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CN-122010553-A - Boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC and preparation method thereof

CN122010553ACN 122010553 ACN122010553 ACN 122010553ACN-122010553-A

Abstract

The invention relates to the technical field of electronic ceramic media, in particular to boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC and a preparation method thereof. The invention discloses boron-nitrogen co-doped barium titanate ceramics for X5R type MLCC and a preparation method thereof, wherein the preparation method comprises the steps of firstly synthesizing calcium-zirconium co-doped barium titanate nanocrystalline powder through hydrothermal co-precipitation; and then uniformly coating a reaction precursor containing boron, nitrogen and fluorine elements on the surface of the powder by adopting a liquid-phase mechanochemical method, and obtaining the composite powder by spray drying. Mixing the composite powder with self-made low-temperature glass powder and an organic carrier to prepare casting slurry, and performing casting, printing nickel internal electrodes, lamination and isostatic pressing to prepare a green body. The method does not add any rare earth element, realizes low-temperature co-firing with a nickel electrode, ensures that the capacitance change rate of the prepared ceramic medium is less than or equal to +/-10% in a temperature range of-55-85 ℃, ensures that the insulation resistance is more than or equal to 6.21 multiplied by 10 11 Ω at 125 ℃, has high dielectric constant, low loss and high reliability, and provides a new material system for the rare earth-free high-performance MLCC.

Inventors

  • XU HAIBO
  • DU PANFEI
  • Guan Riyu
  • Ge Ahui
  • LIU SHIXING

Assignees

  • 杭州兴容科技有限公司

Dates

Publication Date
20260512
Application Date
20251229

Claims (10)

