{"id":{"repo_id":"njit","oai_identifier":"oai:digitalcommons.njit.edu:theses-1258"},"canonical_url":"https://search.dev.ndltd.org/etd/njit/oai:digitalcommons.njit.edu:theses-1258","repository":{"repo_id":"njit","name":"NJIT","base_url":"https://digitalcommons.njit.edu/do/oai/"},"display":{"title":"Thermoelectric properties of silicon-germanium alloys","abstract":"Direct energy conversion from thermal to electrical energy, based on thermoelectric effects, is attractive for potential applications in waste heat recovery and environmentally friendly refrigeration. The energy conversion efficiency of thermoelectric devices is related to the thermoelectric figure of merit ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity. Currently, the low ZT values of available materials restrict the large scale applications of this technology. Recently, however, significant enhancements in ZT have been reported in nanostructured materials such as super-lattices mainly due to their low thermal conductivities. According to the studies on heat transfer mechanisms in nanostructures, the reduced thermal conductivity of nanostructures is mainly attributed to the increased scattering of phonons at the interfaces. Based on this idea, nanocomposites are also expected to have a lower thermal conductivity than their bulk counterparts of the same chemical configuration. Nanocomposites are materials with constituents of less than 100 nm in size. They can be fabricated at low cost by mixing nano-sized particles followed by consolidation of nano-sized powders. In this thesis, SiGe nanocomposites are investigated for various parameters, such as thermal conductivity, electrical conductivity and Seebeck coefficient, which are needed for thermoelectrics. Grain boundaries in nanocomposites can scatter phonons, when their mean free path is longer than the grain size. Mean free path of electrons is usually shorter than the grain size of nanocomposites, so that the electrical conductivities of nanocomposites are not expected to change significantly. However, the results show that, at the nano scale, the electron transport properties are affected. The electronic and thermal properties are calculated using MATLAB software. The results are compared with the literature. The studies show an enhancement in ZT for n-type and p-type SiGe alloys mostly due to the reduction in the thermal conductivity. Such a reduction is due to both the alloying effect and increased phonon interface scattering at grain boundaries.","abstract_html":"Direct energy conversion from thermal to electrical energy, based on thermoelectric effects, is attractive for potential applications in waste heat recovery and environmentally friendly refrigeration. The energy conversion efficiency of thermoelectric devices is related to the thermoelectric figure of merit ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity. Currently, the low ZT values of available materials restrict the large scale applications of this technology. Recently, however, significant enhancements in ZT have been reported in nanostructured materials such as super-lattices mainly due to their low thermal conductivities. According to the studies on heat transfer mechanisms in nanostructures, the reduced thermal conductivity of nanostructures is mainly attributed to the increased scattering of phonons at the interfaces. Based on this idea, nanocomposites are also expected to have a lower thermal conductivity than their bulk counterparts of the same chemical configuration. Nanocomposites are materials with constituents of less than 100 nm in size. They can be fabricated at low cost by mixing nano-sized particles followed by consolidation of nano-sized powders. In this thesis, SiGe nanocomposites are investigated for various parameters, such as thermal conductivity, electrical conductivity and Seebeck coefficient, which are needed for thermoelectrics. Grain boundaries in nanocomposites can scatter phonons, when their mean free path is longer than the grain size. Mean free path of electrons is usually shorter than the grain size of nanocomposites, so that the electrical conductivities of nanocomposites are not expected to change significantly. However, the results show that, at the nano scale, the electron transport properties are affected. The electronic and thermal properties are calculated using MATLAB software. The results are compared with the literature. The studies show an enhancement in ZT for n-type and p-type SiGe alloys mostly due to the reduction in the thermal conductivity. Such a reduction is due to both the alloying effect and increased phonon interface scattering at grain boundaries.","abstract_has_math":false,"creators":["Maske, Aniket Annasaheb"],"institution":null,"degree_name":"Master of Science in Materials Science and Engineering - (M.S.)","degree_level":null,"degree_discipline":"Committee for the Interdisciplinary Program in Materials Science and Engineering","degree_department":null,"school":null,"contributors":["N. M. Ravindra","Michael Jaffe","Eon Soo Lee"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-01-31T08:00:00Z","date_published":"2016-01-31T08:00:00Z","updated_at":"2026-07-24T03:22:34Z","subjects":["Silicon-germanium alloys","Thermoelectric properties","Materials Science and Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.njit.edu/theses/259","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["N. M. Ravindra","Michael Jaffe","Eon Soo Lee"]},{"key":"dc:creator","label":"Author","values":["Maske, Aniket Annasaheb"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Committee for the Interdisciplinary Program in Materials Science and Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science in Materials Science and Engineering - (M.S.)