| Summary: | The performance of potassium sodium niobate ((K, Na) NbO<sub>3</sub>, KNN)-based lead-free piezoelectric ceramics has significantly improved over the past decade. However, the performance bottlenecks of KNN-based ceramics cannot be ignored. Here, the Nb<sub>2</sub>O<sub>5</sub> precursor is obtained after thermal pretreatment, which can evidently improve the piezoelectric properties and strain temperature stability of KNN-based ceramics. With the help of the Nb<sub>2</sub>O<sub>5</sub> precursor treated at 800 °C, the optimal piezoelectric constant <i>d</i><sub>33</sub> of 303 pC/N, inverse piezoelectric constant <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mover><mi>d</mi><mo>*</mo></mover><mn>33</mn></msub></mrow></semantics></math></inline-formula> of 378 pm/V, Curie temperature <i>T</i><sub>C</sub> of 310 °C and electromechanical coupling factor <i>k</i><sub>p</sub> of 42% are obtained, and the value of <i>d</i><sub>33</sub> improves by about 30% compared with that of the ceramic prepared with untreated Nb<sub>2</sub>O<sub>5</sub> as raw material. Additionally, in comparison with the strain temperature stability of the ceramics prepared with untreated Nb<sub>2</sub>O<sub>5</sub> as raw material, the temperature stability is enhanced. Therefore, this study provides a useful approach to break the existing performance bottleneck and further improve the properties of KNN-based ceramics.
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