X7R type MLCC anti-aging ceramic dielectric material and preparation method thereof

Abstract

The application relates to the technical field of ceramic compositions, and discloses an X7R type MLCC anti-aging ceramic dielectric material and a preparation method thereof, which comprises barium titanate, magnesium oxide, lutetium oxide, manganese dioxide and glass frit; wherein magnesium ions and lutetium ions occupy titanium positions on the surface layer of the barium titanate crystal lattice and combine with oxygen vacancies to generate ternary composite defect clusters; the ternary composite defect clusters are locally distributed in the shell layer region of the barium titanate crystal grain and are used for improving the long-range electric migration activation energy of the oxygen vacancies; through the construction of an ion and electron double shielding network, the directional migration of the oxygen vacancies under high-temperature direct current bias is inhibited, the contradiction between the conventional anti-aging means and the dielectric constant maintenance is solved, the high dielectric activity of the polarization area of the barium titanate is ensured, the high-temperature insulation reliability of the ceramic dielectric material is enhanced, and the capacitance aging process is delayed.

Description

Technical Field

[0001] This invention relates to an X7R type MLCC anti-aging ceramic dielectric material and its preparation method, belonging to the field of ceramic composition technology. Background Technology

[0002] Currently, multilayer ceramic capacitors are key components of electronic systems, and the performance of their dielectric materials directly determines the reliability of the components. In industrial production, barium titanate is often used as the main crystalline phase, and rare earth elements are added to form a core-shell structure with ferroelectric active centers and paraelectric shells, thereby meeting the temperature characteristics requirements of X7R. As the size of the components shrinks and the layer thickness decreases, the DC bias field intensity that a single layer of dielectric can withstand increases significantly. Under the coupling effect of high temperature and strong electric field, oxygen vacancies generated inside the barium titanate lattice undergo long-range electromigration. These defect sites accumulate at grain boundaries or electrode interfaces, leading to distortion of the built-in electric field, causing a decrease in the logarithm of the capacitance value and deterioration of the insulation resistance, resulting in severe capacitor aging.

[0003] Conventional methods typically rely on increasing the acceptor ion doping concentration to compensate for oxygen vacancies. However, due to the thermodynamic random diffusion laws of solid-state reactions, acceptor ions are randomly distributed within the crystal lattice, resulting in limited pinning efficiency. To achieve anti-aging targets, excessive acceptor components are often introduced. This approach easily disrupts the stability of the core-shell structure, induces abnormal grain growth, and dilutes the dielectric activity of the main crystalline phase. This creates a difficult-to-reconcile technical contradiction between anti-aging reliability and high dielectric constant. The industry has attempted to optimize dielectric stability through multi-component modification, for example, as described in publication CN12. Chinese invention patent application 1044893A discloses a ceramic dielectric material, its preparation method, and its application. It utilizes the stress coupling effect generated by the solid solution of calcium zirconate and barium titanate to broaden the phase transition temperature range and improve the capacity temperature coefficient. However, the modification logic depends on the disordered random substitution of ions. Under high-temperature DC strong electric field conditions, there is a lack of potential well pinning for the migration path of oxygen vacancies. Defect sites are still prone to long-range migration and aggregation, making it difficult to block the aging path from a kinetic perspective. The global component solid solution dilutes the polarization activity of the main crystal phase, resulting in a technical contradiction between anti-aging reliability and high dielectric constant.

[0004] Therefore, the technical problem to be solved by this invention is how to construct a stable oxygen vacancy trapping network by controlling the surface defect configuration while maintaining dielectric properties, thereby physically blocking the aging path. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: An X7R type MLCC anti-aging ceramic dielectric material, comprising the following components by weight: Barium titanate: 100 parts; Magnesium oxide: 0.45 to 1.25 parts; Lutene oxide: 0.35 to 1.85 parts; Manganese dioxide: 0.05 to 0.25 parts; Glass frit: 0.85 to 2.45 parts; In the evolution of the sintered surface layer of ceramic dielectric materials, magnesium ions and lutetium ions occupy the titanium sites of the barium titanate lattice surface layer and combine with the oxygen vacancies of the barium titanate lattice surface layer through Coulomb attraction to generate ternary composite defect clusters. Ternary composite defect clusters enable the long-range electromigration activation energy of oxygen vacancies inside ceramic dielectric materials to be no less than 1.60 eV. The ternary composite defect clusters are localized in the shell region of barium titanate grains. They pin oxygen vacancies by generating lattice distortion potential wells, thereby restricting the directional migration path of oxygen vacancies under DC bias and 125°C conditions. In the phase construction of ceramic dielectric materials, the glass frit is in a glass phase state that wets the surface of barium titanate grains, which is used to carry the diffusion mass transfer of magnesium ions and lutetium ions, and to make the ternary composite defect clusters have a predetermined distribution density in the shell region of barium titanate grains. Manganese ions in manganese dioxide are distributed in a variable valence state at the grain boundary layer of the ceramic dielectric material, forming electron traps to capture free electrons. These traps, together with ternary composite defect clusters, construct an ion-electron dual shielding network. This network is used to protect the ceramic dielectric material at 125℃ and... The absolute value of the capacitance change rate after 2000 hours of DC electric field application is limited to within 5.5%.

[0006] Preferably, the ceramic dielectric material has a main crystalline phase, a grain boundary layer, and a core-shell structure layer encapsulating the main crystalline phase; wherein, the ternary composite defect cluster Distributed within the core-shell structure layer, with a thickness ranging from 25.6 to 45.8 nm; the main crystalline phase is a tetragonal barium titanate structure, used to maintain dielectric activity at 125 °C, in order to cooperate with the core-shell structure layer to ensure that the temperature capacitance change rate of the ceramic dielectric material meets the X7R standard in the range of -55 °C to 125 °C; the core-shell structure layer interrupts the migration kinetic path of oxygen vacancies inside the main crystalline phase through the local electric field gradient generated by the ternary composite defect cluster.

