NBT-based ceramic material with medium and low temperature dielectric loss frequency sensitivity and preparation method of NBT-based ceramic material

Abstract

The invention discloses a medium and low temperature dielectric loss frequency sensitive NBT-based ceramic material and a preparation method thereof. The method comprises the following steps: weighing Na < 0.465 > Li < 0.07 > Bi < 0.465 > Ta < 0.07 > Ti < 0.93 > O < 3 > and MgAl < 2 > O < 4 > powder according to a stoichiometric formula of 0.99 Na < 0.465 > Li < 0.07 > Bi < 0.465 > Ta < 0.07 > Ti < 0.93 > O < 3 >-0.01 MgAl < 2 > O < 4 >, and uniformly mixing to form a full ingredient; carrying out ball milling, drying and sieving on the full ingredients to form sieved materials; and pressing the sieved material into a green body, heating the green body to 1250-1350 DEG C in 250-270 minutes in a box-type furnace, preserving heat for 1.5-2.5 hours, cooling to 480-520 DEG C in 150-170 minutes, and finally cooling to room temperature along with the furnace, thereby obtaining the ceramic material with strong dielectric loss frequency sensitivity in a medium-low temperature region of 200-300 DEG C. Due to the unique dielectric loss spectrum characteristic of the material, the material has irreplaceable advantages in specific sensing and filtering applications, and the problems that an existing material is gentle in response and insufficient in sensitivity in a medium and low temperature interval are solved.

Description

Technical Field

[0001] This invention belongs to the field of functional ceramic materials, specifically relating to a medium- and low-temperature dielectric loss frequency-sensitive NBT-based ceramic material and its preparation method. Background Technology

[0002] In existing technologies, research on dielectric ceramic materials has largely focused on two extremes: one is pursuing stability over a wide temperature and frequency range (such as Class I ceramics) for use in capacitors; the other is pursuing high ionic conductivity at high temperatures (such as electrolyte ceramics). However, with the development of smart sensing and Internet of Things technologies, the demand for special functional materials that exhibit significant responses to frequency changes in the medium-low temperature range (200-300°C) is becoming increasingly urgent.

[0003] For example, in fields such as automotive exhaust treatment and industrial process monitoring, there are numerous working environments ranging from 200 to 300°C. There is an urgent need for sensitive materials that can operate directly at this temperature and infer environmental parameters (such as gas concentration and slight temperature changes) through changes in electrical signals (such as impedance and loss). However, the frequency response of existing materials in this temperature range is often too flat, resulting in insufficient sensitivity. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material and its preparation method. In the temperature range of 200-300°C, its dielectric loss exhibits a strong frequency dependence, solving the problem of slow response and insufficient sensitivity of existing materials in the medium-low temperature range.

[0005] This invention is achieved through the following technical solution: A medium-to-low temperature dielectric loss frequency-sensitive NBT-based ceramic material, with the stoichiometric formula: 0.99Na 0.465 Li 0.0 7Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4.

[0006] A method for preparing the medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material includes the following steps: Step 1: According to the stoichiometric formula 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4, weigh Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti0.93 O3 powder and MgAl2O4 powder are mixed evenly to form the complete formula; Step 2: According to the mass ratio of 1:(4.8-5.2):(0.8-1.2), the whole batch of materials is mixed with zircon spheres and deionized water, then ball-milled, dried and sieved to form sieved material; Step 3: Press the sieved material described in Step 2 into a green body, and heat the green body in a box furnace to 1250-1350℃ for 250-270 minutes, hold it at that temperature for 1.5-2.5 hours, then cool it down to 480-520℃ for 150-170 minutes, and finally cool it to room temperature with the furnace to obtain a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material.

[0007] Furthermore, in step 1, Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder consists of Na2CO3, Bi2O3, and TiO2. 2、 The product was obtained by ball milling and drying of Li2CO3 and Ta2O5.

