We prepared ZnSb containing Zn3P2 particles of size ranging from a few tens to several hundred nanometers by melting powders of Zn, Sb, and P. Materials with Zn3P2 content up to 3.75% were made and subsequently ball-milled and hot pressed. A reduction in the thermal conductivity of 15% was achieved. By adding 0.2% Cu the carrier concentration increased an order of magnitude, to 2.0 × 1019 cm−3, while the mobility remained unaffected. The resulting increase in electrical conductivity together with the reduced thermal conductivity, led to a significant increase in the dimensionless figure of merit, in excess of 0.9 around 550 K.

In the last few years much attention has been given to the promising thermoelectric material Zn 4 Sb 3 . The related ZnSb phase features a high Seebeck coefficient at room temperature. Its thermoelectric conversion efficiency, however, is low due to its relatively high thermal conductivity. ZnSb has potential as a thermoelectric material if this can be reduced. Nanostructuring of bulk materials and introducing extrinsic particles have been shown to lower lattice thermal conductivity. In this study we created the microstructure by ball-milling of bulk ZnSb and added Ag particles which attain sizes in the micrometer range in this milling process. Hot-pressing was used to obtain dense samples. Several techniques were used for structural characterization.Here we report on scanning electron microscopy, transmission electron microscopy, and x-ray diffraction analysis. Thermoelectrical measurements were conducted around room temperature. Thermal conductivity was reduced by up to 40% by the reported nanostructuring. However, the electrical conductivity and the Seebeck coefficient were adversely affected, leading to no overall improvement in performance.

ZnSb samples have been doped with copper and phosphorus and sintered at 798 K. Electronic transport properties are interpreted as being influenced by an impurity band close to the valence band. At low Cu dopant concentrations, this impurity band degrades the thermoelectric properties as the Seebeck coefficient and effective mass are reduced. At carrier concentrations above 1 Â 10 19 cm À3 , the Seebeck coefficient in Cu doped samples can be described by a single parabolic band. V

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Abstract.We present a method to measure the in-plane thermal conductivity of thin films by the laser flash technique. The method uses a well-defined structure for the analysis. We have realised the structure by conformal deposition of ZnO films of different thicknesses using atomic layer deposition onto a 20 µm thick ion track etched polycarbonate membrane as substrate. By using this procedure we could determine the thermal conductivity of the deposited thin film from the total thermal diffusivity of the nanocomposite structures. The method has been used to obtain the in-plane thermal conductivity of the deposited ZnO layers within the thickness range of less than 100 nm.