Core-Shell Dielectric Composition for High DC Bias Capacitors
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Solution Overview
Problem
Existing dielectric compositions for laminated ceramic capacitors face challenges in maintaining high dielectric constant and resistivity under high DC bias and elevated temperatures, particularly at high voltages and ambient temperatures, due to polarization reversal and reduced reliability.
Innovation Solution
A dielectric composition with a perovskite crystal structure, featuring a core-shell structure of Bi, Na, and Sr, where the Bi content in the core portion is limited to no more than 0.83 times that in the shell portion, along with specific molar ratios and auxiliary components, enhances DC bias resistivity and high-temperature load lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If BaTiO3 is used as the main component to achieve high dielectric constant, then the dielectric constant is improved, but the resistivity and reliability deteriorate under high DC bias and elevated temperatures
Solution Approach 1:
The patent employs a composite dielectric composition consisting of multiple oxide components (BaTiO3, Bi2O3, Na2TiO3, SrTiO3, and auxiliary components) in specific ratios. This composite structure combines the high dielectric constant of BaTiO3 with the high resistivity and thermal stability of Bi2O3-based components, achieving both high capacitance and high reliability under DC bias conditions
Solution Approach 2:
The patent introduces auxiliary components (Li2O-SiO2-Al2O3 system and SiO2-TiO2-BaO system) at specific ratios (0.1-5.0 wt% and 0.05-3.0 wt% respectively) to locally modify the dielectric properties. These auxiliary components form glass phases that fill grain boundaries and inhibit oxygen vacancy migration, thereby improving resistivity without significantly reducing the overall dielectric constant
2Area of stationary object
If the dielectric composition is optimized for high dielectric constant, then the capacitance is improved, but the high-temperature load lifespan deteriorates
Solution Approach 1:
The patent precisely controls the ratios of oxide components within specific ranges (Bi2O3: 0.5-5.0 wt%, Na2TiO3: 0.5-5.0 wt%, SrTiO3: 0.5-5.0 wt%, auxiliary components: 0.1-5.0 wt%) to optimize the balance between dielectric constant and thermal stability. This parameter optimization ensures stable electrical properties under high-temperature operating conditions, extending the component lifespan
Solution Approach 2:
The auxiliary components (Li2O-SiO2-Al2O3 and SiO2-TiO2-BaO systems) act as intermediary phases that form protective glass matrices around the perovskite grains. These glass phases serve as barriers to oxygen vacancy diffusion and cation migration at high temperatures, thereby maintaining electrical stability and extending the high-temperature load lifespan
3Quantity of substance
If miniaturization is pursued to increase circuit density, then the capacity is improved, but the electrical characteristics under high voltage deteriorate
Solution Approach 1:
The multi-component composite dielectric system combines materials with complementary properties: BaTiO3 provides high dielectric constant for capacitance, while Bi2O3-based components provide high breakdown voltage and resistivity. This composite structure enables miniaturized capacitors to maintain excellent electrical characteristics under high voltage stress despite reduced size
Solution Approach 2:
The auxiliary glass-forming components create intermediary protective phases at grain boundaries that prevent electrical breakdown under high voltage. These glass phases act as insulating barriers that inhibit the formation and propagation of conductive filaments, thereby maintaining high voltage withstanding capability in miniaturized structures
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 dielectric composition achieves a high dielectric constant, high resistivity, and extended high-temperature load lifespan, suitable for medium- and high-voltage applications, with improved DC bias characteristics and reliability.
Implementation Method 1
the direction of the polarization axis in the domain is likely to be arranged in the direction of application of DC bias
Implementation Method 2
particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti
Implementation Method 3
dielectric compositions having a structure in which an auxiliary component is diffused in the surface region of BaTiO3 particles (what is known as a 'core-shell' structure)
Data Source
AI summary
A dielectric composition, a dielectric element, an electronic component and a laminated electronic component are disclosed. In an embodiment the dielectric composition includes particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti, wherein at least some of the particles have a core-shell structure including a core portion and a shell portion, and wherein the content of Bi present in the core portion is no greater than 0.83 times the content of Bi present in the shell portion.