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Spectroscopical Analysis of Mechano-chemically Activated Surfaces

By Rodrigo Cooper

Abstract

Mechano-chemical activation is fundamentally different than chemical activation in that energy is added to alter the state of bond energy instead of exciting electrons to produce a chemical reaction. Mechano-chemical activation has demonstrated to alter the chemical reaction and rates. There remains no development of a model to quantify the changes in reactions due to mechano-chemical activation. This research aims in expanding our understanding of the influence of mechanochemical activation methods. The dynamics and kinetics of mechano-chemically activated surfaces will be studied using x-ray spectroscopy methods. Mechano-chemical interactions can be quantified through the study of electron energies. X-ray spectroscopy is a useful method of analyzing and quantifying electron energy states. X-ray absorbance is used to study the valence state electron shells of iron undergone activation through sliding friction of naturally produced wax. In-situ x-ray photoemission spectroscopy is employed to instantaneously characterize single crystal tantalum samples of each principal crystallographic orientation during oxidation. Sliding friction of the naturally produced wax resulted in a reduction in the binding energy of the iron 2p electrons by approximately one electron-volt. This reduction in binding energy is attributed to ferrocene which is an organo-metallic alloy, Fe(C5H5)2. Mechanical strain of the crystal lattices of tantalum resulted in altered activation energies. Activation energy increased with the application of lattice strain. At increasing strain, oxide properties become more dependent on the lattice strain than the crystal orientation and temperature. A model system is developed incorporating mechanical strain into the prediction of activation energy and rates

Topics: oxidation, in-situ, spectroscopy
Year: 2011
OAI identifier: oai:oaktrust.library.tamu.edu:1969.1/ETD-TAMU-2011-08-10138

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