Characteristics of giant piezoelectricity around the rhombohedral-tetragonal phase boundary in (K,Na)NbO₃-based ceramics with different additives

Abstract

In this work, we confirmed the electric -induced transition (EPT) in (K,Na)NbO 3 -based ceramics through experiment and theory. Through in-situ x-ray diffraction measurement, electric field -induced phases (EP) could be observed in the ceramics. To explain the appearance of EP, a new function ex E λ ( ) was introduced to the six order Devonshire theory when the external electric field was applied. The further studies indicate that EPT had two possible forms, i.e., tetragonal -electric induced phase transition (T-EP) and rhombohedral -electric induced phase transition (R-EP), and then T-EP plays a more positive role than R-EP in terms of piezoelectric response. Also, a giant piezoelectricity (d 33 =435~490 pC/N), a high Curie temperature (T C =205~235°C), and converse piezoelectric coefficient (d 33 * =500~890 pm/V) can be achieved by choosing optimum metal oxides as well as their content. We believe that a) Corresponding

Monoclinic (K,Na)NbO3 Ferroelectric Phase in Epitaxial Films

“…Most high-performance piezoelectric materials are based on Pb(Zr,Ti)O 3 (PZT) and related perovskite solid solutions. [24,25] However, there have been no experimental reports about monoclinic phases at TPB in KNN-based materials. [1] Monoclinic phases have been reported by Noheda et al at MPB in PZT [2] and other lead-based piezoelectric materials, including Pb(Zn 1/3 Nb 2/3 )O 3 -PbTiO 3 (PZNPT) [3,4] and Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMNPT).…”

Composition and temperature dependence of structure and piezoelectricity in (1−x)(K1−yNay)NbO3‐x(Bi1/2Na1/2)ZrO3 lead‐free ceramics

“…Recently, PZT‐like morphotropic phase boundary (MPBs) (R‐T) have been reported in KNN‐based ceramics by integrating compositions which were previously used to optimize the O‐T and R‐O phase boundaries . In 2011, Zuo et al.…”

“…obtained d 33 ∼ 425 pC/N . But more recently, Sb together with (Bi,M)NO 3 (M=Na, K, Li, Ag, N=Zr, Hf, Sn) have been used to enhance d 33 and electromechanical strain ( S ) with d 33 and S improved to >400 pC/N and 0.46% at 3 kV/cm, respectively . Despite promising d 33 and S values there are still a number of concerns.…”

Progress on the doping and phase boundary design of potassium–sodium niobate lead-free ceramics

“…18 The XRD patterns and expanded XRD patterns of KNNS-BNKZ ceramics with different additives were shown in Fig. 12.…”

“…15 Some methods have been proposed and examined, such as ion substitutions, 16,17 sintering aids, [18][19][20] preparation methods 21,22 and construction of the phase boundary near room temperature, [23][24][25][26] to solve these problems and obtain dense and well-sintered KNN ceramics with excellent piezoelectric properties.…”