Piezoelectric Element Lead Concentration Gradient
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Solution Overview
Problem
Piezoelectric elements used in liquid ejecting heads face challenges in achieving sufficient performance due to deterioration of crystals near the interface between the piezoelectric layer and electrodes, requiring improved crystal quality and durability.
Innovation Solution
A piezoelectric element with a compound oxide layer containing lead, zirconium, and titanium, featuring a lead concentration gradient region between the conductive layers, which enhances crystal quality and durability by optimizing lead composition and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform piezoelectric material layer is formed over the entire surface and cut by lithography, then the piezoelectric element can be driven independently for each pressure-generating chamber, but the crystal quality deteriorates near the interface between the piezoelectric layer and electrodes
Solution Approach 1:
The invention applies local quality by creating a lead concentration gradient within the piezoelectric layer, where the lead concentration varies from 95-98 atom% near the first electrode interface to 98-100 atom% in the bulk region. This spatial variation in composition optimizes crystal quality at the critical electrode interface while maintaining the overall functionality of the piezoelectric element for independent chamber driving.
2Manufacturing precision
If the piezoelectric layer is formed by depositing thin films multiple times, then a stable engineered domain with preferential orientation can be achieved, but the crystal deterioration near electrode interfaces still occurs
Solution Approach 1:
The invention employs parameter changes by modifying the lead concentration parameter within the piezoelectric layer. By controlling the lead concentration to increase from the electrode interface toward the bulk (95-98 atom% at interface to 98-100 atom% in bulk), the crystal quality is improved at the critical interface region while maintaining the engineered domain structure and preferential orientation achieved through multi-step thin film deposition.
3Reliability
If lattice matching between electrode material and piezoelectric layer is improved, then crystal quality may be enhanced, but additional material lamination increases device complexity
Solution Approach 1:
Rather than adding intermediate layers throughout the structure, the invention uses local quality by implementing a lead concentration gradient specifically at the electrode-piezoelectric layer interface. This compositional gradient (95-98 atom% Pb near interface increasing to 98-100 atom% in bulk) provides the necessary lattice matching and crystal quality improvement without increasing overall device complexity through additional material lamination.
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 lead concentration gradient region improves crystal orientation and durability, leading to enhanced displacement and electric field distribution, resulting in improved performance and longevity of the piezoelectric element.
Implementation Method 1
Piezoelectric elements have a structure in which a piezoelectric material composed of a crystallized piezoelectric ceramic or the like is interposed between two electrodes. Therefore, the piezoelectric elements can exhibit deformations such as expansion and contraction or the like by applying an electric field to the piezoelectric material.
Data Source
AI summary
A piezoelectric element includes a first conductive layer, a second conductive layer disposed to face the first conductive layer, and a piezoelectric layer disposed between the first conductive layer and the second conductive layer and composed of a compound oxide containing at least lead, zirconium, titanium, and oxygen. The piezoelectric layer includes a lead concentration gradient region in which the lead concentration increases from the first conductive layer side to the second conductive layer side. The lead concentration gradient region is disposed on the first conductive layer side of the piezoelectric layer.