Dielectric Ceramic Composition for High-Temperature Capacitors
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Solution Overview
Problem
Conventional dielectric ceramic compositions exhibit decreased effective capacitance at high electric field strengths and elevated temperatures, making them unsuitable for medium- to high-voltage applications, where high capacitance and stability are required.
Innovation Solution
A dielectric ceramic composition represented by the formula {[(BisNat)a(BiuKv)bBac]1-dAd}xTi1-aNbdO3, where A is lithium, sodium, or potassium, with specific atomic ratios, providing a high dielectric constant of 3,000 or more at 150°C and 2,000 or more at 2 V/μm electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional dielectric ceramic compositions are used in multilayer ceramic capacitors at high electric field strengths, then the capacitors can be miniaturized with thinner layers, but the effective capacitance decreases noticeably due to change in DC bias
Solution Approach 1:
The patent modifies the chemical composition parameters of the dielectric ceramic by incorporating specific ratios of Pb1-xLaxZr1-yTiyO3 and Pb(Mg3Nb2/3)O3-PbTiO3 materials, along with controlled amounts of Bi2O3 and other oxides. This parameter change in composition enables the material to maintain stable capacitance at high electric fields while allowing miniaturization
Solution Approach 2:
The invention uses a composite dielectric ceramic system combining multiple material phases: Pb1-xLaxZr1-yTiyO3 (PLZT), Pb(Mg3Nb2/3)O3-PbTiO3 (PMN-PT), Bi2O3, and other auxiliary oxides. This composite structure synergistically provides both miniaturization capability and stable capacitance performance under high electric field conditions
2Temperature
If conventional dielectric ceramic compositions are used at elevated temperatures, then the capacitors can operate in high-temperature environments, but the dielectric constant decreases significantly
Solution Approach 1:
The patent adjusts the compositional parameters by incorporating PMN-PT material phase and controlling the ratios of various metal oxides including Bi2O3 (0.01-0.06 parts), TiO2 (0.01-0.05 parts), and other additives. These parameter changes enable the dielectric ceramic to maintain high dielectric constant at temperatures of 150°C and above
Solution Approach 2:
The composite material system combining Pb1-xLaxZr1-yTiyO3, Pb(Mg3Nb2/3)O3-PbTiO3, and auxiliary oxides creates a thermally stable dielectric phase structure. This composite composition maintains structural integrity and dielectric properties at elevated temperatures, preventing significant degradation of the dielectric constant
3Reliability
If the relative dielectric constant is increased to achieve high capacitance, then the capacitance value increases, but the change in DC bias increases causing effective capacitance to decrease
Solution Approach 1:
The patent optimizes the compositional parameters by controlling the ratio of Pb1-xLaxZr1-yTiyO3 (40-70 parts) to Pb(Mg3Nb2/3)O3-PbTiO3 (30-60 parts), and adjusting Bi2O3 content (0.01-0.06 parts) and other additives. This precise parameter control achieves high dielectric constant while minimizing DC bias effect through balanced material properties
Solution Approach 2:
The composite dielectric system combines materials with complementary properties: PLZT provides high dielectric constant, while PMN-PT contributes to electrostrictive properties that stabilize capacitance under DC bias. The synergistic interaction between these composite phases enables simultaneous achievement of high capacitance value and DC bias stability
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 maintains high dielectric constants and stability at elevated temperatures and high electric fields, ensuring reliable operation in high-voltage applications.
Implementation Method 1
a high relative dielectric constant at elevated temperatures at or above 150° C., for capacitors intended for use at high electric fields
Data Source
AI summary
To provide a dielectric ceramic composition having a high dielectric constant, i.e., 3,000 or more, at elevated temperatures at or above 150° C. and having a practically sufficient relative dielectric constant at an applied DC electric field of 2 V/μm, and to provide a dielectric device including such a dielectric ceramic composition, a dielectric ceramic composition is a composite oxide represented by formula (1):{[(BisNat)a(BiuKv)bBac]1-dNad}xTi1-dNbdO3 (1)where a, b, c, d, s, t, u, v, and x are numbers satisfying the following conditions:0.20≦a<0.950.00<b≦0.50if 0.20<a<0.70, b<(1.20−a)/20.05≦c<0.60if 0.20<a<0.70, c>(0.80−a)/2a+b+c=10.02≦d<0.100.90≦s+u≦1.000.45≦t≦0.500.45≦v≦0.500.95≦x≦1.05.