BaTiO3 Dielectric Ceramic with La, Nd, Y, Mg, Fe Dopants
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Solution Overview
Problem
Dielectric ceramics used in capacitors for middle to high voltages face reliability issues after moisture-resistance loading tests, particularly due to increased leakage current and significant changes in electrostatic capacitance with temperature.
Innovation Solution
A dielectric ceramic with a perovskite-type compound containing Ba, Ti, La, Nd, Y, Mg, and Fe, with specific molar ratios, is developed, which is fired in an atmosphere and features electrodes formed by a sputtering method on both principal surfaces, ensuring minimal capacitance change with temperature and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric ceramic is used for middle to high voltage capacitors, then capacitance value is achieved, but leakage current increases and reliability deteriorates after moisture-resistance loading test
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by introducing specific rare earth elements (La, Nd) at controlled concentrations (0.15-3 parts by mole per 100 parts Ti), along with Y, Mg, and Fe in specific ranges. This compositional parameter change resolves the contradiction by reducing leakage current while maintaining high voltage capacitance, thereby improving reliability after moisture-resistance loading tests.
Solution Approach 2:
The patent creates a composite dielectric ceramic material by combining perovskite-type compound with multiple dopants including rare earth elements (La, Nd), Y, Mg, and Fe. This composite approach allows the material to achieve both low leakage current and high reliability under moisture conditions, resolving the technical contradiction between capacitance value and harmful leakage effects.
2Stability of the object's composition
If conventional dielectric ceramic is used for middle to high voltage capacitors, then capacitance value is achieved, but electrostatic capacitance changes significantly with temperature
Solution Approach 1:
The patent modifies the dielectric ceramic's thermal stability by adjusting compositional parameters, specifically incorporating rare earth elements (La, Nd) and other dopants in controlled amounts. This parameter change stabilizes the electrostatic capacitance across temperature variations while preserving the required capacitance value for middle to high voltage applications.
3Stability of the object's composition
If dielectric ceramic with improved temperature stability is used, then capacitance stability is achieved, but reliability after moisture-resistance loading test deteriorates
Solution Approach 1:
The patent employs a multi-element composite strategy combining rare earth elements (La, Nd) with Y, Mg, and Fe dopants. This composite composition simultaneously achieves both temperature stability of electrostatic capacitance and high reliability after moisture-resistance loading tests, resolving the contradiction between thermal stability and moisture resistance.
Solution Approach 2:
The patent applies local quality by introducing specific dopants at controlled concentrations to address different functional requirements: rare earth elements (La, Nd) primarily improve temperature stability, while Y, Mg, and Fe contribute to moisture resistance and reliability. This localized functional assignment resolves the contradiction between temperature stability and moisture resistance.
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 exhibits stable electrostatic capacitance and enhanced reliability after a moisture-resistance loading test, maintaining insulation properties and AC voltage characteristics even under high voltage conditions.
Implementation Method 1
the dielectric ceramic according to the present invention contains, as its main constituent, a perovskite-type compound containing Ba and Ti, and further contains Re1 (Re1 is at least one element of La and Nd), Y, Mg, and Fe
Implementation Method 2
a single-plate capacitor including: the dielectric ceramic mentioned above; and electrodes formed by a sputtering method on both principal surfaces of the dielectric ceramic
Implementation Method 3
the perovskite-type compound as the main constituent is preferably barium titanate, and α=1. Furthermore, the dielectric ceramic according to the present invention is preferably obtained by firing in the atmosphere
Data Source
AI summary
A dielectric ceramic that contains, as its main constituent, a perovskite-type compound containing Ba and Ti, and, with respect to the Ti content of 100 parts by mole, contains Re1 (Re1 is at least one element of La and Nd) in the range of 0.15 to 3 parts by mole, Y in the range of 0.1 to 3 parts by mole, Mg in the range of 0.3 to 13 parts by mole, and Fe in the range of 0.01 to 5 parts by mole.