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Enhanced Electrostrain in Polarized Cu-Doped KTN Single Crystals by Reversible Domain Switching
Yingxu Zhu1, Yuanyuan Zhang1, Huadi Zhang1,2
1Advanced Materials Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China.
Copper doping in KTN crystals enhances electrostrain by enabling reversible domain switching. This leads to a significant 0.32% unipolar strain, promoting practical applications for lead-free piezoelectric materials.
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Improving electrostrain in lead-free piezoelectric materials is crucial for technological advancement.
- Potassium niobate-tantalate (KTN) crystals are promising candidates, but their electrostrain needs enhancement for practical applications.
Purpose of the Study:
- To enhance the electrostrain of KTN crystals through Cu doping and optimized electric field application.
- To elucidate the underlying mechanisms responsible for the improved electrostrain.
Main Methods:
- Cu2+ doping of KTN crystals.
- Polarization and application of electric fields perpendicular to the polarization direction.
- Raman spectroscopy, High-resolution transmission electron microscopy (HRTEM), and Electron Paramagnetic Resonance (EPR) spectroscopy.
Main Results:
- A large unipolar strain of 0.32% was achieved in 0.36 wt% Cu-doped KTN crystals at 15 kV/cm.
- Cu doping induced lattice contraction, significant internal stress/strain, and polar defect dipoles.
- Reversible domain switching and double hysteresis loops were observed, correlating with enhanced strain.
Conclusions:
- Cu doping effectively enhances electrostrain in KTN crystals by enabling reversible domain switching.
- The restoring force from polar defect dipoles is key to achieving large strain and double hysteresis loops.
- This research advances the practical application of lead-free piezoelectric materials.
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