Effective reduction in thermal conductivity by high-density dislocations in SrTiO3

Abstract

Decreasing thermal conductivity is important for designing efficient thermoelectric devices. Traditional engineering strategies have focused on point defects and interface design. Recently, dislocations as line defects have emerged as an additional tool for regulating thermal conductivity. In ceramics-based thermoelectric materials, the key challenge lies in achieving a sufficiently high dislocation density to effectively scatter phonons, as the typical dislocation density in ceramics after bulk deformation is constrained to ∼1012 m−2. In this work, we adopted the mechanical imprinting method and achieved a dislocation density of ∼1015 m−2 in single-crystal SrTiO3, which is known for its room-temperature plasticity and acts as a promising material for thermoelectric applications. Using the time-domain thermoreflectance method, we measured a ∼50% reduction in thermal conductivity over a broad temperature range (80–400 K) with the engineered high-density dislocations. These results suggest that tuning dislocations could offer an alternative path to minimizing thermal conductivity for engineering thermoelectric materials.