Multiferroic properties of layer-structured Bi5Fe0.5Co0.5Ti3O15 ceramics

Abstract

Layer-structured, single phase Bi5Fe0.5Co0.5Ti3O15 ceramics was synthesized following a multicalcination procedure. Magnetic moment increases more than three times by substituting half Fe sites by Co ions. The material exhibits an Aurivillius phase with a four-layer unit cell structure, and presents a remarkable coexistence of ferroelectricity and ferromagnetism above room temperature. The measured 2Pr and 2Mr are 13 μC/cm2 and 7.8 memu/g, respectively. The material’s magnetic behavior below 275 °C is relaxationlike and its magnetic Curie temperature is ∼345 °C.

Room temperature electromechanical and magnetic investigations of ferroelectric Aurivillius phase Bi5Ti3(FexMn1−x)O15 (x = 1 and 0.7) chemical solution deposited thin films

“…Since room temperature ferroelectric switching was observed for the BTFO and BTF7M3O thin films, the Bi mþ1 Fe mÀ3 Ti 3 O 3mþ3 Aurivilllius phase system could act as a perfect precursor for multiferroic thin film materials via B site substitution using alternative magnetic cations. Indeed, the coexistence of ferroelectricity and ferromagnetism above room temperature has recently been reported 21 Along with the potential commercial applications of these novel ferroelectric thin films as lead-free piezoelectrics for adverse environments, the ability of the ferroelectric BTFO and BTF7M3O thin films to exist in and switch between two polarized states and retain polarization for a finite period makes possible their application as the active component of energy efficient FeRAM capacitors. Ferroelectric lithography investigations of BTF7M3O on silicon demonstrate that polarisation information can be stored in the films and recovered by PFM.…”

The structural and piezoresponse properties of c-axis-oriented Aurivillius phase Bi5Ti3FeO15 thin films deposited by atomic vapor deposition

“…[11][12][13][14][15][16][17][18][19] While methods such as sol-gel, 12,19 solid-state reaction, 17,18 and pulsed laser deposition 4 20,21 Atomic vapor deposition (AVD) is based on pulsed liquid-injection chemical vapor deposition with a volume of each pulse of the order of microlitres. 22 It has been proved that AVD can deposit high-quality high-k dielectric or ferroelectric films with a largely uniform film thickness, composition, and electrical properties and is highly suitable for mass production.…”

Crystallographic and magnetic identification of secondary phase in orientated Bi5Fe0.5Co0.5Ti3O15 ceramics

“…The M-H loops confirm the existence of a ferromagnetic phase within the material, however, the inability to saturate the sample even at a field of 5 T, suggests the presence of additional magnetic phases. The in-plane magnetization values of BFCT produced from the molten salt method is approximately ten times greater than that reported for BFCT by Mao et al, 6 which was made from a conventional solid state reaction method.…”

“…21 Depending on the grain size, magnetic Curie temperature ranges of 520 C-557 C and 187 C have been identified for CoFe 2 O 4 and Co 2 FeO 4 , respectively. 14,15,22-24 Mao et al 6 claimed a Curie temperature of 345 C for BFCT. Consequently, by investigating the Curie temperature of BFCT prepared in this study, it would be possible to identify the influence of the CoFe 2 O 4 secondary phase on the magnetic properties of the main BFCT phase.…”

“…The structure can be described as layers comprising m simple unit cells of perovskite [ 6 This result is significant as this material would be the only currently-known material that is both ferroelectric and ferromagnetic at room temperature.…”