[0008] Furthermore, the MgAl2O4 powder in step 1 is obtained through the following steps: MgO and Al2O3 are weighed and mixed in a molar ratio of 1:1 to form mixture A. Mixture A, zircon and deionized water are mixed in a mass ratio of 1:(4.8-5.2):(0.8-1.2). After mixing, the mixture is ball-milled, dried and calcined at 1150-1250℃ for 3-4 hours to obtain powder B. Powder B was mixed with zircon and deionized water at a mass ratio of 1:(4.8-5.2):(0.8-1.2), and then ball-milled, dried, and calcined at 1150-1250℃ for 3-4 hours to obtain MgAl2O4.

[0009] Furthermore, the ball milling time is 12-24 hours, and the product is dried at 85-100℃ for 24 hours.

[0010] Furthermore, the mesh size of the sieve used in step 2 is 140-160 mesh.

[0011] Furthermore, the pressing process in step 3 specifically involves holding the pressure at 180-220 MPa for 2-4 minutes, then holding the pressure at 170-200 MPa for 4-6 minutes, and finally releasing the pressure at 30-50 MPa / min to form a blank through cold isostatic pressing.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention exhibits significant frequency sensitivity to dielectric loss at medium and low temperatures. Based on sodium bismuth titanate, it achieves this frequency sensitivity through Mg and Al synergistic doping. 2+ The ionic radius of Mg is relatively large, making it difficult for it to enter the A-site or B-site of NBT in large quantities. Therefore, during the sintering process, Mg... 2+ It tends to diffuse and enrich at the grain boundaries of NBT; Al 3+ (Replaces Ti) 4+） As an acceptor dopant, the difference in valence state introduces negatively charged defects. To maintain charge neutrality, positively charged defects (oxygen vacancies or A-site cation vacancies) are generated in the lattice to compensate, initially introducing a controllable defect concentration within the NBT lattice. At 200-300°C, oxygen vacancies and space charges in the interface layer become mobile. Due to the significant difference in electrical properties (conductivity, dielectric constant) between the NBT grains and the (Mg, Al)-O interface layer, a large amount of charge accumulates at the interface under an alternating electric field, resulting in strong Maxwell-Wagner-Sillars (MWS) interface polarization. The relaxation time of this interface polarization is distributed in the low to mid-frequency range (1kHz - 1000kHz). When the frequency of the external electric field changes, the establishment and disappearance of the polarization process change drastically, macroscopically manifested as a strong frequency dependence of the dielectric loss (tanδ). This invention demonstrates that, within a temperature range of 200-300℃ and a frequency range of 1kHz-1000kHz, the dielectric loss value decreases sharply from (0.02) to (0.002) when the frequency changes from 1kHz to 1000kHz, a change exceeding one order of magnitude. The low-temperature dielectric loss frequency-sensitive ceramic material prepared by this invention is suitable for applications such as gas sensors and temperature-sensitive switches. By adjusting the frequency, its loss value can be significantly modified, making it highly suitable for developing novel frequency-modulated sensors and signal processing components.

[0013] This invention uses the traditional solid-phase reaction method, which is mature, low-cost, and easy to scale up for production. Attached Figure Description

