Piezoelectric Element with 90° Domain Rotation for Ultrasonic Transducers
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Solution Overview
Problem
Existing piezoelectric elements used in ultrasonic measuring apparatuses and liquid ejecting heads have limitations in achieving high piezoelectric constants, particularly when utilizing 90° domain rotation, which is essential for improved performance and efficiency in these applications.
Innovation Solution
A piezoelectric element is designed with a composite oxide layer having a perovskite structure, specifically formulated as xPb(Ni1/3,Nb2/3)O3-yPbZrO3-zPbTiO3, where the crystal is oriented to {100} and includes regions with (100) and (001) surfaces orthogonal to the stacking direction, allowing for efficient 90° domain rotation and enhanced piezoelectric characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric layer using 90° domain rotation is employed, then displacement characteristics are improved, but the piezoelectric constant remains insufficient for high-performance applications
Solution Approach 1:
The patent changes the compositional parameters of the piezoelectric material by introducing a multi-component system (Pb-Ni-Nb-Zr-Ti) with specific ratio ranges. This compositional parameter optimization enables simultaneous achievement of high piezoelectric constant and effective 90° domain rotation characteristics that were not attainable with conventional single-component materials.
Solution Approach 2:
The patent employs a composite piezoelectric material combining multiple elements (Pb, Ni, Nb, Zr, Ti) in a perovskite structure. This composite approach integrates the beneficial properties of different materials - PZT provides high piezoelectric constant while PNN contributes to 90° domain rotation capability - achieving synergistic effects that resolve the contradiction between piezoelectric constant and displacement efficiency.
2Reliability
If conventional piezoelectric materials are used, then manufacturing is simpler, but piezoelectric characteristics are insufficient for high-density liquid ejecting heads
Solution Approach 1:
The patent defines specific compositional parameter ranges (x: 10-40, y: 0.1-0.7, z: 0.1-0.7) that optimize piezoelectric characteristics while maintaining manufacturability. These parameter specifications provide clear manufacturing guidelines that balance performance requirements with production feasibility.
Solution Approach 2:
The composite Pb-Ni-Nb-Zr-Ti perovskite material combines multiple functional components in a unified crystal structure. This composite approach achieves superior piezoelectric characteristics compared to conventional materials while using standard ceramic processing techniques, making the complexity manageable through established manufacturing methods.
3Productivity
If crystal orientation is optimized for 90° domain rotation, then displacement efficiency improves, but piezoelectric constant decreases
Solution Approach 1:
The patent optimizes the compositional parameters to achieve a specific c-axis to a-axis ratio range (1.015-1.026) in the tetragonal crystal structure. This parameter optimization creates a balanced crystal structure that maintains both the piezoelectric constant and the efficiency of 90° domain rotation, resolving the trade-off between these two characteristics.
Solution Approach 2:
The composite material structure with mixed (100) and (001) crystal regions creates a unique microstructure that enables simultaneous optimization of piezoelectric constant and 90° domain rotation efficiency. The perovskite structure with specific element distribution allows both characteristics to coexist at high levels.
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
This configuration significantly improves the piezoelectric constant and piezoelectric characteristics of the element, enabling higher efficiency in displacement and ultrasonic wave transmission/reception, and allows for the development of high-performance liquid ejecting heads and ultrasonic measuring apparatuses.
Implementation Method 1
PZT basically has a structure of a rhombohedral crystal and shows piezoelectric characteristics (distortion quantity) by inducing electric dipole moment which occurs by applying an electric field
Implementation Method 2
an electric field is applied to a tetragonal crystal in which an a-axial component, a b-axial component, and c-axial component are mixed, and thus the a-axial component and the b-axial component are rotated by 90° for the c-axial component
Data Source
AI summary
Provided is a piezoelectric element in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate, the piezoelectric layer being formed of composite oxide having a perovskite structure which contains at least Pb, Nb, and Ti, in which the piezoelectric layer has a tetragonal crystal structure, the crystal is oriented to {100} against the substrate, and regions are mixed in a crystal lattice, each region including a (100) plane and a (001) plane which are orthogonal to a stacking direction, and the composite oxide of the piezoelectric layer is represented by the following general expression.xPb(Ni1/3,Nb2/3)O3-yPbZrO3-zPbTiO3 (10≦x≦40, 0<y≦40, 50≦z≦90)