Engineering topics

Stahn, J

Publications and source records attributed to Stahn, J.

2 records

DOE OSTI2011

Iron and nitrogen self-diffusion in non-magnetic iron nitrides

The self-diffusion of iron and nitrogen is measured in nm range non-magnetic iron nitride thin films. Two non-magnetic iron nitrides, Fe{sub 2.23}N and FeN, were studied using neutron reflectivity. Neutron reflectivity with a depth resolution in the sub-nm range has a different scattering cross section for isotopes, providing a unique opportunity to measure very small diffusivities. The isotope heterostructure in thin film multilayers [Fe-N/{sup 57}Fe-N]{sub 10} and [Fe-N/Fe-{sup 15}N]{sub 10} were prepared using magnetron sputtering. It was observed that nitrogen diffuses slower than iron although the atomic size of iron is larger than that of nitrogen. It was found that a significantly larger group of N atoms participates in the diffusion process than of Fe, making N diffusion slower than that of Fe.

36 MATERIALS SCIENCE↗

DOE OSTI2011

Interdiffusion in W/Si Multilayers with Boron Carbide Interlayers

W/Si multilayers with B{sub 4}C as a diffusion barrier were deposited using ion beam sputtering technique. It was found that incorporation of B{sub 4}C at both interfaces of Si enhances the reflectivity of the multilayer. Though the interface of W/Si or W/B{sub 4}C has been studied in literature, what happens at Si/B{sub 4}C interfaces is largely unknown. This is primarily due to absence of contrast between Si/B{sub 4}C for x-rays. For neutrons there is significant contrast between Si and B{sub 4}C, therefore we used neutron reflectivity to study thermal stability of Si/B{sub 4}C multilayers. It was found that up to an annealing temperature of 573 K, the multilayer remains intact however at higher temperature interdiffusion starts.

36 MATERIALS SCIENCE↗