Papers by Stephen Garofalini
The Journal of Physical Chemistry, 1996
![Research paper thumbnail of In Situ Deposition and Ultrahigh Vacuum STM/AFM Study of V[sub 2]O[sub 5]/Li[sub 3]PO[sub 4] Interface in a Rechargeable Lithium-Ion Battery](https://attachments.academia-assets.com/74891103/thumbnails/1.jpg)
Journal of The Electrochemical Society, 2001
A thin-film solid-state battery was prepared with a vanadium pentoxide cathode and a lithium phos... more A thin-film solid-state battery was prepared with a vanadium pentoxide cathode and a lithium phosphate electrolyte and studied in situ by ultrahigh vacuum scanning tunneling microscope/atomic force microscopy ͑STM/AFM͒. Orientation of the ͑001͒ plane of V 2 O 5 parallel to the substrate was detected via observation of the periodicity of 11.7 Ϯ 0.5 Å, which is consistent with the unit cell spacing in the ͗100͘ direction. Conductance of the battery was studied locally with the probe tip of the STM/AFM in the regime of mechanical contact with a constant repulsive force. Lateral variation of contact conductance from 0.4 to 2.2 nA was detected as a function of position of the tip in contact with the cathode. The device revealed an extremely high current density of 1 A/cm 2 due to the low thickness of the electrolyte and the cathode and the concentration of electric field under the scanning probe microscope tip. Transformation of cathode structure due to Li ion intercalation was observed in real time.
Chemical Physics Letters, 1993
ABSTRACT
Surface Science Letters, 1993
The Journal of Physical Chemistry, 1996
Catalysis Letters, 1994
Molecular dynamics simulations of the pure and doped surfaces of 7-A1203 were performed. Thermal ... more Molecular dynamics simulations of the pure and doped surfaces of 7-A1203 were performed. Thermal behavior of both the D-layer of the (110) surface and the E-layer of the (001) surface was examined. An abrupt increase in mobility of surface ions was observed at high temperatures. An onset of diffusion occurs for the pure (110) surface at 1200 K. The instability is caused by the cation vacancies adjacent to the surface. Silicon and cerium ions deposited into the sub-surface vacancies reduce the mobility of the surface ions and prevent the onset of diffusion, cerium being more efficient in stabilization than silicon. This forms a microscopic picture of the role of additives in the stabilization of the T-A1203 surfaces.
Physical Review Letters, 2003
Molecular dynamics simulations of fused silica at shock pressures reproduce the experimental equa... more Molecular dynamics simulations of fused silica at shock pressures reproduce the experimental equation of state of this material and explain its characteristic shape. We demonstrate that shock waves modify the medium-range order of this amorphous system, producing changes that are only clearly revealed by its ring size distribution. The ring size distribution remains practically unchanged during elastic compression but varies continuously after the transition to the plastic regime.
Langmuir, 2009
Experimental measurements of the thermal expansion coefficient (R), permeability (k), and diffusi... more Experimental measurements of the thermal expansion coefficient (R), permeability (k), and diffusivity (D) of water and 1 M solutions of NaCl and CaCl 2 are interpreted with the aid of molecular dynamics (MD) simulations of water in a 3 nm gap between glass plates. MD shows that there is a layer ∼6 Å thick near the glass surface that has R ∼2.3 times higher and D about an order of magnitude lower than bulk water. The measured D is ∼5 times lower than that for bulk water. However, when the MD results are averaged over the thickness of the 3 nm gap, D is only reduced by ∼30% relative to the bulk, so the measured reduction is attributed primarily to tortuosity of the pore space, not to the reduced mobility near the pore wall. The measured R can be quantitatively explained by a volume-weighted average of the properties of the high-expansion layer and the "normal" water in the middle of the pore. The permeability of the porous glass can be quantitatively predicted by the Carman-Kozeny equation, if 6 Å of water near the pore wall is assumed to be immobile, which is consistent with the MD results. The properties and thickness of the surface-affected layer are not affected significantly by the presence of the dissolved salts.
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Papers by Stephen Garofalini