Lead-Free Piezoelectric Ceramic Composition for High d33
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Solution Overview
Problem
Existing lead-free piezoelectric ceramic compositions face challenges in achieving high piezoelectric d constants in both low and high electric fields, with known compositions either insufficiently increasing the d constant or compromising other properties like electromechanical coupling and dielectric constant.
Innovation Solution
A piezoelectric ceramic composition with a main component of (1 - x)(K 1-a-b Na a Li b ) m (Nb 1-c-d Ta c Sb d )O 3 - x(M1 0.5 Bi 0.5 ) n M2O 3, where M1 is K or Na and M2 is Ti, Zr, or Sn, and incorporating 0.1 to 10 mol of specific elements like In, Sc, Y, and Eu, to enhance relative dielectric constant, electromechanical coupling factor, and Curie point, while expanding the firing temperature range for stable sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric ceramic composition is used to reduce environmental load, then environmental compatibility is improved, but piezoelectric d constant decreases compared to lead-based compositions
Solution Approach 1:
The patent uses a composite ceramic system combining KNbO3-KTaO3-KNb4O11 with Li2SiO3 and B2O3 additives, creating a multi-phase composite that achieves both lead-free environmental compatibility and high piezoelectric d constant through synergistic interactions between different phases and components
Solution Approach 2:
The patent systematically varies compositional parameters (ratios of KNbO3, KTaO3, KNb4O11, Li2SiO3, and B2O3) and sintering temperature parameters to optimize the piezoelectric d constant while maintaining lead-free composition, demonstrating parameter optimization to resolve the contradiction
2Manufacturing precision
If firing temperature is controlled precisely to achieve stable sintering, then sintering quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent determines specific sintering temperature ranges for the optimized composition, enabling stable sintering within defined temperature windows that balance manufacturing precision requirements with process simplicity
Solution Approach 2:
The patent develops a composition that exhibits self-adjusting sintering behavior within an optimized temperature range, where the material composition itself promotes stable densification and phase formation without requiring extremely precise temperature control, reducing manufacturing complexity
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 composition achieves high piezoelectric d constants in both low and high electric fields, with improved electromechanical properties and a wider firing temperature range, enhancing productivity and consistency in producing piezoelectric ceramic electronic components.
Implementation Method 1
a piezoelectric ceramic composition, which does not contain Pb (lead), and a piezoelectric ceramic electronic component that includes the piezoelectric ceramic composition, such as a piezoelectric actuator or a piezoelectric buzzer
Data Source
Figure 1~2
AI summary
A main component has a general formula of {(1 - x)(K1-a-bNaaLib)m(Nb1-c-dTacSbd)O3-x(M10.5Bi0.5)nM2O3} (wherein M1 is Ca, Sr or Ba, M2 is Ti, Zr or Sn, 0.005 ≤ x ≤ 0.5, 0 ≤ a ≤ 0.9, 0 ≤ b ≤ 0.3, 0 ≤ a + b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.1, 0.9 ≤ m ≤ 1.1, and 0.9 ≤ n ≤ 1.1). At least one specific element selected from the group consisting of In, Sc, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu is contained at 0.1 to 10 mol in total per 100 mol of the main component (preferably, 1.5 to 10 mol). This provides a piezoelectric ceramic composition and a piezoelectric cerami.c. electronic component that can have a desired high piezoelectric d constant in a consistent and highly efficient manner in both a very low electric field and a high electric field.