Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Nano-EngineeredThermoelectric Materials for Waste Heat Recovery
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. mohsin.saleemi@mmk.su.ORCID iD: 0000-0001-5380-975X
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy crisis and thermal management related issues have been highlighted in the modern century due to escalating demands for energy consumption and global warming from fossil fuels. Sustainable and alternative energy sources are an ever growing global concern. Thermoelectric (TE) materials have gained significant interest, due to effective solid-state energy conversion from waste heat to useful electrical energy and vice versa.   Clean, noise-free, and environment-friendly operation of TE devices has triggered great attention in viable technologies including automotive, military equipment, aerospace, and industries to scavenge waste heat into power. To date, conventional TE materials have shown limited energy conversion efficiency, i.e. TE Figure of Merit (ZT). However, the concept of nanostructuring and development of novel TE materials have opened excellent avenues to improve significantly the ZT values. Nano-engineered bulk TE materials allow effective phonon scattering at the high density of grain boundaries, which offer a way of lowering the thermal conductivity. 

Large-scale synthesis of TE nanomaterials is a challenge for the TE industry because of expensive fabrication processes involved. This thesis reports several nano-engineering approaches for fabricating large quantities of bulk nanostructured TE materials. We have developed bottom-up chemical synthesis routes, as well as top-down mechanical alloying methodologies, to produce highly pure, homogenous and highly crystalline TE nanomaterials. State of the art chalcogenide, iron antimonide, and silicide based TE materials have been investigated in this thesis. Chalcogenide are the best candidates for TE devices operating at temperature range up to 450 K.  Iron antimonide (FeSb2) have shown attractive performance below room temperature. Earth abundant and environment friendly, silicide based materials have better ZT performance in the range of 600-900 K.  Spark plasma sintering (SPS) was utilized to preserve the nanostructuring and to achieve the highest compaction density. Comprehensive physiochemical characterizations were performed on as-prepared and SPS compacted samples. Detailed TE evaluation of the fabricated materials showed significant improvement in ZT for all categories of TE materials.

Place, publisher, year, edition, pages
Stockholm 2014: KTH Royal Institute of Technology, 2014. , xi, 52 p.
Series
TRITA-ICT/MAP AVH, ISSN 1653-7610 ; 2014:12
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-151363ISBN: 978-91-7595-210-9 (print)OAI: oai:DiVA.org:kth-151363DiVA: diva2:748119
Public defence
2014-10-03, SAl B, Electrum 229, Isafajordsgatan 22, Kista, 14:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 36656-1EU, FP7, Seventh Framework Programme, 263167Swedish Foundation for Strategic Research , EM11-0002EU, FP7, Seventh Framework Programme, 228882
Note

QC 20140918

Available from: 2014-09-18 Created: 2014-09-18 Last updated: 2014-09-18Bibliographically approved
List of papers
1. Synthesis, processing, and thermoelectric properties of bulk nanostructured bismuth telluride (Bi(2)Te(3))
Open this publication in new window or tab >>Synthesis, processing, and thermoelectric properties of bulk nanostructured bismuth telluride (Bi(2)Te(3))
Show others...
2012 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 2, 725-730 p.Article in journal (Refereed) Published
Abstract [en]

