Nano Complex Oxide Doped BaTiO3 for Base Metal Capacitors
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Solution Overview
Problem
Current multilayer ceramic capacitors face challenges in achieving ultrafine grain size and temperature stability while using base metals as internal electrodes, as they tend to oxidize easily and require high sintering temperatures, affecting dielectric properties and production costs.
Innovation Solution
A nano complex oxide doped dielectric ceramic material is developed using barium titanate with a specific molar ratio and particle size, coated through a chemical or sol-gel process, allowing for the use of base metals as internal electrodes in a reducing atmosphere to achieve ultrafine grain size and temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If base metals such as Ni or Cu are used as internal electrodes and fired in conventional firing conditions, then production cost is reduced, but the base metals would be oxidized easily and lose functions as internal electrodes
Solution Approach 1:
The patent employs a reducing atmosphere (inert environment) during firing to prevent oxidation of base metal internal electrodes. By controlling the atmospheric composition with low oxygen partial pressure, the base metals maintain their conductive properties and functional integrity throughout the sintering process, resolving the contradiction between cost reduction and reliability maintenance
Solution Approach 2:
The patent modifies firing parameters including temperature (900-1200°C), time (1-10 hours), and atmospheric composition to optimize both the prevention of base metal oxidation and the achievement of desired dielectric properties. These parameter changes enable simultaneous attainment of low cost and high reliability
2Reliability
If base metals are used as internal electrodes and fired in neutral or reducing atmosphere, then oxidation is prevented, but high sintering temperatures are required which affect dielectric properties
Solution Approach 1:
The patent utilizes a composite dielectric system comprising BaTiO3 as the primary phase with multiple dopants (Mn, Mg, and rare earth elements) that work synergistically. This composite structure enables effective base metal protection and desired dielectric properties at reduced sintering temperatures (900-1200°C), resolving the contradiction between reliability and temperature control
Solution Approach 2:
The patent optimizes sintering temperature parameters within the range of 900-1200°C, which is lower than conventional temperatures. This parameter change, combined with controlled atmosphere and doping, achieves both base metal protection and superior dielectric properties without requiring excessively high temperatures
3Reliability
If non-reducible dielectric ceramic materials are used to prevent oxidation, then base metal stability is improved, but grain size control becomes difficult and dielectric properties are unstable
Solution Approach 1:
The patent employs a composite doping strategy combining Mn, Mg, and rare earth elements in a BaTiO3 matrix. This multi-component composite system provides both the chemical stability needed to protect base metals and the grain growth control necessary for achieving uniform, fine-grained microstructures with stable dielectric properties
Solution Approach 2:
The dopants are distributed throughout the BaTiO3 matrix to create local regions with modified properties. Mn and Mg provide oxidation resistance at grain boundaries, while rare earth elements control grain growth kinetics, achieving both base metal stability and precise grain size control through localized functional zones
4Volume of moving object
If grain size is reduced to achieve ultrafine grained structure, then capacitor miniaturization is enabled, but dielectric constant decreases
Solution Approach 1:
The patent uses a composite doping system with Mn, Mg, and rare earth elements that work synergistically to maintain high dielectric constant in ultrafine-grained BaTiO3. The rare earth elements specifically address the dielectric constant reduction issue by modifying the permittivity at the nanoscale, while Mn and Mg maintain the ultrafine grain structure, resolving the contradiction between miniaturization and dielectric performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in multilayer ceramic capacitors with dielectric constants of 2000 to 2600 and temperature coefficients within ±15%, meeting X5R/X7R standards, with high insulation resistance and uniform grain sizes less than 300 nm, suitable for miniaturized electronic devices.
Implementation Method 1
a nano complex oxide dopant with the following formula (1): wA+xB+yC+zD (1) wherein, A represents one or more selected from the group consisting of CaTiO3, CaO, BaO, SrO and MgO; B represents one or more selected from the group consisting of MnO2, CO2O3, CO3O4, Fe2O3 and Y2O3; C represents one or more selected from the group consisting of SiO2, B2O3 and Li2O; D represents an oxide of Re, wherein Re is one or more rare-earth elements
Implementation Method 2
The doped dielectric ceramic material can be prepared by a chemical coating process, wherein the doped elements are coated on the surface of the barium titanate particles through a co-precipitation process
Implementation Method 3
The nano complex oxide dopant is prepared by a sol-gel method firstly with a particle size of 10 to 80 nm
Implementation Method 4
a base-metal internal electrode multilayer ceramic capacitor using the above-described nano complex oxide doped dielectric ceramic material as the material of dielectric layers
Data Source
AI summary
The present invention provides a nano complex oxide doped dielectric ceramic material used for a multilayer ceramic capacitor using a base metal as a material of internal electrodes. The doped dielectric ceramic material comprises barium titanate and a nano complex oxide dopant, wherein the molar ratio of the barium titanate to the nano complex oxide dopant is in the range of (90 to 98):(2 to 10), the average particle size of the barium titanate is 50 to 300 nm and the nano complex oxide dopant has the following formula (1): wA+xB+yC+zD. The present invention also provides processes for preparing the nano complex oxide doped dielectric ceramic material and ultrafine-grained and temperature-stable multilayer ceramic capacitors using the nano complex oxide doped dielectric ceramic material as a material of dielectric layers.