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- Title
Complex dielectric behaviours in BiFeO<sub>3</sub>/Bi<sub>2</sub>Fe<sub>4</sub>O<sub>9</sub> ceramics.
- Authors
Orr, Gilad; Gorychev, Andrey; Ishai, Paul Ben
- Abstract
The complex dielectric permittivity of a sintered ceramic tablet consisting of 70.5% BiFeO3, 27.7% Bi2Fe4O9 and 1.8% Bi25FeO40 was analyzed as a function of temperature from – 120 °C to 230 °C in two separate temperature runs. The results reveal a complicated dielectric response with two temperature activated relaxation processes. The first is purely Arrhenius relaxation related to hopping processes between Fe3+ and Fe2+ traps induced by oxygen vacancies at grain boundaries. The second process is more unusual. Its characteristic relaxation time follows a quasi-Vogel–Tammann–Fulcher temperature behavior and from fitting the critical temperature point is estimated at T 0 = 766 K . It is absent in the second temperature run. It can be related to dynamic rearrangements of domain boundaries between different crystallites in the ceramic. The results also reveal a ferroelectric phase transition that decayed with repeated heating cycles of the tablet. The ferroelectric phase transition in pure BiFeO3 is 1098 K, whereas the current results show it at 373 K. The origin of this reduction in the critical temperature of the phase transition is traced to locally induced strains on grain boundaries mainly because of unit cell size mismatch between BiFeO3 and Bi2Fe4O9.
- Subjects
PHASE transitions; DIELECTRIC relaxation; CRITICAL temperature; TRANSITION temperature; FERROELECTRIC transitions; DIELECTRICS; CERAMICS
- Publication
Applied Physics A: Materials Science & Processing, 2022, Vol 128, Issue 12, p1
- ISSN
0947-8396
- Publication type
Article
- DOI
10.1007/s00339-022-06234-0