[0007] Preferably, the variable-valence manganese ions distributed in the grain boundary layer reduce space charge polarization by capturing space charge under a strong electric field, and together with the ternary composite defect clusters distributed in the core-shell structure layer, they construct an ion-electron dual shielding network. The ion-electron dual shielding network maintains the insulation reliability of the ceramic dielectric material under high temperature DC bias by synergistically restricting electrons and ions.

[0008] Preferably, the molar ratio of magnesium oxide to manganese dioxide is 3.5:1 to 8.2:1; within the molar ratio range, the ceramic dielectric material maintains the lattice electroneutrality during the reducing atmosphere sintering process, thereby limiting the solid solution depth of manganese dioxide into the core region of the barium titanate lattice to within the thickness of the core-shell structure layer.

[0009] Preferably, the glass frit is a Ba-Ca-Si-B series low-melting-point glass; the glass frit exhibits a low-viscosity glass phase that wets the surface of barium titanate grains within the sintering range of 950 to 1150°C, which is used to assist magnesium ions and lutetium ions in directional rearrangement on the surface of barium titanate grains.

[0010] Preferably, the average grain size of the ceramic dielectric material is between 0.15 and 0.28. The lattice distortion field generated by the ternary composite defect cluster is used to apply pinning force to the grain boundary movement, so as to suppress the abnormal growth of barium titanate grains during sintering and make the room temperature dielectric constant of the ceramic dielectric material not lower than 3200.

[0011] Preferably, the effective ionic radius of lutetium ions is smaller than that of magnesium ions, forming a ternary composite defect cluster. binding energy The following rules must be met: ,in, The binding energy of the composite defect cluster, and This refers to the effective charge of opposite-charged defects within a composite defect cluster. denoted as the local dielectric constant, and r as the equilibrium spacing between defects; lutetium ions enhance the thermal stability of the ternary composite defect cluster to oxygen vacancies by reducing the equilibrium spacing r.

[0012] Preferably, the ceramic dielectric material is at 125°C and After being continuously subjected to a DC electric field for 2000 hours, the leakage current growth rate caused by internal oxygen vacancy migration was less than 1.5. Lutene oxide is composed of lutetium oxide with an ionic radius of 0.085 to 0.095 nm, which is used to increase the solid solubility of lutetium ions on the surface of barium titanate lattice.

[0013] Preferably, the method includes the following steps: Step S1, mixing barium titanate, magnesium oxide, lutetium oxide, manganese dioxide and glass frit according to the specified ratio to obtain a premix; Step S2, sintering the premix, specifically including: Step S21, raising the temperature to 950 to 1150°C to generate glass phase diffusion channels through the glass frit; Step S22, maintaining the temperature within a preset sintering temperature range for 1.5 to 3.5 hours to induce magnesium ions and lutetium ions to diffuse to the surface of the barium titanate lattice, thereby generating ternary composite defect clusters in situ.

[0014] A method for developing an X7R type MLCC anti-aging ceramic dielectric material includes the following steps: Provide 100 parts of barium titanate; 0.45 to 1.25 parts of magnesium oxide; 0.35 to 1.85 parts of lutetium oxide; 0.05 to 0.25 parts of manganese dioxide; and 0.85 to 2.45 parts of glass frit, and mix them evenly to obtain a premix. The premixed material is sintered in a reducing atmosphere at a temperature of 950 to 1150°C for a holding time of 1.5 to 3.5 hours. During sintering, the glass phase diffusion channels formed by the glass charge wetting the surface of barium titanate grains induce magnesium and lutetium ions to diffuse to the titanium sites on the surface of the barium titanate lattice and undergo lattice solid solution. This allows magnesium and lutetium ions to combine with oxygen vacancies on the surface of the barium titanate lattice, generating ternary composite defect clusters in situ. .

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In X7R type MLCC anti-aging ceramic dielectric material, through the synergistic effect of medium-radius rare earth elements, small-radius rare earth elements and transition metal acceptor systems under a specific temperature and pressure field, a targeted defect anchoring effect is generated inside the material. Utilizing the specific rheological properties of the liquid phase sintering aid when the cooling stage is in the range of 1050 to 1100℃, small-radius rare earth ions and magnesium ions migrate directionally to the oxygen vacancy region on the surface of the barium titanate lattice through the liquid phase channel, and assemble in situ to form a composite defect cluster with high binding energy. This composite defect cluster increases the migration activation energy of oxygen vacancies to above 1.6 eV, so that oxygen vacancies are in a deep potential well pinned state under high temperature and high DC bias conditions, inhibiting electromigration behavior from the surface dynamic path, thereby delaying the capacitor aging process of the dielectric material.

[0016] 2. By utilizing the transformation of component distribution from thermodynamic random disorder to local order, the inherent contradiction between anti-aging performance and dielectric activity in conventional technologies is resolved. Since the formation of defect clusters depends on the short-range directional rearrangement of ions rather than large-dose doping of the entire system, while ensuring that oxygen vacancies are effectively pinned, the excessive solid solution of acceptor ions in the main crystal phase is reduced, maintaining the thermodynamic stability of the barium titanate core polarization region. This mechanism avoids abnormal grain growth and initial dielectric constant degradation caused by excessive acceptor doping, enabling the material to maintain high reliability while retaining a high dielectric constant and breakdown field strength.

