Browsing by Author "Rodel, J"

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    Domain fragmentation during cyclic fatigue in 94%Bi(1/2)Na(1/2)TiO3-6%BaTiO3.
    (American Institute of Physics, 2012-01-01) Simons, H; Glaum, J; Daniels, JE; Studer, AJ; Liess, A; Rodel, J; Hoffman, M
    The fatigue of the lead-free piezoceramic 94%(Bi1/2Na1/2)TiO3-6%BaTiO3 was investigated under bipolar electric fields. Degradation of the polarization, strain, and permittivity was measured during the fatigue process, and correlated with structural data measured at incremental points in the fatigue process using neutron diffraction. The results suggest a two-stage fatigue mechanism whereby, following a field-induced phase transformation to a poled ferroelectric state, the domain structure becomes progressively fragmented by a repetitive process of domain wall pinning and subdivision. © 2012, American Institute of Physics.
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    Electric-field-induced strain mechanisms in lead-free 94%(Bi1/2Na1/2)TiO3–6%BaTiO3.
    (American Institute of Physics, 2011-02-21) Simons, H; Daniels, JE; Jo, W; Dittmer, R; Studer, AJ; Avdeev, M; Rodel, J; Hoffman, M
    High resolution neutron diffraction has been used to investigate the structural origin of the large electric-field-induced remanent strain in 94(Bi1/2Na1/2)TiO3–6BaTiO3 ceramics. The virgin material was found to be a mixture of near-cubic phases with slight tetragonal and rhombohedral distortions of a0a0c+ and a−a−a− octahedral tilt type, respectively. Application of an electric field of 4.57 kV/mm transformed the sample to a predominantly rhombohedral a−a−a− modification with a significantly higher degree of structural distortion and a pronounced preferred orientation of the c-axis along the field direction. These electric field-induced structural effects contribute significantly to the macroscopic strain and polarization of this system. © 2011, American Institute of Physics