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Improved piezoelectric and strain performance of Na2B4O7-doped (Li,K,Na)NbO3 lead-free piezoceramics
- Zhao, Yongjie, Liu, Jialin, Yan, Dong
- Journal of materials science 2019 v.54 no.2 pp. 1126-1135
- ambient temperature, ceramics, phase transition
- A polymorphic phase transition effect has been employed to regulate the piezoelectric property of lead-free (K,Na)NbO₃-based materials, which intrinsically bear the disadvantage of the evident temperature sensitivity. In this research, Li₀.₀₄[(K₀.₄₉Na₀.₅₁)]₀.₉₆NbO₃–xNa₂B₄O₇ piezoceramics were prepared through a conventional solid-state reaction. A piezoelectric coefficient d₃₃ of about 285 pC/N and a unipolar strain of 0.14%@5 kV/mm were achieved in the ceramics with x = 0.5%. These improved properties can be ascribed to the coexistence of orthorhombic and tetragonal phase structure around room temperature. Besides, the field-induced unipolar strain varied less than 15% in the temperature region from room temperature to 180 °C. The stability of strain property could be rationally interpreted by a quantitative approach of electrostrictive coupling to the polarization amplitude.