We present a specimen preparation procedure for atom-probe tomography using SemGlu from Kleindiek Nanotechnik, an adhesive that hardens under electron beam irradiation. The SemGlu adhesive is used in place of focused-ion-beam-induced deposition of organo-metallic Pt, W, or C to form a bond between the sample and the substrate during the specimen preparation procedure. We demonstrate the utility of this adhesive-based specimen preparation technique with a correlated atom-probe tomography-scanning transmission electron microscopy study of the iron-nickel alloy kamacite (ferrite, ɑ-iron) in the Bristol iron meteorite and two steel specimens.

Primitive meteorites contain small amounts of presolar minerals that formed in the winds of evolved stars or in the ejecta of stellar explosions. Silicon carbide is the best studied presolar mineral. Based on its isotopic compositions it was divided into distinct populations that have different origins: Most abundant are the mainstream grains which are believed to come from 1.5–3 M⊙ AGB stars of roughly solar metallicity. The rare Y and Z grains are likely to come from 1.5–3 M⊙ AGB stars as well, but with subsolar metallicities (0.3–0.5 times solar). Here we report on C and Si isotope and trace element (Zr, Ba) studies of individual, submicrometer-sized SiC grains. The most striking results are: (1) Zr and Ba concentrations are higher in Y and Z grains than in mainstream grains, with enrichments relative to Si and solar of up to 70 times (Zr) and 170 times (Ba), respectively; (2) For the Y and Z grains there is a positive correlation between Ba concentrations and amount of s-process Si. This correlation is well explained by predictions for 2–3 M⊙ AGB stars with metallicities of 0.3–0.5 times solar. This confirms low-metallicity stars as most likely stellar sources for the Y and Z grains.

Knowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of μm) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC ‘Jumbo’ grains that range from close to zero to ∼850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic rays.