Bismuth telluride (Bi(2)Te(3)) is the best-known commercially used thermoelectric material in the bulk form for cooling and power generation applications at ambient temperature. However, its dimensionless figure-of-merit-ZT around 1 limits the large-scale industrial applications. Recent studies indicate that nanostructuring can enhance ZT while keeping the material form of bulk by employing an advanced synthetic process accompanied with novel consolidation techniques. Here, we report on bulk nanostructured (NS) undoped Bi(2)Te(3) prepared via a promising chemical synthetic route. Spark plasma sintering has been employed for compaction and sintering of Bi(2)Te(3) nanopowders, resulting in very high densification (>97%) while preserving the nanostructure. The average grain size of the final compacts was obtained as 90 +/- 5 nm as calculated from electron micrographs. Evaluation of transport properties showed enhanced Seebeck coefficient (-120 mu V K(-1)) and electrical conductivity compared to the literature state-of-the-art (30% enhanced power factor), especially in the low temperature range. An improved ZT for NS bulk undoped Bi(2)Te(3) is achieved with a peak value of similar to 1.1 at 340 K.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-75521 (URN)10.1039/c1jm13880d (DOI)000299020000062 ()2-s2.0-83455224189 (Scopus ID)
Note
QC 20120206Available from: 2012-02-06 Created: 2012-02-06 Last updated: 2017-12-08Bibliographically approved
2. Evaluation of the Structure and Transport Properties of Nanostructured Antimony Telluride (Sb2Te3)
Open this publication in new window or tab >>Evaluation of the Structure and Transport Properties of Nanostructured Antimony Telluride (Sb2Te3)
Show others...
2014 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 43, no 6, 1927-1932 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Antimony telluride (Sb2Te3), thermoelectrics, synthesis, anisotropy
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-147732 (URN)10.1007/s11664-013-2911-6 (DOI)000336372400067 ()2-s2.0-84901920224 (Scopus ID)
Note

QC 20140707

Available from: 2014-07-07 Created: 2014-07-03 Last updated: 2017-12-05Bibliographically approved
3. Chemical synthesis of iron antimonide (FeSb2) and its thermoelectric properties
Open this publication in new window or tab >>Chemical synthesis of iron antimonide (FeSb2) and its thermoelectric properties
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-151375 (URN)
Note

QS 2014

Available from: 2014-09-18 Created: 2014-09-18 Last updated: 2014-09-18Bibliographically approved
4. Spark plasma sintering and thermoelectric evaluation of nanocrystalline magnesium silicide (Mg2Si)
Open this publication in new window or tab >>Spark plasma sintering and thermoelectric evaluation of nanocrystalline magnesium silicide (Mg2Si)
Show others...
2013 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 5, 1940-1946 p.Article in journal (Refereed) Published
Abstract [en]

Recently magnesium silicide (Mg2Si) has received great interest from thermoelectric (TE) society because of its non-toxicity, environmental friendliness, comparatively high abundance, and low production material cost as compared to other TE systems. It also exhibited promising transport properties, including high electrical conductivity and low thermal conductivity, which improved the overall TE performance (ZT). In this work, Mg2Si powder was obtained through high energy ball milling under inert atmosphere, starting from commercial magnesium silicide pieces (99.99 %, Alfa Aesar). To maintain fine microstructure of the powder, spark plasma sintering (SPS) process has been used for consolidation. The Mg2Si powder was filled in a graphite die to perform SPS and the influence of process parameters as temperature, heating rate, holding time and applied pressure on the microstructure, and densification of compacts were studied in detail. The aim of this study is to optimize SPS consolidation parameters for Mg2Si powder to achieve high density of compacts while maintaining the nanostructure. X-Ray diffraction (XRD) was utilized to investigate the crystalline phase of compacted samples and scanning and transmission electron microscopy (SEM & TEM) coupled with Energy-Dispersive X-ray Analysis (EDX) was used to evaluate the detailed microstructural and chemical composition, respectively. All sintered samples showed compaction density up to 98 %. Temperature dependent TE characteristics of SPS compacted Mg2Si as thermal conductivity, electrical resistivity, and Seebeck coefficient were measured over the temperature range of RT 600 A degrees C for samples processed at 750 A degrees C, reaching a final ZT of 0.14 at 600 A degrees C.