[0014] Figure 1 The dielectric constant and dielectric loss of the ceramic material prepared in Example 1 of this invention vary with frequency at different temperatures. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0016] In this invention, Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93O3 powder is obtained through the following steps: Weigh Na2CO3, Bi2O3 and TiO2 according to a molar ratio of 1:1:(3.5-4.5) and mix them to form mixture C. Take mixture C, zircon and deionized water and mix them according to a mass ratio of 1:(4.8-5.2):(0.8-1.2). Then, ball mill, dry and calcine at 850-860℃ for 3-4 hours to obtain powder D. The powder D was mixed with zircon and deionized water in a mass ratio of 1:(4.8-5.2):(0.8-1.2), and then ball-milled, dried, and calcined at 850-860℃ for 3-4 hours to obtain Na. 0.5 Bi 0.5 TiO3 powder; Li2CO3 and Ta2O5 were weighed and mixed in a molar ratio of (0.8-1.2):(0.8-1.2) to form mixture E. Mixture E, zircon, and deionized water were taken and mixed in a mass ratio of 1:(4.8-5.2):(0.8-1.2). The mixture was then ball-milled, dried, and calcined at 850-860℃ for 3-4 hours to obtain powder F. The powder F was mixed with zircon and deionized water in a mass ratio of 1:(4.8-5.2):(0.8-1.2), and then ball-milled, dried, and calcined at 850-860℃ for 3-4 hours to obtain LiTaO3 powder. Weigh the Na according to the molar ratio (92-94):(6-8). 0.5 Bi 0.5 TiO3 and the LiTaO3 powder are mixed A mixture G is formed. The mixture G, zircon, and deionized water are mixed in a mass ratio of 1:(4.8-5.2):(0.8-1.2). The mixture is then ball-milled, dried, and calcined at 850-860℃ for 3-4 hours to obtain powder H. The powder H was mixed with zircon and deionized water in a mass ratio of 1:(4.8-5.2):(0.8-1.2), and then ball-milled, dried, and calcined at 850-860℃ for 3-4 hours to obtain Na. 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder.

[0017] Example 1 The purity of Na2CO3, Bi2O3, TiO2, Li2CO3, Ta2O5, MgO, and Al2O3 mentioned below is all above 99.0%, and a planetary ball mill is used for ball milling.

[0018] A medium-to-low temperature dielectric loss frequency-sensitive NBT-based ceramic material with a stoichiometric formula of 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4.

[0019] A method for preparing a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material includes the following steps: Step 1: Preparation of Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder, according to the stoichiometric formula 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4, weigh Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder are mixed evenly to form the complete formula; Among them, Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 The preparation of O3 powder is as follows: Na₂CO₃, Bi₂O₃, and TiO₂ were weighed according to a molar ratio of 1:1:4. 2， Mixtures are combined to form mixture C. Mixture C, zircon, and deionized water are mixed in a mass ratio of 1:5:1 and then ball-milled, dried, and calcined at 850°C for 4 hours to obtain powder D. The powder D was mixed with zircon and deionized water in a mass ratio of 1:5:1, and then ball-milled, dried, and calcined at 850°C for 4 hours to obtain Na. 0.5 Bi 0.5 TiO3 powder; Li2CO3 and Ta2O5 were weighed and mixed in a molar ratio of 1:1 to form mixture E. Mixture E, zircon, and deionized water were mixed in a mass ratio of 1:5:1 and then ball-milled, dried, and calcined at 850°C for 4 hours to obtain powder F. The powder F was mixed with zircon and deionized water in a mass ratio of 1:5:1, and then ball-milled, dried and calcined at 850°C for 4 hours to obtain LiTaO3 powder. The Na was weighed according to a molar ratio of 93:7. 0.5 Bi 0.5 TiO3 and the LiTaO3 powder are mixed to form mixture G. Take the mixture G, zircon and deionized water, mix them in a mass ratio of 1:5:1, and then ball mill, dry and calcine at 850°C for 4 hours to obtain powder H; The powder H was mixed with zircon and deionized water in a mass ratio of 1:5:1, and then ball-milled, dried, and calcined at 850°C for 4 hours to obtain Na. 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder.

[0020] The preparation of MgAl2O4 powder is as follows: MgO and Al2O3 were weighed and mixed in a molar ratio of 1:1 to form mixture A. Mixture A, zircon and deionized water were taken and mixed in a mass ratio of 1:5:1. The mixture was then ball-milled, dried and calcined at 1200℃ for 3 hours to obtain powder B. The powder B was mixed with zircon and deionized water in a mass ratio of 1:5:1, and then ball-milled, dried and calcined at 1200℃ for 3 hours to obtain MgAl2O4. Step 2: Mix the prepared ingredients with zircon and deionized water in a mass ratio of 1:5:1, then ball mill and dry the mixture. Grind the dried material through a 140-mesh sieve. The ball milling process described in steps 1 and 2 above lasts for 12 hours, followed by drying at 85-100℃ for 24 hours.

