Lead-Free Piezoelectric Element Microstructure Optimization
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Solution Overview
Problem
Lead-based piezoelectric elements pose environmental concerns due to lead contamination, and lead-free alternatives suffer from insufficient vibration velocity and excessive power consumption.
Innovation Solution
A lead-free piezoelectric element with alternately laminated piezoelectric and electrode layers, featuring specific thickness and diameter ratios of crystal particles and void portions, and a barium titanate-based material, ensuring high piezoelectric constant and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric material is used to reduce environmental impact, then lead contamination is minimized, but vibration velocity becomes insufficient and power consumption increases
Solution Approach 1:
The patent changes the microstructural parameters of the piezoelectric material by controlling crystal particle size (5-20 μm) and creating a specific void portion structure with controlled size (0.1-5 μm) and distribution. These parameter changes optimize the piezoelectric properties to achieve sufficient vibration velocity while maintaining lead-free composition
Solution Approach 2:
The patent creates a composite microstructure within the piezoelectric material layer that includes crystal particles and void portions. This composite structure at the microscale enhances the piezoelectric constant and vibration characteristics while maintaining the lead-free bulk material composition
2Object-affected harmful factors
If lead-free piezoelectric material is used to reduce environmental impact, then lead contamination is minimized, but power consumption becomes excessive
Solution Approach 1:
The patent optimizes microstructural parameters including crystal particle size (5-20 μm) and void portion characteristics (size 0.1-5 μm, volume ratio 1-30%) to enhance piezoelectric efficiency. These parameter changes reduce energy loss and improve conversion efficiency, thereby reducing power consumption while maintaining lead-free composition
3Power
If sintering temperature is increased to increase particle diameter and piezoelectric constant, then piezoelectric constant increases, but flatness of piezoelectric material layer is lost causing warpage and interlayer peeling
Solution Approach 1:
The patent changes the sintering parameters by using a lower temperature range (900-1100°C) compared to conventional methods. This parameter change prevents excessive particle growth and maintains layer flatness while still achieving the desired piezoelectric constant through optimized particle size control (5-20 μm) and void structure creation
Solution Approach 2:
The patent introduces a controlled porous structure with void portions (size 0.1-5 μm, volume ratio 1-30%) in the piezoelectric material layer. This porous microstructure accommodates thermal stress and prevents warpage and interlayer peeling during sintering, maintaining flatness while achieving adequate piezoelectric constant
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 enables efficient driving of piezoelectric elements, vibrators, vibration wave motors, and electronic devices with improved vibration velocity and reduced power consumption while minimizing environmental impact.
Implementation Method 1
The piezoelectric element has a structure in which piezoelectric material layers and electrode layers are laminated and obtains large deformation and distortion at a low voltage
Data Source
AI summary
A piezoelectric element, in which a piezoelectric material layer has a plurality of crystal particles and a plurality of void portions and, in at least one of two or more of the piezoelectric material layers, when the average thickness in the lamination direction of the piezoelectric material layer is defined as TP, the average circle-equivalent diameter of the plurality of crystal particles is defined as DG, the maximum length in the lamination direction of the plurality of void portions not contacting the electrode layers is defined as LV, and the average thickness of the electrode layers contacting the at least one piezoelectric material layer is defined as TE, 0.07TP≤DG≤0.33TP and TE≤LV≤0.3TP are established and the lead content is less than 1000 ppm.