  The electronic structure, chemical bonding and interface component in ZrN-AlN
nanocomposites formed by phase separation during thin film deposition of
metastable Zr1-xAlxN (x=0.0, 0.12, 0.26, 0.40) is investigated by resonant
inelastic X-ray scattering/X-ray emission and X-ray absorption spectroscopy and
compared to first-principles calculations including transitions between orbital
angular momentum final states. The experimental spectra are compared with
different interface-slab model systems using first-principle all electron
full-potential calculations where the core states are treated fully
relativistic. As shown in this work, the bulk sensitivity and element
selectivity of X-ray spectroscopy enables to probe the symmetry and orbital
directions at interfaces between cubic and hexagonal crystals. We show how the
electronic structure develop from local octahedral bond symmetry of cubic ZrN
that distorts for increasing Al content into more complex bonding. This results
in three different kinds of bonding originating from semi-coherent interfaces
with segregated ZrN and lamellar AlN nanocrystalline precipitates. An
increasing chemical shift and charge transfer between the elements takes place
with increasing Al content and affects the bond strength and increases
resistivity.
