*3.2.1 Ferroelectric hysteresis*

The ferroelectric properties of the PF, prepared from PVDF/*n*- BaTiO3, the polarization versus electric field (P ~ E) of both the pure materials are given (**Figure 2**) at different voltages. **Figure 2a** shows narrow hysteresis loops for pure PVDF due the mixed phases [α, β, γ, δ & ε] as well as the electrical non-poling of the polymer PVDF.

The polarization versus electric field (P-E hysteresis loop) of the PF under different voltages for various *f*BaTiO3 = 0.2 (**Figure 3a**), *f*BaTiO3 = 0.3 (**Figure 3b**) *f*BaTiO3 = 0.4 (**Figure 3c**) and *f*BaTiO3 = 0.5 (**Figure 3d**) are shown. All the samples show symmetrical P-E hysteresis loops. The loop area increases of with increasing

#### **Figure 1.**

*FESEM micrographs of cold pressed PF (a) pure PVDF (lower resolution) (b) pure PVDF (higher resolution) (c) fBaTiO3 = 0.2 (lower resolution) (d) fBaTiO3 = 0.2 (higher resolution) (e) fBaTiO3 = 0.6 (lower resolution) (f) fBaTiO3 = 0.6 (higher resolution).*

the dc voltage from 5 kV to 10 kV. A comparison of P-E hysteresis loops, demonstrate that the samples with *f*BaTiO3 = 0.2 & 0.3 shows better ferroelectric hysteresis (higher hysteresis loop area) as compared to *f*BaTiO3 = 0.4 & 0.5. For precise assessment, the hysteresis loops at 8 kV for all the samples shows that the hysteresis loop area increases as a function of *f*BaTiO3, up to 0.30 (**Figure 1a**–**d**). On the other hand, beyond *f*BaTiO3 = 0.30, the heterogeneity/disordered structure is accountable for the decrement of ferroelectric properties and that is also accredited to the clustering of n-BaTiO3 into the polymer medium (**Figure 1e** and **f**). It is also experiential that with rising the field, the saturation polarization (*P*s), remnant polarization (*P*r) and the coercive field (*E*c) also increases as a function of *f*BaTiO3 and the finest result is obtained for the sample with *f*BaTiO3 = 0.3.

To have a thorough analysis and cross examination of the ferroelectric behavior of the PF, the P-E hysteresis loop of all the samples as a function of *f*BaTiO3 for different fields from 5 kV/cm to 8 kV/cm is shown in **Figure 4**. At all the fields, the ferroelectric behavior from the P-E hysteresis loops, are characterized by the change of *P*r, *P*s and *E*c.

**93**

**Figure 3.**

*Ferroelectric, Piezoelectric and Dielectric Properties of Novel Polymer Nanocomposites*

*(color online) polarization (P) vs. applied electric field (E) hysteresis loop measured at a frequency of 1 Hz* 

The experimental observation is that with increasing of the *f*BaTiO3 in the PF, the *P*r, *P*s and *E*c also increases. This obviously indicates that the addition of *n*-BaTiO3 enhances the ferroelectric nature of the polymer material. But when the amount of *n*-BaTiO3 filler content improved, there is trivial agglomeration of filler in the PVDF matrix. The agglomeration of *n*-BaTiO3 act as hindrances, which eliminate PVDF Polymer from flowing into the BaTiO3 agglomerates and the aggregated filler causes poor enhancement in ferroelectric nature (decrement in

*with different fields for different fBaTiO3 (a) 0.20 (b) 0.30 (c) 0.40 (d) 0.50.*

*(color online) polarization (P) vs. applied electric field (E) hysteresis loop measured at a frequency of 1 Hz* 

*DOI: http://dx.doi.org/10.5772/intechopen.96593*

*with different voltages for pure (a) PVDF (b) n-BaTiO3.*

**Figure 2.**

*Ferroelectric, Piezoelectric and Dielectric Properties of Novel Polymer Nanocomposites DOI: http://dx.doi.org/10.5772/intechopen.96593*

