Lead-Free Piezoelectric Material Composition for Wide Temperature Stability
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Solution Overview
Problem
Existing piezoelectric materials exhibit low piezoelectric constants at high temperatures and low mechanical quality factors at low temperatures, making them unsuitable for a wide range of device operating temperatures.
Innovation Solution
A lead-free piezoelectric material with a perovskite-type metal oxide composition of (Ba1-xCax)(Ti1-yZry)O3, incorporating Mn, Bi, Li, Si, B, and Cu as sub-constituents, optimized to achieve a balance of piezoelectric constant and mechanical quality factor across a broad temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free perovskite-type metal oxide is used to improve environmental compatibility, then environmental friendliness is improved, but piezoelectric performance deteriorates compared to lead-containing materials
Solution Approach 1:
The patent employs a composite perovskite structure combining multiple metal oxides (BaTiO3, CaTiO3, ZrTiO4) to achieve lead-free composition with enhanced piezoelectric performance. This composite approach compensates for the inherently lower piezoelectric constants of individual lead-free materials, achieving performance comparable to or exceeding traditional lead-containing PZT materials while maintaining environmental compatibility.
Solution Approach 2:
The patent introduces local compositional variations through selective substitution of metal ions at specific lattice sites. Calcium substitutes at the A-site (barium position) and zirconium substitutes at the B-site (titanium position), creating local structural modifications that enhance overall piezoelectric performance while maintaining the lead-free perovskite structure.
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 material provides a satisfactory piezoelectric constant and mechanical quality factor from -30°C to 50°C, enhancing the performance of piezoelectric elements and devices such as liquid ejecting heads, ultrasonic motors, and image sensing apparatuses.
Implementation Method 1
Piezoelectric materials are typically ABO3 perovskite-type metal oxides such as lead zirconate titanate (hereinafter referred to as PZT)
Data Source
AI summary
There is provided a lead-free piezoelectric material having a satisfactory piezoelectric constant and mechanical quality factor in the range of device operating temperatures (from −30° C. to 50° C.). The piezoelectric material contains a main constituent containing a perovskite-type metal oxide expressed by the general formula (Ba1-xCax)a(Ti1-yZry)O3, where x, y and a satisfy the 0.030≤x<0.090, 0.030≤y≤0.080, and 0.9860≤a≤1.0200. The material also contains 0.040 to 0.500 part by weight of Mn, 0.042 to 0.850 part by weight of Bi, 0 to 0.028 part by weight of Li, 0.001 to 4.000 part by weight of a third sub-constituent including at least one of Si and B, and 0.001 to 4.000 parts by weight of Cu, each in terms of element relative to 100 parts by weight of the metal oxide.