Dielectric Ceramic Composition for Stable DC-Biased Capacitors
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Solution Overview
Problem
Current dielectric ceramic compositions, such as those with a tetragonal tungsten bronze structure, face challenges in maintaining a high relative dielectric constant and resistivity under direct-current voltage, limiting their application in ceramic capacitors.
Innovation Solution
A dielectric ceramic composition with a specific molar ratio of K, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Y, Sc, Nb, and Ta, along with Mn, is developed, which enhances the relative dielectric constant and resistivity, and improves performance under direct-current voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ferroelectric ceramics such as barium titanate with perovskite structure are used, then high relative dielectric constant is achieved, but relative dielectric constant decreases under direct-current voltage due to ferroelectricity
Solution Approach 1:
The patent changes the crystal structure parameter from perovskite to tetragonal tungsten bronze structure, which fundamentally alters the dielectric properties. This structural parameter change suppresses ferroelectricity while maintaining high dielectric constant, resolving the contradiction between achieving high dielectric constant and maintaining stability under DC voltage
Solution Approach 2:
The patent creates a composite dielectric ceramic composition containing multiple elements (Ba, Sr, Ca, rare-earth elements, Nb, Ta, and other metal elements) in specific proportions. This composite approach combines the advantages of different materials to achieve both high relative dielectric constant and stability under direct-current voltage by suppressing ferroelectric effects through the specific composite structure
2Reliability
If dielectric ceramic compositions with tetragonal tungsten bronze structure are used to suppress ferroelectricity, then stability under direct-current voltage improves, but relative dielectric constant decreases
Solution Approach 1:
The patent optimizes the compositional parameters within the tetragonal tungsten bronze structure by precisely controlling the ratios of A-site elements (Ba, Sr, Ca, rare-earth elements) and B-site elements (Nb, Ta, and other metal elements). This parameter optimization maintains the structural advantages for DC voltage stability while enhancing the dielectric constant through compositional tuning
Solution Approach 2:
The patent introduces specific metal elements (Al, Si, B, Li, and other metal elements) in controlled amounts to locally modify the dielectric properties. These localized compositional adjustments enhance the overall relative dielectric constant while maintaining the tetragonal tungsten bronze structure's inherent stability under direct-current voltage
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 a high relative dielectric constant and resistivity, with a significant improvement under direct-current voltage, making it suitable for advanced ceramic capacitors with reduced power loss during charge and discharge.
Implementation Method 1
a first value, ε, of the relative dielectric constant and a second value, ρ, of the resistivity, wherein the dielectric ceramic composition has a tetragonal tungsten bronze structure
Data Source
AI summary
A dielectric ceramic composition that contains an oxide of A, R, and B and an oxide of Mn. The A is at least one selected from the group consisting of K and Na. The R is at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc. The B is at least one selected from the group consisting of Nb and Ta. The molar ratio of the A:R:B:Mn is 2−x:1+x/3:5+y:z. The x, y, and z satisfy −0.3≤x≤0.6, −0.5≤y≤0.5, and 0.001≤z≤0.5, respectively.