Local field engineering for tailoring electrical properties in ferroelectric-metallic particles composites

The present work shows the possibility of tuning the dielectric and ferroelectric properties in metallic-dielectric composites by local field engineering. The effective macroscopic properties in such composites can be... [ view full abstract ]

The present work shows the possibility of tuning the dielectric and ferroelectric properties in metallic-dielectric composites by local field engineering. The effective macroscopic properties in such composites can be tailored by exploiting the local field inhomogeneity via an adequate choice of phase constituents and phase interconnectivity type [1].

            Based on this idea, Finite Element Model (FEM) calculations have been performed to compute local field distributions in realistic microstructures of dielectric-metallic inclusions composites in order to explore the possibility to maximize their ferroelectric or non-linear dielectric responses (tunability) and increase permittivity level. Two types of composites with metallic inclusions into polymer-based and ferroelectric BaTiO₃ matrices will be shown: (i) Au nanoparticles – Chitosan flexible composites with enhanced permittivity and tunability (Fig.1) [2,3] and (ii) Ag-BaTiO₃ ceramics with high permittivity as result of a synergic effect of grain size of 1µm and presence of metal inclusions (Fig.2) [4]. Interfaces in composites with combinations of di-similar materials may be used as an elegant tool to enhance functionalities as result of the field concentration in specific regions.

Fig. 1 S-SNOM image of Chitosan - Au films and their tunability.

Fig. 2 FEM calculations on a 2D system based on the microstructure of Ag-BT ceramic sintered at 1200°C: (a) SEM micrograph; (b) EDS elemental mapping of silver; (c) 2D FEM model system; (d) FEM simulation of local field image.

Acknowledgements: This work was supported by the Romanian UEFISCDI PN-III-P4-ID-PCE-2016-0817 grant.

References

• L. Padurariu et al., Phys. Rev. B85, 224111 (2012)
• A. Cazacu et al., Appl. Phys. Lett. 102, 222903 (2013)
• A.M. Neagu et al., Composites: Part B, 66, 109–116 (2014); 71, 210–217 (2015) 
• I. Turcan et al., J. Eur. Ceram. Soc., 2018.