Size-dependent ferroelectric behaviors of BaTi O3 nanowires

Landau-Ginsburg-Devonshire theory is introduced to investigate the size-dependent ferroelectric properties of BaTi O3 nanowires, with the consideration of polarization orienting along the radial direction. It is shown that the Curie temperature, mean polarization, and area enclosed by hysteresis loop decrease with the reducing diameter of the nanowire. However, this size effect becomes obvious only when the diameter is below 20 nm. Above this, the ferroelectric behaviors of nanowires are almost the same as those of bulk materials. Furthermore, there exists a temperature-dependent critical diameter for BaTi O3 nanowire below which the hysteresis loops vanish and it is 3.6 nm at room temperature.