Polarization dependence of physisorption on ferroelectric substrates
The ability to manipulate dipole orientation in ferroelectric oxides holds promise as a method to tailor surface reactivity for specific applications. As ferroelectric domains can be patterned at the nanoscale, domain-specific surface chemistries may provide a method for fabrication of nanoscale devices. Although studies over the past 50 years have suggested that ferroelectric domain orientation may affect the energetics of adsorption, definitive evidence is still lacking. Domain-dependent sticking coefficients are observed using temperature programmed desorption (TPD) and scanning surface potential microscopy (SSPM), supported by first-principles calculations of the reaction coordinate. The first unambiguous observations of differences in the energetics of physisorption on ferroelectric domains are presented here for CH3OH and CO2 on BaTiO3 and Pb(Ti0.52Zr0.48)O3 surfaces.
TPD on BaTiO3 thin film with in situ polarization control
|CH3OH and CH2O desorption signals for a series of TPD runs where the polarization was changed in the following order: c+, unpoled, c−.|
Precursor-mediated adsorption on defective ferroelectric oxide surfaces
|The gas-phase molecule physisorbs to the oxide surface, where it diffuses until reaching and chemisorbing at an O vacancy, or eventually desorbing.|
|Schematic diagram of the potential energy as a function of the distance from the surface.|