Piezoelectric Element Grain Boundary Potassium Gradient
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Solution Overview
Problem
Current piezoelectric elements, particularly those using potassium sodium niobate (KNN) materials, face challenges in optimizing piezoelectric characteristics and reducing crack formation due to variations in potassium and sodium concentrations at grain boundaries and within crystal grains, which affect the material's performance in applications like liquid ejecting heads.
Innovation Solution
A piezoelectric element with a specific atom concentration ratio of potassium and sodium at grain boundaries and within crystal grains, where the concentration of potassium at grain boundaries is higher than in the crystal grains, and sodium is lower, ensuring a stable and enhanced piezoelectric characteristic by controlling the layer structure and heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potassium concentration at grain boundaries is increased to improve piezoelectric characteristics, then piezoelectric performance is enhanced, but crack formation may increase due to compositional imbalance
Solution Approach 1:
The patent applies local quality by creating a specific compositional gradient where potassium concentration is higher at grain boundaries (NK1/NK2 ≥ 1.0) while sodium concentration is lower at grain boundaries (NNa1/NNa2 ≤ 0.75). This localized compositional control enhances piezoelectric characteristics at grain boundaries without causing the compositional imbalance that would lead to crack formation, thereby resolving the contradiction between improved piezoelectric performance and crack resistance.
2Object-affected harmful factors
If non-lead-based piezoelectric materials like KNN are used to reduce ecological load, then environmental friendliness is improved, but control over grain boundary composition becomes more challenging
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atomic concentration ratios of potassium and sodium at grain boundaries versus crystal grains. By设定 specific ranges for NK1/NK2 (≥1.0) and NNa1/NNa2 (≤0.75), the patent achieves optimal grain boundary composition in non-lead-based KNN materials, making the manufacturing process more controllable despite the complexity of working with alternative piezoelectric materials.
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 controlled atom concentration ratios improve piezoelectric characteristics and reduce crack formation, leading to better performance and reliability in piezoelectric elements used in liquid ejecting heads and other applications.
Implementation Method 1
a piezoelectric element... a piezoelectric layer including a plurality of crystal grains containing potassium, sodium, and niobium... an electromechanical conversion characteristic
Data Source
AI summary
Provided is a piezoelectric element including a first electrode provided above a substrate, a piezoelectric layer including a plurality of crystal grains containing potassium, sodium, and niobium and provided above the first electrode, and a second electrode provided above the piezoelectric layer. An atom concentration NK1 (atm %) of potassium contained in grain boundaries of the crystal grains and an atom concentration NK2 (atm %) of potassium contained in the crystal grains satisfy a relationship of 1.0<NK1/NK2≤2.4.