  Low-dimensional materials with chain-like (one-dimensional) or layered
(twodimensional) structures are of significant interest due to their
anisotropic electrical, optical, thermal properties. One material with
chain-like structure, BaTiS3 (BTS), was recently shown to possess giant
in-plane optical anisotropy and glass-like thermal conductivity. To understand
the origin of these effects, it is necessary to fully characterize the optical,
thermal, and electronic anisotropy of BTS. To this end, BTS crystals with
different orientations (aand c-axis orientations) were grown by chemical vapor
transport. X-ray absorption spectroscopy (XAS) was used to characterize the
local structure and electronic anisotropy of BTS. Fourier transform infrared
(FTIR) reflection/transmission spectra show a large inplane optical anisotropy
in the a-oriented crystals, while the c-axis oriented crystals were nearly
isotropic in-plane. BTS platelet crystals are promising uniaxial materials for
IR optics with their optic axis parallel to the c-axis. The thermal
conductivity measurements revealed a thermal anisotropy of ~4.5 between the c-
and a-axis. Time-domain Brillouin scattering showed that the longitudinal sound
speed along the two axes is nearly the same suggesting that the thermal
anisotropy is a result of different phonon scattering rates.
