Double PZT Piezoelectric Actuator with Different Permittivities
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Solution Overview
Problem
Existing piezoelectric actuators using tetragonal-system PZT piezoelectric layers face issues with surface roughness leading to deteriorated breakdown voltage characteristics due to local electric field focusing and generation of leakage paths, which are not effectively addressed by previous methods that either complicate manufacturing or result in mechanical instability.
Innovation Solution
A piezoelectric actuator design where a first PZT piezoelectric layer with a higher relative permittivity is formed on a lower electrode layer, followed by a second PZT piezoelectric layer with a lower relative permittivity, achieved through controlled evaporation amounts in an arc discharge ion plating process, reducing surface roughness and suppressing leakage path generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single PZT piezoelectric layer is used, then the manufacturing process is simple, but the breakdown voltage characteristics deteriorate due to surface roughness causing local electric field focusing and leakage path generation
Solution Approach 1:
The single PZT layer is divided into multiple PZT piezoelectric layers with different relative permittivities (first PZT layer with higher permittivity, second PZT layer with lower permittivity). This segmentation reduces surface roughness and prevents leakage path formation, thereby improving breakdown voltage characteristics while maintaining manufacturing simplicity through sequential deposition processes
Solution Approach 2:
The patent uses a composite structure of multiple PZT layers with different relative permittivities (different compositional ratios of PbZr1-xTixO3). The first PZT layer has a higher relative permittivity (larger x value) and the second PZT layer has a lower relative permittivity (smaller x value), creating a composite material system that reduces surface roughness and improves electrical breakdown characteristics
2Reliability
If multiple PZT layers with different permittivities are used, then breakdown voltage characteristics improve, but the device structure becomes more complex
Solution Approach 1:
Different regions of the piezoelectric structure are assigned different local properties: the first PZT layer has a higher relative permittivity (larger x value in PbZr1-xTixO3) to provide strong piezoelectric effect, while the second PZT layer has a lower relative permittivity (smaller x value) to reduce surface roughness. This local quality differentiation improves breakdown voltage characteristics without requiring complex external control systems
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 approach significantly improves breakdown voltage characteristics by minimizing surface roughness and preventing leakage path formation, while maintaining comparable piezoelectric performance.
Implementation Method 1
arc discharge ion plating process
Implementation Method 2
arc discharge ion plating process
Implementation Method 3
PZT generates a polarization when PZT is distorted along its c-axis direction or a-axis direction, thus exhibiting an excellent piezoelectric characteristic
Data Source
AI summary
In a piezoelectric actuator including a lower electrode layer, a first PZT piezoelectric layer having a first relative permittivity is formed on the lower electrode layer, and a second PZT piezoelectric layer having a second relative permittivity smaller than said first relative permittivity is formed on the first PZT piezoelectric layer.