**Figure 2.**

*Multifunctional Ferroelectric Materials*

the dc voltage from 5 kV to 10 kV. A comparison of P-E hysteresis loops, demonstrate that the samples with *f*BaTiO3 = 0.2 & 0.3 shows better ferroelectric hysteresis (higher hysteresis loop area) as compared to *f*BaTiO3 = 0.4 & 0.5. For precise assessment, the hysteresis loops at 8 kV for all the samples shows that the hysteresis loop area increases as a function of *f*BaTiO3, up to 0.30 (**Figure 1a**–**d**). On the other hand, beyond *f*BaTiO3 = 0.30, the heterogeneity/disordered structure is accountable for the decrement of ferroelectric properties and that is also accredited to the clustering of n-BaTiO3 into the polymer medium (**Figure 1e** and **f**). It is also experiential that with rising the field, the saturation polarization (*P*s), remnant polarization (*P*r) and the coercive field (*E*c) also increases as a function of *f*BaTiO3 and the finest result is

*FESEM micrographs of cold pressed PF (a) pure PVDF (lower resolution) (b) pure PVDF (higher resolution) (c) fBaTiO3 = 0.2 (lower resolution) (d) fBaTiO3 = 0.2 (higher resolution) (e) fBaTiO3 = 0.6 (lower resolution) (f)* 

To have a thorough analysis and cross examination of the ferroelectric behavior of the PF, the P-E hysteresis loop of all the samples as a function of *f*BaTiO3 for different fields from 5 kV/cm to 8 kV/cm is shown in **Figure 4**. At all the fields, the ferroelectric behavior from the P-E hysteresis loops, are characterized by the change of *P*r, *P*s and *E*c.

**92**

**Figure 1.**

*fBaTiO3 = 0.6 (higher resolution).*

obtained for the sample with *f*BaTiO3 = 0.3.

*(color online) polarization (P) vs. applied electric field (E) hysteresis loop measured at a frequency of 1 Hz with different voltages for pure (a) PVDF (b) n-BaTiO3.*

**Figure 3.**

*(color online) polarization (P) vs. applied electric field (E) hysteresis loop measured at a frequency of 1 Hz with different fields for different fBaTiO3 (a) 0.20 (b) 0.30 (c) 0.40 (d) 0.50.*

The experimental observation is that with increasing of the *f*BaTiO3 in the PF, the *P*r, *P*s and *E*c also increases. This obviously indicates that the addition of *n*-BaTiO3 enhances the ferroelectric nature of the polymer material. But when the amount of *n*-BaTiO3 filler content improved, there is trivial agglomeration of filler in the PVDF matrix. The agglomeration of *n*-BaTiO3 act as hindrances, which eliminate PVDF Polymer from flowing into the BaTiO3 agglomerates and the aggregated filler causes poor enhancement in ferroelectric nature (decrement in

**Figure 4.** *(color online) polarization (P) vs. applied electric field (E) hysteresis loop measured at a frequency of 1 Hz with different fBaTiO3 for different fields (a) 5 kV/cm (b) 6 kV/cm (c) 7 kV/cm (d) 8 kV/cm.*

the ferroelectric polarization) as evident from **Figure 4**. Conversely the dielectric properties, such as the effective dielectric constant (εeff) and loss tangent (Tan δ) of all the PF becomes a linear dependence of *f*BaTiO3 (**Figure 5**), i.e. the static εeff enhances from 10 for pure PVDF to 400 for *f*BaTiO3 = 0.6, whereas the loss tangent increases from 0.09 for pure PVDF to 0.9 for *f*BaTiO3 = 0.6 [14]. The variation in the dielectric and ferroelectric behavior is credited to the different types of structures responsible for the two altered electrical properties respectively. The dielectric properties are connected with the more interfaces in the PF, hence εeff & Tan δ enhances linearly with *f*BaTiO3 and the ferroelectric properties are associated with the ordered structure of the PF.
