Lead-Free Piezoelectric Element with Manganese Doping
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Solution Overview
Problem
Lead-containing piezoelectric materials, such as PZT, pose environmental concerns and require high voltage due to low piezoelectric properties and are prone to depolarization at elevated temperatures, limiting their stability in wide operating temperature ranges.
Innovation Solution
A lead-free piezoelectric element using a perovskite-type metal oxide with a specific composition of (Ba1-xCax)(Ti1-yZry)O3, incorporating manganese (Mn), which improves mechanical quality factors and piezoelectric properties, allowing stable operation across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric materials like barium titanate are used, then environmental compatibility is improved, but piezoelectric properties deteriorate requiring high voltage operation
Solution Approach 1:
The patent uses a composite perovskite-type metal oxide material with specific composition (Ba1-xCax)(Ti1-yZry)O3 where x and y are controlled within specific ranges. This composite approach combines multiple elements to achieve both environmental compatibility (lead-free) and adequate piezoelectric properties through synergistic effects of the constituent elements.
Solution Approach 2:
The patent optimizes the compositional parameters x and y within specific ranges (0 < x ≤ 0.30, 0 < y ≤ 0.10) to balance environmental requirements and piezoelectric performance. By precisely controlling these parameters, the material achieves improved piezoelectric properties while maintaining lead-free composition.
2Ease of manufacture
If piezoelectric materials with low Curie temperature are used, then ease of manufacture is improved, but reliability deteriorates due to depolarization in severe environments
Solution Approach 1:
The patent carefully controls the Curie temperature by adjusting the compositional parameters x and y within specific ranges. This optimization ensures the Curie temperature is above 80°C to prevent depolarization in severe environments while maintaining manufacturability through moderate sintering temperatures.
Solution Approach 2:
The patent introduces manganese (Mn) at specific locations (0.02 ≤ Mn content ≤ 0.40 parts by weight relative to 100 parts by weight of the metal oxide) to locally enhance piezoelectric properties and mechanical quality factor without significantly affecting the overall Curie temperature and thermal stability.
3Strength
If barium titanate with Mn, Fe, or Cu addition is used, then mechanical quality factor is improved, but piezoelectric properties deteriorate
Solution Approach 1:
The patent optimizes the concentration of manganese (Mn) within a specific range (0.02 ≤ Mn content ≤ 0.40 parts by weight relative to 100 parts by weight of the metal oxide). This precise parameter control balances the enhancement of mechanical quality factor with the maintenance of adequate piezoelectric properties, avoiding the deterioration seen in prior art.
Solution Approach 2:
The patent creates a composite material system combining barium titanate with controlled additions of Mn, Ca, and Zr in specific proportions. This composite approach achieves synergistic effects where Mn improves mechanical quality factor while Ca and Zr modifications maintain or enhance piezoelectric properties.
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 lead-free piezoelectric element exhibits enhanced piezoelectric properties and stability, reducing the need for high voltage and maintaining performance in severe environments, making it suitable for applications like liquid discharge heads, ultrasonic motors, and optical apparatuses.
Implementation Method 1
ABO3 perovskite-type metal oxides such as lead zirconate titanate (referred to as 'PZT' hereinafter) are typically used as piezoelectric materials
Implementation Method 2
incorporating manganese (Mn), which improves mechanical quality factors and piezoelectric properties
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A piezoelectric material comprises crystal grains of a perovskite-type metal oxide represented by general formula (1) as a main component, (Ba1-xCax)a(Ti1-yZry)O3 (where 1. 00 ≤ a ≤ 1.01, 0.020 ≤ x ≤ 0.300, 0.020 ≤ y ≤ 0.095, and y ≤ x) (1), and a manganese component, wherein a manganese content incorporated in the piezoelectric material relative to 100 parts by weight of the perovskite-type metal oxide is 0.02 parts by weight or more and 0.30 parts by weight or less on a metal basis.