Lead-Free Piezoelectric Material Composition for High Insulation

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Solution Overview

Problem

Existing piezoelectric materials face challenges in achieving a balance between high piezoelectric performance and mechanical quality factor, particularly in sodium niobate and barium titanate (NN-BT) compositions, which often result in low insulation resistance and reduced polarization.

Innovation Solution

A lead-free and potassium-free piezoelectric material is developed, comprising a perovskite-type metal oxide with specific compositions of sodium, barium, niobium, titanium, zinc, magnesium, and manganese, optimized to enhance piezoelectric constants and mechanical quality factors while maintaining satisfactory insulation properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cobalt is added to increase piezoelectric constant, then piezoelectric performance is improved, but insulation resistance deteriorates

Engineering Contradiction:
Improvepiezoelectric constantVSAvoidinsulation resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention removes cobalt from the piezoelectric material composition to eliminate the harmful effect of deteriorated insulation resistance while maintaining lead-free and potassium-free formulation. This extraction of the problematic element resolves the contradiction by sacrificing some piezoelectric enhancement in exchange for significantly improved insulation properties.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention optimizes the compositional parameters of the perovskite-type metal oxide by precisely controlling the ratios of sodium, barium, niobium, and titanium within specific ranges. This parameter optimization achieves satisfactory piezoelectric performance without requiring cobalt addition, thereby maintaining high insulation resistance.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If barium titanate concentration is increased to improve piezoelectric constant, then piezoelectric performance is improved, but mechanical quality factor decreases

Engineering Contradiction:
Improvepiezoelectric constantVSAvoidmechanical quality factor
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention optimizes the barium titanate concentration within a specific range (9% to 11% as disclosed in PTL 1, but improved in this invention) and balances it with precise control of sodium niobate content and stoichiometric ratios. This parameter optimization achieves a balance point where both piezoelectric constant and mechanical quality factor are satisfactory simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite perovskite structure combining sodium niobate and barium titanate in optimized proportions, along with other elements, to achieve synergistic effects that simultaneously improve piezoelectric constant and mechanical quality factor, resolving the trade-off between these two properties.

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If lead-free and potassium-free composition is used, then environmental compatibility is improved, but achieving high piezoelectric performance and mechanical quality factor simultaneously becomes difficult

Engineering Contradiction:
Improveenvironmental compatibilityVSAvoidpiezoelectric performance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention develops a multi-element composite perovskite-type metal oxide containing sodium, barium, niobium, titanium, and other elements in specific ratios. This composite formulation achieves high piezoelectric performance and mechanical quality factor simultaneously without using lead or potassium, thus maintaining environmental compatibility.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention optimizes the compositional parameters including the ratios of A-site elements (sodium, barium) and B-site elements (niobium, titanium) within specific ranges to achieve satisfactory piezoelectric performance in a lead-free, potassium-free system, resolving the difficulty of achieving high performance without toxic elements.

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 material achieves high piezoelectric constants and mechanical quality factors, along with improved insulation properties, making it suitable for various applications without environmental concerns associated with lead and potassium.

Implementation Method 1

Piezoelectric materials are generally ABO3 perovskite-type metal oxides such as lead zirconate titanate (hereinafter referred to as 'PZT')

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The piezoelectric material according to aspects of the present invention for solving the above-mentioned problems includes a main component containing a perovskite-type metal oxide represented by Formula (1), a Zn component, a Mg component, and a Mn component

Methodology Applied
Scientific EffectDoping effect: Dopants

Data Source

PatentEP3278376B1Piezoelectric material, piezoelectric element, and electronic apparatus
Publication Date: 2020.12.02 CANON KK
  • EP3278376B1 patent drawingFigure 1
  • EP3278376B1 patent drawingFigure 2A~2B
  • EP3278376B1 patent drawingFigure 3A~3B

AI summary

The disclosed piezoelectric material includes a perovskite-type metal oxide (NaxBa1-y)(NbyTi1-y)O3, where 0.83≦x≦0.95, 0.85≦y≦0.95, 0.95≦x/y≦1.05, as a main component, Zn, and Mg. The Zn content is between 0.5 and 5 mol% and the Mg content is between 0.1 and 2 mol% based on the perovskite-type metal oxide.