We investigated the high-temperature thermoelectric properties of misfit layered n-type (LaS) 1.20 CrS 2 and p-type (LaS) 1.14 NbS 2 . The samples were prepared by CS 2 sulfurization of 6 or 12 h duration and then consolidated using pressure-assisted sintering to produce randomly and highly oriented samples whose microstructures were tunable. Transmission electron microscopy analysis showed that perfectly layered structures containing some stacking faults had formed. The randomly and highly oriented natural superlattices provided ultralow lattice thermal conductivities (as low as ∼0.9 and ∼0.5 W K −1 m −1 , respectively, at 950 K) perpendicular to the pressing axis. The improved electrical conductivities of the oriented CrS 2 and NbS 2 samples resulted in high power factors of 170 and 410 μW K −2 m −1 , respectively. The highly oriented texture produced the highest thermoelectric figure of merit ZT of 0.14 at 950 K among the (LaS) 1.20 CrS 2 system, whereas the weakly/randomly oriented texture produced the highest ZT of 0.15 at 950 K among the (LaS) 1.14 NbS 2 system. These misfit layered sulfides exhibit phonon glass−electron crystal behavior and provide tremendous opportunities for further enhancing ZT by optimizing the thermoelectric properties.

GeTe, which undergoes phase transition between low symmetric rhombohedral to high symmetric cubic phase between 550 – 700 K (depending on the dopant and composition) and its alloys have widely...