Realizing Enhanced Electrical Properties of CaBi₂Nb₂O₉-Based High-Temperature Piezoceramics by Constructing a Pseudophase Boundary

Abstract

It is well-known that the regulation of the phase boundary is an efficient strategy to boost the piezoelectric performance of perovskite structure ceramics. However, it is seldomly used in the bismuth-layered structure high-temperature piezoelectric ceramic research field because of the lack of an available morphotropic phase boundary (MPB). In this work, a pseudo-MPB was constructed by the dual introduction of Ce and Cr ions to the CBN ceramic, which remarkably optimized the piezoelectricity and ferroelectricity. Furthermore, the Ce and Cr ions evidently suppressed the oxygen vacancy concentration, leading to improvements in resistivity and thermal stability. Optimized performances with a satisfactory piezoelectric coefficient (d 33 ∼ 17 pC/N) and an elevated resistivity (ρ) of 1.35 × 105 Ω·cm (at 600 °C) were realized in the Ca0.97Ce0.03Bi2Nb1.985Cr0.015O9 ceramic, accompanied by a high Curie temperature (T C ∼ 934 °C) and good piezoelectric thermal stability. These results reveal that the Ca0.97Ce0.03Bi2Nb1.985Cr0.015O9 ceramic could be a prospective piezoelectric material for sensor applications at high temperatures. Moreover, this work provides a feasible strategy for optimizing the piezoelectric performances of the CBN-based ceramics by constructing the pseudo-MPB.

Origin of strong piezoelectric enhancement in bismuth titanate‐ferrite for high‐temperature applications

“…55 The decrease of T C for x > 0.08 is associated with the enhanced tetragonal distortion, because the phase transition temperature of BLSFs is closely associated with the orthorhombic distortion. [56][57][58] As shown in Figure 4B 2 , the dielectric loss tanδ for x > 0.08 varies slightly and remains lower than 0.09 at temperatures < 400 • C, which is only half that of Bi 5 Ti 3 FeO 15 (< 0.19). The decrease of dielectric loss tanδ is attributed to the suppressed formation of oxygen vacancies.…”

“…For x < 0.08, the increase of T C is mainly ascribed to the decreased tolerance factor t ( t = ( R A + R O )/$$\sqrt {\mathrm{2}} $$( R B + R O ), where R A , R B , and R O represent the ionic radius of the A ‐, B ‐site cations, and oxygen ions, respectively), as the radius of XII Eu 3+ (122 pm) is smaller than that of XII Bi 3+ (145 pm) 55 . The decrease of T C for x > 0.08 is associated with the enhanced tetragonal distortion, because the phase transition temperature of BLSFs is closely associated with the orthorhombic distortion 56–58 . As shown in Figure 4B 2 , the dielectric loss tan δ for x > 0.08 varies slightly and remains lower than 0.09 at temperatures < 400°C, which is only half that of Bi 5 Ti 3 FeO 15 (< 0.19).…”

High‐performance bismuth titanate‐ferrite (Bi5Ti3FeO15) for high‐temperature piezoelectric applications

“…To date, numerous efforts have been made to enhance the piezoelectric performances of BLSFs. The most investigated BLSFs with T C values >600 • C are CaBi 2 Nb 2 O 9 (CBN), [12][13][14][15] Bi 3 TiNbO 9 (BTN), [16][17][18][19] CaBi 4 Ti 4 O 15 (CBT), [20][21][22][23] and Bi 4 Ti 3 O 12 (BIT). [24][25][26][27] With these previous works in mind, it was clear that elemental substitution is an effective approach to tailor the crystalline structure and microscopic morphology to effectively improve the piezoelectric and electrical properties of BLSFs.…”