Core-Shell Barium Titanate Capacitor for Insulation Reliability

Solution Overview

Problem

Capacitors with dielectric layers containing rare earth elements face a decrease in insulation reliability due to oxygen defects in barium titanate, which are exacerbated by the presence of holmium.

Innovation Solution

A capacitor design incorporating a dielectric layer with crystal grains having a core-shell structure, where the shell contains holmium, nickel, and iron in specific atomic percentages, enhancing the insulation reliability by inhibiting oxygen defect migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If rare earth elements are added to the dielectric layer to improve capacitance and high-temperature load life, then the capacitance and high-temperature load life are improved, but the insulation reliability decreases due to oxygen defects in barium titanate

Engineering Contradiction:

Improvehigh-temperature load lifeVSAvoidinsulation reliability

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the shell portion has a different composition than the core. The shell contains holmium at 0.5-5 at% along with nickel and iron, which are specifically distributed in the shell region to suppress oxygen defect migration at the grain boundaries, while the core maintains the barium titanate base composition for capacitance. This localized compositional differentiation resolves the contradiction by protecting the grain boundary regions where oxygen defects typically migrate, thereby improving insulation reliability without sacrificing the high-temperature load life benefits of rare earth element addition.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining barium titanate with rare earth elements (holmium, nickel, iron) in a core-shell structured crystal grain. The shell portion acts as a composite layer with specific elemental composition designed to suppress oxygen defect migration, while the core maintains the dielectric properties. This composite structure allows the capacitor to simultaneously achieve improved high-temperature load life through rare earth element addition and maintained insulation reliability through the protective shell composition.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the content of rare earth elements in the dielectric layer is increased to improve capacitance, then the capacitance is improved, but the proportion of barium titanate with oxygen defects increases, causing a decrease in insulation reliability

Engineering Contradiction:

ImprovecapacitanceVSAvoidinsulation reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the shell portion has a different composition than the core. The shell contains holmium at 0.5-5 at% along with nickel and iron, which are specifically distributed in the shell region to suppress oxygen defect migration at the grain boundaries, while the core maintains the barium titanate base composition for capacitance. This localized compositional differentiation resolves the contradiction by protecting the grain boundary regions where oxygen defects typically migrate, thereby improving insulation reliability without sacrificing the high-temperature load life benefits of rare earth element addition.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful effect of rare earth elements (which increase oxygen defects) into a beneficial effect by using holmium, nickel, and iron in the shell portion to suppress oxygen defect migration. The same rare earth elements that would normally harm insulation reliability are instead used to create a protective shell that prevents oxygen defect migration, thereby converting the harm into a benefit for maintaining insulation reliability while preserving capacitance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20260004973A1Capacitor and method of manufacturing the same

Publication Date: 2026.01.01 TAIYO YUDEN KK

AI summary

One object is to improve the insulation reliability of capacitors having dielectric layers containing rare earth elements. An aspect of the present disclosure provides a capacitor including a body, a first external electrode provided on the body, and a second external electrode provided on the body. The body has a first internal electrode layer, a second internal electrode layer, and a dielectric layer disposed between the first internal electrode layer and the second internal electrode layer. The dielectric layer contains crystal grains of barium titanate. The crystal grains each include a core portion and a shell portion covering the core portion. The concentration of Ho in the shell portion is from 0.5 at % to 5 at %. The concentration of Ni and the concentration of Fe in the shell portion are from 0.3 at % to 3 at %.