On the synthesis and structural evolution of artificial CrN/TiN nanocomposites

The synthesis of nanocomposites is limited to thermodynamically immiscible phases or to phase separation by exceeding the limits of solution. Hence, the formation of nanocomposites based on transition metals, revealing a nanocrystalline Metal-Nitride/nanocrystalline Metal-Nitride structure, is restricted. These restrictions can be overruled by a spatially separated synthesis of the two phases and a recombination during the deposition. With this approach, the limits of current systems can be expanded, enabling the synthesis of artificial nanocomposites based on a variety of materials. We demonstrate the synthesis of a composite of two nanocrystalline phases of the miscible transition metal-nitrides CrN and TiN. TiN nanoparticles were synthesized using an atmosphericpressure arc reactor and in-situ injected into a growing CrN thin film. The thin films are analyzed regarding their physical- and microstructure using two-dimensional GIXRD, XPS based on synchrotron radiation and TEM. The CrTiN thin film reveals a two-phase structure consisting of nanocrystalline CrN and TiN phases with crystallite sizes of 9 nm and 4 nm according to GIXRD. XPS indicates bonding of Cr-N, Cr-Cr, and Ti-N. No hint for Cr-Ti bonding was found, excluding (Cr,Ti)N solid solution formation. Based on the TEM-investigations, TiN nanoparticles are embedded as agglomerates in the CrN matrix.

Automated summary

The synthesis of nanocomposites is limited by the thermodynamic immiscibility of phases, but this restriction can be overcome by spatially separated synthesis of two phases and recombination during deposition. In this study, a composite of two nanocrystalline phases of CrN and TiN was successfully synthesized, expanding the limits of current systems.