Inorganic ferroelectrics

In the EFM, an electric field is created at the surface of the sample by applying a voltage to a conductive AFM tip, that is in close proximity to the surface. In the case of thin ferroelectric samples, it is possible to induce extremely strong and localized electric fields and hence to produce domains of electric polarization on a (sub)micrometer scale inside the film. By means of the EFM, the evolution of such domains can be studied both in organic and inorganic ferroelectric films. The interaction between the tip and the sample as a function of the material properties and system geometry can be described within a phenomenological model, described at the end of this contribution. 

Fig. 5 The ratio of the relevant component of the piezoelectric coefficient d and the respective polarization is plotted vs. the reciprocal of the respective elastic modulus Y (i.e., the relevant component of the elastic compliance). From left to right Literature data for inorganic ferroelectrics squares) barium titanate (BaTiOs), lead zirconate titanate (PZT), and lead zirconate niobate (PZN). Ferroelectric polymers triangles) polyamide-11 (PA-11), poly(vinylidene cyanide-vinyl acetate) (P(VDCN-VAc)), polyurea-5, poly(vinylidene fiuoride (PVDF)), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), and poly(vinylidene-hexafiuoropropylene) (P(VDF-HFP)). Polymer ferroelectrets circles) cellular polypropylene (cellular-PP) and tubular-channel poly (fluoro-ethylene-propylene) (FEP) (Qiu et al. 2014)...

Piezo/pyroelectric composite (inorganic ferroelectric particles in polymer matrix) Ions in crystalline particles form ionic dipoles upon symmetry breaking Ionic dipoles deform/ rotate with mechanical (electrical) stress Ferroelectric matrix polymer may compensate piezo-or pyroelectric effect... 

Polymer composites are multiphase materials containing, usually, inorganic fillers or reinforcing materials embedded in an anurphous or polycrystalline matrix. The dielectric properties of the inclusions arc, usually, very different from those of the nutrix. For ferroelectric appUcatioos, inorganic ferroelectric materials (e.g.. ceramics) are often used u fillers. 

The discovery of ferroelectric properties in several polymers preaented an excellent alternative to inorganic ferroelectric materials, which, however, are still used in most applications. 

---