Low-symmetry phases in ferroelectric nanowires.
Ferroelectric nanostructures have recently attracted much attention due to the quest of miniaturizing devices and discovering novel phenomena. In particular, studies conducted on two-dimensional and zero-dimensional ferroelectrics have revealed original properties and their dependences on mechanical and electrical boundary conditions. Meanwhile, researches aimed at discovering and understanding properties of one-dimensional ferroelectric nanostructures are scarce. The determination of the structural phase and of the direction of the polarization in one-dimensional ferroelectrics is of technological importance, since, e.g., a low-symmetry phase in which the polarization lies away from a highly symmetric direction typically generates phenomenal dielectric and electromechanical responses. Here, we investigate the phase transition sequence of nanowires made of KNbO(3) and BaTiO(3) perovskites, by combining X-ray diffraction, Raman spectroscopy, and first-principles-based calculations. We provide evidence of a previously unreported ferroelectric ground state of monoclinic symmetry and the tuning of the polarization's direction by varying factors inherent to the nanoscale.
Louis
L
L
Laboratoire Structures, Propriétés et Modélisation des Solides, CNRS-UMR8580, Ecole Centrale Paris, Grande voie des vignes, Châtenay-Malabry, France.
Gemeiner
P
P
Ponomareva
I
I
Bellaiche
L
L
Geneste
G
G
Ma
W
W
Setter
N
N
Dkhil
B
B
D017609:Barium Compounds / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D053770:Nanowires / Q000737:chemistry*; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D011188:Potassium / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
D017609:Barium Compounds; D010087:Oxides; D009556:Niobium; C477466:potassium niobate; C024547:barium titanate(IV); D014025:Titanium; D011188:Potassium