[0017] 3. By limiting the molar ratio of magnesium ions to manganese ions and matching the atomic-level mass transfer characteristics of the glass phase, an ion-electron dual shielding network is constructed. Under the regulation of a specific micro-reducing atmosphere, manganese ions are localized in the grain boundary region to act as electron traps, capturing free electrons generated under a strong electric field and reducing space charge polarization. Magnesium ions and rare earth ions cooperate to complete the static pinning of oxygen vacancies. This cross-mechanism dynamic linkage enhances the adaptability of the dielectric material to automotive-grade operating conditions, ensuring that the capacitance change rate of the capacitor is controlled within 1.5% after 1000 hours under a high temperature of 125℃ and a strong DC bias, and maintaining the long-term stability of the insulation resistance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the surface defect configuration and dual shielding network principle of the ceramic dielectric material of the present invention; Figure 2 This is a schematic diagram of the evolution path of the anti-aging process and the oxygen vacancy deep potential trap pinning process of the present invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0021] An X7R type MLCC anti-aging ceramic dielectric material, comprising the following components by weight: Barium titanate: 100 parts; Magnesium oxide: 0.45 to 1.25 parts; Lutene oxide: 0.35 to 1.85 parts; Manganese dioxide: 0.05 to 0.25 parts; Glass frit: 0.85 to 2.45 parts; In the evolution of the sintered surface layer of ceramic dielectric materials, magnesium ions and lutetium ions occupy the titanium sites of the barium titanate lattice surface layer and combine with the oxygen vacancies of the barium titanate lattice surface layer through Coulomb attraction to generate ternary composite defect clusters. Ternary composite defect clusters enable the long-range electromigration activation energy of oxygen vacancies inside ceramic dielectric materials to be no less than 1.60 eV. The ternary composite defect clusters are localized in the shell region of barium titanate grains. They pin oxygen vacancies by generating lattice distortion potential wells, thereby restricting the directional migration path of oxygen vacancies under DC bias and 125°C conditions. In the phase construction of ceramic dielectric materials, the glass frit is in a glass phase state that wets the surface of barium titanate grains, which is used to carry the diffusion mass transfer of magnesium ions and lutetium ions, and to make the ternary composite defect clusters have a predetermined distribution density in the shell region of barium titanate grains. Manganese ions in manganese dioxide are distributed in a variable valence state at the grain boundary layer of the ceramic dielectric material, forming electron traps to capture free electrons. These traps, together with ternary composite defect clusters, construct an ion-electron dual shielding network. This network is used to protect the ceramic dielectric material at 125℃ and... The absolute value of the capacitance change rate after 2000 hours of DC electric field application is limited to within 5.5%.

[0022] Preferably, the ceramic dielectric material has a main crystalline phase, a grain boundary layer, and a core-shell structure layer encapsulating the main crystalline phase; wherein, the ternary composite defect cluster Distributed within the core-shell structure layer, with a thickness ranging from 25.6 to 45.8 nm; the main crystalline phase is a tetragonal barium titanate structure, used to maintain dielectric activity at 125 °C, in order to cooperate with the core-shell structure layer to ensure that the temperature capacitance change rate of the ceramic dielectric material meets the X7R standard in the range of -55 °C to 125 °C; the core-shell structure layer interrupts the migration kinetic path of oxygen vacancies inside the main crystalline phase through the local electric field gradient generated by the ternary composite defect cluster.

[0023] Preferably, the variable-valence manganese ions distributed in the grain boundary layer reduce space charge polarization by capturing space charge under a strong electric field, and together with the ternary composite defect clusters distributed in the core-shell structure layer, they construct an ion-electron dual shielding network. The ion-electron dual shielding network maintains the insulation reliability of the ceramic dielectric material under high temperature DC bias by synergistically restricting electrons and ions.

[0024] Preferably, the molar ratio of magnesium oxide to manganese dioxide is 3.5:1 to 8.2:1; within the molar ratio range, the ceramic dielectric material maintains the lattice electroneutrality during the reducing atmosphere sintering process, thereby limiting the solid solution depth of manganese dioxide into the core region of the barium titanate lattice to within the thickness of the core-shell structure layer.

[0025] Preferably, the glass frit is a Ba-Ca-Si-B series low-melting-point glass; the glass frit exhibits a low-viscosity glass phase that wets the surface of barium titanate grains within the sintering range of 950 to 1150°C, which is used to assist magnesium ions and lutetium ions in directional rearrangement on the surface of barium titanate grains.

[0026] Preferably, the average grain size of the ceramic dielectric material is between 0.15 and 0.28. The lattice distortion field generated by the ternary composite defect cluster is used to apply pinning force to the grain boundary movement, so as to suppress the abnormal growth of barium titanate grains during sintering and make the room temperature dielectric constant of the ceramic dielectric material not lower than 3200.

[0027] Preferably, the effective ionic radius of lutetium ions is smaller than that of magnesium ions, forming a ternary composite defect cluster. binding energy The following rules must be met: ,in, The binding energy of the composite defect cluster, and This refers to the effective charge of opposite-charged defects within a composite defect cluster. denoted as the local dielectric constant, and r as the equilibrium spacing between defects; lutetium ions enhance the thermal stability of the ternary composite defect cluster to oxygen vacancies by reducing the equilibrium spacing r.

[0028] Preferably, the ceramic dielectric material is at 125°C and After being continuously subjected to a DC electric field for 2000 hours, the leakage current growth rate caused by internal oxygen vacancy migration was less than 1.5. Lutene oxide is composed of lutetium oxide with an ionic radius of 0.085 to 0.095 nm, which is used to increase the solid solubility of lutetium ions on the surface of barium titanate lattice.

[0029] Preferably, the method includes the following steps: Step S1, mixing barium titanate, magnesium oxide, lutetium oxide, manganese dioxide and glass frit according to the specified ratio to obtain a premix; Step S2, sintering the premix, specifically including: Step S21, raising the temperature to 950 to 1150°C to generate glass phase diffusion channels through the glass frit; Step S22, maintaining the temperature within a preset sintering temperature range for 1.5 to 3.5 hours to induce magnesium ions and lutetium ions to diffuse to the surface of the barium titanate lattice, thereby generating ternary composite defect clusters in situ.

