Abstract
The current work aims to compare the effects of systematic A-site substitutions on the electrical properties of potassium sodium niobate (KNN)-based coating. The A-site elements were replaced by Li+ to form (K0.4675Na0.4675Li0.065) NbO3 (KNLN). The pure KNN coating and the Li+-doped potassium sodium niobate (KNLN) coating with dense morphology and single perovskite structure were successfully prepared by supersonic plasma spraying, and the phase composition, microscopic morphology and electrical properties of the two coatings were compared and analyzed in detail by XRD, XPS, three-dimensional morphology and SEM on an Agilent 4294A (Santa Clara, CA, USA) and FE-5000 wide-range ferroelectric performance tester. The results show that: as the polarization voltage increases, the pure KNN coating is flatter and fuller, but the leakage current is large. The KNLN coating has a relatively long hysteresis loop and is easily polarized. The domain deflection responds faster to the external electric field, and the resistance of the domain wall motion to the external electric field is small. The dielectric constant of KNLN coating is 375, which is much higher than that of the pure KNN coating with 125, and the dielectric loss is stable at 0.01, which is lower than that of pure KNN coating at 0.1–0.35. This is because Li+ doping has successfully constructed a polycrystalline phase boundary in which O-T phases coexist, and has higher dielectric properties, piezoelectric properties and ferroelectric properties. At the same time, due to the high-temperature acceleration process in supersonic plasma spraying, the violent volatilization of the alkaline elements Li+, Na+ and K+ leads to the presence of oxygen vacancies and part of Nb4+ in the coating, which seriously affects the electrical properties of the coating.
Highlights
At present, the research field of structural health monitoring is very wide, and it is widely used in various structures
As a kind of thermal spraying technology, supersonic plasma spraying technology can quickly impact the powder on the substrate so that the probability of phase change in the process from the powder to the coating is reduced, and to make the prepared coating maintain the excellent performance of the powder with the greatest probability, which is important for the preparation of smart sensor coatings
It is dominated by the orthogonal phase, containing a small amount of tetragonal high temperature will lead to the volatilization of basic elements Na and K, leaving cation vacancies, and Li+ first occupies these vacancies, replacing A-site K+ or Na+ to form a new solid solution [15]
Summary
The research field of structural health monitoring is very wide, and it is widely used in various structures. On the other hand, the supersonic plasma spraying technology can minimize the volatilization of components and the generation of the second phase, so as to obtain higher piezoelectric performance. Another limitation on the development of PZT piezoelectric coatings is the material itself, because it contains more than 60% of the volatile heavy metal lead. The latest research is from the Kui Yao team of Singapore National University They were the first to prepare KNN-based piezoelectric coatings and BNT coatings with a dense morphology and a single perovskite phase by supersonic plasma spraying [11,12]. We suggested that the enhancement in electrical properties was attributed to the decreasing of unmelted particles and the result of doping behavior
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
