Nanoscale Perspectives of Metal Degradation via In Situ Atom Probe Tomography

We report a unique in situ instrument development effort dedicated to studying gas/solid interactions relevant to heterogeneous catalysis and early stages of oxidation of materials via atom probe tomography and microscopy (APM). An in situ reactor cell, similar in concept to other reports, has been developed to expose nanoscale volumes of material to reactive gas environments, in which temperature, pressure, and gas chemistry are well controlled. We demonstrate that the combination of this reactor cell with APM techniques can aid in building a better mechanistic understanding of resultant composition and surface and subsurface structure changes accompanying gas/surface reactions in metal and metal alloy systems through a series of case studies: O2/Rh, O2/Co, and O2/Zircaloy-4. In addition, the basis of a novel operando mode of analysis within an atom probe instrument is also reported. The work presented here supports the implementation of APM techniques dedicated to atomic to near-atomically resolved gas/surface interaction studies of materials broadly relevant to heterogeneous catalysis and oxidation.

A von Hamos spectrometer for in situ sulfur speciation by non-resonant sulfur Kα emission spectroscopy

A von Hamos geometry based wavelength dispersive spectrometer combined with an in situ reactor cell has been developed to measure non-resonant sulfur Kα emission for the in situ speciation of low concentrations of sulfur.