[0030] A method for developing an X7R type MLCC anti-aging ceramic dielectric material includes the following steps: Provide 100 parts of barium titanate; 0.45 to 1.25 parts of magnesium oxide; 0.35 to 1.85 parts of lutetium oxide; 0.05 to 0.25 parts of manganese dioxide; and 0.85 to 2.45 parts of glass frit, and mix them evenly to obtain a premix. The premixed material is sintered in a reducing atmosphere at a temperature of 950 to 1150°C for a holding time of 1.5 to 3.5 hours. During sintering, the glass phase diffusion channels formed by the glass charge wetting the surface of barium titanate grains induce magnesium and lutetium ions to diffuse to the titanium sites on the surface of the barium titanate lattice and undergo lattice solid solution. This allows magnesium and lutetium ions to combine with oxygen vacancies on the surface of the barium titanate lattice, generating ternary composite defect clusters in situ. .

[0031] Example 1: In the deployment scenario of high-reliability electronic systems for new energy vehicle power inverters, multilayer ceramic capacitors need to operate under an ambient temperature of 125℃ and a continuous DC bias of 25V / μm. Due to the reduction of the dielectric layer thickness to below the micrometer level, oxygen vacancies generated within the barium titanate lattice undergo long-range electromigration under the drive of an electric field, accumulating towards grain boundaries, resulting in capacitance aging and insulation resistance degradation. Traditional methods of increasing the concentration of a single acceptor dopant induce abnormal growth of barium titanate grains and dilute the polarization activity of the ferroelectric nuclei, leading to a mutually exclusive problem between a decrease in initial dielectric constant and anti-aging reliability. The technical solution of this invention constructs ions through a specific component ratio under the above conditions. The shielding network is based on 100 parts by weight of barium titanate as the main crystalline phase, and is compounded with 0.45 to 1.25 parts of magnesium oxide, 0.35 to 1.85 parts of lutetium oxide, 0.05 to 0.25 parts of manganese dioxide, and 0.85 to 2.45 parts of Ba-Ca-Si-B glass frit as a flux. The medium-radius rare earth element dysprosium and the small-radius rare earth element lutetium generate differentiated occupancy in the liquid phase mass transfer channel formed by the glass frit. Dysprosium ions preferentially generate a diffuse distribution on the outer shell to suppress grain boundary movement, while lutetium ions directionally occupy the titanium sites on the surface of the barium titanate lattice to generate negative charge centers. The gradient distribution of rare earth ions with different radii provides a lattice framework for the subsequent assembly of composite defect clusters.

[0032] To resolve the conflict between anti-aging properties and maintaining dielectric constant, a specific thermodynamic stagnation procedure is employed during the sintering cooling stage. When the temperature drops to the range of 1050 to 1100°C, this temperature range is maintained for 150 to 240 minutes while adjusting the oxygen partial pressure to [missing value]. to In a slightly reduced state, the glass frit is at this time... to The rheological viscosity window allows magnesium and lutetium ions to migrate short-range directionally to the oxygen vacancy regions on the surface of the barium titanate lattice via the glass phase liquid bridge, resulting in the in-situ formation of ternary composite defect clusters. The Coulomb gravitational field and lattice distortion potential well generated by the defect cluster pin the oxygen vacancies, raising the long-range electromigration activation energy of the oxygen vacancies to no less than 1.60 eV. Thus, without increasing the absolute concentration of acceptor doping, the oxygen vacancies are brought into a deep-level pinned state by changing the energy state of the defect structure, thereby cutting off the aging path at the kinetic level.

[0033] By utilizing the electron traps generated by manganese ions of varying valence in manganese dioxide at the grain boundary layer, a dual ion-electron shielding network is constructed together with the ternary composite defect clusters within the shell. Based on the chemical space charge confinement theory of solid defects, the transition metal ions of varying valence distributed in the grain boundary region undergo valence state transformation according to their own redox potential to capture free electrons in the conduction band. The acceptor-donor composite defect clusters located in the perovskite lattice shell rely on local lattice distortion to generate electrostatic attraction to fix oxygen vacancies. Based on the spatially independent and isolated physical mechanism of electron ionization and ion migration, the release of manganese ions of varying valence from manganese dioxide is determined. Localization at the grain boundary layer forms an electron trap, which, together with the ternary composite defect cluster, constructs a structural entity consisting of an alternating grain boundary electron depletion layer and a shell ion pinning region. This structural entity is an ion-electron dual shielding network, which controls the absolute value of the capacitance change rate of the ceramic dielectric material after 2000 hours of exposure to a DC electric field of 25V / μm at 125℃ to within 5.5% and the leakage current growth rate to less than 1.5. This surface material entity, shaped by a specific process, decouples the dielectric activity and high-temperature reliability of the material, and solves the aging problem of ferroelectric ceramics by controlling the defect configuration rather than increasing the component concentration.

[0034] Example 2: In a reliability verification platform simulating the high-temperature and high-pressure operating environment of a new energy vehicle inverter, the aging characteristics of ceramic dielectric materials under continuous electric field load were quantitatively evaluated. The test platform included a vacuum atmosphere sintering furnace with independent temperature control for each zone and a matching high-temperature DC leakage current testing system. The oxygen partial pressure control accuracy of the sintering furnace was maintained at a certain level using a zirconia sensor and a high-precision flow meter. to Within the specified range, the current measurement resolution of the test system in a constant temperature oil bath environment at 125℃ is no less than 1pA. The experiment uses barium titanate powder with an average particle size of 150nm and a purity of no less than 99.9% as the raw material. During the ball milling process, environmental vibration disturbance with a signal-to-noise ratio of 20dB is simulated to verify the stability of the component distribution. The sampling period is set to 1s. This value setting takes into account the balance between the real-time data acquisition and the system processing load. Under the condition that the densification rate of the ceramic green body is within this preset range, the sampling theorem requirements of the liquid phase sintering kinetic model of barium titanate-based ceramics are met.