[0021] Step 3: The sieved material is first pressed at 200MPa for 2 minutes, then at 180MPa for 4 minutes, and finally depressurized at 30MPa / min to form a green body by cold isostatic pressing; in a box furnace, the temperature is first raised to 1300℃ in 260 minutes and held for 2 hours, then cooled to 500℃ in 160 minutes and finally cooled to room temperature with the furnace to obtain a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material.

[0022] The obtained materials were subjected to performance tests, such as: Figure 1As shown, the horizontal axis represents temperature, the upper half represents dielectric constant, and the lower half represents dielectric loss. Different colors represent different frequencies, and the values ​​increase exponentially with the arrows, specifically 1 kHz, 10 kHz, 100 kHz, and 1000 kHz. At medium and low temperatures of 200°C-300°C, dielectric loss changes significantly with increasing frequency. For example, at 250°C, dielectric loss decreases from 1 kHz (0.02) to 100 kHz (0.002), a change of an order of magnitude. This indicates that the introduction of MgAl2O4 significantly enhances the dielectric loss sensitivity of the material at medium and low temperatures and provides high dielectric constant performance.

[0023] Performance Analysis This excellent frequency sensitivity stems from the fact that the relaxation times of various polarization mechanisms present in the material of this invention are precisely distributed in the mid-to-low frequency range. These polarization mechanisms may include: Maxwell-Wagner-Sillars (MWS) interface polarization: Due to the difference in conductivity and dielectric constant between the NBT and MgAl2O4 phases, a large amount of space charge accumulates at the heterogeneous interface. At 200-300°C, the migration and relaxation of these charges are extremely sensitive to low-frequency electric fields.

[0024] Oxygen vacancy dipole orientation polarization: High-density oxygen vacancies introduced at the interface form electric dipoles with surrounding ions. At medium and low temperatures, these dipoles can align in response to low-frequency electric fields, but at high frequencies, they cannot keep up with changes in the electric field, resulting in decreased losses.

[0025] This invention precisely modulates the characteristic time distribution of these relaxation processes by using composite MgAl2O4, so that it mainly falls within the operating frequency range of 1kHz-1000kHz, thereby creating this unique 'frequency switching' effect.

[0026] Example 2 A medium-to-low temperature dielectric loss frequency-sensitive NBT-based ceramic material with a stoichiometric formula of 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4.

[0027] A method for preparing a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material includes the following steps: Step 1: Preparation of Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder, according to the stoichiometric formula 0.99Na0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4, weigh Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder are mixed evenly to form the complete formula; Among them, Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 The preparation of O3 powder is as follows: Weigh out Na₂CO₃, Bi₂O₃, and TiO₂ in a molar ratio of 1:1:3.5. 2， Mixtures are combined to form mixture C. Mixture C, zircon, and deionized water are mixed in a mass ratio of 1:4.8:0.8, and then ball-milled, dried, and calcined at 860°C for 3 hours to obtain powder D. The powder D was mixed with zircon and deionized water in a mass ratio of 1:4.8:0.8, and then ball-milled, dried, and calcined at 860°C for 3 hours to obtain Na. 0.5 Bi 0.5 TiO3 powder; Li2CO3 and Ta2O5 were weighed and mixed in a molar ratio of 0.8:1.2 to form mixture E. Mixture E, zircon, and deionized water were mixed in a mass ratio of 1:4.8:0.8 and then ball-milled, dried, and calcined at 860°C for 3 hours to obtain powder F. The powder F was mixed with zircon and deionized water in a mass ratio of 1:4.8:0.8, and then ball-milled, dried and calcined at 860°C for 3 hours to obtain LiTaO3 powder. The Na was weighed according to a molar ratio of 92:6. 0.5 Bi 0.5 TiO3 and the LiTaO3 powder are mixed to form mixture G. Take the mixture G, zircon and deionized water, mix them in a mass ratio of 1:4.8:0.8, and then ball mill, dry and calcine at 860℃ for 3 hours to obtain powder H; The powder H was mixed with zircon and deionized water in a mass ratio of 1:4.8:0.8, and then ball-milled, dried, and calcined at 860°C for 3 hours to obtain Na. 0.465 Li 0.07 Bi 0.465 Ta0.07 Ti 0.93 O3 powder.

