Temperature‐insensitive piezoelectricity in lead‐free NaNbO₃‐based ceramics

Abstract

In this work, we report a lead‐free piezoelectric ceramic of (0.9‐x)NaNbO3‐0.1BaTiO3‐xBaZrO3, and the effects of BaZrO3 on the phase structure, microstructure, electrical properties and temperature stability are investigated. A morphotropic phase boundary‐like region consisting of rhombohedral (R) and tetragonal (T) phases is constructed in the compositions with x = 0.035‐0.04. More importantly, in situ temperature independence of the piezoelectric effect {piezoelectric constant (d33) and strain} can be achieved below the Curie temperature (Tc). Intriguingly, the electric field‐induced strain is still observed at T ≥ Tc due to the combined actions of the electrostrictive effect and the electric field‐induced phase transition. We believe that NaNbO3‐based ceramics of this type have potential for applications in actuators and sensors.

Compositionally Graded KNN‐Based Multilayer Composite with Excellent Piezoelectric Temperature Stability

“…Although ultrahigh piezoelectricity was reported in barium titanate (BT)-based ceramics, [38] their low Curie temperatures (T C < 120 °C) lead to complete depolarization of the ceramics with temperature approaching 100 °C. Similar phenomenon was also reported in sodium niobate (NN)-based ceramics due to the relatively low T C. [39] Figure 3e further summarizes the piezoelectric variation [Δd 33 = |(d 33T /d 33RT ) − 1| *100%] of some representative KNN-based ceramics in the temperature range of 25-100 °C. It can be observed that there is always a large d 33 variation reported in traditionally designed KNN-based cer amics, [16,17,19,21,23,24] while the studied composite KNN-based ceramics exhibit an average room temperature d 33 value of ≈330 pC N −1 with variation below 6% up to 100 °C.…”

“…The new concept of the phase transition gradient can effectively solve the temperature instability of d 33 inherently associated with PPB, which is not achievable in conventional strategies including texture technique, [5,21,37] fine composition tuning, [26] and diffused phase transition. [22] The in situ d 33 -T of the structural gradient multilayer composite is compared to the actively studied lead-free ceramic systems (Figure 3d), [17,38,39] demonstrating a superior piezoelectric temperature stability in the temperature range of 25-100 °C. Although ultrahigh piezoelectricity was reported in barium titanate (BT)-based ceramics, [38] their low Curie temperatures (T C < 120 °C) lead to complete depolarization of the ceramics with temperature approaching 100 °C.…”

Ultrahigh Energy Storage Density and High Efficiency in Lead-Free (Bi0.9Na0.1)(Fe0.8Ti0.2)O3-Modified NaNbO3 Ceramics via Stabilizing the Antiferroelectric Phase and Enhancing Relaxor Behavior

“…Therefore, the lead-free dielectric capacitors have inspired more and more research interest around the world . Among the reported lead-free materials, NaNbO 3 -based solid solutions are a notable environmentally friendly counterpart with excellent piezoelectric, electrostrictive, and electrocaloric properties, as well as energy storage properties. − Pure NaNbO 3 ceramics are antiferroelectric P phase at ambient temperature but generally exhibit square P–E curves because of the appearance of the electric-field-induced metastable ferroelectric Q phase, ,, leading to a large P r and thus an unsatisfied energy storage property. However, the NaNbO 3 -based ceramics with antiferroelectric P phase still exhibit relatively low W rec (<2 J/cm 3 ) as a result of the low driving electric field for antiferroelectric–ferroelectric phase transition.…”