Emerging Applications of Ferroelectric Nanoparticles in Materials Technologies, Biology and Medicine

Consider an insulating system with non-zero spontaneous polarization Ps (dielectric di‐ pole moment per unit volume). If an applied external electric field E that is greater than the so-called coercive field Ec can reverse Ps then our system is a ferroelectric system. Ferroelectricity has a long and exciting history described in [1,2]. In the beginning of its historical development (the Rochelle salt period) ferroelectricity was considered an aca‐ demic curiosity with no practical applications. There was little theoretical interest due to the quality of the ferroelectric materials (very fragile and water-soluble) existing at that time. The discovery of ferroelectricity in robust ceramic materials (barium titanate) dur‐ ing World War II launched a new era of rapid progress in the field. The structural sim‐ plicity of barium titanate stimulated numerous theoretical works, while its physical properties were utilized in many devices. Since that time, ferroelectric response has been found in a wide range of materials, including inorganic, organic, and biological species. According to [3] there are 72 families of ferroelectrics presented in Landolt–Börnstein‐ Vol.III/36 (LB III/36). Forty-nine of these families are inorganic crystals (19 families of ox‐ ides + 30 families of crystals other than oxides), and 23 families are organic crystals, liquid crystals, and polymers.