Although KNN‐based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN‐based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d33 value in this system reaches 501 pC/N with a TC ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well‐preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric‐induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN‐based ceramics, which is expected to promote the practical applications in the future.
CaBi 2 Nb 2 O 9 (CBN), one of the bismuth-layered structural ferroelectrics, with high Curie temperature (T C ), has great potential in high-temperature applications. In this work, high Curie temperature and piezoelectric constant (d 33 ) are realized in modified CaBi 2 Nb 2 O 9 ceramics with Ce-substitution. Ce-substitution changes the crystal structures and domain structures of CBN-based ceramics, so as to improve the piezoelectric properties. The optimal performances are obtained with a high d 33 value (∼18.0 pC/N) and a T C value (∼930 • C), together with a low tan δ value (∼0.028 at 500 • C). Moreover, the thermal stability is also enhanced, where the d 33 value maintains 93.9% of its original value after annealing at 900 • C for 2 h. Thus, these findings play a meaningful role in devices manufacturing, where the apply temperature is often more than 500 • C.
We demonstrate a novel concept of domain engineering to simultaneously achieve outstanding piezoelectricity (d33~191 pC/N) and high Curie temperature (TC~485 °C) in BF ceramics by adding element with high valence...
The performance of potassium sodium niobate ((K, Na) NbO3, 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 Nb2O5 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 Nb2O5 precursor treated at 800 °C, the optimal piezoelectric constant d33 of 303 pC/N, inverse piezoelectric constant d*33 of 378 pm/V, Curie temperature TC of 310 °C and electromechanical coupling factor kp of 42% are obtained, and the value of d33 improves by about 30% compared with that of the ceramic prepared with untreated Nb2O5 as raw material. Additionally, in comparison with the strain temperature stability of the ceramics prepared with untreated Nb2O5 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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