Low dielectric ultra-low loss high temperature stable neodymium oxide and zinc niobate co-doped barium titanate ceramic and method of making

Abstract

The application discloses a kind of low dielectric ultra-low loss high temperature stability neodymium oxide and zinc niobate co-doped barium titanate ceramic and preparation method.The general formula of the ceramic material is (1-x) BaTiO3-xZnNb2O6-xNd2O3, wherein x is 0.1-0.2, and is prepared by traditional solid-phase sintering method, with simple process, good repeatability and high yield.The application introduces Zn 2+ , Nb 5+ And Nd 3+ A / B site collaborative doping is carried out in BaTiO3 matrix, so that the obtained ceramic material realizes excellent comprehensive performance in the range of x=0.145-0.155 while maintaining moderate dielectric constant: extremely low dielectric loss (tanδ≤0.001), excellent temperature stability (ΔC / C 20°C ≤±0.5%, -150-250°C) and high breakdown field strength (E b ≥280kV / cm).The ceramic material is suitable for scenes with strict requirements on dielectric properties, temperature stability and breakdown field strength, and can be applied in fields such as aerospace extreme environment electronic components, new energy vehicle power modules and precision high-frequency sensing equipment, with significant application value and market potential.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, specifically relating to a ceramic material co-doped with neodymium oxide and zinc niobate barium titanate, which has low dielectric constant, ultra-low dielectric loss, and high temperature stability, and its preparation method. Background Technology

[0002] In recent years, with the rapid development of microelectronics technologies such as 5G communication, new energy vehicles, and aerospace, electronic components are rapidly evolving towards miniaturization and integration. Against this backdrop, the demand for dielectric materials with low dielectric loss, high temperature stability, suitable dielectric constant, and high breakdown field strength in key components such as multilayer ceramic capacitors (MLCCs) is becoming increasingly urgent. These dielectric materials are the core support for ensuring the long-term stable operation of high-end electronic equipment; therefore, developing dielectric materials with the aforementioned excellent comprehensive properties has become an important research direction in the field of materials science.

[0003] Currently, the research field has developed a (1-x)BaTiO3-xZnNb2O6 ((1-x)BT-xZN) composite dielectric ceramic system. This system, leveraging the perovskite lattice structure and good ion substitution tolerance of barium titanate (BaTiO3)-based ceramics, as well as the structural regulation effect of zinc niobate (ZnNb2O6), has shown potential in dielectric performance control, becoming one of the research hotspots in the field of dielectric ceramics. However, the existing (1-x)BT-xZN (x=0.005~0.04) system has clear performance shortcomings. Its dielectric constant is generally at a moderate level above 1604, its dielectric loss is relatively high (usually greater than 0.006), and its temperature stability is poor. This means that the system cannot meet the core requirements of high-end electronic devices for low dielectric constant, ultra-low dielectric loss, excellent temperature stability, and high breakdown field strength, thus limiting its practical engineering application value. Summary of the Invention

[0004] The purpose of this invention is to address the problems of easy precipitation of a second phase, high dielectric constant, excessive dielectric loss, and poor temperature stability in the existing (1-x)BT-xZN (x=0.005~0.04) system, and to provide a barium titanate ceramic co-doped with neodymium oxide and zinc niobate with low dielectric constant, ultra-low dielectric loss, and high temperature stability, and to provide a preparation method for this ceramic.

[0005] To achieve the above objectives, the general formula of the neodymium oxide and zinc niobate co-doped barium titanate ceramic provided by the present invention is (1-x)BaTiO3-xZnNb2O6-xNd2O3, where x takes the value of 0.1 to 0.2.

[0006] In the above-mentioned neodymium oxide and zinc niobate co-doped barium titanate ceramics, the preferred value of x is 0.145 to 0.155.

[0007] The preparation method of the neodymium oxide and zinc niobate co-doped barium titanate ceramic of the present invention consists of the following steps:

[0008] Step 1: According to the stoichiometry of (1-x)BaTiO3-xZnNb2O6-xNd2O3, weigh out BaCO3, rutile TiO2, ZnO, Nb2O5 and Nd2O3 with a purity of 98% or higher, mix them thoroughly, ball mill them and then dry them to obtain the raw material mixture.

[0009] Step 2: Pre-calcine the raw material mixture at 1000-1050°C for 2-4 hours, mix thoroughly, ball mill, and then dry to obtain pre-calcined powder.

[0010] Step 3: After granulation, pressing and debinding of the pre-fired powder, sinter it at 1350-1450°C for 2-4 hours under sealed conditions to obtain barium titanate ceramics co-doped with neodymium oxide and zinc niobate.

