| 1. |
- Jacquot, A., et al.
(författare)
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Anisotropy and inhomogeneity measurement of the transport properties of spark plasma sintered thermoelectric materials
- 2013
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Ingår i: Thermoelectric Materials Research and Device Development for Power Conversion and Refrigeration. - : Materials Research Society. - 9781605114675 ; , s. 89-95
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Konferensbidrag (refereegranskat)abstract
- We report on the development and capabilities of two new measurement systems developed at Fraunhofer-IPM. The first measurement system is based on an extension of the Van der Pauw method and is suitable for cube-shaped samples. A mapping of the electrical conductivity tensor of a Skutterudite-SPS samples produced at the Instituto de Microelectrónica de Madrid is presented. The second measurement system is a ZTmeter also developed at the Fraunhofer-IPM. It enables the simultaneous measurement of the electrical conductivity, Seebeck coefficient and thermal conductivity up to 900 K of cubes at least 5x5x5 mm 3 in size. The capacity of this measurement system for measuring the anisotropy of the transport properties of a (Bi,Sb)2Te3 SPS sample produced by KTH is demonstrated by simply rotating the samples.
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| 2. |
- Saleemi, Mohsin, et al.
(författare)
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Fabrication of nanostructured bulk cobalt antimonide (CoSb3) based skutterudites via bottom-up synthesis
- 2013
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Ingår i: Thermoelectric Materials Research and Device Development for Power Conversion and Refrigeration. - : Materials Research Society. - 9781605114675 ; , s. 121-126
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Konferensbidrag (refereegranskat)abstract
- Skutterudites are known to be efficient thermoelectric (TE) materials in the temperature range from 600 K to 900 K. Dimensionless figure of merit (ZT) for filled skutterudite TE materials have been reported as ca. 1 at 800 K. Novel nano- engineering approaches and filling of the skutterudites crystal can further improve the transport properties and ultimately the ZT. Although classified among the promising TE materials, research on their large-scale production via bottom up synthetic routes is rather limited. In this work, large quantity of cobalt antimonide (CoSb3) based skutterudites nanopowder (NP) was fabricated through a room temperature coprecipitation precursor method. Dried precipitates were process by thermo-chemical treatment steps including calcination (in air) and reduction (in hydrogen). CoSb3 NPs were then mixed with silver (Ag) nanopanicles at different weight percentages (1%, 5% and 10% by wt) to form nanocomposites. Skutterudite NP was then consolidated by Spark Plasma Sintering (SPS) technique to produce highly dense compacts while maintaining the nanostructure. Temperature dependent TE characteristics of SPS'd CoSb3 and Ag containing nanocomposite samples were evaluated for transport properties, including thermal conductivity, electrical conductivity and Seebeck coefficient over the temperature range of 300-900 K. Physicochemical, structural and microstructural evaluation results are presented in detail.
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| 3. |
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| 4. |
- Saleemi, Mohsin, et al.
(författare)
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Evaluation of the Structure and Transport Properties of Nanostructured Antimony Telluride (Sb2Te3)
- 2014
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 43:6, s. 1927-1932
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Tidskriftsartikel (refereegranskat)abstract
- Antimony telluride, (Sb2Te3), and its doped derivatives are considered to be among the best p-type thermoelectric (TE) materials for room temperature (300-400 K) applications. However, it is still desirable to develop rapid and economical routes for large-scale synthesis of Sb2Te3 nanostructures. We report herein a high yield, simple and easily scalable synthetic method for polycrystalline Sb2Te3 nanostructures. Prepared samples were compacted into dense pellets by use of spark plasma sintering. The products were characterized by x-ray diffraction and scanning electron microscopy. To investigate the anisotropic behavior of Sb2Te3 TE transport property measurements were performed along and perpendicular to the direction of compaction. Thermal conductivity, electrical conductivity, and Seebeck coefficient measurement over the temperature range 350-525 K showed that the anisotropy of the material had a large effect on TE performance.
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| 5. |
- Battiston, S., et al.
(författare)
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Influence of Al and Mg Addition on Thermoelectric Properties of Higher Manganese Silicides Obtained by Reactive Sintering
- 2017
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 17:3, s. 1668-1673
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Tidskriftsartikel (refereegranskat)abstract
- Higher manganese silicides (HMS), represented by MnSix (x = 1.71-1.75), are promising p-type candidates for thermoelectric (TE) energy harvesting systems at intermediate temperature range. The materials are very attractive as they may replace lead based compounds due to their nontoxicity, low cost of starting materials, and high thermal and chemical stability. Dense pellets were obtained through fast reactive sintering by spark plasma sintering (SPS). The addition -or nanoinclusion, of Al and Mg permitted the figure of merit enhancement of the material obtained with this technique, reaching the highest value of 0.40 at 600 degrees C. Morphology, composition and crystal structure of the samples were characterized by electron microscopies, energy dispersive X-ray spectroscopy, and X-ray diffraction analyses, respectively.
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| 6. |
- Battiston, S., et al.
(författare)
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Synthesis and Characterization of Al-Doped Mg2Si Thermoelectric Materials
- 2013
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Ingår i: Journal of Electronic Materials. - New York : Springer. - 0361-5235 .- 1543-186X. ; 42:7, s. 1956-1959
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium silicide (Mg2Si)-based alloys are promising candidates for thermoelectric (TE) energy conversion for the middle to high range of temperature. These materials are very attractive for TE research because of the abundance of their constituent elements in the Earth's crust. Mg2Si could replace lead-based TE materials, due to its low cost, nontoxicity, and low density. In this work, the role of aluminum doping (Mg2Si:Al = 1:x for x = 0.005, 0.01, 0.02, and 0.04 molar ratio) in dense Mg2Si materials was investigated. The synthesis process was performed by planetary milling under inert atmosphere starting from commercial Mg2Si pieces and Al powder. After ball milling, the samples were sintered by means of spark plasma sintering to density > 95%. The morphology, composition, and crystal structure of the samples were characterized by field-emission scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction analyses. Moreover, Seebeck coefficient analyses, as well as electrical and thermal conductivity measurements were performed for all samples up to 600A degrees C. The resultant estimated ZT values are comparable to those reported in the literature for these materials. In particular, the maximum ZT achieved was 0.50 for the x = 0.01 Al-doped sample at 600A degrees C.
