Piezoelectric Ceramic Composition for Liquid Droplet Ejection Head
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Solution Overview
Problem
The piezoelectric ceramic composition mainly composed of KNbO3 - NaNbO3 has a low piezoelectric constant, making it less suitable for use in liquid droplet ejection heads, and it exhibits a second-order phase transition near room temperature, which can lead to property degradation.
Innovation Solution
A liquid droplet ejection head using a piezoelectric ceramic composition represented by the formula (1-y-z-w)(Kx Na1-x)NbO3 + yLiNbO3 + zSrTiO3 + wBiFeO3, where 0.4 < x < 0.6, 0 < y ≤ 0.1, 0 < z < 0.1, 0 < w < 0.09, and 0.03 < y + z + w ≤ 0.12, which enhances the piezoelectric constant and eliminates the second-order phase transition at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If KNbO3-NaNbO3 piezoelectric ceramic composition is used, then lead-free environmental compatibility is achieved, but piezoelectric constant is too low for practical use
Solution Approach 1:
The patent uses a composite piezoelectric ceramic material combining KNbO3, NaNbO3, LiNbO3, and SrTiO3 in specific proportions. This composite structure maintains the lead-free advantage while achieving a piezoelectric constant of 150 pC/N or more through synergistic effects of the multiple components, particularly utilizing LiNbO3 and SrTiO3 to enhance the piezoelectric properties of the base KNbO3-NaNbO3 system.
Solution Approach 2:
The patent optimizes the compositional parameters by precisely controlling the molar ratios of KNbO3 (0.4-0.6), NaNbO3 (0.03-0.12), LiNbO3 (0.01-0.05), and SrTiO3 (0.01-0.05). This parameter optimization transforms the base material's insufficient piezoelectric constant into a practical value suitable for liquid droplet ejection heads while maintaining environmental compatibility.
2Temperature
If KNbO3-NaNbO3 piezoelectric ceramic composition is used, then high Curie temperature is achieved, but second-order phase transition occurs near room temperature causing property degradation
Solution Approach 1:
The patent modifies the phase transition behavior by changing the compositional parameters. By incorporating LiNbO3 and SrTiO3 into the KNbO3-NaNbO3 system and optimizing their ratios, the second-order phase transition temperature is shifted away from the room temperature range (10-40°C), eliminating the property degradation issue while preserving the high Curie temperature advantage.
Solution Approach 2:
LiNbO3 and SrTiO3 act as intermediary components that mediate the phase transition behavior of the KNbO3-NaNbO3 system. These intermediary materials suppress the harmful second-order phase transition near room temperature through solid solution formation, stabilizing the crystal structure and preventing property degradation during temperature cycling.
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 modified piezoelectric ceramic composition achieves a higher piezoelectric constant and stable liquid ejection properties without second-order phase transitions near room temperature, ensuring reliable performance in liquid droplet ejection heads.
Implementation Method 1
a piezoelectric actuator using a piezoelectric ceramic composition
Data Source
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AI summary
A droplet ejection head provided with a piezoelectric actuator made by using a KNbO3-NabO3 piezoelectric porcelain composition which exhibits a larger piezoelectric constant than those of conventional ones and does not have any secondary phase transition point in the neighborhood of room temperature (from 10 to 40°C) and which is suitable for use in the piezoelectric actuator of a droplet ejection head, that is, a droplet ejection head characterized by being provided with a piezoelectric actuator made by using a piezoelectric porcelain composition represented by the general formula: (1-y-z-w)(KxNa1-x)NbO3 + yLiNbO3 + zSrTiO3 + wBiFeO3, wherein (KxNa1-x)NbO3 represents potassium sodium niobate; LiNbO3 represents lithium niobate; SrTiO3 represents strontium titanate; and RifeO3 represents bismuth ferrate; with the proviso that 0.4 < x <0.6, 0 < y ≤ 0.1, 0 < z < 0.1, 0 < w < 0.09, and 0.03<y+z+w≤0.12.