[0028] The preparation of MgAl2O4 powder is as follows: MgO and Al2O3 were weighed and mixed in a molar ratio of 1:1 to form mixture A. Mixture A, zircon, and deionized water were mixed in a mass ratio of 1:4.8:0.8 and then ball-milled, dried, and calcined at 1150°C for 4 hours to obtain powder B. The powder B was mixed with zircon and deionized water in a mass ratio of 1:4.8:0.8, and then ball-milled, dried and calcined at 1150°C for 4 hours to obtain MgAl2O4. Step 2: Mix the prepared ingredients with zircon and deionized water at a mass ratio of 1:4.8:0.8, then ball mill and dry the mixture. Grind the dried material through a 150-mesh sieve. The ball milling time mentioned above is 20 hours, followed by drying at 85-100℃ for 24 hours; Step 3: The sieved material is first pressed at 180MPa for 3 minutes, then at 170MPa for 6 minutes, and finally depressurized at 40MPa / min to form a green body by cold isostatic pressing; in a box furnace, the temperature is first raised to 1250℃ in 250 minutes and held for 1.5 hours, then lowered to 480℃ in 150 minutes and finally cooled to room temperature with the furnace to obtain a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material.

[0029] Example 3 A medium-to-low temperature dielectric loss frequency-sensitive NBT-based ceramic material with a stoichiometric formula of 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4.

[0030] A method for preparing a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material includes the following steps: Step 1: Preparation of Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder, according to the stoichiometric formula 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4, weigh Na 0.465 Li 0.07 Bi0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder are mixed evenly to form the complete formula; Among them, Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 The preparation of O3 powder is as follows: Weigh out Na₂CO₃, Bi₂O₃, and TiO₂ in a molar ratio of 1:1:4.5. 2， Mixtures are combined to form mixture C. Mixture C, zircon, and deionized water are mixed in a mass ratio of 1:5.2:1.2 and then ball-milled, dried, and calcined at 855°C for 3.5 hours to obtain powder D. The powder D was mixed with zircon and deionized water in a mass ratio of 1:5.2:1.2, and then ball-milled, dried, and calcined at 855°C for 3.5 hours to obtain Na. 0.5 Bi 0.5 TiO3 powder; Li2CO3 and Ta2O5 were weighed and mixed in a molar ratio of 1.2:0.8 to form mixture E. Mixture E, zircon, and deionized water were mixed in a mass ratio of 1:5.2:1.2 and then ball-milled, dried, and calcined at 855°C for 3.5 hours to obtain powder F. The powder F was mixed with zircon and deionized water in a mass ratio of 1:5.2:1.2, and then ball-milled, dried and calcined at 855°C for 3.5 hours to obtain LiTaO3 powder. The Na was weighed according to a molar ratio of 94:8. 0.5 Bi 0.5 TiO3 and the LiTaO3 powder are mixed to form mixture G. Take the mixture G, zircon and deionized water, mix them in a mass ratio of 1:5.2:1.2, and then ball mill, dry and calcine at 855℃ for 3.5 hours to obtain powder H; The powder H was mixed with zircon and deionized water in a mass ratio of 1:5.2:1.2, and then ball-milled, dried, and calcined at 855°C for 3.5 hours to obtain Na. 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder.

