Intrinsic auxetic piezoelectricity in bulk ferroelectrics
Zhi Tan1, He-Meng Sun2,3, Wei Shi1
1College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
National Science Review
|July 2, 2026
Summary
Researchers discovered a new class of materials, Aurivillius ferroelectrics, that exhibit the auxetic piezoelectric effect. This means they expand and contract in all directions simultaneously, even at high temperatures.
Area of Science:
- Materials Science
- Solid State Physics
- Ferroelectricity
Background:
- Piezoelectric materials typically show opposite longitudinal and transverse piezoelectric coefficients.
- The auxetic piezoelectric effect, simultaneous expansion/contraction in all directions, was previously limited to engineered heterostructures.
- A low-cost, intrinsically auxetic piezoelectric bulk material with high-temperature stability was lacking.
Purpose of the Study:
- To predict and experimentally verify bulk materials exhibiting the intrinsic auxetic piezoelectric effect.
- To understand the fundamental mechanism behind this effect in layered ferroelectrics.
- To explore the potential of these materials for enhanced electromechanical applications.
Main Methods:
- First-principles theoretical predictions.
- Experimental synthesis and characterization of Aurivillius ferroelectrics.
- Temperature-dependent measurements (5-1000 K).
Main Results:
- A catalog of bulk Aurivillius ferroelectrics exhibiting the intrinsic auxetic piezoelectric effect was identified.
- The effect originates from relative sliding deformation between charged layers in the Aurivillius structure.
- The auxetic piezoelectric response was robust across a wide temperature range (5-1000 K).
- Enhanced longitudinal piezoelectric response (by an order of magnitude) was achieved in bulk Aurivillius ceramics.
Conclusions:
- Aurivillius ferroelectrics provide a new platform for realizing the auxetic piezoelectric effect in bulk polycrystalline materials.
- These materials offer a combination of strong piezoelectricity, auxetic behavior, and high-temperature stability.
- This discovery opens new possibilities for designing advanced electromechanical devices.
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