Lead-Free Piezoelectric Ceramic Composition for Temperature Stability
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Solution Overview
Problem
There is a need for a piezoelectric ceramic composition that maintains excellent piezoelectric characteristics despite temperature variations near device operating temperatures, as existing lead-free compositions like alkali niobates suffer from reduced performance due to crystal phase transitions.
Innovation Solution
A piezoelectric ceramic composition comprising a perovskite-type oxide with Na, K, Li, Ba, and Sr at the A site and Nb, Ta, and Zr at the B site, with a crystal phase transition in the range of −50 to 150°C and an endotherm of no greater than 4 J/g, which prevents sudden changes in domain structure and maintains polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric ceramic compositions such as alkali niobates are used to reduce lead content, then environmental compatibility is improved, but piezoelectric characteristics are insufficient
Solution Approach 1:
The invention uses a composite perovskite-type oxide system combining multiple elements (Na, K, Li, Ba, Sr at A-site and Nb, Ta, Zr at B-site) to achieve both lead-free composition and excellent piezoelectric properties. This multi-element composite approach allows optimization of both environmental compatibility and functional performance.
Solution Approach 2:
The invention carefully controls the crystal phase transition endotherm parameter to be no greater than 4 J/g, which fundamentally changes the thermal behavior of the material. This parameter control enables the material to maintain stable piezoelectric characteristics across temperature ranges while remaining lead-free.
2Reliability
If alkali niobates with high piezoelectric characteristics are used, then piezoelectric performance is improved, but crystal phase transition near room temperature causes reduction in characteristics under thermal cycles
Solution Approach 1:
The invention utilizes controlled phase transition behavior by designing the perovskite-type oxide to have a crystal phase transition with endotherm ≤4 J/g in the temperature range including room temperature. This controlled phase transition maintains piezoelectric characteristics while providing temperature compensation effects.
Solution Approach 2:
The invention prepares the material composition in advance to have a small endotherm phase transition characteristic, which cushions against sudden domain structure changes during thermal cycling. The pre-designed composition prevents extreme domain reconfiguration that would otherwise occur during temperature variations.
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
This composition effectively minimizes the reduction in piezoelectric characteristics due to temperature variations, ensuring excellent performance across a wide temperature range, making it suitable for devices like actuators and sensors.
Implementation Method 1
the perovskite-type oxide has a crystal phase transition in a temperature range of −50 to 150° C., the crystal phase transition being accompanied by an endotherm of no greater than 4 J/g
Implementation Method 2
Known piezoelectric ceramics exhibit piezoelectricity, whereby application of an electric field generates mechanical strain and stress
Data Source
AI summary
A piezoelectric ceramic composition including a perovskite-type oxide, wherein the perovskite-type oxide has Na, K, Li, Ba and Sr at the A site and Nb, Ta and Zr at the B site, and has a crystal phase transition in a temperature range of −50 to 150° C., the crystal phase transition being accompanied by an endotherm of no greater than 4 J/g, as well as a piezoelectric element 20 provided with a piezoelectric ceramic 1 that contains the piezoelectric ceramic composition.