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Improved piezoelectric and strain performance of Na2B4O7-doped (Li,K,Na)NbO3 lead-free piezoceramics
摘要： 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.
关键词： Piezoelectric coefficient,Lead-free piezoceramics,Temperature stability,Na2B4O7 doping,Polymorphic phase transition
更新于2025-09-23 15:21:01
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Defect-relevant piezoelectric and ferroelectric properties in LiCuTa3O9-doped K0.5Na0.5NbO3 lead-free piezoceramics
摘要： Lead-free K0.5Na0.5NbO3 + x mol LiCuTa3O9 (abbreviated to KNN-xLCT) piezoceramics are synthesized via a conventional sintering technique. All ceramics exhibit perovskite structure and their densification is improved after the addition of LCT. The doping of small quantities of LCT (x ≤ 0.015) results in the generation of two sorts of defect complexes [i.e., ?? V??(Cu???o ) ], inducing greatly hardening electrical behaviors with high mechanical quality factor Qm of ~ 780 at x = 0.015. However, excess LCT (x ≥ 0.015) contributes to the substantial reduction of defect complexes, and thus the ceramics are softened, presenting a relatively low Qm of ~ 480 at x = 0.03. It is noted that the ceramics with x = 0.03 remain comparatively great piezoelectric performances: d33 = 96 pC/N and kp = 37%. Our study indicates that the electrical properties of KNN-based ceramics doped with LCT are closely related with microscopic defect structure in the materials.
关键词： Lead-free piezoceramics,K0.5Na0.5NbO3,Piezoelectric properties,Defect complexes,LiCuTa3O9
更新于2025-09-23 15:19:57
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Self‐Healable Black Phosphorus Photodetectors
摘要： Large‐strain multilayer actuators (MLAs) were fabricated by tape‐casting 0.91(Na1/2Bi1/2)TiO3–0.06BaTiO3–0.03AgNbO3 (NBT‐BT–3AN) lead‐free incipient piezoceramics co‐fired with Pt inner electrodes. Microstructures, dielectric properties, unipolar and bipolar strain, as well as fatigue properties of the MLAs were investigated. It was found that the actuator consisting of 15 ceramic layers with individual thicknesses of 114 μm could output a large unipolar strain of 0.3% and a dynamic displacement of 5 μm at 6 kV/mm at room temperature. It exhibited excellent cycling stability and provided a high strain of 0.23% after 107 cycles at 6 kV/mm. Moreover, these MLAs still can deliver a strain of 0.20% at 125°C.
关键词： lead‐free piezoceramics,multilayer actuators,large strain,cycling stability,temperature stability
更新于2025-09-11 14:15:04
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Temperature-driven phase transitions and enhanced piezoelectric responses in Ba(Ti0.92Sn0.08)O3 lead-free ceramic
摘要： Ferroelectric phases coexistence or transition is an important strategy on generating high piezoelectricity. Here, the temperature-induced phase structural evolution correlated with small signal piezoelectric response d33, bias-field piezoelectric activity dmax33 (E), unipolar and bipolar strain piezoelectric outputs d*33 in Ba(Ti0.92Sn0.08)O3 (BTS0.08) ceramic was investigated in details. Temperature-driven successive phase transitions from rhombohedral(R) to orthorhombic(O), tetragonal(T), finally to cubic(C) phases took place around 14 °C, 38 °C and 61 °C, respectively. The highest d33 value of 675 pC/N is achieved in the T-C phase transition. However, the O-T phase boundary gives the highest dmax33 = 1170 pm/V, bipolar d*33 = 822 pm/V and unipolar d*33 = 1318 pm/V. The temperature-driven phase transition exhibits large enhancements in piezoelectric property comparable to that of composition-induced phase boundary. These features suggest an effective method to design high-performance piezoelectrics by tailoring the types of phase boundary.
关键词： Phase transition,Lead-free piezoceramics,Ferroelectrics,Phase boundary
更新于2025-09-10 09:29:36