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Wet chemical etching of (Ba 1−x Sr x )TiO 3 thin films has been investigated. The etchant was prepared from buffered hydrofluoric acid (BHF) and nitric acid (HNO 3 ), BHF being the reactive agent while HNO 3 acts as a catalyst. X-ray diffraction and energy dispersive X-ray spectrometry were performed in order to qualitatively and quantitatively...
We propose a description of the non-linear response of a ferroïc single crystal to the action of an ac constraint, here an electric field, by examining the polarization. For that, we use the model we have develop to describe the movement of the domain walls [1]. We establish the equation of the polarization or of the strain as a function of the time and we deduce the expression of the hysteresis loop...
The application of an electrical field E or a mechanical stress σ on a ferroïc single crystal leads to the switching of the dipolar moments inducing the motion of domain walls. According to the approach that we have developed to model the movement of domain walls, we established a relationship between the dielectric (or the piezoelectric) properties and the applied constraints. In this model, we calculate...
The response of a single crystal to the application of low constraint amplitudes (electric field E or mechanic stress σ) is generally depicted by the empirical Rayleigh law. According to the model describing the motion of the domain walls and presented else where in this congress, we establish, in the limit of the Rayleigh domain, the variation of the dielectric constant ε and of the piezoelectric...
The ferroïc materials exhibit a nonlinear behavior largely due to the motion of domain walls. To well understand the resulting properties, it is necessary to develop a model describing these movements. In this work, we establish the motion equation of one domain wall induced by application of an electric field E or of a mechanical stress σ. The effects of a magnetic field could also be envisaged....
The characterizations of ferroïc materials are often realized by measuring the minor loops. The polarization P and/or the strain S are reported as a function of the ac electric field E and/or the ac mechanical stress σ. The slope of the loop depends on the real part of ε or d (respectively the dielectric constant and the piezoelectric coefficient) and its opening is related to the imaginary part of...
Ferroelectric materials are interesting for their switching polarization and present a non linear variation of their permittivity which is due to domain wall motion. Currently, this variation of permittivity is described by the Rayleigh law for fields above a threshold field or by a power law in the case of soft ferroelectrics. In this study we propose a hyperbolic law based on domain wall motions...
In this study, the real and imaginary parts of the complex permittivity of PZT ferroelectric thin films are studied in the frequency range of 100 Hz - 100 MHz. The permittivity is well fitted by the Cole-Cole model. The variation of the relaxation time with temperature is described by the Arrhenius law and an activation energy of 0.38 eV is found. Due to its nonlinear character, the dielectric response...
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