Piezoelectric Element Gradient Composition Crystal Quality
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Solution Overview
Problem
Piezoelectric elements 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 for enhanced electromechanical conversion.
Innovation Solution
A piezoelectric element with a compound oxide layer containing lead, zirconium, and titanium, featuring a first crystal layer on one conductive layer side and a second crystal layer closer to the second conductive layer, where lead concentration is lower on the first side and oxygen concentration is higher, improving crystal quality and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a piezoelectric material layer is formed uniformly over the entire surface and cut by lithography, then independent actuation for each pressure-generating chamber is achieved, but crystal deterioration occurs near the interface between the piezoelectric layer and electrodes
Solution Approach 1:
The patent applies local quality by creating a gradient in lead concentration and oxygen concentration within the piezoelectric layer. The lead concentration is lower near the electrode interface and increases toward the center, while oxygen concentration shows the opposite gradient. This non-uniform composition distribution suppresses crystal deterioration at the interface while maintaining piezoelectric functionality, directly addressing the contradiction between achieving independent actuation and preserving crystal quality.
2Stability of the object's composition
If piezoelectric material is applied multiple times to form a piezoelectric layer, then stable formation with preferential orientation is achieved, but sufficient performance becomes difficult to achieve
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the piezoelectric material. Specifically, it establishes a gradient in lead concentration and oxygen concentration within the layer, and optimizes the ratio between titanium and zirconium atoms. These parameter changes enable the material to maintain stable preferential orientation while achieving sufficient piezoelectric performance that cannot be obtained by simple multiple applications.
3Reliability
If lattice matching between electrode material and piezoelectric layer is improved, then crystal quality is enhanced, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating spatially varying composition within the piezoelectric layer. The lead concentration is lower near the electrode interface where crystal deterioration occurs, and increases toward the center. Similarly, oxygen concentration shows a reverse gradient. This local variation in composition suppresses interface degradation and improves overall crystal quality without requiring complex electrode materials or additional lattice-matching layers.
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 enhances the crystal quality and durability of the piezoelectric element, leading to improved displacement and operational characteristics, particularly in liquid ejecting applications.
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 facing the first conductive layer, and a piezoelectric layer between the first and second conductive layers, composed of a compound oxide containing at least lead, zirconium, titanium, and oxygen. The piezoelectric layer includes a first crystal layer on the first conductive layer side of the piezoelectric layer and a second crystal layer continued from the first crystal layer, nearer to the second conductive layer side than the first crystal layer. In the piezoelectric layer, the lead concentration in the first conductive layer side of the first crystal layer is lower than that in the second conductive layer side of the second crystal layer. In the piezoelectric layer, the oxygen concentration in the first conductive layer side of the first crystal layer is higher than that in the second conductive layer side of the second crystal layer.