[0035] The ceramic dielectric material was prepared by precise powder formulation and ball milling. 100 parts by weight of barium titanate were selected, and 0.85 parts by weight of magnesium oxide, 1.15 parts by weight of lutetium oxide, 0.15 parts by weight of manganese dioxide, and 1.65 parts by weight of Ba-Ca-Si-B glass frit were added sequentially. The mixture was stirred in deionized water with a dispersant at 350 rpm for 24 hours using a planetary ball mill. The resulting slurry was then cast and debinded before entering the sintering process. The furnace temperature was increased from room temperature to 1250℃ at a rate of 3℃ / min and held for 2 hours. The temperature was then decreased to 1080℃ and maintained at this thermodynamic stagnation state for 180 minutes, during which the oxygen partial pressure was kept constant. This process parameter induces controlled diffusion of magnesium and lutetium ions to the grain surface. Multiple control groups were subjected to 2000 hours at 125℃ and a 25V / μm DC electric field. The sample group of this invention showed an absolute value of 5.2% in capacitance change and a leakage current increase factor of 1.25. The first control group, with lutetium oxide removed and other conditions unchanged, could not construct a defect pinning potential well due to the lack of negatively charged centers formed by lutetium ions at titanium sites, resulting in an absolute value of 14.2% in capacitance change. The second control group used 0.35 parts by weight of magnesium oxide, which was below the lower limit of the set range. Data showed that the acceptor doping concentration was insufficient to neutralize the reduction. The oxygen vacancies generated by the atmosphere have a long-range electromigration activation energy of 1.25 eV. The insulation resistance decreased significantly in the middle of the test. The third control group selected magnesium oxide with an addition of 1.45 parts by weight, which is higher than the upper limit of the set range. The experiment observed that the average grain size of the ceramic increased from 0.22 μm in the sample group of this invention to 0.48 μm, and the room temperature dielectric constant decreased from 3350 to 2350. Excessive magnesium ion solid solution caused the barium titanate lattice distortion to exceed the critical value, destroying the polarization stability of the ferroelectric core. The experimental data confirmed the logical connection between the ceramic dielectric material preparation process and the thermodynamic stagnation process, and the in-situ induction of the core-shell structure interface. A ternary composite defect cluster, in which... Magnesium ions occupying titanium sites, For oxygen vacancies, The lutetium ions occupying the titanium sites enable the ceramic dielectric material to exhibit a stable anti-aging response under high-temperature electric field conditions. The concentration range of magnesium oxide, lutetium oxide and manganese dioxide constitutes a working window that balances high dielectric activity and anti-potential migration performance. The experimental results confirm the effectiveness of the ion-electron dual shielding network in inhibiting the directional migration of oxygen vacancies.

[0036] Example 3: In the large-scale production of ultra-thin dielectric layer multilayer ceramic capacitors, when the dielectric layer thickness is less than 0.6 μm, fluctuations in the sintering temperature field cause changes in the viscosity of the Ba-Ca-Si-B glass frit. to Fluctuations within a certain range interfere with the migration flux of magnesium and lutetium ions to the surface of the barium titanate lattice, leading to uneven distribution of defect clusters and the risk of insulation breakdown. The preparation process of ceramic dielectric materials is controlled by establishing an interface evolution kinetic model. By measuring the temperature and viscosity characteristic curves of the glass frit in the range of 1050 to 1100℃, the slope of the liquid phase viscosity η as a function of temperature T within this temperature range is determined. During the thermodynamic stagnation stage, an adaptive oxygen partial pressure adjustment method is adopted. When a furnace temperature disturbance of ±2℃ is detected, the control unit synchronously and inversely adjusts the oxygen partial pressure according to the influence of viscosity change on the diffusion coefficient. In practice, the synchronous reverse adjustment of oxygen partial pressure is achieved through a compensation lag algorithm preset in the control unit to eliminate the time scale difference between overall gas field fluctuations and surface interface diffusion. Specifically, since the physical replacement cycle of the gas atmosphere in the furnace is longer than the atomic-scale lattice rearrangement time, the control unit calculates the offset of the atomic diffusion rate based on the current viscosity-temperature sensitivity factor G. By increasing the instantaneous pulse width of the inlet flow proportional valve, a pressure advance compensation zone 1.5 to 2.0 times higher than the target partial pressure is constructed at the far end of the gas path. The pressure gradient is used to accelerate the gas penetration rate to the grain surface, thereby compensating for the diffusion kinetic lag caused by the overall thermal field inertia and maintaining the effective diffusion rate of magnesium ions and lutetium ions in the liquid bridge at a certain level. to Within the target range, transmission electron microscopy revealed that the thickness δ of the interfacial transition zone formed on the surface of the sintered ceramic sample remained stable in the range of 15 to 25 nm.

