Lead-Free Piezoelectric Composition with Rhombohedral-Orthorhombic-Tetragonal Phase
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Solution Overview
Problem
Pb(Zr, Ti)O3 (PZT)-based piezoelectric materials have high toxicity and volatility, leading to environmental pollution, and their Pb-free alternatives exhibit lower piezoelectric characteristics, necessitating the development of Pb-free materials with enhanced piezoelectric properties.
Innovation Solution
A piezoelectric material composition represented by 0.96(NaaK1-a)(Nbb(T1-b))O3-(0.04-x)MAMBO3-x(BicAg1-c)MBO3+d mol % A, where T is Sb, Ta, or V, MA is Sr, Ba, or Ca, MB is Zr, Hf, Ti, or Sn, and A is Fe2O3, Co2O3, Mn2O3, ZnO, GeO2, CuO, or NiO, with specific ratios and additions to enhance sinterability and orientation, forming a rhombohedral-orthorhombic-tetragonal (R-O-T) structure for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PZT-based piezoelectric material is used, then piezoelectric characteristic is improved, but environmental pollution and toxicity increase
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Pb(Zr, Ti)O3 with Pb-free alternatives like (K,Na)NbO3-based materials, adjusting ratios of metal elements (Zr, Ti, Sn, Hf) and adding dopants (Fe, Co, Mn, Zn, Ge, Cu, Ni) to achieve high piezoelectric characteristics without lead, thereby eliminating environmental pollution while maintaining performance
Solution Approach 2:
The patent creates composite piezoelectric materials by combining multiple metal oxides in specific ratios, forming a complex perovskite structure with enhanced piezoelectric properties. The composite composition includes (K,Na)NbO3 as base material with Zr, Ti, Sn, or Hf elements and additional dopants, achieving synergistic effects that improve piezoelectric characteristic without requiring toxic lead
2Object-affected harmful factors
If Pb-free piezoelectric material is used, then environmental pollution is reduced, but piezoelectric characteristic deteriorates
Solution Approach 1:
The patent optimizes compositional parameters including the ratios of K, Na, Nb, Zr, Ti, Sn, Hf, and dopant elements (Fe, Co, Mn, Zn, Ge, Cu, Ni) to achieve maximum piezoelectric coefficient (d33 ≥ 300 pC/N) in Pb-free materials, demonstrating that careful parameter adjustment can overcome the inherent performance limitations of lead-free piezoelectrics
Solution Approach 2:
The patent develops composite (K,Na)NbO3-based materials with multiple metal elements and dopants that create a rhombohedral-orthorhombic-tetragonal (R-O-T) phase structure, where the synergistic interaction between different elements enhances piezoelectric properties to levels comparable with or exceeding traditional PZT materials while remaining environmentally friendly
3Reliability
If complex material composition is used to enhance piezoelectric characteristic, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary mixing and homogeneous distribution of all metal oxide powders before sintering, ensuring uniform composition throughout the material. This preliminary preparation step simplifies the overall manufacturing process by preventing defects and ensuring consistent piezoelectric properties without requiring complex post-processing
4Reliability
If grain orientation is enhanced using template, then piezoelectric characteristic is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent achieves grain orientation by optimizing sintering parameters including temperature gradient, holding time, and cooling rate, along with compositional adjustments. This approach to orientation control avoids the need for complex template-based methods while still achieving high piezoelectric characteristics through controlled crystal growth during sintering
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 proposed composition achieves a high piezoelectric characteristic without lead, reducing production costs and environmental impact, while enabling the use of lower driving voltages and improving manufacturing efficiency, thus providing an environment-friendly and high-performance Pb-free piezoelectric material.
Implementation Method 1
Piezoelectric materials are being widely used as materials of parts such as ultrasound vibrators, electromechanical transducers, and actuators
Implementation Method 2
lead (Pb) is a material having strong toxicity and has high volatility in a sintering process
Data Source
AI summary
A piezoelectric material composition may be represented by Equation 1,0.96(NaaK1-a)(Nbb(T1-b))O3-(0.04-x)MAMBO3-x(BicAg1-c)MBO3+d mol % A[Equation 1]where T is Sb, Ta, or V, MA is Sr, Ba, or Ca, MB is Zr, Hf, Ti, or Sn, and A is Fe2O3, Co2O3, Mn2O3, ZnO, GeO2, CuO, or NiO, and0.40≤a≤0.60, 0.90≤b≤1.00, 0.30≤c≤0.70, 0.00≤x≤0.04, and 0.00<d≤1.00.