Electric-field-induced phase transition and pinched P–E hysteresis loops in Pb-free ferroelectrics with a tungsten bronze structure
| Autor: | Jan Kroupa, Mao Sen Fu, Stanislav Kamba, Xiang Ming Chen, Xiao Li Zhu, Xiao Ma, Xiao Qiang Liu, Kun Li |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Phase transition
Materials science lcsh:Biotechnology chemistry.chemical_element 02 engineering and technology Dielectric Tungsten 01 natural sciences Condensed Matter::Materials Science Electric field lcsh:TP248.13-248.65 0103 physical sciences lcsh:TA401-492 Antiferroelectricity General Materials Science 010302 applied physics Condensed matter physics Transition temperature 021001 nanoscience & nanotechnology Condensed Matter Physics Ferroelectricity Hysteresis chemistry Modeling and Simulation lcsh:Materials of engineering and construction. Mechanics of materials 0210 nano-technology |
| Zdroj: | NPG Asia Materials, Vol 10, Iss 4, Pp 71-81 (2018) |
| ISSN: | 1884-4057 1884-4049 |
| DOI: | 10.1038/s41427-018-0013-x |
| Popis: | Antiferroelectrics are of interest due to their high potential for energy storage. Here, we report the discovery of pinched, polarization-vs.-electric field (P–E) hysteresis loops in the lead-free tungsten bronze ferroelectrics Ba4Sm2Ti4Nb6O30 and Ba4Eu2Ti4Nb6O30, while a broad, single P–E hysteresis loop was observed in the analogue compound Ba4Nd2Ti4Nb6O30. Pinched P–E loops are similar to antiferroelectric hysteresis loops, but in perovskites, they are mostly caused by an extrinsic, internal bias field due to defects, which block domain wall motion. We show that the pinched P–E loops are caused by an intrinsic effect, i.e., by the electric-field-induced phase transition from a non-polar incommensurate to a polar commensurately modulated crystal structure. The in situ electron diffraction results show the coexistence of commensurate polar structural modulation and incommensurate non-polar modulation during the ferroelectric transition and within the ferroelectric phase below the transition temperature. This phase coexistence is the reason for the small remanent polarization. An external electric field transforms the incommensurate component into a commensurate one, and the polarization increases. This new mechanism for pinched P–E hysteresis loops in ferroelectrics not only indicates a new direction for the development of Pb-free ferroelectric materials for energy storage but also significantly contributes to the physical understanding of ferroelectricity in materials with a tungsten bronze structure. An unusual switching action normally associated with crystal defects may be reproduced on demand in eco-friendly ceramics. Electric fields can modulate the polarization of ferroelectric materials, which have spontaneously aligned electric dipoles, and antiferroelectrics, which have adjacent dipoles pointing in opposite directions. These kinds of polarization switches have applications in energy-storage and memory devices. Now, Xiang Ming Chen from Zhejiang University in China and colleagues report compounds that exhibit characteristics of both polar and nonpolar switches. The team found that by modifying the size of rare earth ions encased in lead-free tungsten bronze ceramics, they could create a distinct ‘pinch’ in graphs that plot the polarization response to an electric field—a clear feature of bistable ferroelectric materials. Electron diffraction measurements suggest the pinched hysteresis loops appear from internal, field-induced phase transitions. The present electric-field induced phase transition from non-polar incommensurate to ferroelectric commensurate phase in Pb-free dielectrics with tungsten bronze structure has been proved to be the structural origin of the pinched P-E loops. This new mechanism for pinched P-E hysteresis loops in ferroelectrics not only indicates a new direction to develop Pb-free ferroelectric materials for energy storage but also contributes significantly to physical understanding of ferroelectricity in materials with tungsten bronze structure. |
| Databáze: | OpenAIRE |
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