[0011] Preferably, in steps 1 and 2, the time for thorough mixing and ball milling is 8 to 12 hours, and the drying is carried out at 80 to 100°C for 12 to 24 hours.

[0012] Preferably, in step 2, the raw material mixture is pre-calcined at 1025°C for 2 hours.

[0013] Preferably, in step 2, the heating rate of the preheating is 2-4°C / minute.

[0014] Preferably, in step 3, the pre-calcined powder is granulated under the action of polyvinyl alcohol binder, pressed into tablets under a pressure of 6-10 MPa for 3-6 minutes, then heated to 500°C to remove the adhesive, and then heated to 1375°C to sinter for 2 hours.

[0015] Preferably, in step 3, the heating rate of the adhesive removal is 1-3°C / min; the heating rate of the sintering is 3-5°C / min.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. This invention, through the synergistic doping of ZnNb2O6 and Nd2O3 into barium titanate, enables the ceramic material to exhibit ultra-low dielectric loss and high breakdown field strength under high-temperature conditions, while simultaneously possessing high temperature stability and a moderate dielectric constant. Nd 3+ Doping with Zn can effectively regulate the crystal structure of the BaTiO3 matrix, improve the solid solubility of ZnNb2O6 in the barium titanate matrix, and prevent excessive aggregation of ZnNb2O6 leading to the precipitation of a second phase. 2+ and Nb 5+The co-doping effectively disrupts the long-range ferroelectric order of BaTiO3, transforming it from a normal ferroelectric to a relaxor ferroelectric, thereby suppressing the sharp phase transition peak near the Curie temperature and making the dielectric constant-temperature curve more gradual. This results in a high capacitance change rate ΔC / C within an ultra-wide temperature range of -150 to 250 °C. 20℃ ≤±0.5%, demonstrating excellent temperature stability. Meanwhile, Nd... 3+ Selective grain boundary segregation occurs at grain boundaries, forming a high-resistivity grain boundary layer. This layer, together with the grain interior, constitutes a grain-grain boundary internal barrier capacitance structure. In this structure, the grains provide a suitable dielectric constant, while the high-resistivity grain boundaries effectively suppress carrier migration, thereby significantly reducing dielectric loss. The specific mechanism is as follows: Nb 5+ The introduction of Ti 4+ Restore to Ti 3+ The generated electron carriers are suppressed by a potential barrier when migrating to the grain boundaries, contributing to the dielectric response; while Nd 3+ The doping introduces a suitable amount of oxygen vacancies, further hindering the long-range migration of charge carriers. Under the above synergistic effect, the dielectric loss of the ceramic of this invention is as low as 0.0001–0.001 at 1 kHz, and remains low throughout the entire 10 kHz range. 2 ~10 4 The dielectric loss remains below 0.001 throughout the Hz frequency range. While reducing the dielectric constant (143–167) and dielectric loss, the ceramic of this invention retains the advantage of the original system's high breakdown field strength, reaching 280–320 kV / cm. Through synergistic doping of rare-earth Nd at the A / B sites, not only is the second-phase problem easily generated when ZnNb₂O₆ content is high, improving microstructure uniformity, but the material also exhibits high reliability under high-temperature and high-electric-field environments. The above comprehensive performance (moderate ε) r Ultra-low tanδ, wide temperature range ΔC / C 20℃ ≤ ±0.5%, High E b It is significantly superior to the existing (1-x)BT-xZN system, filling the application gap of this system in the field of high-end dielectric ceramics.

[0018] 2. This invention employs a traditional solid-state sintering method, which features simple process steps, good repeatability, and high yield. It requires no special equipment and is easily mass-produced. The resulting ceramic material fully meets the stringent requirements for dielectric properties, temperature stability, and breakdown field strength in applications such as high-end multilayer ceramic capacitors (MLCCs), aerospace extreme environment electronic components, new energy vehicle power modules, and precision high-frequency sensing equipment, demonstrating significant application value and market potential. Attached Figure Description

[0019] Figure 1The graph shows the relationship between the dielectric constant and dielectric loss of the neodymium oxide and zinc niobate co-doped barium titanate ceramics prepared in Examples 1-3 and the test frequency.

[0020] Figure 2 The graph shows the relationship between the polarization intensity of the neodymium oxide and zinc niobate co-doped barium titanate ceramics prepared in Examples 1-3 and the applied electric field.

