The highly anisotropic material CsBi4Te6 was prepared by the reaction of Cs/Bi2Te3 around 600
°C. The compound crystallizes in the monoclinic space group C2/m with a ) 51.9205(8) Å, b ) 4.4025(1)
Å, c ) 14.5118(3) Å, â ) 101.480(1)°, V ) 3250.75(11) Å3, and Z ) 8. The final R values are R1 ) 0.0585
and wR2 ) 0.1127 for all data. The compound has a 2-D structure composed of NaCl-type [Bi4Te6] anionic
layers and Cs+ ions residing between the layers. The [Bi4Te6] layers are interconnected by Bi-Bi bonds at
a distance of 3.2383(10) Å. This material is a narrow gap semiconductor. Optimization studies on the
thermoelectric properties with a variety of doping agents show that the electrical properties of CsBi4Te6
can be tuned to yield an optimized thermoelectric material which is promising for low-temperature
applications. SbI3 doping resulted in p-type behavior and a maximum power factor of 51.5 íW/cmâK2 at
184 K and the corresponding ZT of 0.82 at 225 K. The highest power factor of 59.8 íW/cmâK2 at 151 K
was obtained from 0.06% Sb-doped material. We report here the synthesis, physicochemical properties,
doping characteristics, charge-transport properties, and thermal conductivity. Also presented are studies
on n-type CsBi4Te6 and comparisons to those of p-type.