Multi-layer Piezoelectric Element Oxygen Vacancy Suppression

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Multi-layer piezoelectric elements experience a decrease in displacement due to increased oxygen vacancies in electric-field concentration parts when continuously driven in high-temperature conditions, leading to deterioration of piezoelectric characteristics.

Innovation Solution

Incorporating a resin that evolves OH− when heated, which supplies oxygen to the piezoelectric layers, thereby suppressing the increase of oxygen vacancies in electric-field concentration parts, and using an imide-series resin with a high imidization rate of 80% to 98% for effective oxygen supply and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multi-layer piezoelectric element is continuously driven in high-temperature conditions, then oxygen vacancies migrate toward electric-field concentration parts, but this causes deterioration of piezoelectric characteristics and decrease of displacement amount

Engineering Contradiction:

Improvepiezoelectric characteristics stabilityVSAvoidoxygen vacancy migration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A resin layer is introduced as an intermediary substance between the piezoelectric layers and the external environment. This resin evolves OH− groups when heated, which act as oxygen donors to suppress oxygen vacancy migration in the piezoelectric layers during high-temperature operation, thereby maintaining piezoelectric characteristics without requiring structural changes to the piezoelectric element itself

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical state of the resin is changed through heating, which triggers the evolution of OH− groups. This parameter change (from stable resin to active oxygen-supplying state) occurs at operating temperatures, dynamically counteracting oxygen vacancy migration only when and where needed during high-temperature driving conditions

Inventive Principle:

Principle #35Parameter changes

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 solution effectively suppresses the increase of oxygen vacancies and maintains the displacement amount even after long-term continuous use in high-temperature conditions, ensuring high reliability and stability of the multi-layer piezoelectric element.

Implementation Method 1

a resin which evolves OH− when being heated

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

a stacked body composed of piezoelectric layers and internal electrode layers

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9932946B2Multi-layer piezoelectric element, and piezoelectric actuator, injection device, and fuel injection system provided with the same

Publication Date: 2018.04.03 KYOCERA CORP

AI summary

There are provided a multi-layer piezoelectric element in which an increase of oxygen vacancies in an electric-field concentration part of piezoelectric layers is suppressed and a decrease of an amount of displacement is suppressed, as well as to provide a piezoelectric actuator, an injection device and a fuel injection system provided with the multi-layer piezoelectric element. A multi-layer piezoelectric element includes a stacked body composed of piezoelectric layers and internal electrode layers which are stacked on each other, and a resin which evolves OH− when being heated. Accordingly, it is possible to obtain a multi-layer piezoelectric element in which an increase of oxygen vacancies in an electric-field concentration part of piezoelectric layers is suppressed and a decrease of an amount of displacement is suppressed.