Unveiling the electrical performance of flash-sintered potassium sodium niobate

In the context of sensor, actuator, and energy harvesting applications, lead-free ferroelectric K 0.5 Na 0.5 NbO 3 (KNN) ceramics offer several advantages, including a high transition temperature and an elevated piezoelectric coefficient. However, producing single-phase KNN ceramics at a low thermal...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024-10, Vol.12 (41), p.16958-16968
Main Authors: Tkach, Alexander, Serrazina, Ricardo, Pereira, Luis, Senos, Ana M. O. R, Vilarinho, Paula M
Format: Article
Language:English
Subjects:
Actuators
Budgets
Ceramics
Crystal defects
Curie temperature
Electric fields
Electrical properties
Electrical resistivity
Energy harvesting
Ferroelectric materials
Ferroelectricity
Heat treatment
Impedance spectroscopy
Lattice vacancies
Lead free
Piezoelectricity
Resistance sintering
Sintering
Spectrum analysis
Transition temperature
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Summary:In the context of sensor, actuator, and energy harvesting applications, lead-free ferroelectric K 0.5 Na 0.5 NbO 3 (KNN) ceramics offer several advantages, including a high transition temperature and an elevated piezoelectric coefficient. However, producing single-phase KNN ceramics at a low thermal budget requires alternative sintering processes such as electric-field- and current-assisted flash sintering. Furthermore, the electrical properties of flash-sintered ferroelectrics are rarely disclosed. Here, based on systematic dielectric and ferroelectric, impedance spectroscopy and DC conductivity measurements, we demonstrate that the electrical performance of flash-sintered KNN is quite dependent on its thermal history, in contrast to the conventionally sintered one. Simultaneously, we demonstrate the successful production of high-performance KNN ceramics with high polarization, dielectric permittivity, Curie temperature, and piezoelectric coefficient using flash sintering, coupled with a carefully chosen post-sintering electrode curing step. Supported by impedance spectroscopy results, indicative of enhanced oxygen vacancy content in flash-sintered KNN, we postulate that post-sintering heat treatment and low-thermal-budget flash sintering are equally critical for KNN applications, complementing the benefits of reducing lattice defects and enhancing electroceramic performance. Our results demonstrate a pathway towards alternative sintering of electroceramics and offer opportunities to control performance. Electrical performance of flash-sintered K 0.5 Na 0.5 NbO 3 ceramics: after annealing, both conventional and flash-sintered KNN ceramics exhibited electrically homogeneous behaviour similar to that of single crystals.
ISSN:2050-7526
2050-7534
DOI:10.1039/d4tc01702a