form a CNT phase powder.

4. The NPO ceramic dielectric material according to claim 1, wherein The modifying additive is one or more of niobium pentoxide and zirconium oxide.

5. The NPO ceramic dielectric material according to claim 1, wherein The sintering aid is one or more of boron oxide and aluminum oxide.

6. The NPO ceramic dielectric material according to claim 5, wherein The sintering aids are boron oxide and aluminum oxide, wherein the weight ratio of the boron oxide to the aluminum oxide is 2:

1.

7. The NPO ceramic dielectric material according to claim 4, wherein The modifying additives are niobium pentoxide and zirconium oxide, wherein the weight ratio of the niobium pentoxide to the zirconium oxide is 1:3.

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