Nano-Ferroelectric Domains Grown Inside Alumina Nano-Pores

This paper reports nanometer-size 180° ferroelectric domains in Rochelle salt (RS) (NaKC4H4O6· 4H2O) single crystals grown inside an array of alumina nano-pores. The RS crystals have a monoclinic phase and uniform crystallographic orientation. The nano-domains are uniformly oriented along the longitudinal axis of the pores, in vertical to the film plane. The domain-boundaries consist of a single crystallographic plane separating between two regions of anti-parallel atomic shear displacements. This configuration of ferroelectric nano-domains results in enhanced polarization relative to bulk-size RS crystals. The pores stabilize the ferroelectric phase up to 55°C (decomposition temperature of RS), which is higher by about 30°C relative to the upper transition temperature of bulk-size RS crystals.