BiFeO₃ Ceramics: Processing, Electrical, and Electromechanical Properties

Abstract

Dedicated to Prof. Dr. Marija Kosec, our Mari cka, who left us after a long struggle in her tenacious spirit in December 2012.Bismuth ferrite (BiFeO 3 ), a perovskite material, rich in properties and with wide functionality, has had a marked impact on the field of multiferroics, as evidenced by the hundreds of articles published annually over the past 10 years. Studies from the very early stages and particularly those on polycrystalline BiFeO 3 ceramics have been faced with difficulties in the preparation of the perovskite free of secondary phases. In this review, we begin by summarizing the major processing issues and clarifying the thermodynamic and kinetic origins of the formation and stabilization of the frequently observed secondary, nonperovskite phases, such as Bi 25 FeO 39 and Bi 2 Fe 4 O 9 . The second part then focuses on the electrical and electromechanical properties of BiFeO 3 , including the electrical conductivity, dielectric permittivity, high-field polarization, and strain response, as well as the weak-field piezoelectric properties. We attempt to establish a link between these properties and address, in particular, the macroscopic response of the ceramics under an external field in terms of the dynamic interaction between the pinning centers (e.g., charged defects) and the ferroelectric/ferroelastic domain walls. J ournalFeature BiFeO 3 ceramics. Among the most interesting are the BiFe-O 3 -PbTiO 3 (BFPT) 14,16 and BiFeO 3 -BaTiO 3 (BFBT) 15,17,18 systems, which provide both enhanced piezoelectricity and a high T C at the MPB, the latter exceeding that of Pb(Zr,Ti)O 3 (PZT) (T C~6 50°C for BFPT, T C~6 00°C for BFBT and T C~3 50°C for PZT at the MPB). In addition, a number of other BiFeO 3 -based lead-free compositions are presently the subject of intensive studies, including BiFeO 3 -REFeO 3 (RE = La, Nd, Sm, Gd, Dy), 19-21 BiFeO 3 -AETiO 3 (AE = Mg, Ca, Sr), 22-26 BiFeO 3 -Bi 0.5 K 0.5 TiO 3 27 , and BiFe-O 3 -Bi(Zn 0.5 Ti 0.5 )O 3 . 28 The piezoelectric properties of many of these ceramic systems have not yet been characterized systematically.The processing of single-phase BiFeO 3 ceramics is difficult; however, significant progress has been made recently, particularly in relation to the identification of the origins of the frequently formed nonperovskite, secondary phases. In addition, the complex relationship between processing and defects, on one hand, and the high-and weak-field electrical and electromechanical properties, on the other, has been addressed to some extent. Up to now, a lot of these new findings, in particular those relating to processing and domain-switching behavior, have not been considered sufficiently or are even ignored in the literature. Along with the aim of presenting a detailed overview of the past and recent results on BiFeO 3 ceramics, this absence or poor coverage of some important topics was one of the motivations that led us to prepare a comprehensive article, which also includes new data.The review comprises two topics on BiFeO 3 that are the most controvers...

Electrical conductivity and thermopower of (1 − x) BiFeO3– xBi0.5K0.5TiO3(x = 0.1, 0.2) ceramics near the ferroelectric to paraelectric phase transition

“…The formation of the secondary phase on the surface is most likely related to the loss of Bi 2 O 3 during the measurements as shown previously for pure BFO. 4 The Seebeck coefficients in the temperature range 650-800 1C in three different atmospheres, shown in Fig. 3, demonstrate clearly the p-type conductivity in air and oxygen and n-type conductivity in an inert atmosphere.…”

Preparation of phase pure, dense fine grained ceramics by conventional and spark plasma sintering of La-substituted BiFeO3 nanoparticles

“…2 Thus, the presence of secondary phases could be due to There is little data in the literature about the density of samples prepared in the system Bi 1-…”

Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

“…8 The high leakage current density in undoped BFO is attributed to the highly volatile nature of Bi with its corresponding off-stoichiometric phases and oxygen vacancies. 9 On the a Author to whom correspondence should be addressed (e-mail): mhrizvi@gce.buet.ac.bd b Author to whom correspondence should be addressed (e-mail): mabasith@phy.buet.ac.bd 2158-3226/2016/6(3)/035314/13 6, 035314-1 © Author(s) 2016.…”