Lead-Free Piezoelectric Ceramic for Stable Droplet Ejection
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Solution Overview
Problem
Piezoelectric ceramic compositions without lead exhibit significant temperature dependence of the piezoelectric constant, leading to unstable liquid ejection properties in liquid droplet ejection heads when used over a wide temperature range.
Innovation Solution
A liquid droplet ejection head employing a piezoelectric actuator with a solid solution of a primary component {Li x (K 1-y Na y ) 1-x }(Nb 1-z-w Ta z Sb w )O 3 and a sub-component ABO 3, where A represents Bi and B represents Fe, In, or Sc, added in less than 1 mol% of the total amount, forming a perovskite structure to reduce temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric ceramic composition is used, then environmental safety is improved, but temperature stability of piezoelectric constant deteriorates
Solution Approach 1:
The patent uses a composite piezoelectric ceramic composition containing multiple phases: a first piezoelectric ceramic phase with perovskite structure (providing piezoelectric properties) and a second ceramic phase (providing thermal stability). This composite structure allows the material to be lead-free while maintaining temperature stability of the piezoelectric constant through the synergistic effect of different phases.
Solution Approach 2:
The patent optimizes specific compositional parameters including the ratio of piezoelectric ceramic to other ceramic (0.2:9.8 to 0.5:9.5), and controls the average particle size (0.5-2.0 μm) and pore volume (30-70%) to achieve both lead-free operation and temperature stability. By carefully adjusting these parameters, the piezoelectric constant maintains stability across temperature ranges.
2Adaptability or versatility
If piezoelectric actuator operates over wide temperature range, then adaptability is improved, but displacement property stability deteriorates
Solution Approach 1:
The composite structure with perovskite-phase piezoelectric ceramic and stabilizing ceramic phase enables the actuator to operate adaptively across wide temperature ranges (0-80°C or wider) while maintaining stable displacement properties. The second ceramic phase acts as a thermal buffer that compensates for temperature-induced variations in the piezoelectric phase.
Solution Approach 2:
The patent creates local structural quality through controlled porosity (30-70% pore volume) and specific particle size distribution (0.5-2.0 μm average) that provides thermal management at the microstructural level, allowing the actuator to maintain displacement stability while adapting to temperature changes.
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 minimizes changes in displacement properties of the piezoelectric actuator, stabilizing liquid ejection properties even with temperature changes, while ensuring the ceramic composition remains lead-free, thus environmentally safe.
Implementation Method 1
a piezoelectric actuator employing a piezoelectric ceramic composition incorporating a solid solution
Data Source
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AI summary
Disclosed is a droplet ejection head comprising a piezoelectric actuator using a piezoelectric porcelain composition containing no lead and having low temperature dependence of piezoelectric constant. Specifically disclosed is a droplet ejection head characterized by comprising a piezoelectric actuator using a piezoelectric porcelain composition containing a solid solution of a main component represented by the general formula (I) below and a sub-component represented by the general formula (II) below which is added in an amount of less than 1 mol% relative to the total amount of the solid solution. General formula (I): {LiX(K1-YNaY)1-X}(Nb1-ZWTazSbW)O3 (wherein 0 ≤ x ≤ 0.2, 0 ≤ y ≤ 1, 0 < z ≤ 0.4, and 0 < w ≤ 0.2) General formula (II): ABO3 (wherein A represents Bi, and B represents at least one of Fe, In and Sc)