Abstract
We present a novel approach to reduce the thermal conductivity (k) in thermoelectric composite materials using acoustic impedance mismatch and the Debye model. Also, the correlation between interface thermal resistance (Rint) and the particle size of the dispersed phase on the k of the composite is discussed. In particular, the k of an oxide composite, which consists of a natural superlattice Aurivillius phase (SrBi4Ti4O15) as a matrix and perovskite (La0.7Sr0.3MnO3) as a dispersed phase, is investigated. A significant reduction in k of composite, even lower than the k of the matrix when the particle size of La0.7Sr0.3MnO3 is smaller than the Kapitza radius (aK) is observed, depicting that Rint dominates for particle size lower than aK due to increased surface to volume ratio. The obtained results have the potential to provide new directions for engineering composite thermoelectric systems with desired thermal conductivity and promising in the field of energy harvesting.
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