Ceramic Capacitor Material for High Dielectric Strength
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Solution Overview
Problem
Existing ceramic materials for capacitors, particularly in multilayer technology, face limitations in achieving high switching field strength and relative permittivity, especially when used in high-power applications, and require sintering temperatures that are challenging for certain materials, leading to suboptimal dielectric properties.
Innovation Solution
A Zr-rich PZT mixed crystal phase doped with a rare earth element and at least one of Ni or Cu, allowing for sintering at 1000° C to 1120° C, enabling co-firing with base metals and achieving higher dielectric constants and switching field strength, while controlling grain size for improved dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PZT ceramic materials are used in multilayer capacitors, then piezoelectric properties are improved, but dielectric properties (switching field strength and relative permittivity) remain suboptimal for high-power applications
Solution Approach 1:
The patent modifies the chemical composition parameters of PZT ceramic by introducing specific dopants (Nb at 0.02-0.08 mol fraction, Ta at 0.02-0.08 mol fraction) and controlling Zr/Ti ratios, which changes the material's dielectric properties to achieve higher switching field strength and relative permittivity while reducing energy losses
Solution Approach 2:
The patent creates a composite ceramic system by combining PZT base material with multiple dopants (Nb, Ta) and ad混 phases, forming a multi-component system that synergistically improves dielectric properties beyond what single-component PZT can achieve
2Reliability
If high sintering temperatures are used to achieve optimal dielectric properties, then material performance is improved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The introduction of Nb and Ta dopants modifies the sintering behavior of PZT ceramic, enabling adequate densification and phase formation at lower temperatures (reducing the sintering temperature range to 950-1150°C) while maintaining or improving dielectric properties through compositional optimization
3Ease of manufacture
If base metals (Ag, Cu) are used for internal electrodes to reduce cost, then manufacturing cost is reduced, but electrode stability at high sintering temperatures deteriorates
Solution Approach 1:
By lowering the sintering temperature to 950-1150°C through dopant addition, the patent enables the use of base metal electrodes (Ag, Cu) that would otherwise be unstable at conventional higher sintering temperatures, thus reducing cost while maintaining electrode integrity
Solution Approach 2:
The Nb and Ta dopants act as intermediaries that modify the interaction between base metal electrodes and the ceramic matrix, improving interfacial stability and preventing electrode degradation during sintering at reduced temperatures
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 ceramic material exhibits enhanced dielectric constants and switching field strength, with reduced energy losses and improved sintering efficiency, enabling effective use in high-power capacitors with lower sintering temperatures and maintaining performance across varying electric field strengths.
Implementation Method 1
The properties of ceramic capacitors are essentially determined by the polarization properties of the ceramic dielectric
Implementation Method 2
If the direction of the spontaneous polarization can be changed by applying an electric field (or mechanical stress), the materials are called ferroelectric
Implementation Method 3
If, during the phase transition from the paraelectric phase, the ions of a ferroelectric material do not move parallel to one another but antiparallel to one another, the material is referred to as antiferroelectric
Implementation Method 4
allowing for sintering at 1000° C to 1120° C, enabling co-firing with base metals and achieving higher dielectric constants and switching field strength, while controlling grain size for improved dielectric properties
Data Source
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AI summary
The present patent application relates to a ceramic material for capacitors in multilayer technology of the general formula: (I) Pb(1-1.5a+e)AaBb(Zr1-xTix)1-cCeSicO3 + y·PbO where A is selected from the group consisting of La, Nd, Y, Eu, Gd, Tb, Dy, Ho, Er and Yb; C is selected from the group consisting of Ni and Cu; and 0 < a < 0.12 0.05 ≤ x ≤ 0.3 0 ≤ c < 0.12 0.001 < e < 0.12 0 ≤ y < 1. The present patent application also relates to a capacitor comprising the aforementioned ceramic material.