  1. 1. A preparation method of boron-nitrogen co-doped barium titanate ceramics for X5R type MLCC comprises ceramic powder synthesis, green body manufacturing, high-temperature sintering, end electrode preparation and post treatment, and is characterized in that the ceramic powder synthesis comprises doped powder preparation and grinding reaction treatment, the doped powder preparation adopts a hydrothermal co-precipitation method, ca 2+ ions and Zr 4+ ions are co-doped into a barium titanate crystal lattice at the initial stage of crystal growth according to a perovskite crystal structure, a pre-strained crystal lattice framework with intrinsic stress is constructed, the grinding reaction treatment comprises the steps of preparing precursor powder of a core-shell structure by utilizing cyclic grinding with a multi-element additive, the core-shell structure takes the doped powder as a core, a B, N, ba, F element active layer anchored on the surface of the core as a shell, the green body manufacturing comprises adding a glass phase additive during tape casting slurry preparation, the high-temperature sintering temperature is limited to 900-950 ℃, and the high-temperature sintering temperature is limited to 900-900 ℃ and then is reduced to form composite phase insulating crystal boundaries of Bah- 2 and BaF- 2 after the temperature reduction.
  2. 2. The preparation method of the boron-nitrogen co-doped barium titanate ceramic for the X5R type MLCC is characterized by comprising the steps of taking barium hydroxide octahydrate as a barium source, calcium hydroxide as a calcium source, tetrabutyl titanate as a titanium source, tetrabutyl zirconate as a zirconium source, carrying out synchronous hydrolysis and crystallization reaction in an alkaline hydrothermal environment protected by nitrogen, and synthesizing calcium/zirconium co-doped barium titanate nano powder with a perovskite structure in one step, wherein the multielement additive consists of triethyl borate, urea and barium fluoride.
  3. 3. The method for preparing boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC according to claim 1, wherein the glass phase additive is ZnO-B 2 O 3 -SiO 2 ternary system glass powder, and the mass ratio of the components is ZnO: B 2 O 3 :SiO 2 =47:31:22.
  4. 4. The method for preparing the boron-nitrogen co-doped barium titanate ceramic for the X5R type MLCC according to claim 1, comprising the following steps: S1, adding deionized water, ethanol, barium hydroxide octahydrate and calcium hydroxide into a container, heating and pulping, then dropwise adding tetrabutyl titanate and tetrabutyl zirconate at a constant speed, sealing the container after the dropwise adding, introducing nitrogen to replace air, heating and preserving heat, performing suction filtration after the reaction is finished, and drying a filter cake to obtain calcium/zirconium co-doped barium titanate nano powder; S2, circularly grinding the obtained calcium/zirconium co-doped barium titanate nano powder, absolute ethyl alcohol, triethyl borate, urea and barium fluoride, then spray drying the slurry, setting the temperature of air inlet and outlet, and collecting powder after instant drying to obtain boron-nitrogen-fluorine uniformly coated precursor powder; s3, ball milling the obtained boron-nitrogen-fluorine uniformly coated precursor powder, self-made zinc oxide barium oxide-silicon oxide low-temperature glass powder and an organic casting auxiliary agent, and then vacuum defoaming to obtain casting slurry; s4, forming the casting slurry into a green tape, drying, printing electrode patterns, laminating, cutting into green chips after isostatic pressing, sequentially discharging glue from the green chips in a protective atmosphere, performing densification sintering, performing a controlled cooling-constant temperature heat treatment procedure, finally cooling to room temperature, and preparing through a terminal electrode to obtain the boron-nitrogen co-doped barium titanate ceramic finished product for the X5R type MLCC.
  5. 5. The preparation method of the boron-nitrogen co-doped barium titanate ceramic for the X5R type MLCC according to claim 4, wherein the mass ratio of the barium hydroxide octahydrate to the calcium hydroxide is 41.3-62, the mass ratio of the tetrabutyl titanate to the tetrabutyl zirconate is 26.6:35.5, and the temperature is kept after the temperature is raised, so that the temperature is required to be raised to 150-170 ℃.
  6. 6. The method for preparing boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC according to claim 4, wherein the mass ratio of the triethyl borate, urea and barium fluoride in S2 is 4:2:1-8:4:3, and the air inlet and outlet temperature is set to be 170-190 ℃.
  7. 7. The preparation method of the boron-nitrogen co-doped barium titanate ceramic for the X5R type MLCC according to claim 4, wherein the mass ratio of S3 to self-made zinc oxide barium oxide-silicon oxide low-temperature glass powder to organic casting auxiliary agent is 3:57-8:83, and the ball milling is carried out under the conditions of 1-3 m/S of rotation linear speed and 4-6 m/S of revolution linear speed for 2-4 hours.
  8. 8. The method of claim 4, wherein S4 is a dense sintering process, which is performed by heating to 900-950 ℃, and the cooling-constant temperature heat treatment process is performed by cooling to 800-900 ℃ at 1-3 ℃ per min and keeping the temperature for 2-10 hours.
  9. 9. The boron-nitrogen co-doped barium titanate ceramic for the X5R type MLCC of any of claims 1-8 is characterized by comprising, by weight, 100 parts of barium titanate, 45 parts of deionized water, 35 parts of absolute ethyl alcohol, 24,8 parts of barium hydroxide octahydrate, 0.40-0.60 part of calcium hydroxide, 21.3 parts of tetrabutyl titanate, 0.60-0.80 part of tetrabutyl zirconate, 0.70-1.50 parts of a multi-element additive, 0.3-0.8 part of a glass phase additive and 5.7-8.3 parts of an organic casting auxiliary agent.
  10. 10. The boron-nitrogen co-doped barium titanate ceramic for X5R-type MLCCs of claim 9, wherein said barium titanate ceramic has a dielectric constant of equal to or greater than 2963, a dielectric loss of equal to or less than 0.87%, a temperature characteristic of equal to or less than + -15%, an insulation resistance of equal to or greater than 6.21X 10 11 Ω, and a rate of change of capacitance of equal to or greater than-6.51%.

