Browsing by Author "Amin, Ahmed"

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    Electromechanical and elastic isotropy in the (011) plane of 0.7Pb(Mg1/3Nb2/3)O-3-0.3PbTiO(3) crystals: Inhomogeneous shearing of polarization
    Viehland, Dwight D.; Li, Jiefang; Amin, Ahmed (American Institute of Physics, 2002-10-01)
    Temperature dependent electromechanical investigations of <110>, <001>, and <111> oriented morphotropic phase boundary compositions of Pb(Mg1/3Nb2/3)O-3-PbTi0(3) crystals have been performed. Softening of the dielectric constant, piezoelectric constant, and Young's modulus was found for all three orientations, near a ferroelectric rhombohedral to ferroelectric tetragonal transformation. However, the value of Young's modulus was an order of magnitude higher along <111>, than either <001> or <110>. An unusual electromechanical and elastic equivalence was found between the <110> and <001> directions. This result demonstrates that the enhanced electromechanical performance of oriented piezocrystals is not constrained to the <001> orientation, but rather to the (011) plane. (C) 2002 American Institute of Physics.
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    Temperature stability of the piezoelectric and elastic response of dc biased 001 and 110 oriented Pb(Zn1/3Nb2/3)O-3-PbTiO3 single crystals
    Amin, Ahmed; Viehland, Dwight D. (American Institute of Physics, 2004-11-01)
    Temperature and field dependent investigations of the longitudinal electromechanical properties of [001]- and [110]-oriented 0.955Pb(Zn1/3Nb2/3)O-3-0.045PbTiO(3) single crystals have been performed. Electromechanical equivalence was found between [001] and [110] orientations in the ferroelectric rhombohedral FEr phase region, but not in the ferroelectric tetragonal FEt one. A dc bias of 0.4 MV/m did not affect this equivalence. Softening of the dielectric constant (K), piezoelectric coefficient (d(33)), and Young's modulus (Y) were observed along both the [001] and [110] orientations in the FEr phase region on heating towards the FEt one. Above the FEr-FEt phase transition, a significant anisotropy was observed in the electromechanical and elastic coefficients. These results demonstrate that the enhanced length extensional (33-mode) electromechanical coupling k(33) of rhombohedral crystals far from the morphotropic phase boundary is not constrained to the <001> orientation, but rather to the (110) plane. (C) 2004 American Institute of Physics.