[0021] Figure 3 This is a graph showing the relationship between the capacitance change rate and the test temperature of the neodymium oxide and zinc niobate co-doped barium titanate ceramics prepared in Examples 1-3 at 100 kHz. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0023] Example 1

[0024] Step 1: According to the stoichiometry of 0.855BaTiO3-0.145ZnNb2O6-0.145Nd2O3, weigh out 15.0573g of raw materials BaCO3 (99% purity), 6.1564g of TiO2 (98% purity), 1.0532g of ZnO (99% purity), 3.4223g of Nb2O5 (99.5% purity), and 4.3109g of Nd2O3 (99.99% purity), and put them into a nylon can. Use zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium. The mass ratio of anhydrous ethanol to the total raw materials is 1:1.2. Ball mill at 401 rpm for 12 hours. Separate the zirconium balls, dry the ball-milled raw materials at 80℃ for 24 hours, and grind them in a mortar for 30 minutes to obtain the raw material mixture.

[0025] Step 2: Place the raw material mixture in an alumina crucible, cover it, heat it to 1025℃ at a heating rate of 3℃ / min and hold it at that temperature for 2 hours. Let it cool naturally to room temperature, remove it from the furnace, grind it in a mortar for 5 minutes, put it back into a nylon can, use zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium, with an anhydrous ethanol to raw material mass ratio of 1:1.2, and ball mill it at 401 rpm for 12 hours. Separate the zirconium balls, dry the ball-milled raw material at 80℃ for 24 hours, and grind it in a mortar for 30 minutes to obtain pre-calcined powder.

[0026] Step 3: Add a 5% (w / w) polyvinyl alcohol aqueous solution to the pre-fired powder. The amount of polyvinyl alcohol aqueous solution added is 50% of the mass of the pre-fired powder. Granulate the powder and pass it through a 120-mesh sieve to form spherical powder particles. Place the spherical powder particles into a stainless steel mold with a diameter of 11.5 mm and press them into cylindrical blanks with a thickness of 1.5 mm using a powder press at a pressure of 6 MPa for 3 minutes. Spread a layer of pre-fired powder on a zirconia plate, place the cylindrical blank on the zirconia plate, spread another layer of pre-fired powder on the blank, and then place the zirconia plate in an alumina ceramic boat. First, heat the furnace to 500°C at a rate of 1.5°C / min in a muffle furnace and hold for 3 hours. Then, allow the furnace to cool naturally to room temperature. Finally, heat the furnace in a tube furnace under closed conditions at a rate of 4... The temperature was increased to 1375℃ at a heating rate of ℃ / min, held for 2 hours, and then naturally cooled to room temperature in the furnace to obtain a barium titanate ceramic co-doped with neodymium oxide and zinc niobate: 0.855BaTiO3-0.145ZnNb2O6-0.145Nd2O3.

[0027] Example 2

[0028] In step 1 of this embodiment, the raw materials BaCO3 (99% purity) 14.8805g, TiO2 (98% purity) 6.0841g, ZnO (99% purity) 1.0830g, Nb2O5 (99.5% purity) 3.5193g, and Nd2O3 (99.99% purity) 4.4331g were weighed according to the stoichiometry of 0.85BaTiO3-0.15ZnNb2O6-0.15Nd2O3, and placed in a nylon can. Zirconium balls were used as grinding balls, and anhydrous ethanol was used as the grinding medium. The mass ratio of anhydrous ethanol to the total raw materials was 1:1.2. The mixture was ball-milled at 401 rpm for 12 hours. The zirconium balls were separated, and the ball-milled raw materials were dried at 80°C for 24 hours. The mixture was then ground in a mortar and pestle for 30 minutes to obtain the raw material mixture. The other steps are the same as in Example 1, resulting in a barium titanate ceramic co-doped with neodymium oxide and zinc niobate: 0.85BaTiO3-0.15ZnNb2O6-0.15Nd2O3.

[0029] Example 3

[0030] In step 1 of this embodiment, the raw materials BaCO3 (99% purity) 14.7057g, TiO2 (98% purity) 6.0126g, ZnO (99% purity) 1.1125g, Nb2O5 (99.5% purity) 3.6152g, and Nd2O3 (99.99% purity) 4.5539g were weighed according to the stoichiometry of 0.845BaTiO3-0.155ZnNb2O6-0.155Nd2O3, and placed in a nylon can. Zirconium balls were used as grinding balls, and anhydrous ethanol was used as the grinding medium. The mass ratio of anhydrous ethanol to the total raw materials was 1:1.2. The mixture was ball-milled at 401 rpm for 12 hours. The zirconium balls were separated, and the ball-milled raw materials were dried at 80°C for 24 hours. The mixture was then ground in a mortar and pestle for 30 minutes to obtain the raw material mixture. The other steps are the same as in Example 1, resulting in a barium titanate ceramic co-doped with neodymium oxide and zinc niobate: 0.845BaTiO3-0.155ZnNb2O6-0.155Nd2O3.