[0031] The preparation of MgAl2O4 powder is as follows: MgO and Al2O3 were weighed and mixed in a molar ratio of 1:1 to form mixture A. Mixture A, zircon, and deionized water were mixed in a mass ratio of 1:5.2:1.2 and then ball-milled, dried, and calcined at 1250°C for 3.5 hours to obtain powder B. Powder B was mixed with zircon and deionized water in a mass ratio of 1:5.2:1.2, and then ball-milled, dried, and calcined at 1250°C for 3.5 hours to obtain MgAl2O. 4； Step 2: Mix the prepared ingredients with zircon and deionized water at a mass ratio of 1:5.2:1.2, then ball mill and dry them. Grind the dried material through a 160-mesh sieve. The ball milling process described in steps 1 and 2 above lasts for 24 hours, followed by drying at 85-100℃ for 24 hours.

[0032] Step 3: The sieved material is first pressed at 220MPa for 4 minutes, then at 200MPa for 5 minutes, and finally depressurized at 50MPa / min to form a green body by cold isostatic pressing; in a box furnace, the temperature is first raised to 1350℃ in 270 minutes and held for 2.5 hours, then lowered to 520℃ in 170 minutes and finally cooled to room temperature with the furnace to obtain a medium-low temperature dielectric loss frequency sensitive ceramic.

Claims

1. A medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material, characterized in that, The stoichiometric formula is: 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4.

2. A method for preparing a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material as described in claim 1, characterized in that, Includes the following steps: Step 1: According to the stoichiometric formula 0.99Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3-0.01MgAl2O4, weigh Na 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder and MgAl2O4 powder are mixed evenly to form the complete formula; Step 2: According to the mass ratio of 1:(4.8-5.2):(0.8-1.2), the whole batch of materials is mixed with zircon spheres and deionized water, then ball-milled, dried and sieved to form sieved material; Step 3: Press the sieved material described in Step 2 into a green body, and heat the green body in a box furnace to 1250-1350℃ for 250-270 minutes, hold it at that temperature for 1.5-2.5 hours, then cool it down to 480-520℃ for 150-170 minutes, and finally cool it to room temperature with the furnace to obtain a medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material.

3. The method for preparing the medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material according to claim 2, characterized in that, Na in step 1 0.465 Li 0.07 Bi 0.465 Ta 0.07 Ti 0.93 O3 powder consists of Na2CO3, Bi2O3, and TiO2. 2、 The product was obtained by ball milling and drying of Li2CO3 and Ta2O5.

4. The method for preparing the medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material according to claim 2, characterized in that, The MgAl2O4 powder in step 1 is obtained through the following steps: MgO and Al2O3 are weighed and mixed in a molar ratio of 1:1 to form mixture A. Mixture A, zircon and deionized water are mixed in a mass ratio of 1:(4.8-5.2):(0.8-1.2). After mixing, the mixture is ball-milled, dried and calcined at 1150-1250℃ for 3-4 hours to obtain powder B. Powder B was mixed with zircon and deionized water at a mass ratio of 1:(4.8-5.2):(0.8-1.2), and then ball-milled, dried, and calcined at 1150-1250℃ for 3-4 hours to obtain MgAl2O4.

5. The method for preparing medium- and low-temperature dielectric loss frequency-sensitive NBT-based ceramic materials according to claim 2, 3, or 4, characterized in that, The ball milling time is 12-24 hours, and the ball is dried at 85-100℃ for 24 hours.

6. The method for preparing the medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material according to claim 2, characterized in that, The sieve used in step 2 has a mesh size of 140-160.

7. The method for preparing the medium-low temperature dielectric loss frequency-sensitive NBT-based ceramic material according to claim 2, characterized in that, The pressing process in step 3 specifically involves holding the pressure at 180-220 MPa for 2-4 minutes, then holding the pressure at 170-200 MPa for 4-6 minutes, and finally releasing the pressure at 30-50 MPa / min to form a blank through cold isostatic pressing.

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