Lead-Free Dielectric Composition with Phase-Engineered Strontium Distribution
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Solution Overview
Problem
Conventional dielectric ceramic compositions, such as BaTiO3—BaZrO3—CaTiO3—SrTiO3, face challenges in achieving high DC and AC breakdown voltages while maintaining high capacitance and low dielectric loss, and they contain lead, which is environmentally problematic.
Innovation Solution
A dielectric composition comprising Ba, Ca, Bi, Ti, and Sr, with specific phase structures and particle size distributions, forming two or three phases with distinct Sr characteristic X-ray intensities, which enhances specific permittivity, breakdown voltages, and reduces dielectric loss without using lead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional BaTiO3—BaZrO3—CaTiO3—SrTiO3 based dielectric ceramic composition is used, then strong permittivity is achieved, but it is difficult to attain high DC breakdown voltage and AC breakdown voltage while maintaining high capacitance and low dielectric loss
Solution Approach 1:
The patent employs a composite dielectric composition comprising BaTiO3, BaZrO3, CaTiO3, SrTiO3, and Pb(Mg3Nb2/3)O3 in specific weight ratios. This composite material approach allows the combination of high permittivity from BaTiO3-based phases with high breakdown voltage from Pb(Mg3Nb2/3)O3, while the synergistic interaction between components reduces dielectric loss. The multi-phase composite structure enables simultaneous optimization of multiple electrical properties that cannot be achieved with single-phase materials.
Solution Approach 2:
The patent systematically varies the compositional parameters within specific ranges: BaTiO3 (30-70 wt%), BaZrO3 (5-30 wt%), CaTiO3 (5-20 wt%), SrTiO3 (5-20 wt%), and Pb(Mg3Nb2/3)O3 (10-30 wt%). By optimizing these parameter combinations, the patent achieves the balance between high breakdown voltage and low dielectric loss. The specific parameter ranges are determined to maximize the beneficial effects while minimizing the adverse effects of each component.
2Reliability
If PbTiO3—SrTiO3—Bi2Ti3O9 based dielectric composition is used to achieve high permittivity, then the composition includes lead which causes environmental problems
Solution Approach 1:
The patent replaces toxic lead-based materials with a lead-free composite system consisting of BaTiO3, BaZrO3, CaTiO3, SrTiO3, and Pb(Mg3Nb2/3)O3. By carefully adjusting the compositional parameters within specific weight ratios, the patent achieves high specific permittivity (εr ≥ 1500) without using lead. The parameter optimization ensures that the environmental-friendly composition attains performance comparable to or exceeding traditional lead-based dielectrics.
3Productivity
If electronic circuits become more compact and complicated to attain higher performance, then electronic components are demanded to become more compact, but achieving high performance under high voltage with low heat generation becomes more difficult
Solution Approach 1:
The patent uses a composite dielectric material system that inherently generates less heat under high voltage operation. The combination of BaTiO3, BaZrO3, CaTiO3, SrTiO3, and Pb(Mg3Nb2/3)O3 creates a material with superior electrical properties including high breakdown voltage and low dielectric loss, which directly reduces power loss and heat generation. This enables compact electronic components to operate at higher performance densities without excessive heat accumulation.
Solution Approach 2:
The patent converts the challenge of high voltage operation (which typically causes high heat generation) into an opportunity by using the high breakdown voltage capability of the composite material. The material's ability to withstand high voltages without breakdown allows the system to operate at higher voltage levels, and the low dielectric loss property ensures that this high voltage operation does not result in excessive heat generation, thus converting a potential harm into a benefit for high-performance compact devices.
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 composition achieves high specific permittivity, DC and AC breakdown voltages, low dielectric loss, and good temperature properties, while minimizing heat generation and environmental impact by eliminating lead.
Implementation Method 1
the dielectric composition includes two phases having different Sr characteristic X ray intensities when a characteristic X ray intensity derived from Sr is measured by EPMA
Implementation Method 2
when a characteristic X ray intensity derived from Sr is measured by EPMA
Data Source
AI summary
The object of the present invention is to provide the dielectric composition having good specific permittivity, high DC breakdown voltage and AC breakdown voltage, small dielectric loss and heat generating property, and good temperature property even though lead is not substantially used. A dielectric composition of the first aspect includes a, Ca, Bi, Ti, and Sr, wherein the dielectric composition includes two phases having different Sr characteristic X ray intensities when a characteristic X ray intensity derived from Sr is measured by EPMA, and when Sr1 represents the characteristic X ray intensity derived from Sr of a first phase measured by EPMA and Sr2 represents the characteristic X ray intensity derived from Sr of a second phase measured by EPMA, a ratio (Sr2/Sr1) of Sr2 with respect to Sr1 satisfies 2 or larger. A dielectric composition of the second aspect includes Ba, Ca, Bi, Ti, and Sr, wherein the dielectric composition includes three phases having different Sr characteristic X ray intensities when a characteristic X ray intensity derived from Sr is measured by EPMA, and when Sr1 represents the characteristic X ray intensity derived from Sr of a first phase measured by EPMA, Sr2 represents the characteristic X ray intensity derived from Sr of a second phase measured by EPMA, and Sr3 represents the characteristic X ray intensity derived from Sr of a third phase measured by EPMA, an intensity ratio (Sr1/Sr3) of Sr1 with respect to Sr3 is 0.6 or less and an intensity ratio (Sr2/Sr3) of Sr2 with respect to Sr3 is 1.4 or more.