  We demonstrate a new focused ion beam sample preparation method for atom
probe tomography. The key aspect of the new method is that we use a neon ion
beam for the final tip-shaping after conventional annulus milling using gallium
ions. This dual-ion approach combines the benefits of the faster milling
capability of the higher current gallium ion beam with the chemically inert and
higher precision milling capability of the noble gas neon ion beam. Using a
titanium-aluminum alloy and a layered aluminum/aluminum oxide material as test
cases, we show that atom probe tips prepared using the combined gallium and
neon ion approach are free from the gallium contamination that typically
frustrates composition analysis of these materials due to implantation,
diffusion, and embrittlement effects. We propose that by using a focused ion
beam from a noble gas species, such as the neon ions demonstrated here, atom
probe tomography can be more reliably performed on a larger range of materials
than is currently possible using conventional techniques.
