title: Ferroelectric phase transition in individual single-crystalline BaTiO3 nanowires.
abstract: 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.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Spanier
authors.forename: Alexie M
authors.initials: AM
authors.lastname: Kolpak
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Urban
authors.forename: Ilya
authors.initials: I
authors.lastname: Grinberg
authors.forename: Lian
authors.initials: L
authors.lastname: Ouyang
authors.forename: Wan Soo
authors.initials: WS
authors.lastname: Yun
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Rappe
authors.forename: Hongkun
authors.initials: H
authors.lastname: Park
mesh_terms: 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
chemical_list: D017609:Barium Compounds; C024547:barium titanate(IV); D014025:Titanium