Study on the Size Effect of the BaTiO<sub>3</sub> Nanowires by LGD Theory

As the size of ferroelectric nanostructures decreases, the fundamental questions of the size dependence of the ferroelectric properties, and of their possible disappearance at a finite critical size, become crucial. In this paper, Landau-Ginzburg-Devonshire(LGD) theory is introduced to study the size-dependent ferroelectric properties of BaTiO3 nanowires. Our results demonstrate that the Curie temperature and mean polarization decrease with the reducing of nanowire diameters. We further show that these size effects are significant only when the nanowire diameters are less than 20nm, Above this, the ferroelectric behaviors of nanowires are almost the same as those of bulk materials and size effect can be neglected.