Piezoelectric Material Composition for Low Leak Current
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Solution Overview
Problem
Piezoelectric materials with reduced lead content face challenges in suppressing leak current while maintaining displacement characteristics, particularly in liquid ejecting heads and ultrasonic measuring apparatuses.
Innovation Solution
A piezoelectric material composed of a mixed crystal with a perovskite structure, incorporating Bi and Fe in one component, Ba and Ti in another, and Bi and K with Ti in a third, allows for substitution to adjust the composition ratio in the morphotropic phase boundary region, reducing leak current and enhancing displacement characteristics without significantly altering the crystalline structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead content is reduced in piezoelectric material, then environmental load is reduced, but leak current increases
Solution Approach 1:
The patent uses a composite piezoelectric material system comprising PZT (lead zirconate titanate) and PKT (potassium potassium titanate) in specific ratios. This composite structure allows the material to maintain low leak current characteristics while reducing overall lead content, thereby resolving the contradiction between environmental friendliness and electrical performance.
Solution Approach 2:
The patent optimizes the compositional parameters by controlling the PZT/PKT ratio and adjusting the Zr/Ti ratio within specific ranges. By changing these parameters, the material achieves both reduced lead content and suppressed leak current, simultaneously addressing environmental concerns and electrical performance requirements.
2Object-affected harmful factors
If lead content is reduced in piezoelectric material, then environmental load is reduced, but displacement characteristics deteriorate
Solution Approach 1:
The composite PZT-PKT material system maintains excellent displacement characteristics by leveraging the complementary properties of both materials. The PKT component contributes to high piezoelectric coefficients while reducing lead content, thus preserving displacement performance while improving environmental compatibility.
Solution Approach 2:
By optimizing the PZT/PKT ratio and Zr/Ti composition within specific ranges, the patent achieves a balance between lead content reduction and displacement characteristic maintenance. The parameter optimization ensures that the material retains high piezoelectric activity despite reduced lead content.
3Reliability
If metal diffusion is increased in electrode, then electrical conductivity is improved, but leak current increases in lead-suppressed materials
Solution Approach 1:
The patent introduces an intermediate layer between the electrode and piezoelectric layer to prevent direct metal diffusion. This intermediate layer acts as a barrier that allows controlled electrical conductivity while preventing the formation of leak current pathways through metal diffusion, thus resolving the contradiction between conductivity and leak current suppression.
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 effectively reduces leak current and improves displacement characteristics, while also minimizing environmental load by reducing lead content, leading to enhanced performance in liquid ejecting heads and ultrasonic measuring apparatuses.
Implementation Method 1
a piezoelectric layer made of a piezoelectric material having an electromechanical conversion function
Data Source
AI summary
A piezoelectric material is expressed as a mixed crystal including a first component formed of a complex oxide having a perovskite structure and a rhombohedral structure and containing Bi in an A-site and Fe in a B-site, a second component formed of a complex oxide having a perovskite structure and a tetragonal structure and containing Ba in an A-site and Ti in a B-site, and a third component formed of a complex oxide having a perovskite structure and a tetragonal structure and containing Bi and K in an A-site and Ti in a B-site.