Uniform orientation and size of ferroelectric domains

Rochelle salt (RS) (NaKC(4)H(4)O(6)center dot 4H(2)O) single crystals were grown inside an array of alumina pores having an average diameter of 30 nm and length of about 0.5 mu m. The crystals have a monoclinic crystallographic structure and uniform crystallographic orientation. High-resolution transmission electron microscopy vertical cross section images show multiple nanometer-sized 180 degrees ferroelectric domains in each single crystal having uniform size and orientation along the longitudinal axis of the pores. The nanodomain boundaries consist of a single crystallographic plane of a rotation twin. This configuration of ferroelectric nanodomains results in enhanced polarization, which is higher by one order of magnitude than the maximum polarization values reported for bulk-size RS crystals. The pores stabilize the ferroelectric phase up to 55 degrees C (decomposition temperature of RS), which is higher by about 30 degrees C relative to the upper transition temperature of bulk-size RS crystals. The highly dense array of individual ferroelectric single crystals with uniform polarization orientation and size of nanodomains, as presented in this paper, is a basis for future high-resolution and high-density ferroelectric-based devices, where each nanocrystal inside a pore can serve as a detector, sensor, or actuator.