Vapor-phase synthesis of metallic and intermetallic nanoparticles and nanowires: magnetic and catalytic properties.

In this paper, we present several examples of the vapor-phase synthesis of intermetallic and alloy nanoparticles and nanowires, and investigate their magnetic and catalytic properties. In the first example, we report the vapor-phase synthesis of intermetallic aluminide nanoparticles. Specifically, FeAl and NiAl nanoparticles were synthesized via laser vaporization controlled condensation (LVCC) from their bulk powders. The NiAl nanoparticles were found to be paramagnetic at room temp., with a blocking temp. of approx. 15 K. The FeAl nanoparticles displayed room-temp. ferromagnetism. In the second example, we report the vapor-phase synthesis of cobalt oxide nanoparticle catalysts for low-temp. CO oxidn. The incorporation of Au and Pd nanoparticles into the cobalt oxide support leads to significantly improved catalytic activity and stability of the binary catalyst systems. Finally, we report the synthesis of nanowires of Ge, Mg, Pd, and Pt using the vapor-liq.-solid (VLS) method where the vapor-phase growth of the wire is catalyzed using a proper metal catalyst present in the liq. phase.