Manipulation of defects, ranging from atomic scale to nanometer scale, has leading the advancements in thermoelectrics for many decades through a reduced lattice thermal conductivity. Point defects introduce mass and strain fluctuations that strengthen the scattering phonons, and both fluctuations can be maximized in the cases of vacancies or interstitials. This talk involves vacancy (either intrinsic or extrinsic) and interstitial defects as strategy for effectively scattering phonons. Moreover, the possible clustering of vacancy or interstitial may lead to additional phonon scattering, which opens new possibilities for advancing thermoelectrics. Alternatively focusing on the speed of phonon propagation, low sound velocity or low cut-off frequency of acoustic phonons is also desired for a low lattice thermal conductivity. The utilization of above mentioned strategies indeed lead to a great success in proving the thermoelectric performance of both new and existing materials.
Keywords : Defects, Thermoelectrics, Scattering, Lattice thermal conductivity, Sound velocity.