Piezoelectric Composition Manganese Copper Downsizing
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Solution Overview
Problem
The challenge is to develop a lead-free piezoelectric composition that maintains high mechanical strength and electromechanical coupling coefficient k31, while minimizing defects and volatilization of alkali metal elements during firing, which is crucial for achieving both performance and downsizing of piezoelectric elements.
Innovation Solution
A piezoelectric composition with a perovskite structure, represented by the formula (KxNay)NbO3, incorporating manganese and copper, where the manganese concentration variation (CV value) is between 35% and 440%, and copper content is between 0.20% and 0.80%, enhancing mechanical strength and electromechanical coupling by optimizing the A/B ratio and Mn distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the piezoelectric composition is reduced to achieve downsizing, then the size of the piezoelectric element is reduced, but the mechanical strength of the piezoelectric composition decreases
Solution Approach 1:
The invention changes the chemical composition parameters of the piezoelectric material by incorporating specific amounts of MnO2 (0.1-5.0 wt%) and CuO (0.1-5.0 wt%) into the alkali metal niobate based compound system. This compositional parameter change enhances the mechanical strength of the piezoelectric composition, enabling it to maintain sufficient strength even when the overall size of the piezoelectric element is reduced for downsizing applications.
2Object-affected harmful factors
If alkali metal niobate based compound is used as lead-free piezoelectric composition, then environmental burden is reduced, but alkali metal elements volatilize during firing causing voids and defects
Solution Approach 1:
The invention introduces MnO2 and CuO as intermediary substances that act as volatilization suppressants for the alkali metal elements during the firing process. These intermediaries form stable compounds or surface layers that prevent the direct volatilization of alkali metals, thereby reducing the formation of voids and defects while maintaining the environmentally friendly lead-free composition.
3Strength
If manganese concentration is increased to enhance mechanical strength, then mechanical strength improves, but electromechanical coupling coefficient may be affected
Solution Approach 1:
The invention optimizes the concentration parameters of multiple additives simultaneously, specifying MnO2 content at 0.1-5.0 wt% and CuO content at 0.1-5.0 wt%. This dual-parameter optimization ensures that the mechanical strength is enhanced by manganese while the electromechanical coupling coefficient is maintained or improved through the synergistic effect of copper addition, preventing the deterioration that would occur with manganese alone.
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 composition achieves both high mechanical strength and electromechanical coupling coefficient k31, improving processability and yield by ensuring the piezoelectric element can withstand repeated mechanical and electrical displacements, and reducing defects during processing.
Implementation Method 1
the piezoelectric composition has, based on a spontaneous polarization due to bias of an electric charge in crystals, an effect (a piezoelectric effect) of generating electric charge on the surface due to receiving an external stress and an effect (a converse piezoelectric effect) of generating distortion due to an application of an external electric field
Data Source
AI summary
A piezoelectric composition including manganese and a complex oxide having a perovskite structure represented by a general formula ABO3, wherein an A site element in the ABO3 is potassium or potassium and sodium, a B site element in the ABO3 is niobium, a concentration distribution of the manganese has a variation, and the variation shows a CV value of 35% or more and 440% or less.