Lead-Free Piezoelectric Material Stabilizing Crystal Structure
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Solution Overview
Problem
Existing piezoelectric materials face challenges with significant variations in performance due to phase transitions within operation temperature ranges, leading to unstable piezoelectric properties and low mechanical quality factors, which affects the reliability of devices such as ultrasonic motors and image pickup apparatuses.
Innovation Solution
A lead-free piezoelectric material composed of (Ba,Ca)(Ti,Zr,Sn)O3 with specific doping levels of Mn, Li, and Bi, which stabilizes the crystal structure and enhances mechanical quality factors, preventing phase transitions within the operation temperature range and maintaining high piezoelectric performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If piezoelectric materials are used in resonant devices, then high mechanical quality factor is required for efficient operation, but existing materials exhibit low mechanical quality factor causing high power consumption and heat generation
Solution Approach 1:
The patent changes the compositional parameters of the piezoelectric material by incorporating specific ratios of Ba, Ca, Ti, Zr, Sn, Li, Bi, and Mn elements. This compositional adjustment modifies the material's crystal structure and electrical properties, achieving a high mechanical quality factor (Qm ≥ 500) while maintaining lead-free composition, thereby reducing power consumption and heat generation in resonant devices
Solution Approach 2:
The patent creates a composite piezoelectric material system combining multiple elements (Ba, Ca, Ti, Zr, Sn, Li, Bi, Mn) in a perovskite structure. This composite approach allows synergistic effects where Li and Bi doping enhances piezoelectric properties while Mn addition improves mechanical quality factor, achieving both high efficiency and reliability in ultrasonic motors and other resonant devices
2Reliability
If piezoelectric materials undergo phase transition to maximize piezoelectricity, then piezoelectric performance increases at transition temperatures, but piezoelectric performance varies considerably with temperature changes
Solution Approach 1:
The patent modifies the Curie temperature and phase transition characteristics by adjusting the compositional parameters, particularly the ratios of Zr, Sn, Li, and Bi elements. This shifts the phase transition temperatures outside the operational range (-30°C to 70°C), maintaining stable piezoelectric performance across the entire temperature range without significant variations, thereby improving reliability for household appliance applications
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 material achieves stable piezoelectric properties and high mechanical quality factors, reducing temperature-dependent variations and enhancing the reliability and efficiency of devices like ultrasonic motors and image pickup apparatuses.
Implementation Method 1
preventing phase transitions within the operation temperature range
Implementation Method 2
stabilizes the crystal structure
Implementation Method 3
piezoelectric material composed of (Ba,Ca)(Ti,Zr,Sn)O3
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A piezoelectric material includes a metal oxide represented by general formula (1) below, a Mn content is 0.04 parts by weight or more and 0.36 parts by weight or less, a Li content α is 0.0013 parts by weight or more and 0.0280 parts by weight or less, a Bi content β is 0.042 parts by weight or more and 0.850 parts by weight or less, and the contents α and β satisfy 0.5 ≤ (α·MB) / (β·ML) ≤ 1 (Ba1-xCax)a(Ti1-y-zZrySnz)O3 (1) (where x, y, z, and a satisfy 0.09 ≤ x ≤ 0.30, 0.025 ≤ y ≤ 0.074, 0 ≤ z ≤ 0.02, and 0.986 < a ≤ 1.02). A piezoelectric material according to an embodiment of the present invention contains no lead, has a low degree of temperature dependency of piezoelectric performance within operation temperature ranges of piezoelectric elements, and good piezoelectric properties.