Description

Boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC and preparation method thereof Technical Field The invention relates to the technical field of electronic ceramic media, in particular to boron-nitrogen co-doped barium titanate ceramic for X5R type MLCC and a preparation method thereof. Background Barium titanate-based dielectric ceramics are widely used as dielectric materials for multilayer ceramic capacitors (MLCCs) due to their high dielectric constant and excellent ferroelectric properties. Wherein, the specification of X7R, X, R, X R and other types refers to the requirement of dielectric temperature stability, for example, X7R is required to have a capacitance value within the range of-55 ℃ to 125 ℃ not more than +/-15%, X8R is extended to 150 ℃ +/-15%, and X5R is required to have a capacitance value within the range of-55 ℃ to 85 ℃ +/-15%. In recent years, vehicle regulations and high reliability applications require that the dielectric maintain small capacitance changes over a wider temperature range while having high dielectric constant and low loss. However, achieving these properties typically requires multiple doping modifications to the barium titanate (BaTiO 3) matrix and controlling the sintering process to achieve a specific microstructure. The preparation method comprises the steps of adding a proper amount of mixed powder of barium carbonate, titanium dioxide, nickel oxide and doping agent into a ball milling tank for ball milling to obtain initial barium titanate composite particles, dispersing the initial barium titanate composite particles in an aqueous solution of a growth inhibitor for reaction to form modified barium titanate composite powder, then mixing and pressing the obtained barium titanate composite powder with adhesive polyvinyl butyral to form a biscuit, carrying out cold isostatic pressing, and then annealing and heat preserving in a nitrogen atmosphere after sintering to obtain the defect-controlled barium titanate composite material, wherein the CN120717784A discloses a giant dielectric barium titanate-based ceramic dielectric material, the preparation method and the application thereof, and the giant dielectric barium titanate-based ceramic dielectric material comprises barium titanate and doping elements, wherein the doping elements consist of Mg, ca, RE, al and Si, and the barium titanate content is 90-99.7mol%. 0.1 to 4mol% of Mg, 0.25 to 0.55mol% of Ca, 0.1 to 3.5mol% of RE, 0.002 to 0.3mol% of Al and 0.01 to 4.0mol% of Si. The ceramic dielectric material provided by the method has small average grain size, dielectric constant at room temperature of more than 104 orders of magnitude, high dielectric stability in a wide temperature range and resistivity of more than 109 ohm cm, and is suitable for large-scale industrialization by adopting a traditional solid phase method process. However, since the conventional technology mainly increases the curie temperature and widens the dielectric peak by doping with rare earth elements, rare earth elements are expensive, limited in supply, and require sintering at a high temperature above 1200 ℃ and cannot be co-sintered with low-melting-point nickel internal electrodes. In summary, how to develop a novel barium titanate-based ceramic system, not only can realize low-temperature sintering and nickel electrode cofiring, but also can ensure high dielectric property, wide temperature stability and high reliability, and meanwhile, avoids using expensive rare earth elements, and reduces cost, so that the technical problem to be solved in the field is urgent. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides boron-nitrogen co-doped barium titanate ceramic for an X5R type MLCC and a preparation method thereof, so as to solve the technical problems of uneven doping, low temperature-high reliability contradiction and the like in the prior art. The specific technical scheme is as follows: The preparation method is that composite precursor powder containing calcium, zirconium, boron, nitrogen and fluorine elements is prepared through hydrothermal coprecipitation and liquid phase coating process, and then is subjected to tape casting and low-temperature cofiring with a nickel inner electrode, and then the precursor is triggered to react in situ at a grain boundary in a specific cooling-heat preservation stage to generate a hexagonal boron nitride and barium fluoride interweaved composite insulating phase. Further, the hydrothermal coprecipitation is to synchronously hydrolyze and co-crystallize a barium source and a calcium source with a titanium source and a zirconium source in an alkaline hydrothermal environment protected by nitrogen, so that calcium and zirconium co-doped barium titanate nano powder with a perovskite structure (ABO 3) is synthesized in one step. In the process, calcium ions and zirconium ions respectively enter the top angle (A position) and the center (B