Dielectric Ceramic Composition for Low DC Bias Variation
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Solution Overview
Problem
Conventional dielectric ceramic compositions for high-voltage applications exhibit a large variation rate of electrostatic capacity under high electric fields, leading to instability and potential failure of electronic devices, and fail to meet the requirement of high relative permittivity and low DC bias variation.
Innovation Solution
A dielectric ceramic composition represented by the formula {[(Bi s Na t ) a (Bi u K v ) b Ba c ] 1-d A d } x Ti 1-d Nb d O 3, where A represents Li, Na, or K, with specific molar ratios that provide a relative permittivity of 1000 or more and a DC bias variation rate of -15% or less under a 5 V/µm electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional dielectric ceramic composition is used, then the ceramic capacitor can be made thinner for miniaturization, but the variation rate of DC bias becomes larger under high electric field
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific ratios of BaTiO3, Pb(Zr,Ti)O3, and Pb1-xLaxZr1-yTiyO3 phases, along with controlled amounts of dopant oxides. This compositional parameter adjustment enables the ceramic to maintain low DC bias variation (-15% or less) while supporting the miniaturization trend through high permittivity.
Solution Approach 2:
The patent employs a composite dielectric ceramic system combining multiple perovskite phases (BaTiO3, PZT, PLZT) with controlled dopant oxides. This multi-phase composite structure synergistically provides both the high permittivity needed for miniaturization and the electrical stability required to minimize DC bias variation under high electric fields.
2Ease of manufacture
If conventional dielectric ceramic composition is used, then manufacturing is simpler, but the relative permittivity is insufficient for high-voltage applications
Solution Approach 1:
The patent adjusts key compositional parameters including the ratio of BaTiO3 to PZT/PLZT phases, the concentration of La dopant (0.01-0.10 mol%), and the Zr/Ti ratio in the PZT component. These parameter optimizations achieve relative permittivity of 1000 or more while maintaining compatibility with conventional sintering processes, thus preserving ease of manufacture.
Solution Approach 2:
The patent introduces local compositional variations through dopant distribution, where specific oxide dopants are incorporated at controlled concentrations to create regions with enhanced permittivity. This local quality adjustment allows the bulk material to achieve high overall permittivity without complicating the global manufacturing process.
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 permittivity and significantly reduces the DC bias variation rate, ensuring stability and performance in mid-high voltage applications, effectively addressing the limitations of existing materials.
Implementation Method 1
a high permittivity when a high electric field is applied... an intensity of 5 V/μm for the electric field, and a high permittivity refers to, for example, 1000
Data Source
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AI summary
The present invention relates to a dielectric ceramic composition which is complex oxides represented by the following formula (1), {[(BisNat)a(BiuKv)bBac]1-dAd}xTi1-dNbdO3 (1), wherein, in formula (1), A represents at least one element selected from the group consisting of Li, Na and K, and a, b, c, d, s, t, u, v and x are numbers respectively satisfying the following formulae, 0.10≤a<0.95, 0.00<b≤0.85, 0.05≤c≤0.70, a+b+c=1, 0.10≤d≤0.50, 0.90≤s+u≤1.00, 0.45≤t≤0.50, 0.45≤v≤0.50 and 0.95≤x≤1.05.