[0037] To characterize the correlation between interface structure and performance, the concentration distribution curves of magnesium and lutetium were extracted by micro-area energy dispersive spectroscopy (EDS). The concentration distribution of ternary composite defect clusters within the interface transition region of thickness δ was then calculated. The localized density is not less than The formula for calculating the activation energy of long-range electromigration of oxygen vacancies under this physical state is as follows: The interface structure sensitivity coefficient α was determined based on the fitting of complex impedance spectral data of samples with different core-shell thicknesses in the preliminary experiment, reflecting the contribution weight of the defect cluster electric field gradient to the migration potential well. In the actual calibration process, high-temperature dielectric spectroscopy analysis was performed on ceramic standard samples with gradient interface thicknesses, and the linear slope of the activation energy changing with the logarithm of the thickness was measured to be 0.25. Therefore, the value of this coefficient was locked, referencing the interface thickness benchmark. The value is set to 10 nm, which is based on the physical width of the typical space charge layer on the surface of the barium titanate lattice. It represents the critical diffusion boundary when oxygen vacancies are not affected by defect cluster pinning, and is used as a unified benchmark for calculating the migration energy increment. It is the activation energy for long-range electromigration of oxygen vacancies. δ represents the intrinsic oxygen vacancy migration energy of the barium titanate matrix; α is the interface structure sensitivity coefficient, with a value of 0.25; δ is the measured thickness of the interface transition region. Using 10 nm as the reference interface thickness benchmark, the activation energy for oxygen vacancy migration was determined to be 1.62 eV when the interface transition region thickness was 20 nm, according to the formula. This value is negatively correlated with the high-temperature DC aging rate. Through viscosity compensation and interface thickness calibration procedures, the ceramic dielectric material exhibited stable process consistency in response to furnace temperature uniformity deviations. The capacitance change rate fluctuation variance of multiple batches of samples was less than 0.05 and the insulation resistance degradation rate decreased by 85%. The quantitative control of interface thickness generated a deep-level pinning effect, which physically blocked the migration of oxygen vacancy in the core-shell structure, thus reproducing the anti-aging performance.

[0038] Example 4: In a process initialization scenario addressing batch fluctuations in raw materials, control parameters for the thermodynamic stagnation procedure are determined using rheological benchmark calibration to address differences in the surface energy of barium titanate powder and deviations in the melting characteristics of Ba-Ca-Si-B glass frit. The glass frit is placed in a platinum crucible and heated to 1200°C to maintain a molten state. The dynamic response of viscosity as temperature decreases is monitored using a rotor viscometer, and the viscosity at different temperature ranges is recorded. to The corresponding temperature coordinates within the range, and the viscosity of this batch of glass material reaching... Temperature point at time As the setpoint for the constant temperature control of the cooling section of the sintering furnace, among which, For the characteristic temperature point, the first-order partial derivative of viscosity with respect to temperature is calculated. To determine the correction coefficients for the oxygen partial pressure regulation algorithm, where G is the viscosity-temperature sensitivity factor and η is the dynamic viscosity.

[0039] When the aging of the sintering furnace heating components causes static temperature drift, the control unit corrects the real-time oxygen partial pressure command based on the rheological relationship established during the calibration phase. Atmospheric data is collected using an oxygen partial pressure monitoring sensor within the furnace cavity, and the system detects temperature deviations from the set value. At that time, the oxygen partial pressure is automatically adjusted based on the functional relationship between the partial derivative G and the interfacial diffusion rate. The feed rate is determined based on the equilibrium relationship between defect concentration and oxygen partial pressure exponent in the law of mass action. The system control unit acquires real-time furnace temperature data, calculates the temperature deviation, substitutes it into the oxygen partial pressure control formula, and outputs real-time commands. The specific calculation relationship satisfies the following formula: ,in, This indicates that the control unit outputs the target oxygen partial pressure command value to the intake flow proportional valve. This represents the system calibration reference oxygen partial pressure constant before testing. Under this operating condition, the fixed input is... atm; k represents the dimensionless process compensation coefficient, which matches the hysteresis response characteristics caused by the thermal field volume of the sintering furnace and the gas supply pipe diameter, and is set to 0.15 to 0.25 according to the pre-stored reference table; G represents the viscosity-temperature sensitivity factor determined by the aforementioned calibration process; and These represent the real-time furnace temperature measured by thermocouples and the preset characteristic temperature point parameters, respectively. The system control unit refreshes the output command by cyclically calculating the formula at a control frequency of 10Hz, drives the proportional valve to adjust the air intake flow, keeps the concentration gradient of magnesium ions and lutetium ions in the liquid phase channel constant, locks the thickness δ of the interface transition zone at a depth of 20nm, and keeps the median deviation of the insulation resistance of multiple batches of finished ceramic materials within 2.5% while maintaining a consistent aging rate.

[0040] Example 5: In the initial calibration of the sintering process for X7R type MLCC ceramic dielectric materials in an automated production line, the addition ratio of Ba-Ca-Si-B glass frit was determined using the measured specific surface area of ​​barium titanate powder to address the problem of uneven liquid phase wetting caused by differences in powder activity; for BET specific surface areas ranging from 5.2 to... The barium titanate raw material in the specified range has a glass frit weight percentage of 1.45 parts to ensure that the liquid film thickness on the grain surface is maintained in the range of 2.5 to 4.0 nm at the peak sintering temperature of 1250 °C. This glass frit consists of BaO, CaO, and... in a molar ratio of 30:10:45:15. and It was obtained by melting at 1350℃ and quenching and ball milling to a median diameter of 0.45μm, so that the liquid phase viscosity follows the evolution trajectory output by the aforementioned kinetic model when cooled to the thermodynamic stagnation range.