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| 7. |
- Famengo, A., et al.
(författare)
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Phase Content Influence on Thermoelectric Properties of Manganese Silicide-Based Materials for Middle-High Temperatures
- 2013
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Ingår i: Journal of Electronic Materials. - New York : Springer. - 0361-5235 .- 1543-186X. ; 42:7, s. 2020-2024
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Tidskriftsartikel (refereegranskat)abstract
- The higher manganese silicides (HMS), represented by MnSi (x) (x = 1.71 to 1.75), are promising p-type leg candidates for thermoelectric energy harvesting systems in the middle-high temperature range. They are very attractive as they could replace lead-based compounds due to their nontoxicity, low-cost starting materials, and high thermal and chemical stability. Dense pellets were obtained through direct reaction between Mn and Si powders during the spark plasma sintering process. The tetragonal HMS and cubic MnSi phase amounts and the functional properties of the material such as the Seebeck coefficient and electrical and thermal conductivity were evaluated as a function of the SPS processing conditions. The morphology, composition, and crystal structure of the samples were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction analyses, respectively. Differential scanning calorimetry and thermogravimetric analysis were performed to evaluate the thermal stability of the final sintered material. A ZT value of 0.34 was obtained at 600A degrees C for the sample sintered at 900A degrees C and 90 MPa with 5 min holding time.
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| 8. |
- Fiameni, S., et al.
(författare)
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Effect of Synthesis and Sintering Conditions on the Thermoelectric Properties of n-Doped Mg2Si
- 2014
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 43:6, s. 2301-2306
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium silicide (Mg2Si)-based alloys are promising candidates for thermoelectric (TE) energy conversion in the middle-high temperature range. The detrimental effect of the presence of MgO on the TE properties of Mg2Si based materials is widely known. For this reason, the conditions used for synthesis and sintering were optimized to limit oxygen contamination. The effect of Bi doping on the TE performance of dense Mg2Si materials was also investigated. Synthesis was performed by ball milling in an inert atmosphere starting from commercial Mg2Si powder and Bi powder. The samples were consolidated, by spark plasma sintering, to a density > 95%. The morphology, and the composition and crystal structure of samples were characterized by field-emission scanning electronic microscopy and x-ray diffraction, respectively. Moreover, determination of Seebeck coefficients and measurement of electrical and thermal conductivity were performed for all the samples. Mg2Si with 0.1 mol% Bi doping had a ZT value of 0.81, indicative of the potential of this method for fabrication of n-type bulk material with good TE performance.
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| 9. |
- Fiameni, S., et al.
(författare)
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Introduction of Metal Oxides into Mg2Si Thermoelectric Materials by Spark Plasma Sintering
- 2013
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Ingår i: Journal of Electronic Materials. - New York : Springer. - 0361-5235 .- 1543-186X. ; 42:7, s. 2062-2066
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Tidskriftsartikel (refereegranskat)abstract
- Oxide incorporation into thermoelectric Mg2Si-based materials was performed starting from commercial Mg2Si and commercial metal oxides by applying ball milling and spark plasma sintering (SPS) processing. The SPS conditions, such as sintering temperature, pressure, and holding time, were optimized with the aim of obtaining both full densification and oxide incorporation. Thermoelectric characterizations, such as Seebeck coefficient and electrical and thermal conductivity, were carried out and related to the pellet compositions. The morphology, composition, and crystallographic structure of the samples were characterized by field-emission scanning electron microscopy, energy-dispersive spectrometry, and x-ray diffraction analyses, respectively.
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| 10. |
- Saleemi, M A, et al.
(författare)
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Feeding patterns, diarrhoeal illness and linear growth in 0-24-month-old children.
- 2004
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Ingår i: Journal of tropical pediatrics. - 0142-6338. ; 50:3, s. 164-9
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to study the impact of simple healthcare interventions in 0-24-month-old children living in rural communities outside Lahore, Pakistan. Newborns belonging to four birth cohorts were followed monthly from 0-24 months of age living in rural communities. Three cohorts were from the same village: Cohort A (1984-1987), n = 485; Cohort B (1990-1992), n = 544; and Cohort C (1995-1997), n = 518. A fourth, Cohort D, was from neighbouring villages (1995-1997), n = 444. Findings from Cohort A formed the basis of a healthcare programme, including promotion of optimal breastfeeding practices, advice on oral rehydration therapy, and continued feeding during diarrhoea. The outcome measures studied were time of initiation of breastfeeding, feeding of prelacteals, exclusive breastfeeding, diarrhoeal illnesses, and postnatal linear growth. The median time of initiation of breastfeeding decreased from 47 to 3 h and exclusive breastfeeding increased from 5 per cent in Cohort A to more than 80 per cent in the subsequent cohorts, at 1 month of age. No prelacteals were given to 34 per cent of newborns in later cohorts compared with 100 per cent in Cohort A. Diarrhoeal illnesses during the first 6 months had reduced significantly. Postnatal linear growth improved by about 3 cm in the later cohorts. Appropriate changes in breastfeeding practices through integrated and focused healthcare, especially antenatally, can reduce diarrhoeal illnesses, and sustain and improve linear growth in young children.
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