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Highlights: [•] Fabrication of nanostructured skutterudites ZnO or PbTe/In0.2Co4Sb12. [•] Thermal conductivity modeling accounts for experimental results. [•] Greater lattice thermal conductivity decrease in In0.2Co4Sb12 than in CoSb3. [•] A max ZT of 1.05 is obtained at 700K in a 2wt% ZnO-containing sample. [Copyright &y& Elsevier]

Nanostructured thermoelectric materials generally exhibit enhanced properties. PbTe-CoSb3 thermoelectric composites (0-8 wt% of PbTe) have been successfully prepared by freeze-drying nanoparticles of PbTe (6 nm in diameter, synthesized by laser fragmentation of micron-sized particles in water) with micron-sized skutterudite CoSb3 powders (~5 μm in diameter, synthesized by powder metallurgy), followed by spark plasma sintering. X-ray diffraction analyses and scanning electron microscopy observations have been performed. Microstructures reveal an agglomeration of the PbTe particles at the grain boundaries of CoSb3. Electrical resistivity, thermopower, and thermal conductivity measurements have been performed in the 300-800 K temperature range. The composites exhibit n-type conduction whereas the reference CoSb3 skutterudite is p-type. This change of conduction mode is attributed to substitution of Sb for a minute amount of Te in the composites. The influence of both PbTe nanoparticules and Te on the thermoelectric properties is discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Addition of nanoparticles into bulk materials is one of the strategies designed to synthesize thermoelectric materials with superior efficiency. The presence of nanoparticles is expected to act as a barrier of the heat transport due to an increased amount of nanoscopic interfaces and to enhance the electronic properties via quantum confinement effects. Here, this approach was applied to the skutterudite CoSb3 matrix in which different amounts of ZnO (2–12wt.%) nanoparticles were introduced. The samples were densified by spark plasma sintering and characterized by X-ray diffraction and scanning electron microscopy. The thermoelectric properties were investigated in a broad temperature range (2–800K) to better assess the influence of the ZnO nanoparticles. The nanostructured materials showed a significant enhancement in the thermopower values combined with a slight decrease in the thermal conductivity. A small amount of ZnO nanoparticles (2wt.%) has a beneficial influence on the dimensionless thermoelectric figure of merit ZT suggesting that introducing stable oxide nanoparticles may be an interesting way to improve the thermoelectric properties of skutterudite compounds. [Copyright &y& Elsevier]

Abstract: A new synthesis route has been applied to the preparation of PbTe–CoSb3 thermoelectric composites (0–8 %wt of PbTe) from nanoparticles of PbTe (6 nm in diameter) synthesized by laser fragmentation of micron-sized particles in water and micron-sized skutterudite CoSb3 powders. The freeze-dried powders have been densified by spark plasma sintering. The morphologies and crystallographic structures have been checked by scanning electron microscopy and x-ray diffraction. The obtained microstructures are quite complex, with more or less agglomeration of the PbTe particles at the grain boundaries of CoSb3. The transport properties (electrical resistivity, thermopower, Hall coefficient, thermal conductivity) of the composites have been investigated in the 2–300 K temperature range and compared to those of the reference CoSb3 material. A change of conduction type has been observed for the composites that became n-type. This change was attributed to substitution of a minute amount of Sb for Te. As could be expected from nanostructuring, lower thermal conductivities are achieved in the composites. [Copyright &y& Elsevier]

Abstract: Indium oxide ceramics doped with different doping levels of germanium (from 0 to 10at.%) were prepared with nano-sized powders obtained by citrate gel process. Ge for In substitution in the In2O3 bixbyite structure below the solubility limit (about 0.5–1 atom%) leads to a large decrease in the electrical resistivity and the absolute value of the Seebeck coefficient. X-ray diffraction and scanning electron microscopy show the presence after sintering of well dispersed secondary phases In2Ge2O7 when the Ge solubility in the In2O3 matrix is passed. The thermal properties measurements confirm that the decrease in the lattice thermal conductivity observed in these composite materials can be attributed to the presence of insulating In2Ge2O7 phases. Furthermore, preliminary microwave sintering experiments have been tested in order to keep the nanoscale after sintering. Particular nano–microstructures were obtained due to minimal grain growth induced by this rapid sintering process. [Copyright &y& Elsevier]

