Excellent hardening effect in lead-free piezoceramics by embedding local Cu-doped defect dipoles in phase boundary engineering.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40133302.
- Also identified by DOI 10.1038/s41467-025-58269-5 and PMC identifier 11937428.
- Licence recorded as CC BY-NC-ND.
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Abstract
Piezoceramics for high-power applications require both high piezoelectric coefficient (d<sub>33</sub>) and mechanical quality factor (Q<sub>m</sub>). However, the trade-off between them poses a significant challenge in achieving high values simultaneously, which is more prominent in lead-free piezoceramics. Here, we propose a new strategy, local Cu-acceptor defect dipoles embedded orthorhombic-tetragonal phase boundary engineering (O-T PBE), to balance d<sub>33</sub> and Q<sub>m</sub> in potassium sodium niobate piezoceramics. This is validated in 0.95(K<sub>0.48</sub>Na<sub>0.52</sub>)NbO<sub>3</sub>-0.05(Bi<sub>0.5</sub>Na<sub>0.5</sub>)HfO<sub>3</sub>-0.2%molFe<sub>2</sub>O<sub>3</sub>-xmol%CuO ceramics. Our strategy simultaneously maintains the O-T PBE and introduces local dimeric <math xmlns="http://www.w3.org/1998/Math/MathML"> <msup> <mrow><mrow><mo>(</mo> <mrow> <msubsup><mrow><mi>C</mi> <mi>u</mi></mrow> <mrow><mi>N</mi> <mi>b</mi></mrow> <mrow><mo>″</mo> <mo>'</mo></mrow> </msubsup> <mo>-</mo> <msubsup><mrow><mi>V</mi></mrow> <mrow><mi>O</mi></mrow> <mrow><mo>∙</mo> <mo>∙</mo></mrow> </msubsup> </mrow> <mo>)</mo></mrow> </mrow> <mrow><mo>'</mo></mrow> </msup> </math> and trimeric <math xmlns="http://www.w3.org/1998/Math/MathML"> <msup> <mrow> <mfenced> <mrow> <msubsup><mrow><mi>V</mi></mrow> <mrow><mi>O</mi></mrow> <mrow><mo>∙</mo> <mo>∙</mo></mrow> </msubsup> <mo>-</mo> <msubsup><mrow><mi>C</mi> <mi>u</mi></mrow> <mrow><mi>N</mi> <mi>b</mi></mrow> <mrow><mo>″</mo> <mo>'</mo></mrow> </msubsup> <mo>-</mo> <msubsup><mrow><mi>V</mi></mrow> <mrow><mi>O</mi></mrow> <mrow><mo>∙</mo> <mo>∙</mo></mrow> </msubsup> </mrow> </mfenced> </mrow> <mrow><mo>∙</mo></mrow> </msup> </math> defects. The dimeric defects form defect dipole polarization that pins domain wall motion, while the trimeric ones introduce the local structural heterogeneity that leads to nano-scale multi-phase coexistence and abundant nano-domains. Encouragingly, for the Cu-doped sample with x = 1, Q<sub>m</sub> increases by a factor of 4, but d<sub>33</sub> only decreases by 1/5 (i.e., achieving a d<sub>33</sub> of 340 pC/N and a Q<sub>m</sub> of 256). Our research provides a new paradigm for balancing d<sub>33</sub> and Q<sub>m</sub> in lead-free piezoceramics, which holds promise for high-power applications.