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

Palizdar, Meghdad, Comyn, Tim P., Ward, Mike B., Brown, Andrew P., Harington, John, Kulkarni, Santosh, Keeney, Lynette, Roy, Saibal, Pemble, Martyn, Whatmore, Roger, Quinne, Christopher, Kilcoyne, Susan H. and Bell, Andrew J. (2011) Crystallographic and magnetic identification of secondary phase in orientated Bi5Fe0.5Co0.5Ti3O15 ceramics. In: Applications of Ferroelectrics (ISAF/PFM), 2011 International Symposium on and 2011 International Symposium on Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials , 24-27 July 2011 , Vancouver, BC.

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    Abstract

    Oxide materials which exhibit both ferroelectricity
    and ferromagnetism are of great interest for sensors and memory
    applications. Layered bismuth titanates with an Aurivillius
    structure, (BiFeO3)nBi4Ti3O12, can possess ferroelectric and
    ferromagnetic order parameters simultaneously. It has recently
    been demonstrated that one such example,
    Bi5Fe0.5Co0.5Ti3O15,where n = 1 with half the Fe3+ sites substituted
    by Co3+ ions, exhibits both ferroelectric and ferromagnetic
    properties at room temperature. Here we report the fabrication
    of highly-oriented polycrystalline ceramics of this material,
    prepared via molten salt synthesis and uniaxial pressing of high
    aspect ratio platelets. Electron backscatter images showed that
    there is a secondary phase within the ceramic matrix which is
    rich in cobalt and iron, hence this secondary phase could
    contribute in the main phase ferromagnetic property. The
    concentration of the secondary phase obtained from secondary
    electron microscopy is estimated at less than 2.5 %, below the
    detection limit of XRD. TEM was used to identify the
    crystallographic structure of the secondary phase, which was
    shown to be cobalt ferrite, CoFe2O4. It is inferred from the data
    that the resultant ferromagnetic response identified using VSM
    measurements was due to the presence of the minor secondary
    phase. The Remanent magnetization at room temperature was
    Mr ≈ 76 memu/g which dropped down to almost zero (Mr ≈ 0.8
    memu/g) at 460 oC, far lower than the anticipated for CoFe2O4.

    Item Type: Conference or Workshop Item (Paper)
    Subjects: Q Science > Q Science (General)
    Q Science > QC Physics
    Schools: School of Applied Sciences
    Related URLs:
    Depositing User: Sara Taylor
    Date Deposited: 06 Dec 2011 14:52
    Last Modified: 06 Dec 2011 14:52
    URI: http://eprints.hud.ac.uk/id/eprint/12093

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