We report a study of the oxidation process of individual PtNi nanoparticles (NPs) conducted with a novel scanning multi-layer Laue lens X-ray microscope. The elemental maps reveal that alloyed PtNi NPs were transformed into Pt/NiO core–shell NPs by thermal oxidation. The observations furthermore indicate that a coalescence of Pt/NiO core–shell NPs occurred during oxidation.

We report the synthesis and characterization of Sn-doped β-Ga ₂ O ₃ nanowires (NWs) deposited using radio frequency powder sputtering. The growth sequence of Sn-doped β-Ga ₂ O ₃ NWs is similar to that of the undoped β-Ga ₂ O ₃ NWs. Self-assembled Ga clusters act as seeds for initiating the growth of Sn-doped β-Ga ₂ O ₃ NWs through a vapor–liquid–solid process, while Sn atoms are incorporated into the trunk of NWs uniformly. Different from the straight shape of undoped NWs, the conical shape of NWs is observed, which is attributed to the change in supersaturation conditions and the diffusion of the catalyst tip and reaction species.