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Full-Text Articles in Physics
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Predicting The Hydrogen Pressure To Achieve Ultralow Friction And Diamondlike Carbon Surfaces From First Principles, Haibo Guo, Yue Qi, Xiaodong Li
Faculty Publications
Hydrogen atmosphere can significantly change the tribological behavior at diamond and diamondlike carbon (DLC) surfaces and the friction-reducing effect depends on the partial pressure of hydrogen. We combined density functional theory modeling and thermodynamic quantities to predict the equilibrium partial pressures of hydrogen at temperature T, PH2 (T), for a fully atomic hydrogen passivated diamondsurface. Above the equilibrium PH2 (T), ultralow friction can be achieved at diamond and DLC surfaces. The calculation agrees well with friction tests at various testing conditions. We also show that PH2 (T) …
Atomic Size Mismatch Strain Induced Surface Reconstructions, Jessica E. Bickel, Normand A. Modine, Anton Van Der Ven, Joanna Mirecki Millunchick
Atomic Size Mismatch Strain Induced Surface Reconstructions, Jessica E. Bickel, Normand A. Modine, Anton Van Der Ven, Joanna Mirecki Millunchick
Physics Faculty Publications
The effects of lattice mismatch strain and atomic size mismatch strain on surface reconstructions are analyzed using density functional theory. These calculations demonstrate the importance of an explicit treatment of alloying when calculating the energies of alloyed surface reconstructions. Lattice mismatch strain has little impact on surface dimer ordering for the α2(2×4) reconstruction of GaAs alloyed with In. However, atomic size mismatch strain induces the surface In atoms to preferentially alternate position, which, in turn, induces an alternating configuration of the surface anion dimers. These results agree well with experimental data for α2(2×4) domains in InGaAs∕GaAs surfaces.