Although a heterointerface in oxides plays a crucial role on the properties, such heterointerface effects on oxide nanowires have not been well understood. Here, we demonstrate the crucial role of atomic interdiffusion on the magnetic properties of in situ formed $\mathrm{Mg}\mathrm{O}∕{\mathrm{Fe}}_{3-\delta }{\mathrm{O}}_4$ heterostructured nanowires. The wide variation of nanowire heterointerfaces was found when varying the growth atmosphere. The occurrence of the interdiffusion and the large interface area of nanowires strongly affect the magnetism via forming mixed spinel structures at the heterointerface. Thus, it is crucial to precisely control the atomic interdiffusion at the heterointerface for the desired properties of heterostructured oxide nanowires.

Oxide nanowire growth using a pulsed laser deposition (PLD) is a promising process since this essentially allows incorporating a rich functionality of various transition metal oxides into nanowires via the heterostructures. Here we investigate the effect of ablated particle flux on magnesium oxide nanowire growth by PLD. When varying the distance between the ablated material and the substrate, the small variation in ablated particle flux generated by a different plume expansion time influences mainly the growth rate while keeping the growth regime. However, varying the laser energy changes not only the growth rate but also the growth regime. Below a critical value of the laser energy the surface morphology tends to show an island growth rather than a nanowire growth. We attribute the existence of such a threshold to the desorption process from the catalyst droplet.

A delay-line-type surface acoustic wave (SAW) sensor based on a zinc oxide (ZnO) sensitive layer was developed. Two types of sensitive layers were obtained: ZnO nanowires and ZnO thin films, both deposited using laser methods (VLS-PLD and PLD, respectively) onto quartz substrates. The responses of sensors with two different nanowire lengths (300 and 600 nm) were compared with those of sensors with thin films of different thicknesses (ca. 100 and 200 nm) to different concentrations of hydrogen and deuterium. The experimental results revealed a high response at low concentrations and a rapid saturated response for nanowires, but a low response at low concentrations and a linear response to much higher gas concentrations for the thin-film-based SAW sensors.