Piezoelectric Element Orientation and Cracking Control
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Solution Overview
Problem
Piezoelectric layers composed of Pb(Mg,Nb)O3, PbZrO3, and PbTiO3 in liquid ejecting heads face challenges with orientation difficulties, leading to cracking and increased leakage current, which affect the reliability and performance of these components.
Innovation Solution
A piezoelectric element design featuring a first piezoelectric layer with a perovskite structure containing lead, zirconium, and titanium, and a second piezoelectric layer with a specific complex oxide structure, both preferentially oriented to (100) to enhance stability and reduce cracking, is introduced. The layers are formed using a sol-gel method and include an orientation control layer to improve orientation ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric layer composed of Pb(Mg,Nb)O3, PbZrO3, and PbTiO3 is used, then the piezoelectric characteristics are improved, but the layer is not readily oriented leading to cracking and increased leakage current
Solution Approach 1:
The piezoelectric layer is divided into two distinct layers: a first piezoelectric layer with high orientation ratio and a second piezoelectric layer with specific compositional ratios. This segmentation allows each layer to fulfill different functional requirements - the first layer provides orientation stability while the second layer provides piezoelectric performance
Solution Approach 2:
Different regions of the piezoelectric structure are assigned different material compositions and properties. The first piezoelectric layer uses a composition optimized for orientation (x=0.06-0.15, y=0.40-0.60, z=0.35-0.50), while the second piezoelectric layer uses a composition optimized for piezoelectric characteristics (x=0.15-0.23, y=0.32-0.55, z=0.32-0.54). This local differentiation resolves the contradiction between orientation and piezoelectric performance
2Strength
If the piezoelectric layer is not readily oriented, then cracking may readily occur and leakage current increases
Solution Approach 1:
The first piezoelectric layer is designed with compositional parameters specifically optimized to achieve high orientation ratio before the second layer is formed. This preliminary orientation establishment prevents subsequent cracking issues and ensures proper electrical insulation, making the overall manufacturing process more reliable despite the complexity of dual-layer formation
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 proposed design improves the orientation and reduces cracking and leakage current, leading to enhanced piezoelectric characteristics and reliability in liquid ejecting heads.
Implementation Method 1
a piezoelectric element including a first electrode disposed at a base body, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode
Data Source
AI summary
A piezoelectric element includes a first electrode disposed at a base body, a second electrode, and a piezoelectric layer disposed between the first electrode and the second electrode. The piezoelectric layer includes a first piezoelectric layer containing a complex oxide having a perovskite structure that contains lead, zirconium, and titanium and a second piezoelectric layer containing a complex oxide having a perovskite structure that is denoted by formula (1) below. The first piezoelectric layer is disposed between the first electrode and the second piezoelectric layer and is preferentially oriented to (100) when the crystal structure of the first piezoelectric layer is assumed to be pseudo-cubic,xPb(Mg,Nb)O3-yPbZrO3-zPbTiO3 (1)where in formula (1), 0<x,y,z<1 and x+y+z=1.