[0031] The surfaces of the neodymium oxide and zinc niobate co-doped barium titanate ceramics prepared in Examples 1-3 were polished sequentially with 1000-mesh, 1500-mesh, and 2000-mesh sandpaper to a thickness of 0.6-0.7 mm. Then, silver paste with a thickness of 0.01-0.03 mm was coated onto the upper and lower surfaces of the ceramics, and the ceramics were placed in a resistance furnace and held at 840°C for 30 minutes. The dielectric properties of the ceramics were tested using an Agilent 4294A precision impedance analyzer and a DMS2000 dielectric measurement analyzer, respectively. Simultaneously, the energy storage performance of the ceramics was tested using a P-PM2 ferroelectric hysteresis meter. The results are shown in Table 1, where the dielectric constant and dielectric loss curves as a function of test frequency are shown in Table 1. Figure 1 As shown, the curves showing the relationship between polarization intensity and applied electric field are as follows: Figure 2 As shown, the relationship between the rate of change of capacitance at different frequencies and the test temperature is as follows: Figure 3 As shown.

[0032] Table 1 Electrical properties of ceramics in Examples 1-3

[0033] Combined with Table 1 and Figures 1-3 As can be seen, the neodymium oxide and zinc niobate co-doped barium titanate ceramics prepared in Examples 1-3 exhibit significant advantages over similar low-dielectric-constant dielectric materials in terms of dielectric constant, dielectric loss, temperature stability, and breakdown field strength. When the test frequency is 1 kHz, the dielectric constants of the ceramic materials in Examples 1-3 are 160, 143, and 167, respectively; the dielectric losses are 0.0003, 0.0001, and 0.001, respectively; and the breakdown field strengths are 280 kV / cm, 320 kV / cm, and 300 kV / cm, respectively. Throughout the entire 10... 2 ~10 4Within the Hz frequency range, the dielectric loss remains consistently below 0.001, meeting the low-loss requirements of ceramic materials. Furthermore, all three embodiments exhibit excellent frequency and temperature stability (ΔC / C) over an ultra-wide temperature range of -150 to 250°C. 20℃ (≤ ±0.5%), wherein the capacitance change rate of the ceramic material in Example 2 is stable at -0.5% to 0.5% at a frequency of 100kHz, and the breakdown field strength is as high as 320kV / cm, which significantly improves its working reliability in high temperature and high electric field environments.

Claims

1. A low-dielectric-value, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramic, characterized in that: The general formula of the ceramic material is (1-x)BaTiO3-xZnNb2O6-xNd2O3, where x takes the value of 0.1 to 0.

2.

2. The low dielectric, ultra-low loss, high temperature stability neodymium oxide and zinc niobate co-doped barium titanate ceramic according to claim 1, characterized in that: The value of x ranges from 0.145 to 0.

155.

3. A method for preparing the low-dielectric, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramic according to claim 1, characterized in that... It consists of the following steps: Step 1: According to the stoichiometry of (1-x)BaTiO3-xZnNb2O6-xNd2O3, weigh out BaCO3, rutile TiO2, ZnO, Nb2O5 and Nd2O3 with a purity of 98% or higher, mix them thoroughly, ball mill them and then dry them to obtain a raw material mixture; Step 2: Pre-calcine the raw material mixture at 1000-1050°C for 2-4 hours, mix thoroughly, ball mill, and then dry to obtain pre-calcineed powder; Step 3: After granulation, pressing and debinding of the pre-fired powder, sinter it at 1350-1450°C for 2-4 hours under sealed conditions to obtain barium titanate ceramics co-doped with neodymium oxide and zinc niobate.

4. The method for preparing low-dielectric, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramics according to claim 3, characterized in that: In steps 1 and 2, the ball milling time for thorough mixing is 8 to 12 hours, and the drying is carried out at 80 to 100°C for 12 to 24 hours.

5. The method for preparing low-dielectric, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramics according to claim 3, characterized in that: In step 2, the raw material mixture is pre-calcined at 1025°C for 2 hours.

6. The method for preparing low-dielectric, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramics according to claim 3 or 5, characterized in that: In step 2, the preheating rate is 2-4°C / minute.

7. The preparation method of low dielectric, ultra-low loss, high temperature stability neodymium oxide and zinc niobate co-doped barium titanate ceramics according to claim 3, in step 3, the pre-fired powder is granulated under the action of polyvinyl alcohol binder, pressed into sheets under a pressure of 6-10 MPa for 3-6 minutes, then heated to 500°C to remove the binder, and then heated to 1375°C to sinter for 2 hours.

8. The method for preparing low-dielectric, ultra-low-loss, high-temperature-stability neodymium oxide and zinc niobate co-doped barium titanate ceramics according to claim 3 or 7, characterized in that: In step 3, the heating rate for debinding is 1–3 °C / min; the heating rate for sintering is 3–5 °C / min.

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