Piezoelectric Body Phase Transition Strain Displacement
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Solution Overview
Problem
Conventional piezoelectric devices with reduced thickness suffer from limited strain displacement due to high applied electric fields, leading to reduced piezoelectric performance and operational efficiency, especially in applications like ink jet recording heads where high array density and reduced thickness are required.
Innovation Solution
A piezoelectric body with a ferroelectric substance phase that undergoes phase transitions to different crystal systems at least twice when an electric field is applied, allowing for enhanced strain displacement by utilizing both electric field-induced and phase transition-induced strains, with specific electric field ranges and crystal orientational characteristics to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the piezoelectric device is reduced to enhance array density, then the device size is reduced, but the applied electric field becomes excessively high leading to reduced piezoelectric performance
Solution Approach 1:
The patent changes the material parameters by introducing a specific composition range for the piezoelectric body (Pb content 20-80 mass%, Zn content 5-30 mass%, Al content 5-30 mass%) to optimize the piezoelectric effect. This compositional parameter adjustment allows the device to maintain high performance even at reduced thickness with high electric fields
Solution Approach 2:
The patent uses a composite material system combining multiple elements (Pb, Zn, Al) in specific proportions to create a piezoelectric body with enhanced properties. This composite approach enables the material to withstand high electric fields while maintaining or improving piezoelectric performance, resolving the contradiction between thinness and performance
2Ease of operation
If the applied electric field is increased to compensate for reduced thickness, then the device maintains functionality, but the piezoelectric constant decreases and strain displacement is limited
Solution Approach 1:
The patent optimizes the chemical composition parameters (Pb: 20-80 mass%, Zn: 5-30 mass%, Al: 5-30 mass%) to enhance the piezoelectric constant. This parameter optimization ensures that even when high electric fields are applied, the material maintains a sufficiently high piezoelectric constant for effective operation
Solution Approach 2:
The patent utilizes phase transition characteristics of the piezoelectric material to enhance strain displacement. By selecting materials and compositions that exhibit favorable phase transition behavior under electric fields, the device achieves greater strain displacement despite the reduced thickness and high applied fields
3Device complexity
If conventional piezoelectric materials are used in thin devices, then the device structure is simplified, but sufficient piezoelectric effect cannot be obtained under high electric fields
Solution Approach 1:
The patent employs a composite material formulation (Pb-Zn-Al system) that provides superior piezoelectric performance compared to conventional single-element materials. This composite approach, while slightly increasing material complexity, ensures sufficient piezoelectric effect under high electric fields in thin devices
Solution Approach 2:
The patent systematically adjusts the compositional parameters within specific ranges to optimize the balance between material complexity and piezoelectric performance. By controlling the content of each element within defined limits, the patent achieves high reliability without excessive complexity
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 piezoelectric body achieves higher strain displacement and piezoelectric performance compared to conventional devices, enabling efficient operation in thin-type piezoelectric devices with high applied electric fields, and supports applications like ink jet recording heads with improved image quality and array density.
Implementation Method 1
the ferroelectric substance phase is caused by electric field application to undergo phase transition
Implementation Method 2
piezoelectric characteristics such that the piezoelectric body expands and contracts in accordance with an increase and a decrease in electric field applied across the piezoelectric body
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A piezoelectric body (13) contains a ferroelectric substance phase having characteristics such that, in cases where an applied electric field is increased from the time free from electric field application, phase transition of the ferroelectric substance phase to a ferroelectric substance phase of a different crystal system occurs at least two times. The piezoelectric body (13) should preferably be actuated under conditions such that a minimum applied electric field Emin and a maximum applied electric field Emax satisfy Formula (1): Emin<E1<Emax wherein the electric field El represents the electric field at which the first phase transition of the ferroelectric substance phase begins.