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Silicon-germanium alloys","Thermoelectric properties","Materials Science and Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.njit.edu/theses/259"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Direct energy conversion from thermal to electrical energy, based on thermoelectric effects, is attractive for potential applications in waste heat recovery and environmentally friendly refrigeration. The energy conversion efficiency of thermoelectric devices is related to the thermoelectric figure of merit ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity. Currently, the low ZT values of available materials restrict the large scale applications of this technology. Recently, however, significant enhancements in ZT have been reported in nanostructured materials such as super-lattices mainly due to their low thermal conductivities. According to the studies on heat transfer mechanisms in nanostructures, the reduced thermal conductivity of nanostructures is mainly attributed to the increased scattering of phonons at the interfaces. Based on this idea, nanocomposites are also expected to have a lower thermal conductivity than their bulk counterparts of the same chemical configuration. Nanocomposites are materials with constituents of less than 100 nm in size. They can be fabricated at low cost by mixing nano-sized particles followed by consolidation of nano-sized powders. In this thesis, SiGe nanocomposites are investigated for various parameters, such as thermal conductivity, electrical conductivity and Seebeck coefficient, which are needed for thermoelectrics. Grain boundaries in nanocomposites can scatter phonons, when their mean free path is longer than the grain size. Mean free path of electrons is usually shorter than the grain size of nanocomposites, so that the electrical conductivities of nanocomposites are not expected to change significantly. However, the results show that, at the nano scale, the electron transport properties are affected. The electronic and thermal properties are calculated using MATLAB software. The results are compared with the literature. The studies show an enhancement in ZT for n-type and p-type SiGe alloys mostly due to the reduction in the thermal conductivity. Such a reduction is due to both the alloying effect and increased phonon interface scattering at grain boundaries."]},{"key":"dc:title","label":"Title","values":["Thermoelectric properties of silicon-germanium alloys"]}]}],"canonical_facts":{"dc:contributor":["N. M. Ravindra","Michael Jaffe","Eon Soo Lee"],"dc:creator":["Maske, Aniket Annasaheb"],"dc:description.abstract":["Direct energy conversion from thermal to electrical energy, based on thermoelectric effects, is attractive for potential applications in waste heat recovery and environmentally friendly refrigeration. The energy conversion efficiency of thermoelectric devices is related to the thermoelectric figure of merit ZT, which is proportional to the electrical conductivity, the square of the Seebeck coefficient, and the inverse of the thermal conductivity. Currently, the low ZT values of available materials restrict the large scale applications of this technology. Recently, however, significant enhancements in ZT have been reported in nanostructured materials such as super-lattices mainly due to their low thermal conductivities. According to the studies on heat transfer mechanisms in nanostructures, the reduced thermal conductivity of nanostructures is mainly attributed to the increased scattering of phonons at the interfaces. Based on this idea, nanocomposites are also expected to have a lower thermal conductivity than their bulk counterparts of the same chemical configuration. Nanocomposites are materials with constituents of less than 100 nm in size. They can be fabricated at low cost by mixing nano-sized particles followed by consolidation of nano-sized powders. In this thesis, SiGe nanocomposites are investigated for various parameters, such as thermal conductivity, electrical conductivity and Seebeck coefficient, which are needed for thermoelectrics. Grain boundaries in nanocomposites can scatter phonons, when their mean free path is longer than the grain size. Mean free path of electrons is usually shorter than the grain size of nanocomposites, so that the electrical conductivities of nanocomposites are not expected to change significantly. However, the results show that, at the nano scale, the electron transport properties are affected. The electronic and thermal properties are calculated using MATLAB software. The results are compared with the literature. The studies show an enhancement in ZT for n-type and p-type SiGe alloys mostly due to the reduction in the thermal conductivity. Such a reduction is due to both the alloying effect and increased phonon interface scattering at grain boundaries."],"dc:identifier":["https://digitalcommons.njit.edu/theses/259"],"dc:subject":["Silicon-germanium alloys","Thermoelectric properties","Materials Science and Engineering"],"dc:title":["Thermoelectric properties of silicon-germanium alloys"],"dc:type":["Thesis"],"thesis:degree_discipline":["Committee for the Interdisciplinary Program in Materials Science and Engineering"],"thesis:degree_name":["Master of Science in Materials Science and Engineering - (M.S.)"]},"updated_at":"2026-07-24T03:22:34Z"}