  Although titanium nitride (TiN) is among the most extensively studied and
thoroughly characterized thin-film ceramic materials, detailed knowledge of
relevant dislocation core structures is lacking. By high-resolution scanning
transmission electron microscopy (STEM) of epitaxial single crystal
(001)-oriented TiN films, we identify different dislocation types and their
core structures. These include, besides the expected primary full
a/2{110}<1$\bar{1}$0> dislocation, Shockley partial dislocations
a/6{111}<11$\bar{2}$> and sessile Lomer edge dislocations a/2{100}<011>.
Density-functional theory and classical interatomic potential simulations
complement STEM observations by recovering the atomic structure of the
different dislocation types, estimating Peierls stresses, and providing
insights on the chemical bonding nature at the core. The generated models of
the dislocation cores suggest locally enhanced metal-metal bonding, weakened
Ti-N bonds, and N vacancy-pinning that effectively reduces the mobilities of
{110}<1$\bar{1}$0> and {111}<11$\bar{2}$> dislocations. Our findings underscore
that the presence of different dislocation types and their effects on chemical
bonding should be considered in the design and interpretations of nanoscale and
macroscopic properties of TiN.
