  Atom probe tomography is routinely used for the characterisation of materials
microstructures usually assuming that the microstructure is unaltered by the
analysis. When analysing ionic conductors, however, gradients in the chemical
potential and the electric field penetrating dielectric atom probe specimens
can cause significant ionic mobility. While ionic mobility is undesired when
aiming for materials characterisation it offers a strategy to manipulate
materials directly in-situ in the atom probe. Here, we present experimental
results on the analysis of the ionic conductor Lithium-Manganese-Oxide with
different atom probe techniques. We demonstrate that at a temperature of 30K
characterisation of the materials microstructure is possible without measurable
Li mobility. Contrary, we show that at 298K the material can be deintercalated
in-situ in the atom probe without changing the Manganese-Oxide host structure.
Combining in-situ atom probe deintercalation and subsequent conventional
characterisation we demonstrate a new methodological approach to study ionic
conductors even in early stages of deintercalation.