Zintl phases are currently receiving great attention for their thermoelectric potential typified by the discovery of a high ZT value in YbMnSb-based compounds. Herein, we report on the crystallographic characterization via neutron and x-ray diffraction experiments, and on the thermoelectric properties measured in the 300 K to 1000 K temperature range, of MoSb and its isostructural compounds MoRuSb. Even though MoSb displays rather high ZT values given its metallic character, the partial substitution of Mo by Ru substantially improves its thermoelectric properties, resulting in a ZT value of ∼0.45 at 1000 K for x = 0.8. [ABSTRACT FROM AUTHOR]

Despite the richness of data collected on pesticide concentrations in ambient air in France, knowledge on this topic remains partial and heterogeneous in the absence of specific regulations. The population exposure remains thus difficult to estimate; therefore it was necessary to define modalities for implementing national monitoring of pesticides in ambient air in metropolitan France and in the overseas territories. The objective of this work was to identify which active substances (a.s.) have to be monitored in priority. As part of a collective expertise, a group of multidisciplinary experts has developed a method to rank active substances authorised as plant protection products, biocides and antiparasitic agents, which were available on the French market in 2015. A 3-steps approach has been developed. The first step consisted of a theoretical approach based on a hierarchy of substances according to four criteria: (a) national uses, (b) emission potential to the air, (c) persistence in the air, and (d) chronic toxicity. The three first criteria give information on their potential to be present in the atmosphere, and the fourth criterion allows to consider their potential of hazard. The second step was an observational approach based on existing database on pesticide air measurements in France. In the third step, both approaches were combined using decision trees to select priority pesticides. Among the 1316 a.s. first identified from the EU Pesticides database, 90 were selected, among which 43 required metrological and/or analytical development. The experts recommended confirming the relevance of performing a longer term monitoring of these a. s. after a one-year exploratory campaign. The proposed method is reproduceable, transparent, easy to update (e.g. in the light of a change in product authorization), and can be adapted to other agricultural and geographical conditions, and objectives (e.g. monitoring of the ecotoxicological effects of pesticides)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Soil biotechnology (SBT) is a green engineering approach for wastewater treatment and recycling. Five SBT units located in the Mumbai region were under consideration of which holistic assessment of two SBT plants was carried out considering its technical, environmental and economic aspects and was compared with published research of other three. LCA has been done to evaluate the environmental impacts of construction and operation phase of SBT. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) removal of more than 90% can be achieved using this technology. Also, the nutrient removal proficiency (nitrate, nitrite, ammoniacal nitrogen, TKN, total nitrogen and phosphates) of this technique is good. On the other hand, SBT has low annual operation and maintenance cost, comparable to land-based systems and lower than conventional or advanced technologies. From the life cycle impact assessment, the main contributors for overall impact from the plant were identified as electricity consumption, discharges of COD, P-PO 4 3- and N-NH 4 + and disposal of sludge. The construction phase was found to have significantly more impact than the operation phase of the plant. This study suggests plant I is not relatively as efficient enough regarding sanitation. SBT provides several benefits over other conventional technologies for wastewater treatment. It is based on a bio-conversion process and is practically maintenance free. It does not produce any odorous bio-sludge and consumes the least energy.

Polycrystalline Mo(3)Sb(7-x)Te(x) samples with nominal Te concentrations of x=0.0, 0.3, 1.0, 1.6 and 2.2 have been synthesized by a powder metallurgical route. High temperature thermoelectric properties measurements including thermopower (300-900 K), electrical resistivity (300-800 K) and thermal conductivity (300-1000 K) were carried out. The temperature and compositional variations of the thermopower can be satisfactorily explained by assuming a single parabolic band model with dominant acoustic phonon scattering. However, such a simple model fails to describe the electronic thermal conductivity for low Te concentration. The dimensionless figure of merit, ZT, increases on increasing both the temperature and the Te content to reach a maximum value of 0.3 at 800 K that can be extrapolated to ∼0.6 at 1000 K for Mo(3)Sb(5.4)Te(1.6)., (© 2010 IOP Publishing Ltd)