Lead-Free Piezoelectric Element with Uniaxially Oriented Electrodes
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Solution Overview
Problem
Existing piezoelectric elements, such as those using lead zirconate titanate (PZT), face environmental concerns due to lead content, and lead-free alternatives like Bi(Zn0.5Ti0.5)O3 and BiFeO3 struggle with achieving high piezoelectric strain and practical application, particularly in film-shaped forms.
Innovation Solution
A piezoelectric element featuring a perovskite-type metal oxide film represented by the formula Ax(ZnjTi(1-j))l(MgkTi(1-k))mMnO3, where A includes Bi and other trivalent metals, with specific composition ratios and orientation, is used, along with uniaxially oriented electrodes, to enhance piezoelectric strain and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free perovskite-type metal oxide is used as piezoelectric material, then environmental compatibility is improved, but piezoelectric strain is insufficient
Solution Approach 1:
The invention uses a composite perovskite-type metal oxide containing multiple elements (Bi, Zn, Ti, Mg, and trivalent metal elements Fe, Al, Sc, Mn, Y, Ga, or Yb) to achieve both environmental compatibility and high piezoelectric strain. The specific compositional ratios and the combination of different metal elements create a material that maintains lead-free status while achieving sufficient piezoelectric performance for practical applications.
Solution Approach 2:
The invention applies uniaxial (111) orientation in the thickness direction to create anisotropic piezoelectric properties. By orienting the crystal structure in a specific direction, the piezoelectric strain is enhanced along the thickness direction while maintaining environmental compatibility through the lead-free composition.
2Force
If Bi(Zn0.5Ti0.5)O3 is used as piezoelectric material, then theoretical piezoelectric performance is expected to be excellent, but polarization is difficult due to high Curie temperature
Solution Approach 1:
The invention modifies the compositional parameters by introducing Mg and trivalent metal elements into the Bi(Zn0.5Ti0.5)O3 structure, creating a multi-element perovskite that lowers the Curie temperature while maintaining or enhancing piezoelectric performance. This compositional adjustment makes polarization more achievable in practical manufacturing conditions.
Solution Approach 2:
The invention creates a composite perovskite structure combining Bi, Zn, Ti, Mg, and trivalent metal elements to achieve a balance between Curie temperature and piezoelectric performance. The synergistic effect of multiple elements allows for easier polarization while maintaining excellent theoretical piezoelectric performance.
3Strength
If uniaxially oriented perovskite-type metal oxide electrode is used, then interlayer adhesion is improved, but device complexity increases
Solution Approach 1:
The invention applies uniaxial (111) orientation specifically to the perovskite-type metal oxide electrode layer to improve interlayer adhesion at the interface with the piezoelectric film. This localized orientation approach enhances adhesion without requiring complex structures throughout the entire device, maintaining relative simplicity while achieving improved bonding.
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 provides a lead-free piezoelectric element with high piezoelectric strain, improved interlayer adhesion, and durability, suitable for applications like liquid discharge heads, while maintaining environmental sustainability.
Implementation Method 1
A piezoelectric element featuring a perovskite-type metal oxide film represented by the formula Ax(ZnjTi(1-j))l(MgkTi(1-k))mMnO3
Data Source
AI summary
The piezoelectric element includes, on a substrate: a piezoelectric film; and a pair of electrodes provided in contact with the piezoelectric film; in which the piezoelectric film contains a perovskite-type metal oxide represented by the general formula (1) as a main component:Ax(ZnjTi(1-j))l(MgkTi(1-k))mMnO3 General Formula (1)wherein the perovskite-type metal oxide is uniaxially (111)-oriented in pseudo-cubic notation in a thickness direction, of the pair of electrodes, a lower electrode provided on the substrate side is a multilayer electrode including at least a first electrode layer in contact with the substrate and a second electrode layer in contact with the piezoelectric film, and the second electrode layer is a perovskite-type metal oxide electrode which is uniaxially (111)-oriented in pseudo-cubic notation in a thickness direction.