Dielectric Ceramic Composition for Ni Electrode Capacitors
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Solution Overview
Problem
Dielectric ceramic compositions with alkali metal niobate-based perovskite compounds suffer from poor DC bias characteristics and significant fluctuations in dielectric properties when a DC electric field is applied, despite maintaining good insulating properties in reducing atmospheres.
Innovation Solution
A dielectric ceramic composition with a perovskite crystal structure, primarily containing NaNbO3 and CaZrO3, is optimized by adjusting the blending ratios of Mn, La, Li, and modifying the A and B sites with elements like Ba, Sr, Hf, and Sn, to maintain insulating properties and improve DC bias characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric ceramic composition containing alkali metal niobate-based perovskite compound is used, then good insulating properties and dielectric characteristics are achieved, but DC bias characteristics deteriorate with significant decrease in relative dielectric constant when DC electric field is applied
Solution Approach 1:
The patent applies local quality by introducing specific dopant elements (Mn, La, Li) at controlled concentrations into the dielectric ceramic composition. These dopants are strategically added to modify local regions of the material to suppress oxygen vacancy formation and improve electron trap density, thereby enhancing DC bias characteristics without compromising the overall insulating properties of the alkali metal niobate-based perovskite compound
Solution Approach 2:
The patent employs parameter changes by precisely controlling the composition ratios and doping concentrations of multiple elements in the dielectric ceramic. By adjusting the stoichiometric ratios of alkali metals, niobate content, and dopant concentrations, the material's electrical characteristics are optimized to maintain stable relative dielectric constant under DC electric field while preserving good insulating properties
2Reliability
If the dielectric ceramic composition is optimized for good dielectric characteristics at no load, then fluctuations in dielectric properties occur when DC electric field is applied
Solution Approach 1:
The patent applies preliminary action by pre-doping the dielectric ceramic composition with specific elements (Mn, La, Li) before sintering. This preliminary doping modifies the material's defect structure and electron trap characteristics in advance, creating a more stable dielectric composition that resists fluctuations when DC electric field is subsequently applied, while maintaining good dielectric characteristics at no load
3Ease of manufacture
If inexpensive base metals like Ni are used for internal electrodes, then manufacturing cost is reduced, but insulating properties deteriorate when firing is performed in reducing atmosphere
Solution Approach 1:
The patent introduces dopant elements (Mn, La, Li) as intermediaries between the base metal internal electrodes and the dielectric ceramic matrix. These intermediaries suppress oxygen vacancy formation and reduce electron transfer from the base metal electrodes to the dielectric, thereby maintaining good insulating properties even when inexpensive base metals like Ni are used and when firing is performed in reducing atmosphere
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 optimized composition achieves stable high relative dielectric constants and low dielectric losses, with reduced fluctuations under DC electric fields, and good DC bias characteristics, even when co-fired with inexpensive base metals like Ni in reducing atmospheres.
Implementation Method 1
a dielectric ceramic composition which has good insulating properties even when firing is performed in a reducing atmosphere, has good dielectric characteristics, such as relative dielectric constant εr and dielectric loss tan δ, at no load, has reduced fluctuations in dielectric characteristics even when dc electric field is applied
Data Source
AI summary
A dielectric ceramic composition represented by a general formula {(Na1-v-w-xKvLiwM2x)(Nb1-y-zTayM4z)O3+αMnO+βLa2O3+γLi2O}, wherein 0≤v≤0.01, 0≤w≤0.01, 0.05≤x, z≤0.15, 0≤y≤0.1, 0.003≤α≤0.05, 0.001≤β≤0.05, and 0.005≤γ≤0.05. M2 is Ba, Ca, and/or Sr, and M4 is Zr, Hf, and/or Sn. A ceramic layer is formed of the dielectric ceramic composition, and an internal electrode is formed of a base metal material such as Ni.