Local Field Engineering Approach for Tuning Dielectric and Ferroelectric Properties in Nanostructured Ferroelectrics and Composites

Padurariu, Leontin; Mitoşeriu, Liliana

doi:10.1002/9781118935743.ch18

Cited by 1 publication

(2 citation statements)

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“…Preisach model was usually employed for ferroelectrics to describe the polarization as a function on two parameters: applied electric field ( E app ) and maximum applied electric field ( E max ):

\begin{matrix} P_{up \to down} false(E, E_{max} false) = & P_{truemax} - 2 \cdot {false\int}_{E}^{E_{max}} [{false\int}_{E}^{a} p_{irrev} (a, b) d b] d a \\ - 2 \cdot {false\int}_{E}^{E_{max}} p_{rev} (a) d a, \end{matrix}

for the decreasing region of the polarization and:

\begin{matrix} P_{down \to up} false(E, E_{max} false) = & - P_{truemax} + 2 \cdot {false\int}_{- E_{max}}^{E} [{false\int}_{- E_{max}}^{a} p_{irrev} (a, b) d b] d a \\ + 2 \cdot {false\int}_{- E_{max}}^{E} p_{rev} (a) d a, \end{matrix}

for the increasing curve of the polarization, where p irrev and p rev represent two switching field distributions (irreversible and reversible components) of the local switching entities (“hysterons”). More details about the Preisach model and the meaning of p irrev and p rev distributions can be found elsewhere . In fact, all the ferroelectric systems are characterized by their particular distributions p irrev and p rev , which can be found by First‐Order Reversal Curves measurements, as demonstrated by many reports in literature …”

Section: Model and Discussionmentioning

confidence: 89%

“…More details about the Preisach model and the meaning of p irrev and p rev distributions can be found elsewhere. 41,42 In fact, all the ferroelectric systems are characterized by their particular distributions p irrev and p rev , which can be found by First-Order Reversal Curves measurements, as demonstrated by many reports in literature. [43][44][45][46] In the present simulations, the Preisach model was applied locally for computing the polarization of each element as a function of the local field and maximum local field estimated previously by FEM.…”

Section: Model and Discussionmentioning

confidence: 89%

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Porosity‐dependent properties of Nb‐doped Pb(Zr,Ti)O₃ ceramics

et al. 2016

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In the present work, it is shown how the controlled porosity can be exploited to obtain a compromise between a reduced permittivity down to a few hundreds and maintaining a high tunability level as in the dense material, to fulfill requirements for tunable applications. Nb‐doped Pb(Zr,Ti)O3 ceramics with porosity in the range 5%‐30% have been prepared by direct sintering method. X‐ray diffraction analysis and Rietveld refinement indicated a co‐existence of tetragonal and monoclinic phases in the porous ceramics. Dielectric properties revealed a gradual reduction in permittivity when increasing the porosity level, while maintaining low dielectric losses below 3%. The ferroelectric switching behavior is also influenced by the porosity level: a continuous reduction in the saturation and remnant polarization is observed with increasing porosity. The nonlinear dielectric properties of all the investigated ceramics preserve a high level of tunability in comparison with one of the dense material, irrespective of the porosity level, while zero field permittivity was decreased below 1000. An optimum behavior is found for the ceramic sample with 25% porosity, which shows a high tunability, smaller losses, and moderate dielectric constant (ε ~600).

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