[0041] When the system encounters unsteady-state deviations caused by oxygen partial pressure sensor drift or atmospheric flow fluctuations during operation, the control unit employs an online compensation program based on the residual carbon content of the ceramic green body to eliminate the interference of process condition changes on the assembly efficiency of defect clusters; residual carbon content Real-time acquisition is achieved by configuring an infrared carbon dioxide analyzer at the exhaust end of the sintering furnace. Its working logic is as follows: During the binder removal stage (300℃ to 600℃), the concentration integral of carbon dioxide in the exhaust stream is continuously monitored, and combined with the green body loading and air intake flow rate for real-time mass balance calculation. This allows the calculation of the total residual carbon remaining inside the green body. This value is converted into an electrical signal by the control unit and used as a compensation reference for setting the initial oxygen partial pressure in the subsequent sintering section. If an increase in carbon content is detected, the proportion of reducing gas is automatically increased to eliminate the influence of residual carbon on the interfacial solid solution kinetics. The residual carbon concentration is then used to... As an input parameter for regulating the atmosphere's reducing ability, if the monitored... If the oxygen partial pressure deviates from the 150ppm reference value, the control unit will automatically adjust the set value. Its compensation operator satisfies a linear correspondence. Where ΔP is the oxygen partial pressure compensation amount, and β is the atmosphere compensation factor, with a value of [value missing]. atm / ppm The residual carbon concentration ensures that the migration potential energy of magnesium and lutetium ions to titanium sites is not affected by atmospheric fluctuations, thereby activating the long-range electromigration of oxygen vacancies within the finished ceramic material. It remains stable above 1.60 eV.

[0042] In the reliability optimization scenario for high-capacitance multilayer ceramic capacitors used in high-power automotive inverters, the molar ratio of magnesium oxide to manganese dioxide is precisely adjusted to balance the charge neutrality compensation and electron trapping cross-sectional density within the crystal lattice, thus addressing the risk of insulation resistance drop caused by manganese ion valence state fluctuations during reducing atmosphere sintering. When the molar ratio of magnesium oxide to manganese dioxide is in the range of 3.5:1 to 8.2:1, the acceptor defect concentration and the spatial distribution of manganese ions in varying valence states within the system reach thermodynamic equilibrium. Through the charge compensation effect generated by magnesium ions at titanium sites, the solid solution depth of manganese dioxide into the core region of the barium titanate lattice is increased. To limit the thickness of the core-shell structure layer and prevent excessive manganese ions from entering the ferroelectric active region, which would increase dielectric loss, the molar ratio is chosen based on a nonlinear coupling analysis of manganese ion diffusion flux and magnesium ion vacancy pinning energy. A performance evaluation procedure for the ion-electron dual shielding network based on the molar ratio is executed, considering the leakage current evolution characteristics under different DC bias gradients. If the molar ratio is lower than... If the concentration of host ions is insufficient to completely neutralize the free electrons generated by oxygen vacancies, the leakage current density of the ceramic dielectric under high field strength will increase by orders of magnitude. If the molar ratio is higher than 8.2:1, the excess magnesium oxide will accumulate at the grain boundaries and induce secondary phase precipitation, causing the average grain size to deviate from the optimized range of 0.15 to 0.28 μm, thereby reducing the room temperature dielectric constant of the material to below 3200. By setting the molar ratio to the example midpoint of 5.6:1, combined with the aforementioned blocking effect of ternary composite defect clusters on oxygen vacancy migration, the insulation resistance of the finished material after 2000h aging test was increased by 1.2 orders of magnitude, confirming the necessity of a specific molar ratio for constructing an ion-electron dual shielding network.

[0043] Example 6: For the specific working conditions of the main sintering range of 950 to 1150℃ as defined in this invention, a low-temperature co-firing (LTCC) process without experiencing a high-temperature section above 1200℃ is provided. 100 parts by weight of highly active barium titanate powder with an initial specific surface area of ​​15.5 m² / g and an average particle size of 90 nm are selected, mixed with 0.85 parts by weight of magnesium oxide, 1.15 parts by weight of lutetium oxide, and 0.15 parts by weight of manganese dioxide. The composition ratio of Ba-Ca-Si-B glass frit is adjusted to make the softening point 780℃. The amount of glass frit added is set to the upper limit of 2.45 parts by weight. The prepared green body is placed in a continuous tunnel kiln, and the initial ambient oxygen partial pressure measurement reading is confirmed to fluctuate within ±5%.

[0044] The sintering process was initiated, and the furnace heating components were controlled to reach a constant main sintering temperature of 1120℃ at a heating rate of 5℃ / min. This temperature was maintained for 1.5 hours. Within this main holding temperature range, excess low-softening-point glass material was transformed into a liquid phase, fully encapsulating highly active barium titanate nanocrystals. This reduced the densification sintering temperature of the system and provided a broadened glass phase diffusion channel. The physical mass transfer rate of the channel met the specific activation energy requirements, driving magnesium ions and lutetium ions to penetrate into the titanium sites of the barium titanate surface and combine with oxygen vacancies under a constant temperature of 1120℃. Simultaneously, matrix densification and in-situ assembly of ternary composite defect clusters were completed. After cooling and removal from the furnace, the relative theoretical density of the ceramic sample was measured to be 97.5% using the Archimedes water displacement method. In subsequent aging tests at 125℃ and 25V / μm bias voltage, the leakage current change curves showed characteristics consistent with those of the sample group in Example 1. The procedure confirmed that the technical solution simultaneously achieved ceramic phase construction and defect assembly engineering implementation within a single temperature range of 950 to 1150℃.

