Nanostructured Thermoelectric Oxides for Energy Harvesting Applications

Handle URI:
http://hdl.handle.net/10754/583286
Title:
Nanostructured Thermoelectric Oxides for Energy Harvesting Applications
Authors:
Abutaha, Anas I. ( 0000-0002-8923-5417 )
Abstract:
As the world strives to adapt to the increasing demand for electrical power, sustainable energy sources are attracting significant interest. Around 60% of energy utilized in the world is wasted as heat. Different industrial processes, home heating, and exhausts in cars, all generate a huge amount of unused waste heat. With such a huge potential, there is also significant interest in discovering inexpensive technologies for power generation from waste heat. As a result, thermoelectric materials have become important for many renewable energy research programs. While significant advancements have been done in improving the thermoelectric properties of the conventional heavy-element based materials (such as Bi2Te3 and PbTe), high-temperature applications of thermoelectrics are still limited to one materials system, namely SiGe, since the traditional thermoelectric materials degrade and oxidize at high temperature. Therefore, oxide thermoelectrics emerge as a promising class of materials since they can operate athigher temperatures and in harsher environments compared to non-oxide thermoelectrics. Furthermore, oxides are abundant and friendly to the environment. Among oxides, crystalline SrTiO3 and ZnO are promising thermoelectric materials. The main objective of this work is therefore to pursue focused investigations of SrTiO3 and ZnO thin films and superlattices grown by pulsed laser deposition (PLD), with the goal of optimizing their thermoelectric properties by following different strategies. First, the effect of laser fluence on the thermoelectric properties of La doped epitaxial SrTiO3 films is discussed. Films grown at higher laser fluences exhibit better thermoelectric performance. Second, the role of crystal orientation in determining the thermoelectric properties of epitaxial Al doped ZnO (AZO) films is explained. Vertically aligned (c-axis) AZO films have superior thermoelectric properties compared to other films with different crystal orientations. Third, additional B-site doping of A-site doped SrTiO3 films leads to a prominent reduction in the lattice thermal conductivity without limiting the electrical transport, and hence an improvement in the figure of merit is noticed. Fourth and last, the enhancement of thermoelectric properties of thermally robust, high quality SrTiO3-based superlattices is discussed. Beside the randomly distributed oxygen vacancies and extrinsic dopants, the structure of SrTiO3-based superlattices increases the scattering of phonons at the interfaces between the alternative layers, and hence reducing the thermal conductivity, which leads to a notable enhancement in the figure of merit.
Advisors:
Alshareef, Husam N. ( 0000-0001-5029-2142 )
Committee Member:
Zhang, Xixiang ( 0000-0002-3478-6414 ) ; Ooi, Boon S. ( 0000-0001-9606-5578 ) ; Schwingenschlögl, Udo ( 0000-0003-4179-7231 ) ; Manchon, Aurelien ( 0000-0002-4768-293X )
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program
Program:
Materials Science and Engineering
Issue Date:
24-Nov-2015
Type:
Dissertation
Appears in Collections:
Dissertations; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorAlshareef, Husam N.en
dc.contributor.authorAbutaha, Anas I.en
dc.date.accessioned2015-12-07T08:03:37Zen
dc.date.available2015-12-07T08:03:37Zen
dc.date.issued2015-11-24en
dc.identifier.urihttp://hdl.handle.net/10754/583286en
dc.description.abstractAs the world strives to adapt to the increasing demand for electrical power, sustainable energy sources are attracting significant interest. Around 60% of energy utilized in the world is wasted as heat. Different industrial processes, home heating, and exhausts in cars, all generate a huge amount of unused waste heat. With such a huge potential, there is also significant interest in discovering inexpensive technologies for power generation from waste heat. As a result, thermoelectric materials have become important for many renewable energy research programs. While significant advancements have been done in improving the thermoelectric properties of the conventional heavy-element based materials (such as Bi2Te3 and PbTe), high-temperature applications of thermoelectrics are still limited to one materials system, namely SiGe, since the traditional thermoelectric materials degrade and oxidize at high temperature. Therefore, oxide thermoelectrics emerge as a promising class of materials since they can operate athigher temperatures and in harsher environments compared to non-oxide thermoelectrics. Furthermore, oxides are abundant and friendly to the environment. Among oxides, crystalline SrTiO3 and ZnO are promising thermoelectric materials. The main objective of this work is therefore to pursue focused investigations of SrTiO3 and ZnO thin films and superlattices grown by pulsed laser deposition (PLD), with the goal of optimizing their thermoelectric properties by following different strategies. First, the effect of laser fluence on the thermoelectric properties of La doped epitaxial SrTiO3 films is discussed. Films grown at higher laser fluences exhibit better thermoelectric performance. Second, the role of crystal orientation in determining the thermoelectric properties of epitaxial Al doped ZnO (AZO) films is explained. Vertically aligned (c-axis) AZO films have superior thermoelectric properties compared to other films with different crystal orientations. Third, additional B-site doping of A-site doped SrTiO3 films leads to a prominent reduction in the lattice thermal conductivity without limiting the electrical transport, and hence an improvement in the figure of merit is noticed. Fourth and last, the enhancement of thermoelectric properties of thermally robust, high quality SrTiO3-based superlattices is discussed. Beside the randomly distributed oxygen vacancies and extrinsic dopants, the structure of SrTiO3-based superlattices increases the scattering of phonons at the interfaces between the alternative layers, and hence reducing the thermal conductivity, which leads to a notable enhancement in the figure of merit.en
dc.language.isoenen
dc.subjectThermoelectricen
dc.subjectOxidesen
dc.subjectThis Filmsen
dc.subjectSuperlatticesen
dc.subjectPulsed Laser Deposition (PLD)en
dc.titleNanostructured Thermoelectric Oxides for Energy Harvesting Applicationsen
dc.typeDissertationen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMaterials Science and Engineering Programen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberZhang, Xixiangen
dc.contributor.committeememberOoi, Boon S.en
dc.contributor.committeememberSchwingenschlögl, Udoen
dc.contributor.committeememberManchon, Aurelienen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id115720en
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