Barium and indium double-filled skutterudites BaxInyCo4Sb12−z have been synthesized by a melting method using a series of starting materials with nominal compositions Ba0.3−mInmCo4Sb12 (0⩽m⩽0.3). Rietveld structure refinement shows that both barium and indium occupied the Sb-icosahedron voids in skutterudite structure. The thermal vibration parameter Uiso of indium is an order of magnitude bigger than that of barium. The electron probe microanalysis data prove that the filling fraction limit of indium is about 0.22. Hall effect was measured by the Van de Pauw method at room temperature. All BaxInyCo4Sb12−z compounds exhibit n-type conduction. The temperature dependences of electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured on these compounds in the range of 300–850K. Ba0.13In0.14Co4Sb11.75 with close filling fractions for barium and indium exhibits anomalously excellent thermoelectric properties, which may be due to the presence of the localized state in the gap occupied by one electron from indium impurity. The lattice thermal conductivity of BaxInyCo4Sb12−z is significantly low compared to single barium-filled skutterudite Ba0.27Co4Sb11.85 and reached a minimum for Ba0.13In0.14Co4Sb11.75. The dimensionless thermoelectric figure of merit ZT increased with increasing temperature in the range of 300–675K and reached a maximum value of 1.19 for Ba0.13In0.14Co4Sb11.75 at 850K.

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Enhancement of thermoelectric figure of merit by the insertion of multi-Enhancement of thermoelectric figure of merit by the insertion of multi-walled Enhancement of thermoelectric figure of merit by the insertion of multi-walled carbon nanotubes in α-MgAgSb carbon nanotubes in-MgAgSb

In this study, the plasma resonance in a surface wave sustained plasma was investigated. Surface wave discharges have been successfully generated by a microwave planar vane-type slow wave structure. Experimental results clearly demonstrated that the amplitude of the electric field of the microwave always became a local maximum in the position where the plasma density was equal to the same value. When the operating gas pressure and the input microwave power were varied to change the plasma density profile, the location of the maximum of the electric field was found to shift in compliance with the plasma density profile. Meanwhile, the peak of the resonance response was found to be proportional to the plasma density gradient while the spatial width of plasma resonance was inversely proportional to the plasma density gradient. These results were qualitatively in accordance with the theory.

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α-MgAgSb shows promise as a potential new low-temperature thermoelectric (TE) material and has been widely researched recently. We explored the effects of sintering conditions on the properties of MgAgSb-based thermoelectric materials through manipulating a spark plasma sintering system (SPS), where Ag vacancies and Mg point defects play a dominant role. The transport properties of MgAgSb were optimized effectively and efficiently, especially for electrical transport. As a result, we obtained a steady power factor (PF) of ∼17 μW cm-1 K-2, owing to the optimal carrier concentration of 9.8 × 1019 cm-3. Additionally, α-MgAgSb exhibits an ultralow lattice thermal conductivity of around 0.45 Wm-1 K-1 at 375 K. More importantly, a high ZT value of 0.85 was achieved below 375 K, approaching room temperature.

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