Crystallographic texture and phase structure induced excellent piezoelectric performance in KNN‐based ceramics

Abstract

It is difficult to maintain strong piezoelectric properties over a wide temperature range in (K,Na)NbO 3 (KNN)-based ceramics owing to the polymorphic phase boundary (PPB). Here, we propose advantageously utilizing the synergistic effect of crystal orientation and phase structure to address this issue. The 〈0 0 1〉 pc textured (1 − x)(K 0.48 Na 0.52 )(Nb 0.96 Sb 0.04 )O 3 -x(Bi 0.5 Ag 0.5 )ZrO 3 (KNNS-xBAZ) ceramics with different phase structures were synthesized via the templated grain growth method. A high piezoelectric coefficient (d 33 ) of 505 ± 25 pC/N, an electric field-induced strain of 0.21%, and a superior temperature stability (d 33 exhibited a high retention of ≥78% at the temperature up to 200 • C; strain maintained within 5.7% change over a temperature range of 30-150 • C) were simultaneously achieved in textured KNNS-0.03BAZ ceramics. The flattened Gibbs free energy induced by the R-O-T multiphase coexistence, the strong anisotropy of crystals, and the abundant nanodomains contributed to the enhanced piezoelectric properties. The contribution of the strong anisotropy of crystals in 〈0 0 1〉 pc textured ceramics compensates for the deterioration of the piezoelectric properties caused by the phase structure deviation from the PPB with increasing temperature, which benefits the superior temperature stability of the textured KNNS-0.03BAZ ceramics. The previous merits prove that utilizing the synergistic effect of crystal orientation and phase structure is an effective strategy to boost the piezoelectricity and their temperature stability of KNN-based ceramics.

Decoding intrinsic and extrinsic contributions for high piezoelectricity of CBT-based piezoelectric ceramics

“…Bismuth vacancies and oxygen vacancies are generated during the sintering process [eqn (3)]. In the process of cooling, oxygen atoms enter the lattice to generate holes [eqn (4)].…”

“…Advanced piezoelectric sensors possessing high stability in a wider temperature range have attracted more attention with the rapid development of electronic devices and are in increasing demand. [1][2][3] As core materials of high temperature piezoelectric sensors, bismuth layer-structured ferroelectrics (BLSFs) possess low dielectric loss, high mechanical quality factor, high thermal stability and high Curie temperature (T C ), which enable them to be widely used in such applications. [4][5][6] The chemical formula of BLSFs is (Bi 2 O 2 ) 2+ (A mÀ1 B m O 3m+1 ) 2À , consisting of two layers of (Bi 2 O 2 ) 2+ with m number perovskite-like layers between them.…”

Excellent comprehensive electrical properties in KNN-based ceramics via synergistic effects of structural flexibility and domain engineering

“…However, KNN-based ceramics are highly sensitive to temperature variations, leading to a rapid attenuation of their piezoelectric properties when deviating from the PPB. 13,14 To address this issue, researchers have turned to multilayer composite ceramics with special structures that offer greater flexibility in performance design. Using the tape casting method, excellent temperature stability has been achieved in these multilayer composite KNN-based ceramics, with the variation of d 33 being less than 6% over the temperature range of 25-100 1C.…”