FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics Keith J. Bowman, Purdue University, DMR 0805022. - PowerPoint PPT Presentation
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National Science Foundation FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics Keith J. Bowman, Purdue University, DMR 0805022 Outcome : Purdue University and Illinois Institute of Technology researchers have conducted simulations that describe regions within crystals wherein switching of domains follows the applied field, acts inversely to the applied field or is unresponsive to applied field. Impact : These simulations may advance our understanding of domains in piezoelectric materials and the resulting research also enables an efficient method for describing conditions under which field application to materials may be non-symmetric. Explanation : A computer-generated microstructure that enables tracking of the 180 degree polarization in a two dimensional microstructure responds to an overall applied field. The magnitude of the local field within a region is indicated as positive in the bright regions and negative in bright blue regions. Darker colors indicate values closer to zero. The magnitudes of the external applied field are labeled in the ferroelectric hysteresis loop. In this work, a compact expression enabling reporting of the degree of non-symmetry in applied field was described using an R E - Zizhao Zhao, Keith Bowman, and R. Edwin Garcia, J. American Ceramic Society, 95 [5] 1619–
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FRG: Domain Orientation and Anisotropy in Poled Piezoelectrics Keith J. Bowman, Purdue University, DMR 0805022
Outcome: Purdue University and Illinois Institute of Technology researchers have conducted simulations that describe regions within crystals wherein switching of domains follows the applied field, acts inversely to the applied field or is unresponsive to applied field.Impact: These simulations may advance our understanding of domains in piezoelectric materials and the resulting research also enables an efficient method for describing conditions under which field application to materials may be non-symmetric.Explanation: A computer-generated microstructure that enables tracking of the 180 degree polarization in a two dimensional microstructure responds to an overall applied field.
The magnitude of the local field within a region is indicated as positive in the bright regions and negative in bright blue regions. Darker colors indicate values closer to zero. The magnitudes of the external applied field are labeled in the ferroelectric hysteresis loop. In this work, a compact expression enabling reporting of the degree of non-symmetry in applied field was described using an RE-ratio, by analogy to the commonly used expression for non-symmetric mechanical fatigue of materials where RE = Emin / Emax Zizhao Zhao, Keith Bowman, and R. Edwin Garcia,
J. American Ceramic Society, 95 [5] 1619–1627 (2012)
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Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3
Keith J. Bowman, Purdue University, DMR 0805022
Matthias Ehmke and John E. Blendell (Purdue University), Steven Ehrlich (Brookhaven National Laboratory), and Keith J. Bowman (Illinois Institute of Technology) Bipolar polarization and strain response to applied electrical field for unpoled BZT-BCT materials with compositions that should nominally have rhombohedral crystal structures show slender polarization loops and “seagull”shaped strain loops. These behaviors appear for materials that consist of both rhombohedral and tetragonal phases prior to the application of electrical field.
Matthias C. Ehmke, Steven N. Ehrlich, John E. Blendell, and Keith J. Bowman, J. Appl. Phys. 111, 124110 (2012).
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Christopher M. Fancher, John E Blendell and Keith J. Bowman at Purdue University
Basal textures have been produced in (1‑x-y)Bi0.5Na0.5TiO3-(x)BaTiO3-(y)K0.5Na0.5NbO3 ceramics using tape casting with pure phase Bi0.5Na0.5TiO3templates. The crystallographic preferred orientation of fired ceramics was analyzed by a Rietveld refinement method, using a discrete orientation distribution model. Texturing enhanced the piezoelectric response of all measured compositions; with Bi0.5Na0.5TiO3–(5)BaTiO3 reaching a maximum d33 of 245 pC/N. Textured Bi0.5Na0.5TiO3 alloys reached a maximum d33 at applied voltages below the electrical coercive field.
Poling Effect on d33 in Textured BNT-based MaterialsKeith J. Bowman, Purdue University, DMR 0805022
Reconstructed pole figures of a) BNT, b) BNT-5.7BT, c) BNT-4.7BT-1.9KNN showing a strong {100} fiber texture.
