Ferroelectric phase transition in individual single-crystalline BaTiO3 nanowires.
We report scanned probe characterizations of the ferroelectric phase transition in individual barium titanate (BaTiO3) nanowires. Variable-temperature electrostatic force microscopy is used to manipulate, image, and evaluate the diameter-dependent stability of ferroelectric polarizations. These measurements show that the ferroelectric phase transition temperature (TC) is depressed as the nanowire diameter (dnw) decreases, following a 1/dnw scaling. The diameter at which TC falls below room temperature is determined to be approximately 3 nm, and extrapolation of the data indicates that nanowires with dnw as small as 0.8 nm can support ferroelectricity at lower temperatures. We also present density functional theory (DFT) calculations of bare and molecule-covered BaTiO3 surfaces. These calculations indicate that ferroelectricity in nanowires is stabilized by molecular adsorbates such as OH and carboxylates. These adsorbates are found to passivate polarization charge more effectively than metallic electrodes, explaining the observed stability of ferroelectricity in small-diameter BaTiO3 nanowires.
Spanier
Jonathan E
JE
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Kolpak
Alexie M
AM
Urban
Jeffrey J
JJ
Grinberg
Ilya
I
Ouyang
Lian
L
Yun
Wan Soo
WS
Rappe
Andrew M
AM
Park
Hongkun
H
D016880:Anisotropy; D017609:Barium Compounds / Q000032:analysis / Q000737:chemistry* / Q000528:radiation effects*; D003460:Crystallization / Q000379:methods; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D004574:Electromagnetic Fields; D008280:Magnetics; D008422:Materials Testing; D008968:Molecular Conformation; D043942:Nanotubes / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D044367:Phase Transition; D014025:Titanium / Q000032:analysis / Q000737:chemistry* / Q000528:radiation effects*; D044366:Transition Temperature
D017609:Barium Compounds; C024547:barium titanate(IV); D014025:Titanium