[0045] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An X7R type MLCC anti-aging ceramic dielectric material, characterized in that, Based on parts by weight, it comprises the following components: Barium titanate: 100 parts; Magnesium oxide: 0.45 to 1.25 parts; Lutene oxide: 0.35 to 1.85 parts; Manganese dioxide: 0.05 to 0.25 parts; Glass frit: 0.85 to 2.45 parts; In the evolution of the sintered surface layer of ceramic dielectric materials, magnesium ions and lutetium ions occupy the titanium sites of the barium titanate lattice surface layer and combine with the oxygen vacancies of the barium titanate lattice surface layer through Coulomb attraction to generate ternary composite defect clusters. Ternary composite defect clusters enable the long-range electromigration activation energy of oxygen vacancies inside ceramic dielectric materials to be no less than 1.60 eV. The ternary composite defect clusters are localized in the shell region of barium titanate grains. They pin oxygen vacancies by generating lattice distortion potential wells, thereby restricting the directional migration path of oxygen vacancies under DC bias and 125°C conditions. In the phase construction of ceramic dielectric materials, the glass frit is in a glass phase state that wets the surface of barium titanate grains, which is used to carry the diffusion mass transfer of magnesium ions and lutetium ions, and to make the ternary composite defect clusters have a predetermined distribution density in the shell region of barium titanate grains. Manganese ions in manganese dioxide are distributed in a variable valence state at the grain boundary layer of the ceramic dielectric material, forming electron traps to capture free electrons. These traps, together with ternary composite defect clusters, construct an ion-electron dual shielding network. This network is used to protect the ceramic dielectric material at 125℃ and... The absolute value of the capacitance change rate after 2000 hours of DC electric field application is limited to within 5.5%; Among them, the molar ratio of magnesium oxide to manganese dioxide is 3.5:1 to 8.2:1; within the molar ratio range, the ceramic dielectric material maintains the lattice electroneutrality during the sintering process in a reducing atmosphere, thereby limiting the solid solution depth of manganese dioxide into the core region of the barium titanate lattice to within the thickness of the core-shell structure layer. The glass frit is a Ba-Ca-Si-B series low-melting-point glass. During the sintering range of 950 to 1150℃, the glass frit exhibits a low-viscosity glass phase that wets the surface of barium titanate grains, which is used to assist magnesium ions and lutetium ions in directional rearrangement on the surface of barium titanate grains.

2. The X7R type MLCC anti-aging ceramic dielectric material according to claim 1, characterized in that, Ceramic dielectric materials possess a main crystalline phase, grain boundary layers, and a core-shell structure layer encapsulating the main crystalline phase; among them, ternary composite defect clusters... Distributed within the core-shell structure layer, with a thickness ranging from 25.6 to 45.8 nm; the main crystalline phase is a tetragonal barium titanate structure, used to maintain dielectric activity at 125 °C, in order to cooperate with the core-shell structure layer to ensure that the temperature capacitance change rate of the ceramic dielectric material meets the X7R standard in the range of -55 °C to 125 °C; the core-shell structure layer interrupts the migration kinetic path of oxygen vacancies inside the main crystalline phase through the local electric field gradient generated by the ternary composite defect cluster.

3. The X7R type MLCC anti-aging ceramic dielectric material according to claim 2, characterized in that, Manganese ions in variable valence state distributed in the grain boundary layer reduce space charge polarization by capturing space charge under a strong electric field, and together with ternary composite defect clusters distributed in the core-shell structure layer, they construct an ion-electron dual shielding network. The ion-electron dual shielding network maintains the insulation reliability of ceramic dielectric materials under high temperature DC bias by synergistically restricting electrons and ions.

4. The X7R type MLCC anti-aging ceramic dielectric material according to claim 1, characterized in that, The average grain size of the ceramic dielectric material is 0.15 to 0.28 mm. The lattice distortion field generated by the ternary composite defect cluster is used to apply pinning force to the grain boundary movement, so as to suppress the abnormal growth of barium titanate grains during sintering and make the room temperature dielectric constant of the ceramic dielectric material not lower than 3200.

5. The X7R type MLCC anti-aging ceramic dielectric material according to claim 1, characterized in that, The effective ionic radius of lutetium ions is smaller than that of magnesium ions, resulting in a ternary composite defect cluster. binding energy The following rules must be met: ,in, The binding energy of the composite defect cluster, and ϵ is the effective charge of the opposite-charged defects within the composite defect cluster, r is the local dielectric constant, and lutetium ions enhance the thermal stability of the ternary composite defect cluster to oxygen vacancies by reducing the equilibrium spacing r.

6. The X7R type MLCC anti-aging ceramic dielectric material according to claim 1, characterized in that, Ceramic dielectric materials at 125℃ and After being continuously subjected to a DC electric field for 2000 hours, the leakage current growth rate caused by internal oxygen vacancy migration was less than 1.

5. Lutene oxide is composed of lutetium oxide with an ionic radius of 0.085 to 0.095 nm, which is used to increase the solid solubility of lutetium ions on the surface of barium titanate lattice.

7. The preparation method of an X7R type MLCC anti-aging ceramic dielectric material according to claim 1, characterized in that, Includes the following steps: Step S1: Barium titanate, magnesium oxide, lutetium oxide, manganese dioxide and glass frit are mixed in proportion to obtain a premix; Step S2: The premix is ​​sintered. Step S2 specifically includes: Step S21: The temperature is raised to 950 to 1150°C to generate glass phase diffusion channels through the glass frit. In step S22, the temperature is maintained within a preset sintering temperature range for 1.5 to 3.5 hours to induce magnesium and lutetium ions to diffuse into the surface of the barium titanate lattice, thereby generating ternary composite defect clusters in situ.

8. A method for preparing an X7R type MLCC anti-aging ceramic dielectric material, used to achieve the X7R type MLCC anti-aging ceramic dielectric material as described in claim 1, characterized in that, Includes the following steps: Provide barium titanate: 100 parts; magnesium oxide: 0.45 to 1.25 parts; lutetium oxide: 0.35 to 1.85 parts; Manganese dioxide: 0.05 to 0.25 parts; glass frit: 0.85 to 2.45 parts, and mixed evenly to obtain a premix; The premixed material is sintered in a reducing atmosphere at a temperature of 950 to 1150°C for a holding time of 1.5 to 3.5 hours. During sintering, the glass phase diffusion channels formed by the glass charge wetting the surface of barium titanate grains induce magnesium and lutetium ions to diffuse to the titanium sites on the surface of the barium titanate lattice and undergo lattice solid solution. This allows magnesium and lutetium ions to combine with oxygen vacancies on the surface of the barium titanate lattice, generating ternary composite defect clusters in situ. .

Images