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We report fabrication of nanostructured BiSbTe using hydrothermal method followed by cold-pressing and evacuated-and-encapsulated sintering techniques. To obtain lower resistivity, the reaction temperature in the hydrothermal synthesis is investigated, and the effects on the ZT values of BiSbTe are reported. Both the x = 1.52 and 1.55 samples hydrothermally synthesized at 160°C show lower resistivity than the x = 1.55 sample hydrothermally synthesized at 140°C. However, the power factor is lower for the samples synthesized at 160°C due to the accompanying smaller thermopower. All three samples exhibit remarkably low thermal conductivity of around 0.41 W m K at room temperature. The peak ZT value occurs at 270 K for all three samples, being ZT = 1.75, 1.29, and 1.17 for x = 1.55 (synthesized at 140°C), 1.55 (synthesized at 160°C), and 1.52 (synthesized at 160°C), respectively. [ABSTRACT FROM AUTHOR]

Abstract: The photoluminescent and electrical properties of N-doped ZnO films fabricated by rf magnetron sputtering under various gas-flow ratios of O2/N2 were examined in this study. The dependence of conduction type on the gas-flow rate of O2/N2 was found. The authors identified a direct correlation between the defect spectral feature and conduction type of N-doped ZnO samples and provided a physical model for producing p-type ZnO. According to these observed results, the authors suggested that p-type conversion of N-doped ZnO may be due to a combined effect of the increased acceptor (substitutional nitrogen in oxygen site, zinc vacancy and interstitial oxygen) density and the decreased donor (oxygen vacancy) density. In addition, synthesis of p-type N-doped ZnO was repeated, suggesting that p-type ZnO can be fabricated with excellent reproducibility by rf magnetron sputtering a ZnO target doped with nitrogen. [Copyright &y& Elsevier]