KNN Piezoelectric Layer Composition for Low-Leakage Thin Elements
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Solution Overview
Problem
Piezoelectric elements based on potassium sodium niobate (KNN) face challenges with reduced insulation and leakage characteristics when thinned, and existing solutions do not adequately improve displacement and insulation simultaneously.
Innovation Solution
A piezoelectric element with a piezoelectric layer containing potassium, sodium, niobium, oxygen, and carbon, where the carbon to oxygen intensity ratio is between 3.1×10−3 and 9.1×10−3, and the inclusion of transition metals like manganese or copper to enhance insulation and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the piezoelectric layer containing KNN is thinned to reduce device size, then the displacement amount and response speed are improved, but the insulation is lowered and leakage characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the piezoelectric layer by controlling the ratio of potassium to sodium and adding specific metal elements (Mn, Fe, Co, Ni, Cu, or Zn) at precisely controlled concentrations (0.01-5 wt%). This compositional parameter adjustment enables the thin piezoelectric layer to achieve both good insulation and acceptable leakage characteristics while maintaining the desired device size reduction
Solution Approach 2:
The patent creates a composite piezoelectric material system by combining KNN base material with small amounts of transition metal elements (Mn, Fe, Co, Ni, Cu, or Zn). This composite approach allows the thin piezoelectric layer to achieve both good insulation and acceptable leakage characteristics while maintaining the desired device size reduction
2Reliability
If a material having high insulation is disposed between the piezoelectric layer and upper electrode to improve insulation, then insulation is improved, but the displacement amount of the piezoelectric element is reduced
Solution Approach 1:
Instead of inserting an additional insulating material layer that would reduce displacement, the patent changes the compositional parameters of the piezoelectric layer itself by controlling K:Na ratio and adding transition metal elements. This allows the piezoelectric layer to achieve good insulation inherently while maintaining its electromechanical coupling and displacement capability
3Reliability
If Mn is added to the piezoelectric layer to improve insulation, then insulation is improved, but sufficient insulation is difficult to provide because Mn is contained only in a part of the piezoelectric film
Solution Approach 1:
The patent optimizes the concentration parameter of transition metal elements to 0.01-5 wt%, which is sufficient to improve insulation without causing aggregation or non-uniform distribution. This precise parameter control ensures uniform insulation enhancement throughout the entire piezoelectric layer
Solution Approach 2:
The patent creates a uniformly distributed composite structure where transition metal elements are dispersed at the atomic or molecular level within the KNN matrix. This uniform composite distribution ensures consistent insulation properties throughout the piezoelectric layer, avoiding the localized insulation issues seen with Mn-only additions
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 improves the insulation and leakage characteristics of the piezoelectric element, maintaining excellent piezoelectric performance while reducing carbon concentration, thereby enhancing the overall efficiency of the piezoelectric element.
Implementation Method 1
a piezoelectric layer having an electromechanical conversion characteristic
Data Source
AI summary
A piezoelectric element according to the present disclosure includes: a substrate; a first electrode formed on the substrate; a piezoelectric layer formed on the first electrode; and a second electrode formed on the piezoelectric layer, in which the piezoelectric layer contains potassium, sodium, niobium, oxygen, and carbon, and in secondary ion mass spectrometry in the piezoelectric layer, a ratio of a maximum intensity of carbon to a maximum intensity of oxygen is 3.1×10−3 or more and 9.1×10−3 or less.