National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-117633 (URN)10.1007/s10853-012-6959-0 (DOI)000312906400010 ()2-s2.0-84879797497 (Scopus ID)
Funder
Swedish Foundation for Strategic Research
Note

QC 20130201

Available from: 2013-02-01 Created: 2013-02-01 Last updated: 2017-12-06Bibliographically approved
5. Synthesis and Characterization of Al-Doped Mg2Si Thermoelectric Materials
Open this publication in new window or tab >>Synthesis and Characterization of Al-Doped Mg2Si Thermoelectric Materials
Show others...
2013 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 42, no 7, 1956-1959 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
New York: Springer, 2013
Keyword
Magnesium silicide, aluminum, thermoelectricity
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-125565 (URN)10.1007/s11664-013-2482-6 (DOI)000320890800106 ()2-s2.0-84879795351 (Scopus ID)
Funder
Swedish Foundation for Strategic Research
Note

QC 20130812

Available from: 2013-08-12 Created: 2013-08-09 Last updated: 2017-12-06Bibliographically approved
6. Effect of Synthesis and Sintering Conditions on the Thermoelectric Properties of n-Doped Mg2Si
Open this publication in new window or tab >>Effect of Synthesis and Sintering Conditions on the Thermoelectric Properties of n-Doped Mg2Si
Show others...
2014 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 43, no 6, 2301-2306 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Magnesium silicide, thermoelectricity, SPS
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-147733 (URN)10.1007/s11664-014-3048-y (DOI)000336372400125 ()2-s2.0-84901916139 (Scopus ID)
Note

QC 20140707

Available from: 2014-07-07 Created: 2014-07-03 Last updated: 2017-12-05Bibliographically approved
7. Introduction of Metal Oxides into Mg2Si Thermoelectric Materials by Spark Plasma Sintering
Open this publication in new window or tab >>Introduction of Metal Oxides into Mg2Si Thermoelectric Materials by Spark Plasma Sintering
Show others...
2013 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 42, no 7, 2062-2066 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
New York: Springer, 2013
Keyword
Magnesium silicide, oxide incorporation, thermoelectricity
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-125567 (URN)10.1007/s11664-013-2522-2 (DOI)000320890800124 ()2-s2.0-84879799499 (Scopus ID)
Funder
Swedish Foundation for Strategic Research
Note

QC 20130812

Available from: 2013-08-12 Created: 2013-08-09 Last updated: 2017-12-06Bibliographically approved
8. Phase Content Influence on Thermoelectric Properties of Manganese Silicide-Based Materials for Middle-High Temperatures
Open this publication in new window or tab >>Phase Content Influence on Thermoelectric Properties of Manganese Silicide-Based Materials for Middle-High Temperatures
Show others...
2013 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 42, no 7, 2020-2024 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
New York: Springer, 2013
Keyword
Manganese silicide, thermoelectricity, SPS
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-125566 (URN)10.1007/s11664-013-2507-1 (DOI)000320890800117 ()2-s2.0-84879794976 (Scopus ID)
Funder
Swedish Foundation for Strategic Research
Note

QC 20130812

Available from: 2013-08-12 Created: 2013-08-09 Last updated: 2017-12-06Bibliographically approved
9. Thermoelectric performance of higher manganese silicides nanocomposites
Open this publication in new window or tab >>Thermoelectric performance of higher manganese silicides nanocomposites
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-151376 (URN)
Note

QS 2014

Available from: 2014-09-18 Created: 2014-09-18 Last updated: 2014-09-18Bibliographically approved

Open Access in DiVA

Doctoral Thesis in Materials Chemistry_Mohsin Saleemi(3949 kB)2315 downloads
File information
File name FULLTEXT02.pdfFile size 3949 kBChecksum SHA-512
f30112e7df97bd82bee178e7d71ca0b2f67f7b55ea7d9870a1194da1299d3041c815b066d60e66f80b4215e89a9dda1272aa605ad6a00cfaa95e79f43aa3ad46
Type fulltextMimetype application/pdf

Authority records BETA

Saleemi, Mohsin

Search in DiVA

By author/editor
Saleemi, Mohsin
By organisation
Functional Materials, FNM
Materials Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 2315 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1438 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf